SquamishPhoto said:
Holy cop-out batman!
Not my problem that you don't choose to learn on your own. I have better uses for my time.
Nikon D800? Which lens to get maximum sharpness at closed apertures f20+???
(45 posts) (12 voices)-
Posted 1 year ago #
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There is no shame in bowing out...
Posted 1 year ago # -
Since you are so smart Squamish why don't you inform everyone how lens design makes no difference in the image it takes. I'm sure everyone would be enlightened on how the advent of the digital sensor has created diffraction. Lay it out for us.
Posted 1 year ago # -
You can't be serious. Im not the one making claims like you are and my arguments are not the ones left without any supporting evidence.
Posted 1 year ago # -
TaoTeJared said:
I'm not getting into diffraction even if some take every chance they can to hijack any thread to argue on it.Nor is there enough space to discuss various lens design decisions and make-ups. Sometimes you have to go and search and learn topics on your own. Forums will never be able to give the justice to lens designs. Tessar, Planner, Sonnar, Double-Gauss, Biogon, Catadioptric, and a whole slew of others that all were designed for different purposes and had their own strengths and limits. All of these original designs have been expanded to integrated into various new lenses. To think that all lenses are the same is like saying that every photographer is the same, and it's the camera makes the difference.
You probably mean me TTJ, but I believe this is really a diffraction topic. The only times that I have gotten into diffraction discussions ( off topic ) are the times you say diffraction starts at f22 or so in some lenses or that macro lenses are designed for better diffraction performance. I have specifically tried not be offensive ( or be seen that way ) or personal in my addresses as, for me, this is just a scientific discussion . And to be honest, I hate to be doing it with you - after all your contributions to this forum..
All my arguments are backed by physics/ diffraction tables and serious articles which I have provided and can provide links to. We haven't seen anything from you on any occasion yet you keep giving out the same wrong information any time someone talks about diffraction .
I am still waiting to see a single lens test that includes diffraction as one of the parameters or a test which shows better lens MTF resolution at f16/f22.
Had diffraction been something controllable by design, wouldn't we have seen it included in tests by now - to see how each lens performs for/under diffraction ?
Posted 1 year ago # -
Is this useful?
Posted 1 year ago # -
Not a bit :-) I commented there this morning what a shallow and meaningless article it was. Surprised it took place in NR as none of what the author said was backed up with scientific evidence ; it was purely his opinions with barely a paragraph spared for each subject. As expected, 90% fell for it .
Fortunately, there was the 10% ...
Posted 1 year ago # -
This is not my area of expertise, but according to everything I've just read on the subject of diffraction, it would not be affected by sensors, but it is affected by the quality of the light presented to it and only when light is presented to an aperture 'perfectly' is the lens said to be truly diffraction limited therefore - based on what I have just read - you are likely to get better diffraction performance from some glass than from other glass. As to why it is not mentioned in tests, I am not qualified to say but it may be because a/ the difference is so small as to be irrelevant, or b/ it is too hard for ordinary lens testers to measure. I don't know.
http://en.wikipedia.org/wiki/Airy_disk
I do know for sure that we didn't ought to get bent out of shape about it though - and I am qualified to be able to state that for sure!
Have a nice day everybody.
Posted 1 year ago # -
Now this thread is getting good. And, as now how I have done basic research, albeit in the 1970's, I understand how the bench data is where we must actually start. But, in the discussion of any camera/lens discussion, it makes very little difference what the bench data is when the real world stuff demonstrates the desired end result.
So, it would appear, the only solution to the initial question of "what lens for great depth of field?" is to try the combos in the field and see the results. The final evaluation is what a client desires whether the client is oneself or another.
The usefulness of the knowledge base on this thread suggests maybe the good images could be obtained with the D4, and this is what I think I have demonstrated in the example. I do not have a D800, but would love to see the real world field test comparing the two cameras. Interestingly enough, in viewing some images on the various posts on NRF, I have seen enough to decide I really do not want a D800 as I see no significant difference between what is posted as D800 and my D4 images. Again, this is MY OPINION or MY TASTE applied to the end result. This has no bearing on what someone else may see in a photo or group of photos.
One more note on research as we are trying to figure this out and use research or scientific data as well as real world experience to answer the question. There is an extraordinary amount of scientific information which is bogus. Either the appropriate scientific method was not employed in the gather ing of the data or the information was massaged to obtained the desired results. This can only be determined by careful analysis of the research methods used.
So, someone send to me a D800 and I will go out and photograph the Mack Truck World Headquarters again...
Posted 1 year ago # -
I have to agree with both, Paperman and TTJ.
First of all: diffraction is a function of wavelength and aperture. There is no way around that. Diffraction limits resolution, so the wider your aperture the finer details you can resolve in theory (this is one of the reasons why astronomers use these huge diameter (= aperture) telescopes.
But diffraction does not limit "sharpness". Unfortunately there is no real measurement for "sharpness". The closest thing is the MTF that describes how a lens handles contrast and resolution. You might compare two lenses and one has got a higher MTF value at a given resolution (so it looks sharper here), but drops the MTF dramatically at higher resolutions (so it might not be able to resolve as much as the second one). And this is where lens design does kick in. Both lenses will be limited by diffraction, but how they handle the contrast (MTF) at or close to the diffraction limit might be different. So one looks sharper than the other.
So, no lens can beat the diffraction limit. But lenses can be designed to perform better at closed apertures (have the better MTF) than others. I do not have any evidence at all, but I would suspect that a typical portrait lens (e.g. the 85 mm f/1.4) is optimized for open apertures (shallow depth of field) and macro lenses are optimized for closed apertures.
