"Digiscoping" with spotting scopes is so wrong on multiple levels

Discussion in 'Digital Photography' started by RichA, Aug 25, 2009.

  1. RichA

    RichA Guest

    They did an article on it in Amateur Photographer (British) in the Aug
    1st issue. I didn't like it. So I sent them an email with 5-6
    reasons why using a small astronomical scope was better. They
    published it in their Aug. 22 issue. The main problem with spotting
    scopes or "birder" scopes is that they don't have the focusing range
    to be used in prime focus (no eyepiece) mode. This results in too
    long focal lengths and slow focal ratios. There are other problems as
    well.
    The only real problem with using a small astronomical refractor
    (though you can use compound reflector scopes for longer reach) is
    field curvature. But that generally does not come into play as most
    users of such things are focusing on the bird, or other wildlife
    object in the centre of the field. Additionally, you can buy field
    flattening lenses (positive lenses that flatten the field and reduce
    the effective focal ratio and focal length, usually) for them anyway.
    RichA, Aug 25, 2009
    #1
    1. Advertising

  2. On Mon, 24 Aug 2009 23:37:14 -0700 (PDT), RichA <>
    wrote:

    >They did an article on it in Amateur Photographer (British) in the Aug
    >1st issue. I didn't like it. So I sent them an email with 5-6
    >reasons why using a small astronomical scope was better. They
    >published it in their Aug. 22 issue. The main problem with spotting
    >scopes or "birder" scopes is that they don't have the focusing range
    >to be used in prime focus (no eyepiece) mode. This results in too
    >long focal lengths and slow focal ratios. There are other problems as
    >well.
    >The only real problem with using a small astronomical refractor
    >(though you can use compound reflector scopes for longer reach) is
    >field curvature. But that generally does not come into play as most
    >users of such things are focusing on the bird, or other wildlife
    >object in the centre of the field. Additionally, you can buy field
    >flattening lenses (positive lenses that flatten the field and reduce
    >the effective focal ratio and focal length, usually) for them anyway.



    Let's break this down...

    Any magazine makes its primary income from advertisers. Those advertisers
    get their greatest income from selling exceptionally expensive long
    focal-length prime lenses with extreme retail markup prices. Writing and
    publishing any article that detracts from their source of income always
    results in the authors and editors getting fired. Magazine articles ALWAYS
    equals conflict of interest resulting in complete lack of truth and
    honesty. Magazines are always the worst source of credible information.

    Did anyone write an article yet on why any of your comments are irrelevant
    on so many levels?

    Even if it was in a magazine I'd buy it. At least that article would be
    credible.
    Justin Observation, Aug 25, 2009
    #2
    1. Advertising

  3. RichA

    Martin Brown Guest

    Justin Observation wrote:
    > On Mon, 24 Aug 2009 23:37:14 -0700 (PDT), RichA <>
    > wrote:
    >
    >> They did an article on it in Amateur Photographer (British) in the Aug
    >> 1st issue. I didn't like it. So I sent them an email with 5-6
    >> reasons why using a small astronomical scope was better. They
    >> published it in their Aug. 22 issue. The main problem with spotting
    >> scopes or "birder" scopes is that they don't have the focusing range
    >> to be used in prime focus (no eyepiece) mode. This results in too
    >> long focal lengths and slow focal ratios. There are other problems as
    >> well.


    One important thing that birding scope have going for them is that
    decent ones are weatherproof. They seldom have removable eyepieces and
    modern zooms are surprisingly good. There is nothing much wrong with
    hanging a digital camera on the back of one if you accept that the focal
    ratio is a bit on the slow side. Several companies make inexpensive jigs
    to attach lightweight cameras to birding scopes. It has to be centred on
    axis with the eyepiece exit pupil and dead square to get a decent image.

    >> The only real problem with using a small astronomical refractor
    >> (though you can use compound reflector scopes for longer reach) is
    >> field curvature. But that generally does not come into play as most
    >> users of such things are focusing on the bird, or other wildlife
    >> object in the centre of the field. Additionally, you can buy field
    >> flattening lenses (positive lenses that flatten the field and reduce
    >> the effective focal ratio and focal length, usually) for them anyway.


    And it only works with SLRs. You cannot use a telescopes prime focus
    with a point and shoot, whereas with afocal photography you are just
    shooting through an existing optical instrument, puting the camera where
    your eye would normally be.

    And a cheap astronomical refractor will have terrible edge of field
    chromatic and other geometric aberrations when used in daytime
    conditions for photography (and an expensive one will cost more and be
    slower than a prime photographic lens). There is no free lunch.

    Mirror lenses represent the best bang for the buck if you can live with
    the donut shaped out of focus highlights and strange bokeh.

    > Let's break this down...
    >
    > Any magazine makes its primary income from advertisers. Those advertisers
    > get their greatest income from selling exceptionally expensive long
    > focal-length prime lenses with extreme retail markup prices. Writing and
    > publishing any article that detracts from their source of income always
    > results in the authors and editors getting fired. Magazine articles ALWAYS
    > equals conflict of interest resulting in complete lack of truth and
    > honesty. Magazines are always the worst source of credible information.


