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Why is performance wide open important?
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PostPosted: Sun Nov 01, 2015 2:34 am    Post subject: Reply with quote
tb_a wrote:
radissimo77 wrote:


* the wider open you are the higher ISO you can use and also shutter speed is in your favor to hand held the shot in some circumstances (as mentioned above not a huge issue with current modern cameras]


Well, depends on your own definition of really high quality and sharpness. Ultimate sharp pictures are IMHO only possible at extremely short exposure times and high ISO is in any case degrading picture quality to a certain extent. So from my experience I prefer to use in such cases a tripod or alike and stick rather to the lowest possible ISO setting. However, for not so critical photography you are right IF the lens is able to deliver the expected quality wide open at all and no larger DOF is required. For critical light situations I always have a little tripod with me to cope with such situations much better in favor of the picture quality (at least a pocket-able small one).


Babel again. Laughing

Considering he began "* the wider open you are the higher ISO you can use". Of course the ISO number is lower when lens aperture is opened, correct? Perhaps he means the lower ISO is "higher" quality.


PostPosted: Sun Nov 01, 2015 2:46 am    Post subject: Reply with quote
Edited

Last edited by bernhardas on Wed May 11, 2016 8:42 am; edited 1 time in total


PostPosted: Sun Nov 01, 2015 2:52 am    Post subject: Reply with quote
visualopsins wrote:
tb_a wrote:
radissimo77 wrote:


* the wider open you are the higher ISO you can use and also shutter speed is in your favor to hand held the shot in some circumstances (as mentioned above not a huge issue with current modern cameras]


Well, depends on your own definition of really high quality and sharpness. Ultimate sharp pictures are IMHO only possible at extremely short exposure times and high ISO is in any case degrading picture quality to a certain extent. So from my experience I prefer to use in such cases a tripod or alike and stick rather to the lowest possible ISO setting. However, for not so critical photography you are right IF the lens is able to deliver the expected quality wide open at all and no larger DOF is required. For critical light situations I always have a little tripod with me to cope with such situations much better in favor of the picture quality (at least a pocket-able small one).


Babel again. Laughing

Considering he began "* the wider open you are the higher ISO you can use". Of course the ISO number is lower when lens aperture is opened, correct? Perhaps he means the lower ISO is "higher" quality.


Our understanding is very often totally different. Not to say who is right or who is wrong.

My understanding was that with open lens and high ISO you are rather able to shoot hand held. My answer was accordingly.

Obviously you understood something else.

Bear in mind that English maybe your mother language but it's definitely not mine.

Anyway, I am always happy to amuse you.


PostPosted: Sun Nov 01, 2015 2:58 am    Post subject: Reply with quote
I only shoot WO when the subject calls for it, but I usually also shoot stopped down so I have the choice later on.
I still cherish my lenses that can shoot wide open and still perform, sadly most lenses do need to be stopped down some to look their best, for landscapes it's a no brainer to stop down, though I have shot a few WO landscapes to see what they look like.


PostPosted: Sun Nov 01, 2015 3:07 am    Post subject: Reply with quote
bernhardas wrote:
the wide open performance for a 1.4 lens is not sooo critical. for a 4.0 lens it is.


Depends on usage of course.

The burning questions are:

"Which is sharper at 5.6?" Some will argue "1.4 since the 1.4 lens begins sharper..."

"Do all lenses really look alike at 8?"


PostPosted: Sun Nov 01, 2015 3:30 am    Post subject: Reply with quote
tb_a wrote:
visualopsins wrote:
tb_a wrote:
radissimo77 wrote:


* the wider open you are the higher ISO you can use and also shutter speed is in your favor to hand held the shot in some circumstances (as mentioned above not a huge issue with current modern cameras]


Well, depends on your own definition of really high quality and sharpness. Ultimate sharp pictures are IMHO only possible at extremely short exposure times and high ISO is in any case degrading picture quality to a certain extent. So from my experience I prefer to use in such cases a tripod or alike and stick rather to the lowest possible ISO setting. However, for not so critical photography you are right IF the lens is able to deliver the expected quality wide open at all and no larger DOF is required. For critical light situations I always have a little tripod with me to cope with such situations much better in favor of the picture quality (at least a pocket-able small one).


Babel again. Laughing

Considering he began "* the wider open you are the higher ISO you can use". Of course the ISO number is lower when lens aperture is opened, correct? Perhaps he means the lower ISO is "higher" quality.


Our understanding is very often totally different. Not to say who is right or who is wrong.

