Re: 70-200 or 70-300 for Pentax

Discussion in 'Digital Photography' started by David J Taylor, Jun 22, 2008.

  1. Alfred Molon wrote:
    > Can anybody recommend a 70-200 or 70-300 lens for a Pentax K20D?
    > Should be sharp enough for a 14MP APS-C sensor. Doesn't have to be
    > F2.8, because of weight & bulk & cost - an F4 lens would suffice,
    > provided it's sharp enough. I know that the Pentax 50-135 F2.8 is
    > good, but would prefer a longer lens.


    Alfred,

    If you had bought Nikon, there's a very well respected 70-300mm VR lens:

    http://www.europe-nikon.com/product/en_GB/products/broad/869/overview.html

    David
    David J Taylor, Jun 22, 2008
    #1
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  2. David J Taylor

    John Guest

    David J Taylor wrote:
    > Alfred Molon wrote:
    >> Can anybody recommend a 70-200 or 70-300 lens for a Pentax K20D?
    >> Should be sharp enough for a 14MP APS-C sensor. Doesn't have to be
    >> F2.8, because of weight & bulk & cost - an F4 lens would suffice,
    >> provided it's sharp enough. I know that the Pentax 50-135 F2.8 is
    >> good, but would prefer a longer lens.

    >
    > Alfred,
    >
    > If you had bought Nikon, there's a very well respected 70-300mm VR lens:
    >
    > http://www.europe-nikon.com/product/en_GB/products/broad/869/overview.html
    >
    > David
    >
    >


    Wow, that's a very helpful response.

    John.
    John, Jun 22, 2008
    #2
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  3. David J Taylor

    Ray Fischer Guest

    Alfred Molon <> wrote:
    >In article <Cnn7k.13628$>, David J
    >Taylor says...
    >
    >> If you had bought Nikon, there's a very well respected 70-300mm VR lens:
    >>
    >> http://www.europe-nikon.com/product/en_GB/products/broad/869/overview.html

    >
    >I haven't bought anything yet, but am not considering a Nikon for the
    >moment because they don't have a 14MP model and I don't want to change
    >the camera after a year or two just because the MP count has increased.
    >With a 14MP model I can skip one generation and upgrade when 16-18MP
    >cameras hit the market.


    Why not go straight to a 25MP camera?

    >And please don't tell me I don't need the MP. Alamy is requesting
    >submissions with at least 16.7MP and 14MP is closer to that than 10 or
    >12MP.


    No, they ask for images of at least 17MB, not 17MP.

    Big difference.

    --
    Ray Fischer
    Ray Fischer, Jun 22, 2008
    #3
  4. Alfred Molon <> wrote:
    > In article <Cnn7k.13628$>, David J
    > Taylor says...
    >
    >> If you had bought Nikon, there's a very well respected 70-300mm VR lens:
    >>
    >> http://www.europe-nikon.com/product/en_GB/products/broad/869/overview.html

    >
    > I haven't bought anything yet, but am not considering a Nikon for the
    > moment because they don't have a 14MP model and I don't want to change
    > the camera after a year or two just because the MP count has increased.
    > With a 14MP model I can skip one generation and upgrade when 16-18MP
    > cameras hit the market.


    > And please don't tell me I don't need the MP. Alamy is requesting
    > submissions with at least 16.7MP and 14MP is closer to that than 10 or
    > 12MP.


    That seems odd, so I checked the Alamy web site. Under "preparing your
    images" and "digital cameras" I found this:

    "Use a pro-level camera with a true (non-interpolated) resolution of
    at least 6 megapixels. This will give a file size of at least 17MB at
    8 bit."

    That 17MB refers to file size of something like a TIFF, not camera
    MP. Elsewhere on their web site they explain that they expect you to
    upsample your submissions to reach the high pixel density they require
    on their standardised submissions, specifically recommending Genuine
    Fractals as doing the best job.

    They expect a 6MP pro camera with a good lens will be good enough.

    Which was as I remembered from the last time I checked them out. A
    Sony R1 such as you and I have is more than good enough for Alamy
    submissions.

    --
    Chris Malcolm DoD #205
    IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
    [http://www.dai.ed.ac.uk/homes/cam/]
    Chris Malcolm, Jun 22, 2008
    #4
  5. John wrote:
    > David J Taylor wrote:
    >> Alfred Molon wrote:
    >>> Can anybody recommend a 70-200 or 70-300 lens for a Pentax K20D?
    >>> Should be sharp enough for a 14MP APS-C sensor. Doesn't have to be
    >>> F2.8, because of weight & bulk & cost - an F4 lens would suffice,
    >>> provided it's sharp enough. I know that the Pentax 50-135 F2.8 is
    >>> good, but would prefer a longer lens.

    >>
    >> Alfred,
    >>
    >> If you had bought Nikon, there's a very well respected 70-300mm VR
    >> lens:
    >> http://www.europe-nikon.com/product/en_GB/products/broad/869/overview.html
    >>
    >> David
    >>
    >>

    >
    > Wow, that's a very helpful response.
    >
    > John.


