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Why is performance wide open important?
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PostPosted: Mon Nov 02, 2015 2:25 am    Post subject: Reply with quote
You still haven't said just what these difference you claim to see at f11 are?

By talking about diffraction I'm guessing that you're trying to say differences in sharpness will be apparent?

Here's a very good technical article about diffraction with various sensors:

http://dpnow.com/7644.html

A full frame 24mp sensor has a diffraction limit of f11, whereas a 16mp M4/3 sensor has a diffraction limit of just f5.6. Therefore, assuming the same lens set to f11, you will get fuzzier, less sharp results on the M4/3 sensor.

Quote:

The left half of this magnified portion of our test image was shot at f/22 and the right hand side at f/5.6


PostPosted: Mon Nov 02, 2015 3:57 am    Post subject: Reply with quote
uhoh7 wrote:

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


Thanks for the link. Quite interesting reading.

I have to admit that I didn't educate myself too much with every bits and pieces of the theory behind. However, from practical shooting/developing/enlarging since ages that exactly reflects my experience and that certainly helps a lot also for modern digital photography.

Anyway, I was unlike to some other shooters always more interested in larger DOF (also from macro shooting, which I always liked very much) than in very shallow one and of course I am more a sharpness and contrast fan opposite of producing artistically soft "paintings". So the personal taste and special interest plays obviously some role as to how different folks are selecting and using their lenses and presenting their final work.

As already mentioned here before, some shooters will never know because they always use their lenses fully open. Wink


PostPosted: Mon Nov 02, 2015 7:46 pm    Post subject: Reply with quote
tb_a wrote:

As already mentioned here before, some shooters will never know because they always use their lenses fully open. Wink


Well, there are two type of photographers treated unjustly in this discussion

a. Wildlife/bird photographers who are after every bit of extra shutter speed or means of isolating the object
and of course
b. Mirror lens users Mr. Green


PostPosted: Mon Nov 02, 2015 8:09 pm    Post subject: Reply with quote
[quote="listera"]
tb_a wrote:

b. Mirror lens users Mr. Green


That's funny and true. But really, this thread is not about bashing people who have to use lenses wide open, it's about always shooting wide open even if there is no need to. Or not choosing a superior fast lens for stopped down shooting and choosing a slower lens for the shoot just because it IS slower and can be used wide open (same aperture in both examples). It just seems stubborn and unnecessary to me.


PostPosted: Mon Nov 02, 2015 9:20 pm    Post subject: Reply with quote
listera wrote:
tb_a wrote:

As already mentioned here before, some shooters will never know because they always use their lenses fully open. Wink


Well, there are two type of photographers treated unjustly in this discussion

a. Wildlife/bird photographers who are after every bit of extra shutter speed or means of isolating the object
and of course
b. Mirror lens users Mr. Green


Well, I don't think that somebody is treated unjustly as I already explained in my previous comments how I see the issue and the smiley was additionally a clear indication that I meant it rather ironically as indeed there are shooters around who are only presenting pictures at obvious fully open apertures with very fast lenses. It's also rather clear that sometimes there is not other option than to use any lens fully open. Nothing against that.

Furthermore it goes without saying that if a lens doesn't offer the possibility to stop down the aperture that it can't be used other than fully open.

However, bird shooting is most probably more difficult and depends to a great extent on the type of lens used. For instance I didn't see any deeper sense to buy a 300/2.8 lens for that as I would have never used it fully open. Therefore I bought a 300/4 lens instead where the likelihood is much bigger to use it even fully open, although I would also rather stop down to at least F5.6 if the light is sufficient for that. The more expensive faster lens which is heavier and bigger additionally wouldn't be better if used at same aperture anyway.

I do hope that explains the issue as it was meant.


PostPosted: Mon Nov 02, 2015 9:46 pm    Post subject: Reply with quote
To me rule is very simple how can I get out maximum as possible from every captures, if need stop down I do , if need to shoot wide open (rare really) I do as well.
Extremism rarely good adviser in any situation include shoot wide open or not.


