Home
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

Fast 135mm lenses (and two zooms at f=135mm)
View previous topic :: View next topic  


PostPosted: Sun Aug 02, 2020 11:54 am    Post subject: Reply with quote

Gerald wrote:
visualopsins wrote:
Is the depth of field less at the edges than at the center, or an even thickness center to edges?


Interesting question, I have never seen anyone discussing possible variations of the depth of field throughout the image field. Nonetheless, the depth of field depends on the effective aperture, so, in principle, vignetting would produce a slight increase in depth of field at the edges and corners.

Exactly.

Gerald wrote:

In practice, the increase in depth of field at the edges and corners is not significant enough to be taken into account.

Yes and no. If your lens opening becomes "cateye" shaped towards the edges and corners (especially with fast lenses and wide open!), there will be more depth-of-field (=sharpness) in one direction and less depth-of field (less sharpness) orthogonal (at right angles) to this direction. In other words: That's one possible cause of astigmatism. And astigmatism can be quite disturbing.

S


PostPosted: Sun Aug 02, 2020 12:20 pm    Post subject: Reply with quote

hasenbein wrote:
Waiting for the zoom lenses part... twiddling my thumb...


For time being I have updated the comparison with the data for the Canon nFD 2/135mm and the Nikkor AiS 2/135mm:



No real surprises here - the 2/135mm designs from Canon and Nikon (as well as Minolta) are comparatively new (around 1980) and - for their time - quite advanced. Larger apertures require stronger curved lenses (if the glass remains the same); this in turn increases the monochromatic aberrations. To reduce these monochromatic aberrations, glass with a higher refractive index is used - and such glass usually has a higher dispersion (= more CAs).

The zoom lens data (at f=135mm) of different classical tele zooms will follow shortly:

Canon nFD 4/80-200mm L
Leica R 4/70-210mm
Minolta MD 4/70-210mm
Nikkor AiS 4(80-200mm
Zeiss C/Y 4/80-200mm

S


PostPosted: Sun Aug 02, 2020 1:09 pm    Post subject: Reply with quote

stevemark wrote:
hasenbein wrote:
Waiting for the zoom lenses part... twiddling my thumb...


For time being I have updated the comparison with the data for the Canon nFD 2/135mm and the Nikkor AiS 2/135mm:



No real surprises here - the 2/135mm designs from Canon and Nikon (as well as Minolta) are comparatively new (around 1980) and - for their time - quite advanced. Larger apertures require stronger curved lenses (if the glass remains the same); this in turn increases the monochromatic aberrations. To reduce these monochromatic aberrations, glass with a higher refractive index is used - and such glass usually has a higher dispersion (= more CAs).

The zoom lens data (at f=135mm) of different classical tele zooms will follow shortly:

Canon nFD 4/80-200mm L
Leica R 4/70-210mm
Minolta MD 4/70-210mm
Nikkor AiS 4(80-200mm
Zeiss C/Y 4/80-200mm

S


Very comparable images from the Nikkor and Canon.


PostPosted: Sun Aug 02, 2020 8:14 pm    Post subject: Reply with quote

caspert79 wrote:

Very comparable images from the Nikkor and Canon.


Absolutely. And bokeh at portrait distances is indistinguishable as well.

S


PostPosted: Sun Aug 02, 2020 8:39 pm    Post subject: Reply with quote

Why don't you show us some bokeh examples instead of these pointless corner crops, that would be much more useful.


PostPosted: Sun Aug 02, 2020 10:29 pm    Post subject: Reply with quote

iangreenhalgh1 wrote:
Why don't you show us some bokeh examples instead of these pointless corner crops, that would be much more useful.


My usual work is focused on landscape and architecture photography, and sometimes I'm being asked to shoot objects e. g. for a museum. Delivering 50 MP images which are perfectly sharp to the corners and CA free repeatedly has resulted in well paid contracts. For these purposes I'm using "modern" lenses, not vintage gear. Nevertheless I'm interested in the technical development that has taken place over the years, and occasionally I do test vintage lenses in the same way as I would test those lenses I'm using professionally.

That said, I'm not at all an expert on portrait photography and bokeh. Recently, when i was comparing the bokeh and softening characteristics of four soft focus lenses, some people were complaining that i hadn't been shooting these images with a nice model. They are right, but I have neither the time nor the means to make such extensive tests.

There are lots of people here on the forum shooting portrait and street. I really would like to encourage them not only to provide anecdotal information and occasional images, but to do real tests, comparing several lenses side-by-side!

Stephan


PostPosted: Tue Aug 04, 2020 11:51 am    Post subject: Reply with quote

stevemark wrote:
iangreenhalgh1 wrote:
Why don't you show us some bokeh examples instead of these pointless corner crops, that would be much more useful.


My usual work is focused on landscape and architecture photography, and sometimes I'm being asked to shoot objects e. g. for a museum. Delivering 50 MP images which are perfectly sharp to the corners and CA free repeatedly has resulted in well paid contracts. For these purposes I'm using "modern" lenses, not vintage gear. Nevertheless I'm interested in the technical development that has taken place over the years, and occasionally I do test vintage lenses in the same way as I would test those lenses I'm using professionally.

That said, I'm not at all an expert on portrait photography and bokeh. Recently, when i was comparing the bokeh and softening characteristics of four soft focus lenses, some people were complaining that i hadn't been shooting these images with a nice model. They are right, but I have neither the time nor the means to make such extensive tests.