    It was intended to show there is more to choosing a camera than just the
    MP count. You need to look at the complete system.

    David
    David J Taylor, Jun 22, 2008
    #5
  6. Alfred Molon wrote:
    > In article <Cnn7k.13628$>, David J
    > Taylor says...
    >
    >> If you had bought Nikon, there's a very well respected 70-300mm VR
    >> lens:
    >>
    >>
    >> http://www.europe-nikon.com/product/en_GB/products/broad/869/overview.html

    >
    > I haven't bought anything yet, but am not considering a Nikon for the
    > moment because they don't have a 14MP model and I don't want to change
    > the camera after a year or two just because the MP count has
    > increased. With a 14MP model I can skip one generation and upgrade
    > when 16-18MP cameras hit the market.
    >
    > And please don't tell me I don't need the MP. Alamy is requesting
    > submissions with at least 16.7MP and 14MP is closer to that than 10 or
    > 12MP.


    More MP equals more noise. Are you really sure you want that?

    Others have already mentioned that 6MP is enough to Alamy.

    Cheers,
    David
    David J Taylor, Jun 22, 2008
    #6
  7. Alfred Molon <> wrote:
    >In article <485e1a85$0$17168$>, Ray Fischer
    >> Why not go straight to a 25MP camera?

    >
    >Not available yet,


    Wrong. Has been available for quite a while.
    See e.g. http://www.hasselbladusa.com/promotions/h3dii.aspx (39MP) or
    http://www.mamiya.com/mamiya-645zd.html (ok, that's only 22MP).

    >besides will likely be way above my budget.


    That on the other hand is quite possible considering the price tag for
    those cameras.

    >> >And please don't tell me I don't need the MP. Alamy is requesting
    >> >submissions with at least 16.7MP and 14MP is closer to that than 10 or
    >> >12MP.


    How does that correlate to
    <quote>
    We reject images for):
    [...]
    6. Digital camera not suitable for Alamy (pro level 6 mega pixels)
    </quote>

    >> No, they ask for images of at least 17MB, not 17MP.

    >
    >Nope. They ask for 48 MByte images, which translates into 16.7 MP.


    According to which formula? Doesn't that also depend a lot on the
    compression (lossy as well as lossless) and motive? Very uniform photos
    (it's all blue sky) compress better than photos with many different
    contrasting objects (masses of twigs).

    jue
    jue
    Jürgen Exner, Jun 22, 2008
    #7
  8. Alfred Molon <> wrote:
    >Thanks for your reply, but that still doesn't answer my question ahout
    >the 70-300 lens.
    >
    >Sigma and Tamron have such lenses, but performance is less than stellar.
    >Sony seems to have a good 70-300 lens, which makes me wonder if I should
    >get a A350 instead.


    If you are willing to switch brands anyway then Nikon makes a nice
    70-300 VR lens which for the money is an excellent choice.

    jue
    Jürgen Exner, Jun 22, 2008
    #8
  9. frederick wrote:
    []
    > More MP doesn't have to equal more noise. While shot noise might seem
    > to be more viewed at 100% pixel view, noise on a "whole image" basis
    > can be less if overall sensor efficiency isn't reduced.


    Well it changes the noise spectrum at least, and hence the character of
    the nosie. I don't know whether the eye/brain has a single response to
    the changed noise spectrum, or whether that's something which depends on
    the observer - some people preferring a slightly noisier but crisper
    "grain" structure. It may even be subject-dependant. But I agree in
    general.

    > It could be unwise to pre-judge performance of future ~15mp aps-c
    > sensors based on the poor usable dynamic range of the Pentax K20d and
    > Sony a350 sensors. They are the first examples of dslr makers
    > launching very high MP cameras with worse sensor performance than
    > earlier lower MP models. OTOH, if you can live with low DR - limiting
    > ability to PP the raw images even at base iso - and have lenses that
    > are "up to" the demands of high MP sensors, they might be okay for
    > some people's uses. Unfortunately IMO, the "reason" to have high MP
    > (capturing detail in landscape shooting)is negated by the fact that
    > it's also in landscape shooting where the dynamic range limitation
    > has potential to hurt image quality the most. Other makers have
    > consistently improved overall sensor performance despite increasing
    > pixel counts. I expect that they will continue to do so - or face
    > some serious criticism.


    Indeed there may be scope for sensor improvement - there are arguments
    about the possible practical advantages of front- versus back-illumination
    right now.

    For landscapes I would suggest using the easily available panorama tools -
    even something like Auto Stitch will probably make a better final image
    from two or more shots than a high MP sensor and expensive lens. At
    least, if that's an acceptable way of working for you.

    Cheers,
    David
    David J Taylor, Jun 23, 2008
    #9
  10. Alfred Molon wrote:
    > In article <oOI7k.14168$>, David J
    > Taylor says...
    >
    >> For landscapes I would suggest using the easily available panorama
    >> tools - even something like Auto Stitch will probably make a better
    >> final image from two or more shots than a high MP sensor and
    >> expensive lens.