My understanding was that with open lens and high ISO you are rather able to shoot hand held. My answer was accordingly.

Obviously you understood something else.

Bear in mind that English maybe your mother language but it's definitely not mine.

Anyway, I am always happy to amuse you.


I've noticed that! Laughing I've also noticed how people can total agree, yet say it so different as to appear to be arguing, or to argue when there is no argument.

I believe you take the literal meaning, while I forgive the writer for his (obvious unintentional) mistake.

This sort of communication misunderstanding fascinates me...where people understand the exact opposite.

Sure it is language related. I am native (American) English speaker, no other (fluent) language, yet how I write in English often affects what meaning people of other languages interpret. The opposite of what I intend is the usual case, unfortunate for me. Often a non-English person has rewritten what I say with much more clear meaning than me. That amazes me -- how a non-English can interpret & rephrase better than English...


PostPosted: Sun Nov 01, 2015 4:05 am    Post subject: Reply with quote
calvin83 wrote:
If you use a lens at WO, the performance at WO is important.


Sure it is. It's also very interesting and the warts can really jump out Smile

But often it's the only topic when a lens is discussed. Months ago in a discussion about the 75 lux another member at one point remarked: oh they are all good at 5.6 or f/8.

Certainly that's where the differences need a close eye to see. But if you have a long infinity view with distant details differences become apparent.

The other day I compared the CV 90/3.5 APO to Bokina:
https://www.flickr.com/photos/55299472@N07/albums/72157660482573592

see if you can judge the differences, pick which is which at f/4 and f/8. Smile I put some very distant details in the upper right of the frame.

But f/11 is where things get obvious again. So nice to have a lenses which is still punchy with relatively large DOF.


PostPosted: Sun Nov 01, 2015 5:28 am    Post subject: Reply with quote
Diffraction means with most cameras, sharpness differences will not be apparent at f11:

http://www.lonestardigital.com/aperture_diffraction_limits.htm

Quote:
At f/11 diffraction begins to spill into adjacent pixels.



The nine pixel pattern at f/11 would now look like the sketch shown below. The central peaks of light are within the edges of the pixel boundaries but the secondary rings of have begun to overlap. Some diffraction blurring & softening will occur.




Also, aberrations are reduced at smaller apertures, so what differences are visible at f11 if diffraction means sharpness differences are masked?


PostPosted: Sun Nov 01, 2015 8:39 am    Post subject: Reply with quote
I shoot mostly film these days, and don't always want a tripod with me. WO performance definitely matters Smile

Also, some lenses are actually quite good, but have a different character WO.


PostPosted: Sun Nov 01, 2015 9:10 am    Post subject: Reply with quote
I'd like to add that I shoot wide open quite a lot because I too find it fun. Nothing wrong with shooting wide open. It is when people say that they will only use a fast lens for WO shooting when things go a bit wrong as they miss out on so much. This stubborn idea that I have paid all this money for a really fast lens so now I'm going to get every cents worth by using the lens to it's "fullest potential" is a bit sad but understandable. And, fact is, a lot of fast lenses are not that spectacular at any area which makes them interesting only as tools for short DOF and/or interesting bokeh. But there are spectacular fast lenses as well which deserve to be used as intended, slightly stopped down.


PostPosted: Sun Nov 01, 2015 10:20 am    Post subject: Reply with quote
I shoot M4/3 and the Nikon 1 system with Legacy glass.
With the Nikon 1 systems 1" sensor, fast glass becomes very important.
Alot of times you simply can't get the shot you want without using fast glass wide open.


PostPosted: Sun Nov 01, 2015 10:44 am    Post subject: Reply with quote
visualopsins wrote:

Sure it is language related. I am native (American) English speaker, no other (fluent) language, yet how I write in English often affects what meaning people of other languages interpret. The opposite of what I intend is the usual case, unfortunate for me. Often a non-English person has rewritten what I say with much more clear meaning than me. That amazes me -- how a non-English can interpret & rephrase better than English...


Slightly off topic:

In my previous life I used to participate in an international working group for "simplified English" because it turned out that different folks around the world are differently interpreting things and the field I was working in didn't allow different interpretations for security reasons. So the "how to do" manuals had to be rewritten to make sure that everybody is understanding everything absolutely identical with zero tolerance. That was really a hard time and I've learned a lot about the English language that I didn't learned at school or somewhere else before. I think there are still such groups in existence also under the UN umbrella, so it's an ongoing project. However, once the job was done I stopped to follow the further progress. Anyway at least I've learned to accept the rather huge differences around the globe and also among the native speakers, which was rather surprising me. Fact is that English isn't everywhere the same language, though the grammar or spelling might be same.


