Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Computing > Digital Photography > small aperture test

Reply
Thread Tools

small aperture test

 
 
Bob Larter
Guest
Posts: n/a
 
      11-07-2009
Outing Trolls is FUN! wrote:
> On Fri, 06 Nov 2009 11:56:53 +1000, Bob Larter <(E-Mail Removed)>
> wrote:
>
>> John Navas wrote:
>>> On Thu, 05 Nov 2009 23:39:40 +1000, Bob Larter <(E-Mail Removed)>
>>> wrote in <4af2c78c$(E-Mail Removed)>:
>>>
>>>> The 50mm/F1.8II is a surprisingly good lens for the money. I've taken a
>>>> lot of excellent shots with mine, so please don't sell it short!
>>>> I've since 'upgraded' to a 50mm/F1.4, but it's not as much of an
>>>> improvement as you might expect from the price difference.
>>> What you get for the money with the f/1.4 over the f/1.8 is speed,
>>> not IQ.

>> The f1.4 also has more aperture blades, so the bokeh is a bit nicer as well.

>
> Post-processing plugins with depth-map masks afford an infinite number of
> aperture blades for bokeh,


Um, no, it doesn't.

> as well as even emulating catadioptric lens
> systems no matter what camera took the image, and more.


Why the hell would anyone in their right mind want to emulate the
doughnut-shaped bokeh you get with a cat lens?

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
 
Reply With Quote
 
 
 
 
Bob Larter
Guest
Posts: n/a
 
      11-07-2009
Martin Brown wrote:
> Ofnuts wrote:
>> Trolls is FUN! wrote:
>>> On 06 Nov 2009 07:28:51 GMT, http://www.velocityreviews.com/forums/(E-Mail Removed) (Ray Fischer) wrote:

>>
>> <snip prespoterous claims>
>>
>>>
>>> YOUR LOSS!
>>>
>>> And a huge loss for everyone. Caused by trolls like you. Now everyone
>>> has
>>> to do the searching for that software based only on a vague description.
>>> Good luck finding my most favorite and vastly configurable one as
>>> described
>>> above, I've not seen it on the net for about two years. You useless
>>> trolls
>>> taught me well. NEVER share the most important bits of information as
>>> long
>>> as a news-group is being overrun and taken over by a pack of useless and
>>> pathetic trolls. The trolls will only use that information to be
>>> better at
>>> pretending to be photographers with the next newbies who can't
>>> immediately
>>> see the trolls for what they truly are.

>>
>> I don't believe this stuff exists. Prove me wrong!

>
> Google is your friend.
>
> One such plugin is even unimaginatively called "Bokeh". I don't like the
> results but then I have never been into lenses smeared in vaseline etc. eg.
>
> http://alienskin.com/bokeh/index.aspx
>
> Can't say I would recommend it.


Me either. I prefer the real bokeh you get from good lenses.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
 
Reply With Quote
 
 
 
 
Bob Larter
Guest
Posts: n/a
 
      11-07-2009
Outing Trolls is FUN! wrote:
> On Fri, 06 Nov 2009 09:50:52 +0100, Ofnuts <(E-Mail Removed)>
> wrote:
>
>> Trolls is FUN! wrote:
>>> On 06 Nov 2009 07:28:51 GMT, (E-Mail Removed) (Ray Fischer) wrote:

>> <snip prespoterous claims>
>>
>>> YOUR LOSS!
>>>
>>> And a huge loss for everyone. Caused by trolls like you. Now everyone has
>>> to do the searching for that software based only on a vague description.
>>> Good luck finding my most favorite and vastly configurable one as described
>>> above, I've not seen it on the net for about two years. You useless trolls
>>> taught me well. NEVER share the most important bits of information as long
>>> as a news-group is being overrun and taken over by a pack of useless and
>>> pathetic trolls. The trolls will only use that information to be better at
>>> pretending to be photographers with the next newbies who can't immediately
>>> see the trolls for what they truly are.

>> I don't believe this stuff exists. Prove me wrong!

>
> I suppose I could upload two sample images, one without and one with a
> depth-map catadioptric-lens annulus bokeh applied to it,


Oh, I doubt that.