    >
    > I do in fact lots of panoramas with PTGUI, but it's a lot of work.


    Then take a look at the free AutoStitch or its commercial variants.

    http://www.cs.ubc.ca/~mbrown/autostitch/autostitch.html

    Drop a set of files in a directory, choose your output size and quality,
    and press the Go button. Very little work. Perhaps if you want "superb"
    results you may need to do more, but for just "very good" these tools are
    highly effective.

    Cheers,
    David
    David J Taylor, Jun 23, 2008
    #10
  11. lid wrote:
    []
    > I've tried that several times, and it either simply fails totally,
    > or gives less than optimal results.


    I found that AutoStitch worked very well on 90% of the image sets I tried.
    To get the different projections and automatic ghost-removal, I bought a
    commercial version. Now I get an even better success rate. I've now
    learnt how to take photos with a sufficient overlap and the same exposure
    quite quickly.

    > I'm using Hugin, which often requires manual matchpoint generation,
    > and for gigantic images on my 2 gig computer needs doing in steps,
    > but always works and gives superb results.
    >
    > Doug McDonald


    I'm sure that you can improve on AutoStitch if you want the finest
    possible results, but for me, in the trade-off of "sufficiently good
    quickly" versus "almost perfect but slowly", processing speed wins. I
    rarely need more than 5000 x 2000 pixels.

    Everyone to their own!

    Cheers,
    David
    David J Taylor, Jun 23, 2008
    #11
  12. Alfred Molon wrote:
    []
    > PTGUI will automatically generate the control points and could also
    > automatically generate a panorama.
    >
    > But then each panorama has an optimal projection (rectangular,
    > cylindrical, spherical, mercator etc.) which you have to choose
    > manually. No software is smart enough for that.


    One click in the software I use (Autopano Pro).

    > Then you have to choose the point of view, tilt and rotation
    > parameters. This again is subjective and can make a big difference.
    > How would a software know which is the optimal parameter set.


    I usually choose the point of view when I take the pano.
    Rotation? You want a pano where the horizon is not horizontal?
    There is usually only one correct value of tilt.

    Again, my software does all this automatically, although I can adjust if
    needed.

    > Sometimes PTGUI will choose the wrong control points or there might be
    > some parallax error. In that case you have to do the corrections
    > manually.
    >
    > Finally, it happens that there are moving objects in a panorama
    > sequence. Smartblend can cope with that to a certain extent, but in
    > some cases you will have to choose the layered output option and edit
    > the layers individually, editing away the moving objects.
    >
    > So you see, lots of work for a good panorama.


    I can't be sure whether you have very special requirements, or whether you
    simply haven't tried the options in modern software such as Autopano Pro.
    You appear to be making much heavier weather of making panos than is
    needed - at least for "good" or "very good" results. Of course, if you
    are after "perfection", you may well be right.

    For me, the typical pano takes 30 seconds to 2 minutes.

    Cheers,
    David
    David J Taylor, Jun 24, 2008
    #12
  13. lid wrote:
    []
    > You must have different goals, of subjects!
    >
    > None of the automatchers I have tried work reliably. They often put
    > matchpoints on clouds rather than fixed objects. They often miss
    > obvious but small fixed objects. Sometimes, especially when
    > large areas of the photos are low-contrast jumbles of rocks (scree),
    > they simply fail to even guess at all, even though my eye has no
    > problems. Then there are tough cases like a large series I made in
    > Carlsbad Caverns, where many pictures in the series were say 5 to 10
    > stops underexposed, yet the eye could match them up no problem, and even
    > Hugin's tune-up
    > button works fine if you tell it to accept the very low contrast and
    > feed it a good guess.
    > The shots were so underexposed because I had to expose for the
    > highlights, and be uniform so the noise would look the same
    > everywhere. Unfortunately I didn't have time to take a full double set
    > of images at two
    > exposure times ... the short exposure set was 1/4 second, the long
    > one would have say 5 seconds.
    >
    > Are there better things than Hugin, for doing large panos like
    > using 15 to 30 exposures with a Canon 30D? I've got 3 gigs of
    > memory.
    >
    > Doug McDonald


    Doug,

    My goal is "good but quick", and my subjects are well overlapped and
    typical outdoor subjects with plenty of detail. Not difficult ones, and
    not underexposed 5-10 stops. Clouds are not usually an issue for me, as
    my typical panos comprise images taken within a few seconds of each other
    (the time to expose on the centre shot, swing my body left, and press the
    button). Here's a typical example - I know it's not perfect:

    http://www.david-taylor.myby.co.uk/imaging/2008-03-22-0218-53-CCUL-S-crop.jpg

    My maximum ever pano was a 360-degree, 16 wide x 2 deep set of photos from
    the Kuala Lumpur Tower (not the twin towers) and that did take about
    fifteen minutes, and there was only one small area with needed some
    post-processing. That was done with Autopano Pro, on a dual-core, 3GB
    Windows XP system.

    Cheers,
    David
    David J Taylor, Jun 24, 2008
    #13
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