Hello Ralph,
probably the difference is because of the following reasons.
1. ....
2. .....
3......
Best regards,
Henning
??? Are we talking about LENS resolution, or FILM resolution?
to be precise: We are talking about system resolution. Aron tested his 55m Fuji lens in combination with Ilford Delta 100.
I have tested the Zeiss 2/50 (and other lenses) in combination with Delta 100 (and lots of other films). And with other films, the resolution values differ, of course. In each case a more or less different system resolution dependant on the film used.
The original title was "Very High Resolution LENS" , not "Camera" or "System".
Of course, far more often than not, we will use our lenses in cameras, but I think it is a grave error to judge the value of a LENS from a test with so many potential biases possible from an entire SYSTEM ... and this is done all too frequently in photography. I am NOT trying to be anally "pecise", just clinging, hopefully, to reality.
??? Are we talking about LENS resolution, or FILM resolution?
In LENS testing (at least in the old, Luddite, Optical Bench way), no film or ground glass is used: the microscope is focused on the aerial image - much the same as "Grain Focusing" in the enlarger.
Introducing film into the testing provides the opportunity for a number of elements that will invariably degrade the results: flm flatness, emulsion/ developing charactersitics, mechanical "shake" of the support system ...
Is it possible to see exteremly high resolution in any area of any given lens? Absolutely, but maximum resolution, by itself, is an incomplete test of the performance of a lens.
I think that the sales of second-hand Fujica ST801 Cameras with an EBC Fujinon 1.8/55 lens have risen dramatically since you have made this post.I've made two tests using one of my recently acquired cameras (Fujica ST801 with EBC Fujinon 1.8/55) on the resolving power of the lens. For the first test I used a moderate resolution film (Fomapan 200) and the results showed actually the resolution of the film (110 lp/mm) and not lens.
Today I made new tests using Delta 100 developed in Rodinal 1:25. For the illumination of the test chart I used a 1000W halogen lamp, so contrast was high.
These are my results (lp/mm)
Aperture: centre, very close to edge, edge
f1.8: 85, 57, under 50
f2.8: 156, 69, under 50
f4: 161, 89, under 50
f5.6: 147, 101, 55
f8: 115, 101, 69
f11: 69, 55, 69
f16: 69, 69, 69
Do you think I was doing something wrong during this test or it is actually possible to achieve such a high resolution with this setup? The lens is a 'Planar' type design.The prints from this camera do look very sharp (to me), even heavily cropped ones taken at f1.8. I'm somewhat surprised. :rolleyes:
It also is somewhat interesting for me (I used a Tessar lens for a long time), that diffraction already takes its toll at f5.6-f8, most notably at f11.
The figures look to be about twice what one would expect. How are you counting lp/mm?
Every time I see a lens test I wonder what conditions it was done under. Was the contrast 1000:1 or 50:1? Was a tripod used or was it a bean bag? Was the mirror locked up if an SLR was used? Was a film like TP or Imagelink used or was a less sharp and more grainy film used?
Were the results interpreted by scanning or other digital means?
When I think of a lens like the Zeiss 50/2 macro I'm sure it's quite good. The question for me is whether it is enough of an improvement over a lens like the 55/2.8 Micro Nikkor to make a difference for anything I might do. Very little close-up or macro work is done at f/2. The exception might be some work with micro lenses. These are actually optimized for use at or near wide open.
If I shoot hand held and use Tri-X or TMY2 or Plus-X, will I get these same test results? Will I ever be able to get results like the ones mentioned in practical use? If I just need to make a large print I'll use a 100/3.5Zenzanon PG on a Bronica GS-1 with Pan F+. You can use any other film you like with any Zeiss, Leica, Nikon or Canon lens on a 35mm camera. We'll make 11X14s, 20X30s or even larger prints. The Bronica shots will be better every time. How much was the 100/3.5 Zenzanon? Less than $75. I'm sure it cost a lot more new but some of these lens tests with 35mm equipment are not very useful. If you need to make a large print, use a larger format.
Taking photographs of good subjects is much more fun than shooting Rez-Charts.Taken any pictures lately?
OK, that was perhaps a little flippant, but photography is about more than resolution and LPmm.
It's easy to get too obsessed with testing, rather than looking.
Andrew.
Every time I see a lens test I wonder what conditions it was done under. Was the contrast 1000:1 or 50:1?
No one needs to wonder about tests with contrast of 1000:1 made by photographers using printed test charts.