    AP isn't too bad or supine wrt advertisers. The article Rich objected to
    seemed to be helpful enough for anyone wanting to experiment getting
    pictures through their birding scope.
    >
    > Did anyone write an article yet on why any of your comments are irrelevant
    > on so many levels?


    He is in many people kill files. Most of his trolls are pathetic.

    This one at least needs correcting so that owners of birding scopes are
    not put off trying the combination to record sitings.

    Regards,
    Martin Brown
    Martin Brown, Aug 25, 2009
    #3
  4. On Mon, 24 Aug 2009 23:37:14 -0700 (PDT), RichA <>
    wrote:

    >The main problem with spotting
    >scopes or "birder" scopes is that they don't have the focusing range
    >to be used in prime focus (no eyepiece) mode. This results in too
    >long focal lengths and slow focal ratios.


    These may be factors that are important for terrestrial imaging through
    the scopes, but it isn't clear how they impact astronomical imaging. In
    that case, focal ratio is almost completely unimportant, and with the
    small pixel, large area sensors that are increasingly common, you can
    really take advantage of a long focal length. The primary disadvantage
    of small scopes is just that: small aperture. Exposure time for a given
    S/N scales as the inverse square of aperture. A larger aperture lets you
    use a much shorter total exposure time, which means less opportunity to
    go wrong and looser tracking requirements.
    _________________________________________________

    Chris L Peterson
    Cloudbait Observatory
    http://www.cloudbait.com
    Chris L Peterson, Aug 25, 2009
    #4
  5. RichA

    RichA Guest

    Justin Observation wrote:
    > On Mon, 24 Aug 2009 23:37:14 -0700 (PDT), RichA <>
    > wrote:
    >
    > >They did an article on it in Amateur Photographer (British) in the Aug
    > >1st issue. I didn't like it. So I sent them an email with 5-6
    > >reasons why using a small astronomical scope was better. They
    > >published it in their Aug. 22 issue. The main problem with spotting
    > >scopes or "birder" scopes is that they don't have the focusing range
    > >to be used in prime focus (no eyepiece) mode. This results in too
    > >long focal lengths and slow focal ratios. There are other problems as
    > >well.
    > >The only real problem with using a small astronomical refractor
    > >(though you can use compound reflector scopes for longer reach) is
    > >field curvature. But that generally does not come into play as most
    > >users of such things are focusing on the bird, or other wildlife
    > >object in the centre of the field. Additionally, you can buy field
    > >flattening lenses (positive lenses that flatten the field and reduce
    > >the effective focal ratio and focal length, usually) for them anyway.

    >
    >
    > Let's break this down...
    >
    > Any magazine makes its primary income from advertisers. Those advertisers
    > get their greatest income from selling exceptionally expensive long
    > focal-length prime lenses with extreme retail markup prices. Writing and
    > publishing any article that detracts from their source of income always
    > results in the authors and editors getting fired.


    You don't get it. They did an article suggesting digiscoping, which
    goes against your theory of how they operate. My response had to do
    with what kind of scope works best, not digiscoping versus telephotos.
    RichA, Aug 25, 2009
    #5
  6. RichA

    RichA Guest

    Martin Brown wrote:
    > Justin Observation wrote:
    > > On Mon, 24 Aug 2009 23:37:14 -0700 (PDT), RichA <>
    > > wrote:
    > >
    > >> They did an article on it in Amateur Photographer (British) in the Aug
    > >> 1st issue. I didn't like it. So I sent them an email with 5-6
    > >> reasons why using a small astronomical scope was better. They
    > >> published it in their Aug. 22 issue. The main problem with spotting
    > >> scopes or "birder" scopes is that they don't have the focusing range
    > >> to be used in prime focus (no eyepiece) mode. This results in too
    > >> long focal lengths and slow focal ratios. There are other problems as
    > >> well.

    >
    > One important thing that birding scope have going for them is that
    > decent ones are weatherproof. They seldom have removable eyepieces and
    > modern zooms are surprisingly good. There is nothing much wrong with
    > hanging a digital camera on the back of one if you accept that the focal
    > ratio is a bit on the slow side. Several companies make inexpensive jigs
    > to attach lightweight cameras to birding scopes. It has to be centred on
    > axis with the eyepiece exit pupil and dead square to get a decent image.
    >
    > >> The only real problem with using a small astronomical refractor
    > >> (though you can use compound reflector scopes for longer reach) is
    > >> field curvature. But that generally does not come into play as most
    > >> users of such things are focusing on the bird, or other wildlife
    > >> object in the centre of the field. Additionally, you can buy field
    > >> flattening lenses (positive lenses that flatten the field and reduce
    > >> the effective focal ratio and focal length, usually) for them anyway.