--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
 
Reply With Quote
 
Bob Larter
Guest
Posts: n/a
 
      11-07-2009
Dudley Hanks wrote:
> "Bob Larter" <(E-Mail Removed)> wrote in message
> news:4af37455$(E-Mail Removed)...
>> John Navas wrote:
>>> On Thu, 05 Nov 2009 23:39:40 +1000, Bob Larter <(E-Mail Removed)>
>>> wrote in <4af2c78c$(E-Mail Removed)>:
>>>
>>>> The 50mm/F1.8II is a surprisingly good lens for the money. I've taken a
>>>> lot of excellent shots with mine, so please don't sell it short!
>>>> I've since 'upgraded' to a 50mm/F1.4, but it's not as much of an
>>>> improvement as you might expect from the price difference.
>>> What you get for the money with the f/1.4 over the f/1.8 is speed, not
>>> IQ.

>> The f1.4 also has more aperture blades, so the bokeh is a bit nicer as
>> well.

> Any difference in number / quality of elements?


EF50mm/F1.8II: 5 blades, 6 elements, 5 groups.
EF50mm/F1.4USM: 8 blades, 7 elements, 6 groups.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
 
Reply With Quote
 
Educationg Trolls Is An Endless Task
Guest
Posts: n/a
 
      11-07-2009
On Fri, 06 Nov 2009 15:04:20 -0600, Educationg Trolls Is An Endless Task
<(E-Mail Removed)> wrote:

>You can display the diffraction of
>light with a single knife-edge, no aperture required.


Some interesting images found while bored. Referred to as "Grimaldi's
Shadows" in days of yore. Circa 17th century. The resident-trolls posting
in these news-groups today are 300 to 400 years behind the learning curve.
They're not mental-throw-backs to just last century. I'm not at all
surprised.

Full double-edge razor blade:
<http://micro.magnet.fsu.edu/primer/lightandcolor/images/diffractionfigure2.jpg>

Internal space in a double-edged razor blade:
<http://hyperphysics.phy-astr.gsu.edu/HBASE/PHYOPT/phopic/razcut.jpg>

Razor blade corner (oops, no aperture at all):
<http://hyperphysics.phy-astr.gsu.edu/HBASE/PHYOPT/phopic/razcor.jpg>


Also related to my previous posts:

While finding the above, I stumbled upon a fairly good example of optics
being given the Ronchi-test where the central portion has the worst figure.
<http://www.retrotechnology.com/glass/06mar13_9r.jpg>

Stopping down the aperture will cause softening due to figure errors, not
diffraction.

(For those green to Ronchi-test patterns, here's a quick overview:
<http://schmidling.com/etron.gif> TDE=turned down edge)
 
Reply With Quote
 
Chris Malcolm
Guest
Posts: n/a
 
      11-07-2009
Educationg Trolls Is An Endless Task <(E-Mail Removed)> wrote:
> On 6 Nov 2009 14:50:57 GMT, Chris Malcolm <(E-Mail Removed)> wrote:


>>Not at all. I've worked alongside colleagues who've written books on
>>the subject.


> When a youth was giving himself airs in the Theater and saying, "I am wise,
> for I have conversed with many wise men." Epictetus replied, "I too have
> conversed with many rich men, yet I am not rich."


> You were saying something? LOL!


> I'm sure your colleagues, if you indeed ever had any, kept you around as
> their little puppy dog that didn't piddle on the carpet too often. Or
> conversely, got many laughs out of your incessant piddling habits. As I do
> with how often you piddle your nonsense to usenet.


> Pushing a broom and emptying waste-baskets in a publisher's collating
> department could also be construed as "working alongside .... (authors)".
> If I was forced to assume your trolls' comment above was conveying your
> truth, from the vast amount of misinformation you spew that would be my
> guess of how you came to believe what you believe.


Your research skills are pathetic. It's ridiculously easy to discover
my academic affilation and status.

>>The mathematics of the relationship between lens optical
>>aberrations and diffraction is simple, uncontroversial, and has long
>>been well known. Your position can only logically be maintained if you
>>disagree with one of the following propositions:
>>
>>1. Lens optical errors vary inversely with aperture.