PostPosted: Mon Nov 02, 2015 9:55 pm    Post subject: Reply with quote
I have no interest in fast lenses if they are not usable wide open. Why bother walking around with a chunky heavy expensive lens if it doesn`t perform wide open? Many of my favorite lenses are rather slow Wink


PostPosted: Mon Nov 02, 2015 10:22 pm    Post subject: Reply with quote
Nordentro wrote:
I have no interest in fast lenses if they are not usable wide open. Why bother walking around with a chunky heavy expensive lens if it doesn`t perform wide open? Many of my favorite lenses are rather slow Wink

Nikkor 35mm f1.4 pretty crappy wide open, but around f5.6 was lot better than other 35mm , one example, fast due helps a lot in focusing (SLR,DSLR) not really made for wide open shoots, same apply on several fast lenses, even if we not shoot wide open with them they are helpful in focusing , plus in general they are best lenses from their makers.
Some lens fast and huge and useless if you not use it wide open like Sigma 135mm f1.8 a behemot really, smart to use only if need this speed.


PostPosted: Mon Nov 02, 2015 11:04 pm    Post subject: Reply with quote
I think it depends on what sort of image you are trying to achieve when you capture the image as to what aperture you use. I know that I quite like using wide apertures in landscapes and so on to achieve a specific effect, and if I use my Meyer Optik Somnium lens at f/1.5, I can have sharp focus on a subject at the centre of the image and have the edges gradually lose sharpness and not necessarily focus...



Obviously there is some processing done (vignetting, b&w conversion) but the bit of sharpening applied was to the whole image, so it's a reasonable example of how this particular lens works wide open with regard to sharpness.

I'm sure it would be possible to do something similar in software, but I like having the option of doing it with the lens (and I prefer it that way too).


PostPosted: Tue Nov 03, 2015 1:41 am    Post subject: Reply with quote
What I saw is clearer the lens better it's performance stopped down. Maybe I'm dreaming but I find a 1.2 or 1.4 stopped down to f4 or f5.6 always better then it counterparts darker lenses at the same aperture,


PostPosted: Tue Nov 03, 2015 2:47 am    Post subject: Reply with quote
RSalles wrote:
What I saw is clearer the lens better it's performance stopped down. Maybe I'm dreaming but I find a 1.2 or 1.4 stopped down to f4 or f5.6 always better then it counterparts darker lenses at the same aperture,


Not necessarily. There are many examples where the slightly slower sibling beats or at least equals the faster, bigger and more expensive one.
A good example is e.g. the Minolta MD 200/2.8 compared to the MD 200/4. At F5.6 the slower F4 version is visible better.
You can check that yourself here: http://artaphot.ch/sony-nex/altglas/338-nex-5n-und-minolta-200mm-teleobjektive

So if you don't need the F2.8 there is no sense at all to go for the faster lens. I certainly don't need F2.8 at 200mm and I know what I am speaking about as I have such a lens as well.

Same is true for other focal lengths as well. Maybe in the 50mm class it's more common that the faster versions are rather the better ones as there the slower versions have been rather the "budget" versions.


PostPosted: Tue Nov 03, 2015 3:19 am    Post subject: Reply with quote
So there are as many or even more examples where a clearer lens beats its similar in the same FL at closed aperture.

A cleaver advice is to get the focused main subject in the center of the frame, where sharpness is stronger, and let the rest of the image goes submerged in the bokeh region. This way one can profit of the greater clarity of the glass, using their strength and bypassing their weakness.

At this moment I'm not prepared to counter argument the "fact" that the majority of lens makers have designed a clearer lens to just to have it outperformed by a cheaper one made by the same lens maker, as where you seems to be driving your opinion.

The real danger for lens makers with their price tags going upwards in every lens generation, is not the "more clear glass than mine" competition, but lower noise at high ISO. That's what can be a real game changer, in practical terms.
Why do I need after all a clearer 1/2 stop lens priced 5 times more than the one I already have if I can shoot 1/500 at ISO 6400 wide open with barely visible noise?