    >
    > And it only works with SLRs. You cannot use a telescopes prime focus
    > with a point and shoot, whereas with afocal photography you are just
    > shooting through an existing optical instrument, puting the camera where
    > your eye would normally be.
    >
    > And a cheap astronomical refractor will have terrible edge of field
    > chromatic and other geometric aberrations when used in daytime
    > conditions for photography (and an expensive one will cost more and be
    > slower than a prime photographic lens). There is no free lunch.
    >
    > Mirror lenses represent the best bang for the buck if you can live with
    > the donut shaped out of focus highlights and strange bokeh.
    >
    > > Let's break this down...
    > >
    > > Any magazine makes its primary income from advertisers. Those advertisers
    > > get their greatest income from selling exceptionally expensive long
    > > focal-length prime lenses with extreme retail markup prices. Writing and
    > > publishing any article that detracts from their source of income always
    > > results in the authors and editors getting fired. Magazine articles ALWAYS
    > > equals conflict of interest resulting in complete lack of truth and
    > > honesty. Magazines are always the worst source of credible information.

    >
    > AP isn't too bad or supine wrt advertisers. The article Rich objected to
    > seemed to be helpful enough for anyone wanting to experiment getting
    > pictures through their birding scope.
    > >
    > > Did anyone write an article yet on why any of your comments are irrelevant
    > > on so many levels?

    >
    > He is in many people kill files. Most of his trolls are pathetic.
    >
    > This one at least needs correcting so that owners of birding scopes are
    > not put off trying the combination to record sitings.
    >
    > Regards,
    > Martin Brown


    They shouldn't be put off, just made aware of the shortcomings and
    alternatives.
    RichA, Aug 25, 2009
    #6
  7. RichA

    P.C. Guest

    On 25 Aug., 16:01, Chris L Peterson <> wrote:
    > On Mon, 24 Aug 2009 23:37:14 -0700 (PDT), RichA <>
    > wrote:
    >
    > These may be factors that are important for terrestrial imaging through
    > the scopes, but it isn't clear how they impact astronomical imaging. In
    > that case, focal ratio is almost completely unimportant, and with the
    > small pixel, large area sensors that are increasingly common, you can
    > really take advantage of a long focal length. The primary disadvantage
    > of small scopes is just that: small aperture. Exposure time for a given
    > S/N scales as the inverse square of aperture. A larger aperture lets you
    > use a much shorter total exposure time, which means less opportunity to
    > go wrong and looser tracking requirements.
    > _________________________________________________
    >
    > Chris L Peterson
    > Cloudbait Observatoryhttp://www.cloudbait.com


    I am happy to find this tread that deal with a multible og the issues
    here at hand. I got an Hertel Reuse SDS 4o, , seem a rare variant of
    the old HR 15-60-60 only much shorter and with a button to focus and
    40 in magnification is both handy and the optics nice, but I also
    found for halve price one of these extreeme cheap Seben that when you
    make an objectiv evaluation, is a great buy and so muc better than
    what you would think, even at 60 x it make no trouble and is rugid
    plus reasonable handy, -- even not as handy as the SDS 40 I mention.
    I now got one of these camera attachment from Seben, come today or
    tomorrow, and I am looking forwerds to try it out with a cheap digital
    camera, but also I wnt to test it with a genuine teleskop and an
    analog camera, as I find the Nikon to expensive. --- Something must
    has develobed since the early and now collector item Nikon 10D , it
    can't be true that today there shuld not be something better than an
    6Mp. digital camera with a filter removed, --- there must be better
    alternatives even with plain cheap small digital camera's and an
    attachment so the camera can be used with multible optics.
    P.C., Aug 26, 2009
    #7
  8. On Wed, 26 Aug 2009 06:50:21 -0700 (PDT), "P.C." <>
    wrote:

    >I am happy to find this tread that deal with a multible og the issues
    >here at hand. I got an Hertel Reuse SDS 4o, , seem a rare variant of
    >the old HR 15-60-60 only much shorter and with a button to focus and
    >40 in magnification is both handy and the optics nice, but I also
    >found for halve price one of these extreeme cheap Seben that when you
    >make an objectiv evaluation, is a great buy and so muc better than
    >what you would think, even at 60 x it make no trouble and is rugid
    >plus reasonable handy, -- even not as handy as the SDS 40 I mention.
    >I now got one of these camera attachment from Seben, come today or
    >tomorrow, and I am looking forwerds to try it out with a cheap digital
    >camera, but also I wnt to test it with a genuine teleskop and an
    >analog camera, as I find the Nikon to expensive. --- Something must
    >has develobed since the early and now collector item Nikon 10D , it
    >can't be true that today there shuld not be something better than an
    >6Mp. digital camera with a filter removed, --- there must be better
    >alternatives even with plain cheap small digital camera's and an
    >attachment so the camera can be used with multible optics.