> Wrong. The central part of a lens or lenses may have the greatest figure
> error. Especially in a complex compound lens where one element or group of
> elements may have more imaging weight as aperture is increased or reduced.
> However, for a given amount of effort, fabrication and figuring errors are
> exponentially proportional to size. There is no law on which area of that
> lens may have the greatest error.


Let's get down to specifics and try to avoid confusing the issue with
a smokescreen of rare exceptions. Let's take one of the largest and
simplest kinds of lens aberration -- chromatic aberration.

Do you really seriously claim that what you wrote above usually
applies to chromatic aberration in DSLR camera lenses?

>>2. Lens diffraction errors vary with aperture.


> Wrong. It varies with distance of aperture edge to imaging plane.


Of course it does! But do you not realise that there is no
contradiction between that fact and the fact that the proportion of
diffraction error in an image formed by a given camera lens at a given
image distance increases with aperture?

Your responses in this thread suggest that you do have access to some
reasonably authoritative source of information on the topic, but that
you don't really understand what it means.

> The
> amount of light in the image only reveals or hides the fixed amount of
> diffraction created/caused by distance. You can display the diffraction of
> light with a single knife-edge, no aperture required. This is why shorter
> focal-length lenses have less diffraction problems. This also is why it's
> so easy to create truly diffraction-limited optics for P&S cameras due to
> the smaller focal-lengths required and smaller optics diameters required
> (i.e. for a given effort, a smaller diameter optic is easier to figure
> accurately).


That's exactly what I thought. You don't really understand this at
all. What you say is perfectly true, but if you really understood what
you've written you'd realise that it has nothing to do with the change
in the relative amount of diffraction in an image formed by a
non-diffraction-limited lens at varying apertures.


>>3. Lens errors combine at worst multiplicatively.


> Wrong.


> Grade-School Math 101


You appear to have as little understanding of Maths 101 as Physics 101
or Optics 101. It's a bit pointless citing such elementary sources to
someone whose education has gone well past that point. If you want to
disagree, then rather than vaguely waving your hand at an unspecified
first year undergrafuate textbook, why not try to actually find the
relavant page and quote it?

I am of course generously assuming that you once did such courses and
can still remember what's in the textbooks

>>Can you enlighten us as to which of those you disagree with, or
>>whether you're using a different mathematical foundation for the
>>relationship?


> Three strikes, you're outta here TROLL.


> Blatantly Obvious 101


That's one course I have no doubt you attended

--
Chris Malcolm
 
Reply With Quote
 
Educationg Trolls Is An Endless Task
Guest
Posts: n/a
 
      11-07-2009
On 7 Nov 2009 16:32:35 GMT, Chris Malcolm <(E-Mail Removed)> wrote:

>Educationg Trolls Is An Endless Task <(E-Mail Removed)> wrote:
>
>> Pushing a broom and emptying waste-baskets in a publisher's collating
>> department could also be construed as "working alongside .... (authors)".
>> If I was forced to assume your trolls' comment above was conveying your
>> truth, from the vast amount of misinformation you spew that would be my
>> guess of how you came to believe what you believe.

>
>Your research skills are pathetic. It's ridiculously easy to discover
>my academic affilation and status.
>


Why on earth do you think anyone would be interested enough in you to do
something as hugely pointless a waste of time as that? Your words here
speak for themselves. You're an idiot. A semi-educated idiot. The world is
crawling with them. Some of the most stupid people I have ever met in life
even had PhD and Dr prefacing their names.


>> exponentially proportional to size. There is no law on which area of that
>> lens may have the greatest error.

>
>Let's get down to specifics and try to avoid confusing the issue with
>a smokescreen of rare exceptions.


No smokescreen at all. Poor lens figuring is DIRECTLY RELATED to why you
CANNOT MEASURE the amount of diffraction, especially when stopped down. If
you cannot obtain the sharpest image at full aperture, then that means YOUR
OPTICS ARE NOT DIFFRACTION-LIMITED. Therefore, stopping down that lens is
NO GUARANTEE that the softness you are observing is in any way related to
diffraction. Are you this pathetically stupid that you can't grasp
something so simple?


