small aperture test

On 5 Nov 2009 02:02:28 GMT, Chris Malcolm <> wrote:

>
>You've got it back to front. Since diffraction increases as the lens
>is stopped because because of the change of proportion of lens area to
>lens circumference, the test works for all cases EXCEPT when the
>widest aperture is sharpest.

Go educate your useless **** of an ignorant moron troll self. Resolution
increases with objective optics diameter. IF those optics are of
diffraction limited quality.

Educationg Trolls Is An Endless Task

Dudley Hanks wrote:
> I've heard a lot about how the cropped sensor cameras are defraction limited
> to around f/8 - f/11, so I thought I'd see what kind of an image my XSi puts
> out at a small aperture.
>
> I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
> with a shutter speed of 1 sec.
>
> How did it turn out?

The only way to know is to do a test in series. It looks soft to me.
Sometimes that's OK though, sometimes DOF is more important. This photo:
http://www.flickr.com/photos/edgehill/4075980407
had DOF as a priority though I didn't exceed the diffraction limits and
the lens is near optimum wide open. The power lines in the upper left
are soft due to tilting the focus plane.


> http://www.snaps.blind-apertures.ca/...erPortrait.jpg (quick
> download)
>
> http://www.snaps.blind-apertures.ca/...raitWinter.jpg (full
> size)
>
> Take Care,
> Dudley
>
>


--
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Paul Furman

Dudley Hanks wrote:
> "Chris Malcolm" <> wrote in message
> news:...
>> Dudley Hanks <> wrote:
>>
>>> "David J Taylor"
>>> <david-> wrote in
>>> message news:t6aIm.1501$. ..
>>>> "Dudley Hanks" <> wrote in message
>>>> news:4U9Im.50459$Db2.29545@edtnps83...
>>>>> I've heard a lot about how the cropped sensor cameras are defraction
>>>>> limited to around f/8 - f/11, so I thought I'd see what kind of an
>>>>> image
>>>>> my XSi puts out at a small aperture.
>>>>>
>>>>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at
>>>>> f/22,
>>>>> with a shutter speed of 1 sec.
>>>>>
>>>>> How did it turn out?
>>>>>
>>>>> http://www.snaps.blind-apertures.ca/...erPortrait.jpg
>>>>> (quick
>>>>> download)
>>>>>
>>>>> http://www.snaps.blind-apertures.ca/...raitWinter.jpg
>>>>> (full
>>>>> size)
>>>>>
>>>>> Take Care,
>>>>> Dudley
>>>> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
>>>> loathe), so there could be some diffraction visible, but I'm also not
>>>> convinced that the subject didn't move within the 1 second exposure!
>>>>
>>>> Cheers,
>>>> David
>>> Thanks, David, I'll try it again with an inanimate object, or a faster
>>> shutter speed.
>>> I suppose, if the test is to be useful, I should also take an equivalent
>>> pic
>>> of the subject using a wider aperture so the two images can be compared.
>> The diffraction limit of aperture is usually taken to be the last
>> aperture in a decreasing series of sharper apertures, i.e., stopping
>> down further makes the image softer because of diffraction. But that's
>> not a fixed aperture, it depends on such things as the exact sensor
>> pixel size (or crop factor) not just the nominal "1.5", on the
>> resolution of the lens, and whether you're looking at the centre of
>> the image or the edges or some compromise between the two. Why
>> should it depend on those? Because the point at which an extra stop's
>> worth of diffraction softening becomes larger than how much other
>> kinds of lens aberration are being improved by stopping down obviously
>> will depend on the size of those other errors. In other words better
>> lenses will have larger sharpest apertures.
>>
>> I find for example on my Sony A350 that my general purpose zoom is
>> usually sharpest at f8, but at its soft extremes that becomes f11, and
>> my 50mm prime is sharpest at f5.6.
>>
>> This can only be established for your camera and each of your lenses
>> by taking a comparative series of shots while varying the aperture. On
>> zooms it may change with focal length.
>>
>> --
>> Chris Malcolm
>
> Thanks, Chris, that's good info to have.
>
> This is a pretty cheap lens, and I think its a bit soft to begin with.