    In general, you want a camera with removable lenses, which means a DSLR
    unless you're planning some major mods. Huge pixel counts are not
    necessary for most targets; indeed, the smaller pixel sizes that come
    with increased pixel counts can be undesirable. I'd advise against any
    Nikon cameras for astroimaging, as their internal processing makes
    conventional post-processing steps difficult or impossible. Earlier
    model Canon DSLRs such as the 300D, 350D, and 400D are available used
    for very low prices, and are extremely good choices for digital
    astroimaging.
    _________________________________________________

    Chris L Peterson
    Cloudbait Observatory
    http://www.cloudbait.com
    Chris L Peterson, Aug 26, 2009
    #8
  9. RichA

    Guest

    On Aug 24, 11:37 pm, RichA <> wrote:
    > They did an article on it in Amateur Photographer (British) in the Aug
    > 1st issue.  I didn't like it.  So I sent them an email with 5-6
    > reasons why using a small astronomical scope was better.  They
    > published it in their Aug. 22 issue.  The main problem with spotting
    > scopes or "birder" scopes is that they don't have the focusing range
    > to be used in prime focus (no eyepiece) mode.  This results in too
    > long focal lengths and slow focal ratios.  There are other problems as
    > well.
    > The only real problem with using a small astronomical refractor
    > (though you can use compound reflector scopes for longer reach) is
    > field curvature.  But that generally does not come into play as most
    > users of such things are focusing on the bird, or other wildlife
    > object in the centre of the field.  Additionally, you can buy field
    > flattening lenses (positive lenses that flatten the field and reduce
    > the effective focal ratio and focal length, usually) for them anyway.


    Just a quick comment about "digiscoping..."

    Digiscoping is a term used by birders for afocal imaging. Birds are
    small and it is difficult to get close to them, to get detail and
    image scale on a small bird that may be a hundred feet or a thousand
    feet away or more requires focal lengths in the range of 2000-3000mm
    or longer. Prime focus lens become very expensive at these focal
    lengths.

    The digiscoper achieves long effective focal lengths by combining the
    magnification of a telescope with small pixels and zoom of point and
    shoot camera. The most famous digiscoping camera has been the Coolpix
    990-995-4500 series. These were manufactured prior to the
    introduction of the affordable DSLR and a solidly built. For example
    the 4500 has a magnesium body. They have lens that are enclosed, they
    have small pixels that can provide a well illuminated field from a
    relatively small exit pupil...

    I am sure that the proper prime focus lens combined with a DSLR will
    take better photos than a simple 80mm APO with a Cool Pix 4500 and a
    quality eyepiece... On the other hand, not many of us can afford a
    prime focus lens that might be anywhere from 2000mm to 10000mm in
    length... The next time you see a 8 inch bird on a tree that is 500
    or 1000 yards away and you want to image it, one affordable option is
    digiscoping... THe other is Afocal imaging with a DSLR but the
    advantage of digiscoping is that it is easier to use the autofocus...

    Jon

    Jon
    , Aug 26, 2009
    #9
  10. RichA

    P.C. Guest

    On 26 Aug., 16:25, Chris L Peterson <> wrote:
    > On Wed, 26 Aug 2009 06:50:21 -0700 (PDT), "P.C." <>
    > wrote:
    >
    >
    >
    > >I am happy to find this tread that deal with a multible og the issues
    > >here at hand. I got an Hertel Reuse SDS 4o, , seem a rare variant of
    > >the old HR 15-60-60 only much shorter and with a button to focus and
    > >40 in magnification is both handy and the optics nice, but I also
    > >found for halve price one of these extreeme cheap Seben that when you
    > >make an objectiv evaluation, is a great buy and so muc better than
    > >what you would think, even at 60 x it make no trouble and is rugid
    > >plus reasonable handy, -- even not as handy as the SDS 40  I mention.
    > >I now got one of these camera attachment from Seben, come today or
    > >tomorrow, and I am looking forwerds to try it out with a cheap digital
    > >camera, but also I wnt to test it with a genuine teleskop and an
    > >analog camera, as I find the Nikon to expensive. --- Something must
    > >has develobed since the early and now collector item Nikon 10D , it
    > >can't be true that today there shuld not be something better than an
    > >6Mp. digital camera with a filter removed, --- there must be better
    > >alternatives even with plain cheap small digital camera's and an
    > >attachment so the camera can be used with multible optics.

    >
    > In general, you want a camera with removable lenses, which means a DSLR
    > unless you're planning some major mods. Huge pixel counts are not
    > necessary for most targets; indeed, the smaller pixel sizes that come
    > with increased pixel counts can be undesirable. I'd advise against any
    > Nikon cameras for astroimaging, as their internal processing makes
    > conventional post-processing steps difficult or impossible. Earlier
    > model Canon DSLRs such as the 300D, 350D, and 400D are available used
    > for very low prices, and are extremely good choices for digital
    > astroimaging.
    > _________________________________________________
    >
    > Chris L Peterson
    > Cloudbait Observatoryhttp://www.cloudbait.com


    I am looking forwerds more to a try with a reasnoable priced analog
    before finding the right digital just becaurse of this.
    P.C., Aug 26, 2009
    #10
  11. RichA