Because there are no printed test charts with such a high contrast. It is physically impossible. With printing dyes on paper it is impossible to get contrasts of 1000:1.
And no lens can transfer contrasts of 1000:1 completely. Look at the scientific report of the chief optic designer of Zeiss, Dr. Nasse, published in camera lens news 30. He explaines there exactly that.
Film manufacturers are doing tests with contrast of 1:1000 (and 1:1,6). But they don't do that with printed test charts and lenses. The expose the film in contact copy with resolution patterns, using intense direct light. Thats a complete different thing.
On the market so far I have only seen test charts for photographers with object contrast of 1:10, 1:20 or 1:30. All low or medium contrast.
Here is another sobering thought:
The equation for system resolution is 1/R^2=1/r1^2+1/r2^2+...1/rn^2
What that means is that the resolution of the system is not equal to the lowest resolution of any component in the imaging chain, but lower than the lowest component, following above equation.
Here is an interesting example:
1. 35mm camera lens = 90 lp/mm
2. film = 200 lp/mm
3. enlarger lens = 120 lp/mm
Why are we discussing this?
Forget unrealistic lens tests, which assume ideal conditions, high contrast targets and developers which are optimized for sharpness and not for tonality. Switch to medium format instead.
... your values of 90 lp/mm and 120 lp/mm are already values of system resolution ...
At f4 a good prime lens has an aerial resolution of 200-300 lp/mm, a very good lens has about 350 lp/mm, and an excellent lens has nearly 400 lp/mm. ...
...
2. If we photograph a test chart in a distance of 2 or 3 meters, absolutely exact focussing is necessary to achieve more than 100 lp/mm resolution. The focus must be exactly down on the millimeter.
The problem with focusing is, that we don't have really exact focusing systems. Neither our manuel focusing systems (split image, matte screen, microprism) nor the AF systems deliver the precision we need to exploit the capabilities of our lenses and films.
Therefore we have to do a simple, but effective trick: "Focus bracketing". Shooting several frames, each frame newly focused with a sligtly different focus. We make a series and choose the pictures were the focus is dead on.
When I do my lens and film tests, e.g. with TMX, then always some negatives have resolution values of only 80 or 90 lp/mm. Because the focus is a bit in front of or behind the flat test chart.
But some shots of the test series are absolutely precise in focus, because of the "focus bracketing"...
Henning
The point was and remains true, a jump from 35mm to medium format gives a gigantic increase in image resolution, due to the smaller print magnification required.
Do you think that is realistic for Tmax-100 and a 120:1 contrast ratio target?
Ralph, in general you are right, of course.
But, there is no rule without an exception.
During the last months I have worked a lot with high resolution films in 35mm:
Adox Ortho 25, Rollei Ortho 25, Kodak Imagelink, Adox CMS 20, Rollei ATP and Spur DSX 64.
With the dedicated developers (especially with those from Spur for CMS 20, ATP and DSX) I got outstanding results:
Very good to excellent tonality, extremely fine to unvisible grain, outstanding resolution and sharpness.
I've made very large prints and showed them my photographer friends (all of them with experience in medium format, some doing LF as well):
All of them thougt the prints were made from 120 roll film! But it was 35mm.
With these films and very good lenses you can achieve a technical picture quality which is comparable to medium format.
But you have the flexibilty of the 35mm system.
A very nice combination.
Ralph, it is difficult to say, because I have never used a test target with a 120:1 contrast ratio. 1:30 was my maximum contrast so far.
With TMX I've got similar resolution numbers as with Delta 100. Not much resolution difference, only TMX being a bit finer grained.
And probably my primes are in the 300-400 lp/mm aerial resolution range.
And important: AFAIK this formula is not suitable for exact calculation, it is a rule of thumb.
If you look at the scientific research results of Zeiss (Mr. Nasse) you see that he achieved higher resolution values with TMX that you would expect based on the formula.
Probably this formula is a bit conservative, and resolution values are a bit higher in reality.
I have not used anything but 400 ASA film for years, except for testing purposes. I wouldn't know what to do with ASA 25. That film speed does not suit my type of photography.
Same here.
Two thoughts came to mind when reading "All of them thougt the prints were made from 120 roll film! But it was 35mm. [etc]"
One of them was exactly that: the flexibility of 35 mm format, but at ISO 25?
What flexibility would that be?
Being able to put a small camera with small lenses on a tripod, instead of a slightly larger camera with slightly larger lenses?
The other was: imagine you had indeed used the same film in an MF camera ...
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