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.


--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Bob Larter

Better Info wrote:
> On 4 Nov 2009 17:49:36 GMT, Chris Malcolm <> wrote:
>
>> Dudley Hanks <> wrote:
>>
>>> "David J Taylor"
>>> <david-> wrote in
>>> message news:t6aIm.1501$. ..
>>>> "Dudley Hanks" <> wrote in message news:4U9Im.50459$Db2.29545@edtnps83...
>>>>> I've heard a lot about how the cropped sensor cameras are defraction
>>>>> limited to around f/8 - f/11, so I thought I'd see what kind of an image
>>>>> my XSi puts out at a small aperture.
>>>>>
>>>>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
>>>>> with a shutter speed of 1 sec.
>>>>>
>>>>> How did it turn out?
>>>>>
>>>>> http://www.snaps.blind-apertures.ca/...erPortrait.jpg (quick
>>>>> download)
>>>>>
>>>>> http://www.snaps.blind-apertures.ca/...raitWinter.jpg (full
>>>>> size)
>>>>>
>>>>> Take Care,
>>>>> Dudley
>>>> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
>>>> loathe), so there could be some diffraction visible, but I'm also not
>>>> convinced that the subject didn't move within the 1 second exposure!
>>>>
>>>> Cheers,
>>>> David
>>> Thanks, David, I'll try it again with an inanimate object, or a faster
>>> shutter speed.
>>> I suppose, if the test is to be useful, I should also take an equivalent pic
>>> of the subject using a wider aperture so the two images can be compared.
>> The diffraction limit of aperture is usually taken to be the last
>> aperture in a decreasing series of sharper apertures, i.e., stopping
>> down further makes the image softer because of diffraction. But that's
>> not a fixed aperture, it depends on such things as the exact sensor
>> pixel size (or crop factor) not just the nominal "1.5", on the
>> resolution of the lens, and whether you're looking at the centre of
>> the image or the edges or some compromise between the two. Why
>> should it depend on those? Because the point at which an extra stop's
>> worth of diffraction softening becomes larger than how much other
>> kinds of lens aberration are being improved by stopping down obviously
>> will depend on the size of those other errors. In other words better
>> lenses will have larger sharpest apertures.
>>
>> I find for example on my Sony A350 that my general purpose zoom is
>> usually sharpest at f8, but at its soft extremes that becomes f11, and
>> my 50mm prime is sharpest at f5.6.
>>
>> This can only be established for your camera and each of your lenses
>> by taking a comparative series of shots while varying the aperture. On
>> zooms it may change with focal length.
>
> Your test won't work.

Please, get back to us when you grow a clue. Bye!


--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Bob Larter

Dudley Hanks wrote:
> I've heard a lot about how the cropped sensor cameras are defraction limited
> to around f/8 - f/11, so I thought I'd see what kind of an image my XSi puts
> out at a small aperture.
>
> I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
> with a shutter speed of 1 sec.
>
> How did it turn out?
[...]
> http://www.snaps.blind-apertures.ca/...raitWinter.jpg*(full
> size)

I'll go farther than previous respondents: That photo, from a Canon
XSi at f/22, is obviously not diffraction limited.

The statements you'll hear of the diffraction limit assume everything
else it practically optimal: rock-steady subject, tripod mount,
perfect focus, and unless the claim is about a particular lens, they
mean a laudably sharp one.