    Martin Brown Guest

    P.C. wrote:
    > On 26 Aug., 16:25, Chris L Peterson <> wrote:
    >> On Wed, 26 Aug 2009 06:50:21 -0700 (PDT), "P.C." <>
    >> wrote:
    >>
    >>> I am happy to find this tread that deal with a multible og the issues
    >>> here at hand. I got an Hertel Reuse SDS 4o, , seem a rare variant of
    >>> the old HR 15-60-60 only much shorter and with a button to focus and
    >>> 40 in magnification is both handy and the optics nice, but I also
    >>> found for halve price one of these extreeme cheap Seben that when you
    >>> make an objectiv evaluation, is a great buy and so muc better than
    >>> what you would think, even at 60 x it make no trouble and is rugid
    >>> plus reasonable handy, -- even not as handy as the SDS 40 I mention.
    >>> I now got one of these camera attachment from Seben, come today or
    >>> tomorrow, and I am looking forwerds to try it out with a cheap digital
    >>> camera, but also I wnt to test it with a genuine teleskop and an
    >>> analog camera, as I find the Nikon to expensive. --- Something must
    >>> has develobed since the early and now collector item Nikon 10D , it
    >>> can't be true that today there shuld not be something better than an
    >>> 6Mp. digital camera with a filter removed, --- there must be better
    >>> alternatives even with plain cheap small digital camera's and an
    >>> attachment so the camera can be used with multible optics.

    >> In general, you want a camera with removable lenses, which means a DSLR
    >> unless you're planning some major mods. Huge pixel counts are not
    >> necessary for most targets; indeed, the smaller pixel sizes that come
    >> with increased pixel counts can be undesirable. I'd advise against any
    >> Nikon cameras for astroimaging, as their internal processing makes
    >> conventional post-processing steps difficult or impossible. Earlier
    >> model Canon DSLRs such as the 300D, 350D, and 400D are available used
    >> for very low prices, and are extremely good choices for digital
    >> astroimaging.
    >> _________________________________________________
    >>
    >> Chris L Peterson
    >> Cloudbait Observatoryhttp://www.cloudbait.com

    >
    > I am looking forwerds more to a try with a reasnoable priced analog
    > before finding the right digital just becaurse of this.


    You have it back to front. Perfect your technique with a cheap digital
    camera to get instant feedback. With a digital camera no film is wasted
    and you know immediately what the result is like and can adjust until it
    is right. If you already have any kind of digicam or even a mobile phone
    camera you can obtain an afocal image through a scope.

    Regards,
    Martin Brown
    Martin Brown, Aug 26, 2009
    #11
  12. On Wed, 26 Aug 2009 12:48:47 -0700 (PDT), "P.C." <>
    wrote:

    >I am looking forwerds more to a try with a reasnoable priced analog
    >before finding the right digital just becaurse of this.


    Analog? Do you mean film? Don't waste your time. Film is worse than
    digital in every respect, much harder to get decent results with, and
    will end up costing you a lot more than you'll spend buying a used DSLR.
    _________________________________________________

    Chris L Peterson
    Cloudbait Observatory
    http://www.cloudbait.com
    Chris L Peterson, Aug 26, 2009
    #12
  13. RichA

    P.C. Guest

    On 26 Aug., 23:04, Alan Browne <>
    wrote:
    > P.C. wrote:
    >
    > > I am looking forwerds more to a try with a reasnoable priced analog
    > > before finding the right digital just becaurse of this.

    >
    > Digital:
    >
    >         -less pollution
    >         -instant feedback
    >                 .correct errors
    >                 .correct framing
    >                 .try variations immediately
    >                 .delete pure duds on the spot (more mem avail).
    >         -no documenting exposure for review
    >         -no waiting for film development
    >         -no need to scan for use on the computer
    >
    > Film:
    >         -Resources
    >         -Pollution from developing
    >         -Need to document your shots (exposure)
    >         -recurring film cost
    >         -Wait for developing
    >         -recurring development cost
    >         -Missed chances for re-take
    >         -scanning film is not only time consuming, but a bit of an art in
    > itself to learn.
    >
    > For the budget conscious I'd find a used early generation DSLR (Say a
    > Nikon 70/80, Canon 20D, Maxxum 7D, etc. with a decent kit lens to "learn
    > on".


    For the budget conscious, this is what I wonder about in terms of
    optics, guess this is used as a huge lens in fact.:
    http://cgi.ebay.de/Refraktor-Telesk...ptik?hash=item2ea4ee1a44&_trksid=p3911.c0.m14
    P.C., Aug 27, 2009
    #13
  14. On Wed, 26 Aug 2009 22:06:03 -0500, Rich <> wrote:

    >Word to the wise about those focal lengths: Maksutov or Schmidt-Cassegrain
    >is a better option than any refractive spotting scope.
    >A portable 6" SCT will provide an f16 focal ratio when used at 2500mm as
    >opposed to the the insane f31 focal ratio you'd get with an 80mm spotting
    >scope.


    Focal ratio doesn't matter. It has no significant impact on much of
    anything for astroimaging.