PostPosted: Sun Nov 01, 2015 8:24 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
Diffraction means with most cameras, sharpness differences will not be apparent at f11:


I suggest you test more at F/11.

Which lenses still offer high performance with diffraction? That is the question, and there is huge variation with all types of lenses.

Most are "meh" at F/11. But some are very good as both bench tests and a good personal test will easily show.

The best macro lenses stand out with performance which is still good at f/16, like the macro-elmar-M.
"At 1:5.6 contrast increases a bit due to the reduction of internal reflections. At 1;8 the optimum is reached and this performance holds till 1:16. Only at 1;22 there is a noticeable drop in micro (edge) contrast. This is one of the few lenses that perform equally well at all smaller apertures." Yes, Puts again Smile


PostPosted: Sun Nov 01, 2015 8:37 pm    Post subject: Reply with quote
uhoh7 wrote:
Which lenses still offer high performance with diffraction?


That's easy, none of them, performance can only ever be sub-optimal if there is diffraction.


PostPosted: Sun Nov 01, 2015 9:24 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
uhoh7 wrote:
Which lenses still offer high performance with diffraction?


That's easy, none of them, performance can only ever be sub-optimal if there is diffraction.


Don't you get it? Sub-optimal is relative. End results are a combination of lens performance and diffraction.

You think all 35s are the same at f11?

Pull out your 50s and go out and shoot some long infinity shots at f/11. Compare. Would make an interesting thread if they were up on flickr and we could see the fulls.


PostPosted: Sun Nov 01, 2015 9:37 pm    Post subject: Reply with quote
Optimal means the best the lens can produce. Diffraction is a hard physical limit imposed by the properties of light. Most lenses achieve their peak (optimal) performance a couple of stops wider than the aperture setting at which diffraction occurs.

What differences do you claim to be visible at f11?


PostPosted: Sun Nov 01, 2015 9:47 pm    Post subject: Reply with quote
tb_a wrote:
visualopsins wrote:

Sure it is language related. I am native (American) English speaker, no other (fluent) language, yet how I write in English often affects what meaning people of other languages interpret. The opposite of what I intend is the usual case, unfortunate for me. Often a non-English person has rewritten what I say with much more clear meaning than me. That amazes me -- how a non-English can interpret & rephrase better than English...


Slightly off topic:

In my previous life I used to participate in an international working group for "simplified English" because it turned out that different folks around the world are differently interpreting things and the field I was working in didn't allow different interpretations for security reasons. So the "how to do" manuals had to be rewritten to make sure that everybody is understanding everything absolutely identical with zero tolerance. That was really a hard time and I've learned a lot about the English language that I didn't learned at school or somewhere else before. I think there are still such groups in existence also under the UN umbrella, so it's an ongoing project. However, once the job was done I stopped to follow the further progress. Anyway at least I've learned to accept the rather huge differences around the globe and also among the native speakers, which was rather surprising me. Fact is that English isn't everywhere the same language, though the grammar or spelling might be same.


Thank you! Thanks for infos. I think something similar could be useful at MFlenses.com

I'll try to find that manual & subsequents for here.


PostPosted: Sun Nov 01, 2015 9:56 pm    Post subject: Reply with quote
I've wondered about this notion that all lenses perform the same at f/8 due to diffraction limits, contrasted with what Puts says about higher macro lens diffraction limit. I know my Macro Takumar seems to be sharpest at f/16. How much of that is simple increased dof, I don't know yet. I think it was phrased best by somebody who said as they are stopped down all lens performances approach each other in terms of quality. Rather than all lenses have the same diffraction limit.

The format makes a huge difference, yes? I would think the diffraction limit for 8x10 to be huge, like f/45, true?


PostPosted: Sun Nov 01, 2015 10:01 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
Diffraction means with most cameras, sharpness differences will not be apparent at f11:

http://www.lonestardigital.com/aperture_diffraction_limits.htm

Quote:
At f/11 diffraction begins to spill into adjacent pixels.



The nine pixel pattern at f/11 would now look like the sketch shown below. The central peaks of light are within the edges of the pixel boundaries but the secondary rings of have begun to overlap. Some diffraction blurring & softening will occur.




Also, aberrations are reduced at smaller apertures, so what differences are visible at f11 if diffraction means sharpness differences are masked?