Cheers,

Renato


PostPosted: Tue Nov 03, 2015 3:44 am    Post subject: Reply with quote
RSalles wrote:
So there are as many or even more examples where a clearer lens beats its similar in the same FL at closed aperture.

A cleaver advice is to get the focused main subject in the center of the frame, where sharpness is stronger, and let the rest of the image goes submerged in the bokeh region. This way one can profit of the greater clarity of the glass, using their strength and bypassing their weakness.

At this moment I'm not prepared to counter argument the "fact" that the majority of lens makers have designed a clearer lens to just to have it outperformed by a cheaper one made by the same lens maker, as where you seems to be driving your opinion.

The real danger for lens makers with their price tags going upwards in every lens generation, is not the "more clear glass than mine" competition, but lower noise at high ISO. That's what can be a real game changer, in practical terms.
Why do I need after all a clearer 1/2 stop lens priced 5 times more than the one I already have if I can shoot 1/500 at ISO 6400 wide open with barely visible noise?


Obviously you misunderstood my message. I stated that it is not ALWAYS the case that the faster lens is beating the slower sibling at same aperture and gave you a example which you cannot deny. This is really a matter of fact. Just compare the pictures. The F2.8 delivers strong CA's at similar sharpness and the F4 version is nearly perfect. I did never and nowhere state that the majority of lens makers have designed their slower lenses better than the faster ones.

Furthermore you shouldn't forget that the higher ISO will always degrade the picture quality to a certain extent. Even on the most modern cameras. However this is certainly a matter of taste and everybody might see that differently. I prefer to shoot at lowest available ISO setting for maximum quality. Others do it differently.

To summarize: My point of view is that not always the fastest lens is the best option. For many already explained reasons. Although I have many very fast lenses myself I rarely use them wide open for picture quality reasons. Sometimes the slower sibling is the better option for many explained reasons as well. That has to be checked carefully before buying a new lens. Finally not everything which is promised by lens makers reflects the reality. Only the comparison will tell you the very truth.


PostPosted: Tue Nov 03, 2015 4:48 am    Post subject: Reply with quote
Maybe I misunderstood your message, and the source could be this statement made by you:
- "So if you don't need the F2.8 there is no sense at all to go for the faster lens. I certainly don't need F2.8 at 200mm and I know what I am speaking about...", and
- "Same is true for other focal lengths as well".
For the first statement I understood that the unique advantage between a clearer lens and a not so clearer one is the greater clarity and nothing else, what I can doubt and reserve for it that old adagio which says "it depends".
For the second one, my impression is that you have concluded - from the first statement made - that this argument can be applied to any lens without restriction - what you have denied later, what's its a good conclusion, after all.

To buy a lens only for the WO f-number being lower, or its price being higher then another one less expensive is not a smart decision, but it happens very often - I'm thinking about night street shutters or night sports shutters as well. It's better to read a good and reliable source and the MTF charts, if one is inclined to support foreign opinions with numbers, not bypassing the stabilization capabilities of the lens in question and the camera itself,

Cheers,

Renato


PostPosted: Tue Nov 03, 2015 8:29 am    Post subject: Reply with quote
RSalles wrote:
Maybe I misunderstood your message, and the source could be this statement made by you:
- "So if you don't need the F2.8 there is no sense at all to go for the faster lens. I certainly don't need F2.8 at 200mm and I know what I am speaking about...", and
- "Same is true for other focal lengths as well".
For the first statement I understood that the unique advantage between a clearer lens and a not so clearer one is the greater clarity and nothing else, what I can doubt and reserve for it that old adagio which says "it depends".
For the second one, my impression is that you have concluded - from the first statement made - that this argument can be applied to any lens without restriction - what you have denied later, what's its a good conclusion, after all.