    The 6" SCT has more than three times the aperture area, so it will
    provide about three times shorter exposures for the same S/N.
    _________________________________________________

    Chris L Peterson
    Cloudbait Observatory
    http://www.cloudbait.com
    Chris L Peterson, Aug 27, 2009
    #14
  15. RichA

    Paul Furman Guest

    Re: |GG| Re: "Digiscoping" with spotting scopes is so wrong on multiplelevels

    wrote:
    > On Aug 24, 11:37 pm, RichA <> wrote:
    >> They did an article on it in Amateur Photographer (British) in the Aug
    >> 1st issue. I didn't like it. So I sent them an email with 5-6
    >> reasons why using a small astronomical scope was better. They
    >> published it in their Aug. 22 issue. The main problem with spotting
    >> scopes or "birder" scopes is that they don't have the focusing range
    >> to be used in prime focus (no eyepiece) mode. This results in too
    >> long focal lengths and slow focal ratios. There are other problems as
    >> well.
    >> The only real problem with using a small astronomical refractor
    >> (though you can use compound reflector scopes for longer reach) is
    >> field curvature. But that generally does not come into play as most
    >> users of such things are focusing on the bird, or other wildlife
    >> object in the centre of the field. Additionally, you can buy field
    >> flattening lenses (positive lenses that flatten the field and reduce
    >> the effective focal ratio and focal length, usually) for them anyway.

    >
    > Just a quick comment about "digiscoping..."
    >
    > Digiscoping is a term used by birders for afocal imaging. Birds are
    > small and it is difficult to get close to them, to get detail and
    > image scale on a small bird that may be a hundred feet or a thousand
    > feet away or more requires focal lengths in the range of 2000-3000mm
    > or longer. Prime focus lens become very expensive at these focal
    > lengths.
    >
    > The digiscoper achieves long effective focal lengths by combining the
    > magnification of a telescope with small pixels and zoom of point and
    > shoot camera. The most famous digiscoping camera has been the Coolpix
    > 990-995-4500 series. These were manufactured prior to the
    > introduction of the affordable DSLR and a solidly built. For example
    > the 4500 has a magnesium body. They have lens that are enclosed, they
    > have small pixels that can provide a well illuminated field from a
    > relatively small exit pupil...
    >
    > I am sure that the proper prime focus lens combined with a DSLR will
    > take better photos than a simple 80mm APO with a Cool Pix 4500 and a
    > quality eyepiece... On the other hand, not many of us can afford a
    > prime focus lens that might be anywhere from 2000mm to 10000mm in
    > length... The next time you see a 8 inch bird on a tree that is 500
    > or 1000 yards away and you want to image it, one affordable option is
    > digiscoping... THe other is Afocal imaging with a DSLR but the
    > advantage of digiscoping is that it is easier to use the autofocus...


    I have an unusual old 500mm f/4.5 SLR lens which is not bad, it was good
    in it's day although bulky like a telescope. Previous owner shot
    surfers. I found that an almost as old Tokina 300mm f/2.8 performs
    somewhat better so have no use for it. That is a more expensive lens
    though so no surprise.

    If curious, here's a quick search:
    http://www.flickr.com/search/?q=500mm&w=21068427@N08
    http://www.google.com/search?q=500mm&sitesearch=edgehill.net
    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
    Paul Furman, Aug 27, 2009
    #15
  16. RichA

    Chris.B Guest

    Re: |GG| Re: "Digiscoping" with spotting scopes is so wrong onmultiple levels

    The digital camera has placed techniques in the hands of all which
    were once only available to the paid professional.

    The most obvious of which is the ability to take hundreds of shots in
    the desperate hope that one will be almost usable without further
    adjustment with free software.

    The downside is the crawler speed of the modern computer in accessing
    one's tens or hundreds of thousands of images.

    Somebody should invent a flexible browser for rapidly identifying,
    sorting and naming images on one's hard disk. Faces, bikes, moon,
    beach, trees, family, flowers, clouds, etc. And do so indefinitely
    without altering anything (at all) so it can all be returned to its
    original filing arrangements in an instant when desired. I still have
    a huge file of irreplaceable images from a Picasa duplicate image
    sorting which thankfully I never deleted!
    Chris.B, Aug 27, 2009
    #16
  17. RichA

    Martin Brown Guest

    P.C. wrote:
    > On 26 Aug., 23:04, Alan Browne <>
    > wrote:
    >> P.C. wrote:
    >>
    >>> I am looking forwerds more to a try with a reasnoable priced analog
    >>> before finding the right digital just becaurse of this.

    >> Digital:
    >>
    >> -less pollution
    >> -instant feedback
    >> .correct errors
    >> .correct framing
    >> .try variations immediately
    >> .delete pure duds on the spot (more mem avail).
    >> -no documenting exposure for review
    >> -no waiting for film development
    >> -no need to scan for use on the computer
    >>
    >> Film:
    >> -Resources
    >> -Pollution from developing
    >> -Need to document your shots (exposure)
    >> -recurring film cost
    >> -Wait for developing
    >> -recurring development cost
    >> -Missed chances for re-take
    >> -scanning film is not only time consuming, but a bit of an art in
    >> itself to learn.
    >>
    >> For the budget conscious I'd find a used early generation DSLR (Say a
    >> Nikon 70/80, Canon 20D, Maxxum 7D, etc. with a decent kit lens to "learn
    >> on".