> Let's take one of the largest and
>simplest kinds of lens aberration -- chromatic aberration.
>
>Do you really seriously claim that what you wrote above usually
>applies to chromatic aberration in DSLR camera lenses?
>


Ahhh.... the bleats of a pure troll. Red-herring CA bullshit smokescreens
that have has nothing to do with the diffraction problems being discussed.


>>>2. Lens diffraction errors vary with aperture.

>
>> Wrong. It varies with distance of aperture edge to imaging plane.

>
>Of course it does! But do you not realise that there is no
>contradiction between that fact and the fact that the proportion of
>diffraction error in an image formed by a given camera lens at a given
>image distance increases with aperture?


This will be the last time I tell you this. If the optics are not of
diffraction-limited quality, then your optics CANNOT create diffraction
artifacts to even measure it or detect it.

You only asked that I disagree with three of your points. ALL THREE were
wrong.

I suggest you pay for some courses on these areas of study instead of
trying to manipulate someone far more intelligent than you into educating
you for free.

Go away useless troll. I'm done with you.



 
Reply With Quote
 
Ray Fischer
Guest
Posts: n/a
 
      11-07-2009
Chris Malcolm <(E-Mail Removed)> wrote:
>Educationg Trolls Is An Endless Task <(E-Mail Removed)> wrote:


>> Pushing a broom and emptying waste-baskets in a publisher's collating
>> department could also be construed as "working alongside .... (authors)".
>> If I was forced to assume your trolls' comment above was conveying your
>> truth, from the vast amount of misinformation you spew that would be my
>> guess of how you came to believe what you believe.

>
>Your research skills are pathetic. It's ridiculously easy to discover
>my academic affilation and status.


Don't argue with it. It doesn't care about the truth. It will keep
lying and keep arguing as long as you keep responding to what it
writes.

--
Ray Fischer
(E-Mail Removed)

 
Reply With Quote
 
Educationg Trolls Is An Endless Task
Guest
Posts: n/a
 
      11-07-2009
On 7 Nov 2009 16:32:35 GMT, Chris Malcolm <(E-Mail Removed)> wrote:

>Educationg Trolls Is An Endless Task <(E-Mail Removed)> wrote:
>
>> Pushing a broom and emptying waste-baskets in a publisher's collating
>> department could also be construed as "working alongside .... (authors)".
>> If I was forced to assume your trolls' comment above was conveying your
>> truth, from the vast amount of misinformation you spew that would be my
>> guess of how you came to believe what you believe.

>
>Your research skills are pathetic. It's ridiculously easy to discover
>my academic affilation and status.
>


Why on earth do you think anyone would be interested enough in you to do
something as hugely pointless a waste of time as that? Your words here
speak for themselves. You're an idiot. A semi-educated idiot. The world is
crawling with them. Some of the most stupid people I have ever met in life
even had PhD and Dr prefacing their names.


>> exponentially proportional to size. There is no law on which area of that
>> lens may have the greatest error.

>
>Let's get down to specifics and try to avoid confusing the issue with
>a smokescreen of rare exceptions.


No smokescreen at all. Poor lens figuring is DIRECTLY RELATED to why you
CANNOT MEASURE the amount of diffraction, especially when stopped down. If
you cannot obtain the sharpest image at full aperture, then that means YOUR
OPTICS ARE NOT DIFFRACTION-LIMITED. Therefore, stopping down that lens is
NO GUARANTEE that the softness you are observing is in any way related to
diffraction. Are you this pathetically stupid that you can't grasp
something so simple?


> Let's take one of the largest and
>simplest kinds of lens aberration -- chromatic aberration.
>
>Do you really seriously claim that what you wrote above usually
>applies to chromatic aberration in DSLR camera lenses?
>


Ahhh.... the bleats of a pure troll. Red-herring CA bullshit smokescreens
that have has nothing to do with the diffraction problems being discussed.


>>>2. Lens diffraction errors vary with aperture.

>
>> Wrong. It varies with distance of aperture edge to imaging plane.

>
>Of course it does! But do you not realise that there is no
>contradiction between that fact and the fact that the proportion of
>diffraction error in an image formed by a given camera lens at a given
>image distance increases with aperture?