To buy a lens only for the WO f-number being lower, or its price being higher then another one less expensive is not a smart decision, but it happens very often - I'm thinking about night street shutters or night sports shutters as well. It's better to read a good and reliable source and the MTF charts, if one is inclined to support foreign opinions with numbers, not bypassing the stabilization capabilities of the lens in question and the camera itself,


Thanks for your clarification, Renato. Obviously it was my fault that this misinterpretation was possible. The second statement was in context of my mentioned example of the 300 mm lens mentioned earlier in a previous comment but was not intended to be understood as a general statement.

However, I think our opinions are nor too different after all. Wink

Cheers,


PostPosted: Tue Nov 03, 2015 9:24 am    Post subject: Reply with quote
Just to state the obvious, there are of course lenses which are designed to be used wide open. Who would lug around a Nikkor 200/2 and use it for anything other than wide open shooting. It is possible of course but what is the point?

But someone brought up the example of a 300/2.8 lens and a 300/4 lens. If the 300/4 lens is used wide open most of the time then maybe the 300/2.8 is an even better option if it's performance is better at f4 than the 300/4 lens? If used on a tripod then maybe the size does not matter, only the absolute IQ. Then again, this doesn't have to be the case as was exemplified withe the MD 200/2.8 and the MD 200/4 where the slower lens is sharper at 5.6



PostPosted: Tue Nov 03, 2015 4:03 pm    Post subject: Reply with quote
I recall, back in about 1978 or so, while shopping at a convenience store, my eyes being drawn into an image on the cover of Sports Illustrated magazine. Now, this was a good four years or so before I bought my first "real" camera, a Canon AE-1. Anyway, what captivated me so was what we now refer to as bokeh. The image was of a baseball pitcher in his windup. Only he was in focus, the background was completely blown. I was fascinated by this. And it wasn't until quite a few years later that I realized the photo had to have been taken with at least a 300mm f/2.8, maybe even a 600mm f/4. And it was a few years after that, still, that I could afford my first lens that would deliver this sort of blown-out bokeh. For me, it was the Tamron 300mm f/2.8. I couldn't afford the Canon or Nikon equivalent. I had been trying to get by, pror to that, with a Canon 200mm f/2.8 and 300mm f/4. Both very nice optics, butt they didn't deliver that blown-out bokeh I remembered from that Sports Illustrated photo. It had been a quest that lasted about eight years or so, but finally I had what I considered to be the basic admission ticket for real sports photography -- and other outdoor subjects as well because by that time I'd seen and read up on lots of uses for a lens like a 300mm f/2.8 -- or longer.

I think it's fair to say I remain fascinated by photos in which the subject is totally isolated from the background. But I've learned from doing that this is often easier conceived than done. Even with a very fast lens, situations have to be just right in order to achieve the goal. And of course the lens must be up to the task of rendering sharp focus when used wide open, so not just any fast lens will do.

All the other attributes of fast lenses I can appreciate, but I've always appreciated the separation that can be achieved most.


PostPosted: Tue Nov 03, 2015 4:10 pm    Post subject: Reply with quote
Attila wrote:
Nordentro wrote:
I have no interest in fast lenses if they are not usable wide open. Why bother walking around with a chunky heavy expensive lens if it doesn`t perform wide open? Many of my favorite lenses are rather slow Wink

Nikkor 35mm f1.4 pretty crappy wide open, but around f5.6 was lot better than other 35mm , one example, fast due helps a lot in focusing (SLR,DSLR) not really made for wide open shoots, same apply on several fast lenses, even if we not shoot wide open with them they are helpful in focusing , plus in general they are best lenses from their makers.
Some lens fast and huge and useless if you not use it wide open like Sigma 135mm f1.8 a behemot really, smart to use only if need this speed.


I am pretty sure that there are other slower 35mm lenses with just as good IQ at f/5.6 Wink
I only use Speedmaster 50mm 0.95 if I plan to shoot wide open...


PostPosted: Tue Nov 03, 2015 4:15 pm    Post subject: Reply with quote
I have several lenses that I only ever use wide open.
The reason is simple they don'y have any option for adjusting the aperture!