    >
    > For the budget conscious, this is what I wonder about in terms of
    > optics, guess this is used as a huge lens in fact.:
    > http://cgi.ebay.de/Refraktor-Telesk...ptik?hash=item2ea4ee1a44&_trksid=p3911.c0.m14


    It depends what you already have by way of kit. If you have a birding
    scope then use that with any cheap digicam. Even the rubbish ones in
    mobile phones will give you a good idea of what is possible.

    If you want to get something that works better with an SLR then either
    an ETX scope OTA or the MTO mirror lenses give the longest working focal
    length with near diffraction limited optics and minimal chromatic
    abberation compared to cheap doublet lenses. They are a bit slow at f10. eg

    http://www.teleskop-express.de/shop/index.php?manufacturers_id=74

    I have a very old one. Some are better than others. And you can buy out
    of fashion manual focus fixed long focal length lenses comparatively
    cheaply by scouring the second hand lists.

    Either way with long focal length lenses you need a very sturdy tripod
    and pan tilt head to use it effectively.

    Regards,
    Martin Brown
    Martin Brown, Aug 27, 2009
    #17
  18. RichA

    P.C. Guest

    On 27 Aug., 09:04, Martin Brown <|||>
    wrote:
    > P.C. wrote:
    > > On 26 Aug., 23:04, Alan Browne <>
    > > wrote:
    > >> P.C. wrote:

    >
    > >>> I am looking forwerds more to a try with a reasnoable priced analog
    > >>> before finding the right digital just becaurse of this.
    > >> Digital:

    >
    > >>         -less pollution
    > >>         -instant feedback
    > >>                 .correct errors
    > >>                 .correct framing
    > >>                 .try variations immediately
    > >>                 .delete pure duds on the spot (more mem avail).
    > >>         -no documenting exposure for review
    > >>         -no waiting for film development
    > >>         -no need to scan for use on the computer

    >
    > >> Film:
    > >>         -Resources
    > >>         -Pollution from developing
    > >>         -Need to document your shots (exposure)
    > >>         -recurring film cost
    > >>         -Wait for developing
    > >>         -recurring development cost
    > >>         -Missed chances for re-take
    > >>         -scanning film is not only time consuming, but a bit of an art in
    > >> itself to learn.

    >
    > >> For the budget conscious I'd find a used early generation DSLR (Say a
    > >> Nikon 70/80, Canon 20D, Maxxum 7D, etc. with a decent kit lens to "learn
    > >> on".

    >
    > > For the budget conscious, this is what I wonder about in terms of
    > > optics, guess this is used as a huge lens in fact.:
    > >http://cgi.ebay.de/Refraktor-Teleskop-Spektiv-Kamerascope-oder-fotosc...

    >
    > It depends what you already have by way of kit. If you have a birding
    > scope then use that with any cheap digicam. Even the rubbish ones in
    > mobile phones will give you a good idea of what is possible.
    >
    > If you want to get something that works better with an SLR then either
    > an ETX scope OTA or the MTO mirror lenses give the longest working focal
    > length with near diffraction limited optics and minimal chromatic
    > abberation compared to cheap doublet lenses. They are a bit slow at f10.  eg
    >
    > http://www.teleskop-express.de/shop/index.php?manufacturers_id=74
    >
    > I have a very old one. Some are better than others. And you can buy out
    > of fashion manual focus fixed long focal length lenses comparatively
    > cheaply by scouring the second hand lists.
    >
    > Either way with long focal length lenses you need a very sturdy tripod
    > and pan tilt head to use it effectively.
    >
    > Regards,
    > Martin Brown


    Yes I seen them on Ebay in several variants, the f;10 and the short
    length worry me though, I wonder how these behave with a modern tripod
    with motors.
    P.C., Aug 27, 2009
    #18
  19. RichA

    Martin Brown Guest

    P.C. wrote:
    > On 27 Aug., 09:04, Martin Brown <|||>
    > wrote:


    >> If you want to get something that works better with an SLR then either
    >> an ETX scope OTA or the MTO mirror lenses give the longest working focal
    >> length with near diffraction limited optics and minimal chromatic
    >> abberation compared to cheap doublet lenses. They are a bit slow at f10. eg
    >>
    >> http://www.teleskop-express.de/shop/index.php?manufacturers_id=74
    >>
    >> I have a very old one. Some are better than others. And you can buy out
    >> of fashion manual focus fixed long focal length lenses comparatively
    >> cheaply by scouring the second hand lists.
    >>
    >> Either way with long focal length lenses you need a very sturdy tripod
    >> and pan tilt head to use it effectively.

    >
    > Yes I seen them on Ebay in several variants, the f;10 and the short
    > length worry me though, I wonder how these behave with a modern tripod
    > with motors.


    I have a traditional tripod, but I see no reason why their stubby length
    from folded optics should affect a motorised tripod.