There are lots of people here on the forum shooting portrait and street. I really would like to encourage them not only to provide anecdotal information and occasional images, but to do real tests, comparing several lenses side-by-side!

Stephan


I totally agree with you, corner sharpness is often the only difference between average and exceptional lenses, and is the first thing I check, before bokeh, character, and so on. Those who are not interested in architecture, landscape, furniture, technical photography in general, probably do not understand these needs, but photography is not only portraits and flowers. Moreover it is full of insignificant "tests", absolutely ineloquent photos posted at 2000 pixels, that there is really no need to add more. I appreciate your tests because the conditions are quite standardized, and they only tell us one thing, but they tell us it clearly. However, I would have liked to have two or three crops: (center and corner, or center, midpoint, and corner); I understand BTW that the work would increase a lot this way.


PostPosted: Tue Aug 04, 2020 12:38 pm    Post subject: Reply with quote

Maybe we understand, but could care less....


PostPosted: Tue Aug 04, 2020 1:28 pm    Post subject: Reply with quote

Ultrapix wrote:
stevemark wrote:
iangreenhalgh1 wrote:
Why don't you show us some bokeh examples instead of these pointless corner crops, that would be much more useful.


My usual work is focused on landscape and architecture photography, and sometimes I'm being asked to shoot objects e. g. for a museum. Delivering 50 MP images which are perfectly sharp to the corners and CA free repeatedly has resulted in well paid contracts. For these purposes I'm using "modern" lenses, not vintage gear. Nevertheless I'm interested in the technical development that has taken place over the years, and occasionally I do test vintage lenses in the same way as I would test those lenses I'm using professionally.

That said, I'm not at all an expert on portrait photography and bokeh. Recently, when i was comparing the bokeh and softening characteristics of four soft focus lenses, some people were complaining that i hadn't been shooting these images with a nice model. They are right, but I have neither the time nor the means to make such extensive tests.

There are lots of people here on the forum shooting portrait and street. I really would like to encourage them not only to provide anecdotal information and occasional images, but to do real tests, comparing several lenses side-by-side!

Stephan


I totally agree with you, corner sharpness is often the only difference between average and exceptional lenses, and is the first thing I check, before bokeh, character, and so on. Those who are not interested in architecture, landscape, furniture, technical photography in general, probably do not understand these needs, but photography is not only portraits and flowers. Moreover it is full of insignificant "tests", absolutely ineloquent photos posted at 2000 pixels, that there is really no need to add more. I appreciate your tests because the conditions are quite standardized, and they only tell us one thing, but they tell us it clearly. However, I would have liked to have two or three crops: (center and corner, or center, midpoint, and corner); I understand BTW that the work would increase a lot this way.

I do agree too. I mostly shoot landscapes and corner-to-corner sharpness at infinity is important to me. Yes, I am aware that stopping down to f/8 will give it to me in almost any lens, but I don't always want to stop down that much and if I choose to buy a "faster" lens, it would specifically to not have to stop it down at f/8.

And yes, when I shoot the occasional portrait, the corners' sharpness is not relevant but background blur in the corner because of shallow depth-of-field is not comparable to softness.


PostPosted: Tue Aug 04, 2020 1:59 pm    Post subject: Reply with quote

Gerald wrote:
visualopsins wrote:
Is the depth of field less at the edges than at the center, or an even thickness center to edges?


Interesting question, I have never seen anyone discussing possible variations of the depth of field throughout the image field. Nonetheless, the depth of field depends on the effective aperture, so, in principle, vignetting would produce a slight increase in depth of field at the edges and corners. In practice, the increase in depth of field at the edges and corners is not significant enough to be taken into account.


Thanks. I think I understand less illumination means effective aperture there is greater, but it seems counter-intuitive.

Put lens with APS-C image circle on FF camera -- are you saying the dof surrounding the image circle is infinite?


PostPosted: Tue Aug 04, 2020 2:12 pm    Post subject: Reply with quote

Ultrapix wrote:
I appreciate your tests because the conditions are quite standardized, and they only tell us one thing, but they tell us it clearly.

Thank you Wink

Ultrapix wrote:

However, I would have liked to have two or three crops: (center and corner, or center, midpoint, and corner); I understand BTW that the work would increase a lot this way.


It's not really a matter of additional work (once I have found/acquired the lenses and shot the test images, the only additional work is to prepare additional crops from the existing images), but the sheer amount of information created. Personally I don't like checking dozens of crops to find minor differences, so I try to chose as few as possible (but meaningful) crops. Imagine publishing the test results of ten 80-200mm zooms at f=80mm, f=135mm and f=200mm, each at three apertures and with three different crops (center, midfield, corner). And at different distances of course, maybe "infinity", 2.5 m and 1.2 m (Macro 1:4). That would result in nearly thousand crops ... I as a tester can easily take lots of pictures and then check them even in camera, to get most of the information needed. Instead of publishing all the images it's probably much more useful to write down / publish the essential observations ?!?

Anyway, next time I'll compare only a few lenses (let's say Zeiss Jena Sonnar 3.5/135mm, Pentacon [Meyer] 2.8/135mm, and Zeiss Oberkochen CY Sonnar 2.8/135mm), at three different apertures and with three different crops (center, midfield, corner).

S