This will be the last time I tell you this. If the optics are not of
diffraction-limited quality, then your optics CANNOT create diffraction
artifacts to even measure it or detect it.

You only asked that I disagree with ONE of your points and prove it. ALL
THREE were wrong.

I suggest you pay for some courses on these areas of study instead of
trying to manipulate someone far more intelligent than you into educating
you for free.

Go away useless troll. I'm done with you.



 
Reply With Quote
 
Frank@Zappa.com
Guest
Posts: n/a
 
      11-07-2009
I found a site w/ ISO 12233 photos. You can see how various lenses perform.

http://www.the-digital-picture.com

Look at this and shut up.





On Sat, 07 Nov 2009 12:08:41 -0600, Educationg Trolls Is An Endless Task <(E-Mail Removed)> wrote:

>On 7 Nov 2009 16:32:35 GMT, Chris Malcolm <(E-Mail Removed)> wrote:
>
>>Educationg Trolls Is An Endless Task <(E-Mail Removed)> wrote:
>>
>>> Pushing a broom and emptying waste-baskets in a publisher's collating
>>> department could also be construed as "working alongside .... (authors)".
>>> If I was forced to assume your trolls' comment above was conveying your
>>> truth, from the vast amount of misinformation you spew that would be my
>>> guess of how you came to believe what you believe.

>>
>>Your research skills are pathetic. It's ridiculously easy to discover
>>my academic affilation and status.
>>

>
>Why on earth do you think anyone would be interested enough in you to do
>something as hugely pointless a waste of time as that? Your words here
>speak for themselves. You're an idiot. A semi-educated idiot. The world is
>crawling with them. Some of the most stupid people I have ever met in life
>even had PhD and Dr prefacing their names.
>
>
>>> exponentially proportional to size. There is no law on which area of that
>>> lens may have the greatest error.

>>
>>Let's get down to specifics and try to avoid confusing the issue with
>>a smokescreen of rare exceptions.

>
>No smokescreen at all. Poor lens figuring is DIRECTLY RELATED to why you
>CANNOT MEASURE the amount of diffraction, especially when stopped down. If
>you cannot obtain the sharpest image at full aperture, then that means YOUR
>OPTICS ARE NOT DIFFRACTION-LIMITED. Therefore, stopping down that lens is
>NO GUARANTEE that the softness you are observing is in any way related to
>diffraction. Are you this pathetically stupid that you can't grasp
>something so simple?
>
>
>> Let's take one of the largest and
>>simplest kinds of lens aberration -- chromatic aberration.
>>
>>Do you really seriously claim that what you wrote above usually
>>applies to chromatic aberration in DSLR camera lenses?
>>

>
>Ahhh.... the bleats of a pure troll. Red-herring CA bullshit smokescreens
>that have has nothing to do with the diffraction problems being discussed.
>
>
>>>>2. Lens diffraction errors vary with aperture.

>>
>>> Wrong. It varies with distance of aperture edge to imaging plane.

>>
>>Of course it does! But do you not realise that there is no
>>contradiction between that fact and the fact that the proportion of
>>diffraction error in an image formed by a given camera lens at a given
>>image distance increases with aperture?

>
>This will be the last time I tell you this. If the optics are not of
>diffraction-limited quality, then your optics CANNOT create diffraction
>artifacts to even measure it or detect it.
>
>You only asked that I disagree with three of your points. ALL THREE were
>wrong.
>
>I suggest you pay for some courses on these areas of study instead of
>trying to manipulate someone far more intelligent than you into educating
>you for free.
>
>Go away useless troll. I'm done with you.
>
>

 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
QUESTION: Small vs wide aperture shots in low light BD Digital Photography 53 12-20-2005 04:39 AM
Aperture fixed when 35mm lenses used on small CCD's?? Dave Digital Photography 15 01-04-2005 05:36 PM
10D sensor dust visible only at large F numbers (small aperture) fake name Digital Photography 6 01-23-2004 11:57 PM
When to use a very small aperture johnpower@verobeachlaw.com Digital Photography 7 07-16-2003 08:59 PM
test test test test test test test Computer Support 2 07-02-2003 06:02 PM



Advertisments