    If anything it decreases the vibration from wind loading somewhat. And
    the thing has a gunsight pip on the end for pointing it with and a
    choice of two tripod attachment points for portrait vs landscape.

    It all depends on what you want to do.

    Regards,
    Martin Brown
    Martin Brown, Aug 27, 2009
    #19
  20. RichA

    Guest

    On Aug 26, 8:06 pm, Rich <> wrote:
    > "" <> wrote in news:61782f9e-57a5-4805-
    > :
    >
    >
    >
    > > On Aug 24, 11:37 pm, RichA <> wrote:
    > >> They did an article on it in Amateur Photographer (British) in the Aug
    > >> 1st issue.  I didn't like it.  So I sent them an email with 5-6
    > >> reasons why using a small astronomical scope was better.  They
    > >> published it in their Aug. 22 issue.  The main problem with spotting
    > >> scopes or "birder" scopes is that they don't have the focusing range
    > >> to be used in prime focus (no eyepiece) mode.  This results in too
    > >> long focal lengths and slow focal ratios.  There are other problems as
    > >> well.
    > >> The only real problem with using a small astronomical refractor
    > >> (though you can use compound reflector scopes for longer reach) is
    > >> field curvature.  But that generally does not come into play as most
    > >> users of such things are focusing on the bird, or other wildlife
    > >> object in the centre of the field.  Additionally, you can buy field
    > >> flattening lenses (positive lenses that flatten the field and reduce
    > >> the effective focal ratio and focal length, usually) for them anyway.

    >
    > > Just a quick comment about "digiscoping..."

    >
    > > Digiscoping is a term used by birders for afocal imaging.   Birds are
    > > small and it is difficult to get close to them, to get detail and
    > > image scale on a small bird that may be a hundred feet or a thousand
    > > feet away or more requires focal lengths in the range of 2000-3000mm
    > > or longer.   Prime focus lens become very expensive at these focal
    > > lengths.

    >
    > Word to the wise about those focal lengths:  Maksutov or Schmidt-Cassegrain
    > is a better option than any refractive spotting scope.
    > A portable 6" SCT will provide an f16 focal ratio when used at 2500mm as
    > opposed to the the insane f31 focal ratio you'd get with an 80mm spotting
    > scope.  


    >Word to the wise about those focal lengths: Maksutov or Schmidt-

    Cassegrain
    > is a better option than any refractive spotting scope.
    > A portable 6" SCT will provide an f16 focal ratio when used at 2500mm as
    > opposed to the the insane f31 focal ratio you'd get with an 80mm spotting
    > scope.



    Have you ever tried using a SCT for digiscoping??? I am just curious
    because over the years I have used a variety of scope ranging from a
    70mm Pronto to a 12.5 inch F/4.06 Newtonian, this included my
    C-5.... I have never had much luck with the bigger scopes though
    better luck with the Newt than the C-5.

    I think there are a few reasons... One is thermal, SCTs and Newts are
    just not that stable and out in the sun or during the day, there are
    real problems. Another is ease of finding the target, centering the
    target and focusing. Birds tend to move, one has to be quick to get
    that perfect shot starting with a widefield of view, centering the
    target, focusing and zooming needs to be done quickly. Since focusing
    through the finder is not possible, one needs to first focus the
    eyepiece by eye...

    As far as the effective focal length and the amount of light... Things
    are not quite what they seem...

    It is important to remember that these long focal lengths are
    "effective focal lengths", i.e. in comparison to a 35mm frame size.
    Computing the effective focal ratio is not so easy because the
    effective focal length calculation is based on a 35mm frame size but
    the cameras use very small chips so the actual focal length is much
    shorter, this is a key to understanding the effectiveness of
    digiscoping. For example the CoolPix 4500 has an effective focal
    length of 144mm at 4x zoom but an actual focal length of 32 mm. When
    computing the overall focal ratio, it would be that 32mm one would
    use. These days I am using an Astrotech 102ED at F/7, most often with
    a 32mm Plossl. At 4X zoom this provides an effective/comparative
    focal length of 22x 144mm= 3200mm but the actual focal length is only
    709mm (32mm x 22.x) which is F/7. During the day the shutter speeds
    tend to be 1/250sec or faster, this would be typical of an F/7 system,
    not an F/31 system.

    The C-5, when one includes the two mirrors, the corrector and the
    central obstruction has the through put of a 4 inch refractor,
    assuming the C-5 is in good shape... Not any advantage there. The C-6
    would have a bit of an advantage. But given the disadvantages
    previously mentioned, the refractor would be my choice every time.

    Digiscoping is really the Rube Goldberg of the photographic world...
    It can work surprisingly well with the right camera, the right scope
    and the right tripod. And of course it requires a lot of
    experimentation... The most difficult task is getting a good sharp
    focus. It needs to be done quickly but accurately, otherwise all that
    focal length goes to waste.

    Maybe others of you have had good success with CATs and Newts but from
    what I have seen, digiscoping seems to be best done with a refractor.

    Jon
    , Aug 27, 2009
    #20
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