That data is "made up". Try to focus a point source of light onto one pixel. Laughing

I'm not saying the data is wrong. Perhaps he had a sensor with big pixels.


PostPosted: Sun Nov 01, 2015 10:07 pm    Post subject: Reply with quote
Yes, large format has a much higher diffraction limit - f64 is a commonly used aperture among 8x10 shooters.

The data isn't 'made up', those white blobs represent the airy disks.


PostPosted: Sun Nov 01, 2015 10:53 pm    Post subject: Reply with quote
visualopsins wrote:

Thanks for infos. I think something similar could be useful at MFlenses.com


You're welcome. This time I'm 100% on your side. Wink


PostPosted: Sun Nov 01, 2015 11:40 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
Yes, large format has a much higher diffraction limit - f64 is a commonly used aperture among 8x10 shooters.

The data isn't 'made up', those white blobs represent the airy disks.


Yes I realized that after "Submit"... those aren't pixels; it is only a grid placed over many pixels.

The physics is there...on closing the aperture, at some diameter the diffraction of light around the aperture blades causes the airy disk to grow, whereas before that point the airy disk gets smaller, or, perhaps doesn't grow as quickly...


PostPosted: Mon Nov 02, 2015 1:54 am    Post subject: Reply with quote
visualopsins wrote:
I've wondered about this notion that all lenses perform the same at f/8 due to diffraction limits, contrasted with what Puts says about higher macro lens diffraction limit. I know my Macro Takumar seems to be sharpest at f/16. How much of that is simple increased dof, I don't know yet. I think it was phrased best by somebody who said as they are stopped down all lens performances approach each other in terms of quality. Rather than all lenses have the same diffraction limit.

The format makes a huge difference, yes? I would think the diffraction limit for 8x10 to be huge, like f/45, true?


There is no question that diffraction exists, and that you get less with larger formats.

Anyone who often shoots at f/11 with a variety of lenses must notice they do not all perform the same (assuming the 135 format)or they are simply not reviewing the results closely. If you think this is not true: imagine if you are wrong. You would be missing a huge picture when making your choices. So perhaps you should step away from the computer, get out of the house (you need real infinity, not bookshelves) and take a number of lenses to a hill and shoot them all at f/11. Since everybody has lots of 50s that might be easiest.

That other members notice this should give you pause, that Erwin Puts declares it outright, an evidence based reporter, should give you more pause yet. Go see for yourself. And hopefully you will let your own education benefit others with fulls on fllckr we can all see. You will not be the first photographer who had done quite a bit of shooting but was unaware of small aperture visissitudes:
http://www.lensrentals.com/blog/2013/03/overcoming-my-fentekaphobia

Note Puts calls that performance of the 90 Elmar-M at f/11 rare. Yes it is. That's the whole point. You want the rare lens, not the common one.

Last edited by uhoh7 on Mon Nov 02, 2015 2:03 am; edited 1 time in total


PostPosted: Mon Nov 02, 2015 1:59 am    Post subject: Reply with quote
I don't see the point in doing a test at f11 just to see if the laws of physics are correct or not. Diffraction limits resolution, that is the physical properties of light, don't need to test that, t's science fact.

You still haven't explained just what these differences you claim to be able to perceive are? A difference in the level of correction of one or more aberrations? If so, which aberrations? A difference in contrast, macro or micro? Or light intensity or falloff?

Just a blanket statement and some sneering about trying it myself is not a valid argument.


PostPosted: Mon Nov 02, 2015 2:08 am    Post subject: Reply with quote
iangreenhalgh1 wrote:
I don't see the point in doing a test at f11 just to see if the laws of physics are correct or not. Diffraction limits resolution, that is the physical properties of light, don't need to test that, t's science fact.


So where did you get your physics degree?
And no scientist worth the name is against experiment.

Sorry but you don't understand how the science applies to photography in the real world.

Another fellow who's knows alot more about lenses than you or I on this subject:
http://www.lensrentals.com/blog/2013/03/overcoming-my-fentekaphobia

"I have to admit I was a bit shocked. Just as expected, the resolution starts to decrease after f/8, but it doesn't decrease all that much. Even at f/16 the resolution is still quite a bit higher than it was at f/1.4."
"Diffraction softening is fairly constant, but lens sharpening as the aperture decreases is not. Different lenses behave differently."
Roger Cicala, Lens Rentals. Charts included.

You should paypal me a six-pack for the free education. Smile
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