If there's a control to adjust the aperture, then I use as the subject demands - sometimes shooting wide open for minimal DOF or maximum light (and often wanting more of light!) If low light isn't an issue most of the time I'll stop down at least a stop or two.


PostPosted: Tue Nov 03, 2015 6:43 pm    Post subject: Reply with quote
cooltouch wrote:
I think it's fair to say I remain fascinated by photos in which the subject is totally isolated from the background. But I've learned from doing that this is often easier conceived than done. Even with a very fast lens, situations have to be just right in order to achieve the goal. And of course the lens must be up to the task of rendering sharp focus when used wide open, so not just any fast lens will do.

All the other attributes of fast lenses I can appreciate, but I've always appreciated the separation that can be achieved most.


Like 1


PostPosted: Tue Nov 03, 2015 8:09 pm    Post subject: Reply with quote
RSalles wrote:
What I saw is clearer the lens better it's performance stopped down. Maybe I'm dreaming but I find a 1.2 or 1.4 stopped down to f4 or f5.6 always better then it counterparts darker lenses at the same aperture,


I've wondered about this since somebody asked me years ago.

Thanks for sharing your experience.

May I ask please what you find better?


PostPosted: Tue Nov 03, 2015 10:29 pm    Post subject: Reply with quote
@Ian. TY for that link as I am discussing that very issue in another forum, where they are all telling me 42mp is no problem with extra diffraction because the effect disappears in the down size. Meaning they say if you downsize your 42mp to 24mp then the diffraction will be the same. I didn't think that made total sense. Now I have more ammo. TY.

Now where I shoot most of the time is 18mp, the M9, and thats where some lenses appear better to me than others at f/11. I have tested this very little on the A7.mod but am interested in comparing the two in light of the controversy.

But this article is by Ian Burley, is that you?

Pontus wrote:
Just to state the obvious, there are of course lenses which are designed to be used wide open. Who would lug around a Nikkor 200/2 and use it for anything other than wide open shooting. It is possible of course but what is the point?


The point is DOF and Sharpness. Yes that 200/2 is spectacular at F/2: so good it's no problem to use the shots. But your DOF is nothing. And it is sharper yet at f/4.

The last two lenses I have bought look very similar to your 200/2:

300/2.8 ais by unoh7, 300/2.8 EDIF

500 P by unoh7, 500/4 P

And as noted above, for birding or wildlife I need a fast shutter so I am going to be using them WO fairly often, where they perform extremely well. But the DOF is NOTHING!

Baaaa by unoh7, 500 at f/4

This means focus is much harder and everything but your subject is blury. Which is fine sometimes. BUT NOT ALL THE TIME Smile So of course, I will stop them down whenever it's possible and I'm not going for the "nocti WO" look LOL

Luckily these two lenses have the best bokeh of any nikkor lenses I've ever seen and in that regard they equal any Leitz lens.


Bo Peep by unoh7, 300/2.8 WO
But really I should have some down in this last one to 5.6 as there is no way at 2.8 to get much in focus, but I like the shot anyway Smile


PostPosted: Wed Nov 04, 2015 12:55 am    Post subject: Reply with quote
No my name is Greenhalgh. I linked to Ian Burley's article earlier, it has useful pictures showing what diffraction looks like.

One thing about diffraction - unless it's severe, sharpening usually overcomes it.

Downsampling from 42 to 24 would do it too.

There is definitely a difference in diffraction between sensors and it's not just due to pixel density, other factors like the thickness of the glass stack, the design of the microlenses and the strength of the AA filter (if it has one) are all factors.


PostPosted: Wed Nov 04, 2015 3:40 am    Post subject: Reply with quote
visualopsins wrote:
RSalles wrote:
What I saw is clearer the lens better it's performance stopped down. Maybe I'm dreaming but I find a 1.2 or 1.4 stopped down to f4 or f5.6 always better then it counterparts darker lenses at the same aperture,


I've wondered about this since somebody asked me years ago.

Thanks for sharing your experience.

May I ask please what you find better?