Bryan

Dudley Hanks wrote:
> "David J Taylor"
> <david-> wrote in
> message news:t6aIm.1501$. ..
>> "Dudley Hanks" <> wrote in message news:4U9Im.50459$Db2.29545@edtnps83...
>>> I've heard a lot about how the cropped sensor cameras are defraction
>>> limited to around f/8 - f/11, so I thought I'd see what kind of an image
>>> my XSi puts out at a small aperture.
>>>
>>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
>>> with a shutter speed of 1 sec.
>>>
>>> How did it turn out?
>>>
>>> http://www.snaps.blind-apertures.ca/...erPortrait.jpg (quick
>>> download)
>>>
>>> http://www.snaps.blind-apertures.ca/...raitWinter.jpg (full
>>> size)
>>>
>>> Take Care,
>>> Dudley
>> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
>> loathe), so there could be some diffraction visible, but I'm also not
>> convinced that the subject didn't move within the 1 second exposure!
>>
> Thanks, David, I'll try it again with an inanimate object, or a faster
> shutter speed.
>
> I suppose, if the test is to be useful, I should also take an equivalent pic
> of the subject using a wider aperture so the two images can be compared.

If you are serious about being able to tell include a few ball bearings
on black velvet in the picture composition. Specular highlights are
about the easiest thing to see if an image is diffraction limited.

Or you could just use a pinhole over the lens and a verry long exposure.

Regards,
Martin Brown

Martin Brown

"Bob Larter" <> wrote in message
news:4af2c78c$...
> Dudley Hanks wrote:
>> "Chris Malcolm" <> wrote in message
>> news:...
>>> Dudley Hanks <> wrote:
>>>
>>>> "David J Taylor"
>>>> <david-> wrote in
>>>> message news:t6aIm.1501$. ..
>>>>> "Dudley Hanks" <> wrote in message
>>>>> news:4U9Im.50459$Db2.29545@edtnps83...
>>>>>> I've heard a lot about how the cropped sensor cameras are defraction
>>>>>> limited to around f/8 - f/11, so I thought I'd see what kind of an
>>>>>> image
>>>>>> my XSi puts out at a small aperture.
>>>>>>
>>>>>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at
>>>>>> f/22,
>>>>>> with a shutter speed of 1 sec.
>>>>>>
>>>>>> How did it turn out?
>>>>>>
>>>>>> http://www.snaps.blind-apertures.ca/...erPortrait.jpg
>>>>>> (quick
>>>>>> download)
>>>>>>
>>>>>> http://www.snaps.blind-apertures.ca/...raitWinter.jpg
>>>>>> (full
>>>>>> size)
>>>>>>
>>>>>> Take Care,
>>>>>> Dudley
>>>>> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
>>>>> loathe), so there could be some diffraction visible, but I'm also not
>>>>> convinced that the subject didn't move within the 1 second exposure!
>>>>>
>>>>> Cheers,
>>>>> David
>>>> Thanks, David, I'll try it again with an inanimate object, or a faster
>>>> shutter speed.
>>>> I suppose, if the test is to be useful, I should also take an
>>>> equivalent pic
>>>> of the subject using a wider aperture so the two images can be
>>>> compared.
>>> The diffraction limit of aperture is usually taken to be the last
>>> aperture in a decreasing series of sharper apertures, i.e., stopping
>>> down further makes the image softer because of diffraction. But that's
>>> not a fixed aperture, it depends on such things as the exact sensor
>>> pixel size (or crop factor) not just the nominal "1.5", on the
>>> resolution of the lens, and whether you're looking at the centre of
>>> the image or the edges or some compromise between the two. Why
>>> should it depend on those? Because the point at which an extra stop's
>>> worth of diffraction softening becomes larger than how much other
>>> kinds of lens aberration are being improved by stopping down obviously
>>> will depend on the size of those other errors. In other words better
>>> lenses will have larger sharpest apertures.
>>>
>>> I find for example on my Sony A350 that my general purpose zoom is
>>> usually sharpest at f8, but at its soft extremes that becomes f11, and
>>> my 50mm prime is sharpest at f5.6.
>>>
>>> This can only be established for your camera and each of your lenses
>>> by taking a comparative series of shots while varying the aperture. On
>>> zooms it may change with focal length.
>>>
>>> --
>>> Chris Malcolm
>>
>> Thanks, Chris, that's good info to have.
>>
>> This is a pretty cheap lens, and I think its a bit soft to begin with.
>
> 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.