To the OP: I can't give you any real hint on what lens to use. I think all of the lenses mentioned are excellent ones (and I do not own any of those). If you need "sharp" images use a tripod if your shooting style allows it. Take a look at the MTF of the lenses (for example at DXO mark) and compare them to your existing ones. The higher the MTF is at a given aperture the sharper the images will look.
Hope this helps.
Posted 1 year ago # -
Oops
Posted 1 year ago # -
spraynpray said:
@Gareth: Doesn't the dof end up the same as you move back then crop to the original size?no. try it. take a shot of a relatively close object(3-6'). take a step or two back and take the same shot. then crop so they look the same. you will need a short to mid tele, or your perspective will change too much.
this is why fx has shallower dof than dx. you need to be closer to you subject to frame the same shot. it makes a big difference.
Posted 1 year ago # -
Gareth said:
no. try it. take a shot of a relatively close object(3-6'). take a step or two back and take the same shot. then crop so they look the same. you will need a short to mid tele, or your perspective will change too much.this is why fx has shallower dof than dx. you need to be closer to you subject to frame the same shot. it makes a big difference.
And why with 4" x5" or better yet, 8" x 10" we were always shooting at f/45 to obtain depth of field. DOF is a function of lens focal length and thus the little point and shoots with the 5mm lens focal lengths have incredible DOF.
Posted 1 year ago # -
Correlli said:
I have to agree with both, Paperman and TTJ.You can not agree with us both, Corelli :-)) ....
Think of a PERFECT lens with no flaws - no aberrations, no distortions , no vignetting , no loss of sharpness at edges , etc ...
This lens is best at diffraction at its WIDEST aperture ; the image quality starts to deteriorate as you close down the aperture hole. This is what laws of physic say. In other words, your lens would be best at f1.4, worst at f32 - had it been a PERFECT lens ( maybe a lens with no lens :-) ) .
However, as we all know, there is no perfect lens - there are the flaws I mentioned above and a whole lot more. The designers play with them all, trying to get the best combination for the purpose of that specific lens .
The fact that a lens is sharpest ( for example ) at f8 does not mean its diffraction is handled to be better at f8 . It's just that optical flaws that effect resolution are more when you move away from that aperture .
At f8 ,let's say you are at ZERO optical fault - only diffraction
If you close down the aperture towards minimum, it becomes + diffraction + optical flaw.
If you open the aperture towards maximum , it is + optical flaws - diffraction .( to be cont'd )
Posted 1 year ago # -
Sounds pretty reasonable to me. Thanks for the detailed explanation. :]
Posted 1 year ago # -
I thought that macro lenses were just designed to perform better at closer focussing distance than a normal lens?
Posted 1 year ago # -
( Continuing from where I left )
Looking at how most lenses perform, we all know it is probably easiest/cheapest to design a lens that will work at its best around 2 f-stops smaller than maximum aperture.
Going into extremes, you will get the super telephotos like 400mm f2.8 or 600mm f4 which would leave you $5,000-10,000 poorer but will provide you sharpest images at maximum apertures. ( Let's not forget , diffraction is on your side when you are at max aperture )
Having said all this, now one can always think of a crazy designer who will diminish his company resources designing the lens - had there been no diffraction - that would give maximum performance at f22 . Is it possible ? - most probably yes, with the sole purpose being macro photography . However , the performance of the lens had to be so good - so good that the diffraction loss ( which I would say is around 1200-1500 lw less than it would be at f5.6 - I checked some lens tests to get a figure ) would not wipe away what his f22 perfect design had brought .
And let's not forget this lens would be pretty useless for anything other than macro as all lens designs are compromises.
Out of curiosity, just checked resolution tests of 3 macro lenses .
Canon 100mm f2.8 USM L Macro .
3391 lw/ph at f2.8 , 3511 lw at f5.6 , 2478 lw at f22Sigma 150mm f2.8 EX DG HSM APO Macro
3459 lw/ph at f2.8 , 3737 lw at f5.6 , 2524 lw at f22Micro Nikkor 40mm G f2.8 DX ( couldn't find a decent micro on same site )
2565 lw/ph at f2.8 , 2804 lw at f5.6 , 1953 lw at f22And we were saying macro lenses for designed for better resolution at smaller apertures ??
Posted 1 year ago # -
Paperman said:
You can not agree with us both, Corelli :-)) ....But I do! :)
I agree with you that you cannot beat the diffraction limit and I agree with TTJ that lens design does have an impact on how a lens performs at f/22 regarding sharpness (which has only little to do with resolution or diffraction).
Paperman said:
And we were saying macro lenses for designed for better resolution at smaller apertures ??Not really (at least I was not). I was assuming that the MTF (contrast at a given resolution) and therefore the perceived sharpness of the image at closed aperture might be better with macro lenses than with non-macro ones.
By the way, what does "lw" or "lw/ph" in your resolution values stand for?
Posted 1 year ago # -
line widths/picture height - a unit for measuring sharpness.
And none of what I wrote was intended for you Correlli - except the first sentence. Sorry if it was understood that way.
Posted 1 year ago # -
Let's see what Nikon suggests in the D800 technical guide about diffraction. ( Page 13&16 - increasing optical performance . Thanks Dehidding )
http://www.nikonusa.com/en_US/o/Y6wrkA9OU_z04IreazIXl_22UII/PDF/D800_TechnicalGuide_En.pdf
Posted 1 year ago #
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