The first example that I can remember is Zeiss Contax Planar 1.7/50 and 1.4/50 as I had both, and preserved the faster for the reasons I explained above. Other samples are Canon EOS 50/1.4 and 50/1.2 L, tried both and the 1.2 sample was a little better, colors were stunning and a excellent tool for portraits of full body at mid distance.

Cheers,

Renato


PostPosted: Wed Nov 04, 2015 5:27 am    Post subject: Reply with quote
@Renato: I think you need Canon EF 50/1L Smile

iangreenhalgh1 wrote:
No my name is Greenhalgh. I linked to Ian Burley's article earlier, it has useful pictures showing what diffraction looks like.

One thing about diffraction - unless it's severe, sharpening usually overcomes it.

Downsampling from 42 to 24 would do it too.

There is definitely a difference in diffraction between sensors and it's not just due to pixel density, other factors like the thickness of the glass stack, the design of the microlenses and the strength of the AA filter (if it has one) are all factors.

TY Ian Smile

These extra factors: thickstack=earlier diffraction? (f/8 with thick f/10 with thin?) any reference or links I'd love to see (seriously--just to learn what others think--as I would suspect the thicker glass makes it happen sooner, I can't really back that up LOL)

Microlens design effect on diffraction? It's not that I don't believe it, but would love to see the references to learn more about it.

AA filter? I have the impression this mellows the diffraction effect from my reading, but common sense tells me no AA filter could be potentially better, or have downsides somewhere else. Again any links you have or find, whenever appreciated. Smile

I've been boning up at cambridge color, where there are two good (and more I'm sure) articles witch relate to diffraction and digital cameras:
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm
http://www.cambridgeincolour.com/tutorials/lens-quality-mtf-resolution.htm

Here a interesting quote from one of these:
"The aperture corresponding to the maximum MTF is the so-called "sweet spot" of a lens, since images will generally have the best sharpness and contrast at this setting. On a full frame or cropped sensor camera, this sweet spot is usually somewhere between f/8.0 and f/16, depending on the lens. The location of this sweet spot is also independent of the number of megapixels in your camera."

A little self-defense: Wink
The last sentence seems to contradict the 42mp problem (early diffraction), but anyway, f/11 is certainly between f/8 and f/16, not to mention the M9 is sensor is not diffraction-limited at f/11, though A7r is Wink ,so real world, this is a very sharp aperture with many lenses and at least astigmatic aberrations, coatings, tolerances, grinding methods, and maybe other factors will discriminate lenses, thus vindicating the contention of me and Puts, that yes, some lenses stand well apart at f/11 Smile

I think your remark about the sharpening potential for f/11-f/16 and maybe beyond is well taken, I need to try it more. I found this quote tonight:
"What I've found most helpful is deconvolution sharpening (not typical edge sharpening) for the capture sharpening step. This is available in various software (Iridient Raw Developer is one I'm aware of), but I am especially fond of using it in Lightroom since that is my preferred workflow. In the sharpening panel, when you move the Detail slider all the way to the right (+100) it turns the algorithm into essentially all deconvolution (according to Jeff Schewe who helped design this part of LR). Start with amount between 40 to 50, radius 0.8, and masking at 0 (and raise the masking amount depending on the image content, such as if there is sky or smooth tones you don't want sharpened). The 645D, and even more the Z, will take large amounts of sharpening extremely well without visible artifacts. In addition to losing sharpness to diffraction, it also robs your image of micro and global contrast, but adding a few points of Contrast and Clarity in Lightroom nicely restores that."
SeattleDucks
Read more at: http://www.pentaxforums.com/forums/48-pentax-medium-format/299252-diffraction-killing-your-645z-images.html#ixzz3qUuSAf4b

Lastly, for anyone interested: here is a youtube video with a great introduction to how digital sensors work, by the inventor of the CMOS, and at 38 mins he goes into major rant about megapixel marketing, declaring: the force of marketing is greater than the force of engineering. Technically the pixel density makes no sense, but it sells!
https://www.youtube.com/watch?feature=player_embedded&v=JkBh71zZKrM

Smile
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