Originally, I bought it for my Canon A2, but didn't use it a lot. I used it
a bit for blurred background shots of the kids, flowers, etc.

However, with the crop factor of the XSi, it's now a great portrait lens,
and it still has a fairly respectable aperture when I add in my 2x
converter, giving me a (35mm equiv) f/3.5 160mm lens.

I'm finding myself falling back on it a lot these days.

Take Care,
Dudley

Dudley Hanks

On Thu, 05 Nov 2009 23:40:44 +1000, Bob Larter <>
wrote:

>Better Info wrote:
>> On 4 Nov 2009 17:49:36 GMT, Chris Malcolm <> wrote:
>>
>>> Dudley Hanks <> wrote:
>>>
>>>> "David J Taylor"
>>>> <david-> wrote in
>>>> message news:t6aIm.1501$. ..
>>>>> "Dudley Hanks" <> wrote in message news:4U9Im.50459$Db2.29545@edtnps83...
>>>>>> I've heard a lot about how the cropped sensor cameras are defraction
>>>>>> limited to around f/8 - f/11, so I thought I'd see what kind of an image
>>>>>> my XSi puts out at a small aperture.
>>>>>>
>>>>>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
>>>>>> with a shutter speed of 1 sec.
>>>>>>
>>>>>> How did it turn out?
>>>>>>
>>>>>> http://www.snaps.blind-apertures.ca/...erPortrait.jpg (quick
>>>>>> download)
>>>>>>
>>>>>> http://www.snaps.blind-apertures.ca/...raitWinter.jpg (full
>>>>>> size)
>>>>>>
>>>>>> Take Care,
>>>>>> Dudley
>>>>> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
>>>>> loathe), so there could be some diffraction visible, but I'm also not
>>>>> convinced that the subject didn't move within the 1 second exposure!
>>>>>
>>>>> Cheers,
>>>>> David
>>>> Thanks, David, I'll try it again with an inanimate object, or a faster
>>>> shutter speed.
>>>> I suppose, if the test is to be useful, I should also take an equivalent pic
>>>> of the subject using a wider aperture so the two images can be compared.
>>> The diffraction limit of aperture is usually taken to be the last
>>> aperture in a decreasing series of sharper apertures, i.e., stopping
>>> down further makes the image softer because of diffraction. But that's
>>> not a fixed aperture, it depends on such things as the exact sensor
>>> pixel size (or crop factor) not just the nominal "1.5", on the
>>> resolution of the lens, and whether you're looking at the centre of
>>> the image or the edges or some compromise between the two. Why
>>> should it depend on those? Because the point at which an extra stop's
>>> worth of diffraction softening becomes larger than how much other
>>> kinds of lens aberration are being improved by stopping down obviously
>>> will depend on the size of those other errors. In other words better
>>> lenses will have larger sharpest apertures.
>>>
>>> I find for example on my Sony A350 that my general purpose zoom is
>>> usually sharpest at f8, but at its soft extremes that becomes f11, and
>>> my 50mm prime is sharpest at f5.6.
>>>
>>> This can only be established for your camera and each of your lenses
>>> by taking a comparative series of shots while varying the aperture. On
>>> zooms it may change with focal length.
>>
>> Your test won't work.
>
>Please, get back to us when you grow a clue. Bye!


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Bob Larter is Lionel Lauer - Look it up.

On Fri, 06 Nov 2009 11:56:53 +1000, Bob Larter <>
wrote:

>John Navas wrote:
>> On Thu, 05 Nov 2009 23:39:40 +1000, Bob Larter <>
>> wrote in <4af2c78c$>:
>>
>>> 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, as well as even emulating catadioptric lens
systems no matter what camera took the image, and more.

Catch up, know-nothing snapshooter DSLR-Troll!

Outing Trolls is FUN!

John Navas wrote:
> On Thu, 05 Nov 2009 23:39:40 +1000, Bob Larter <>
> wrote in <4af2c78c$>:
>
>> 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.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Bob Larter