Lens Resolution Lines/mm

[Michael Erlewine]

Lens Resolution Lines/mm

I am trying to better understand how lens resolution works in “Lines per mm,” often used in describing high-resolution lenses in the past. Perhaps, not so much today. L/mm is the same as LP/mm, since a line is always a pair of lines (one white and one black).

I picked up a lens that resolves at 160 lines per millimeter. How does that compare to other lenses used for high-resolution work?

[MEPER]

Many years ago I played with a BW film called "Gigabit film". I was in contact with an expert and asked about which "budget" lens he could suggest that could utilize the high resolution of the film. He suggest that I should get a few Nikkor H-C 50/2 lenses and select the best one. He claimed that a good one could resolve 400 lp/mm at its optimum setting. I think that is about f 5.6. If the 400 lp/mm is true or not I don't know but it did make very sharp images on Gigabit film. A 55 mm micro nikkor is probably also a good lens to select for high resolution depending of distance.

I can see the web still exists:
http://www.gigabitfilm.de/html/english/information/24x36/examples/examples.php?Layout=normal

…...I think I remember I asked which lens was used to make the x1000 enlargement example. I am not 100% sure but my memory says something like a hand picked Vivitar Series 1 lens.....

Which lens did you get?

[Michael Erlewine]

Which lens did you get?

I have a number lenses that have good resolution, but this particular one is a rare REPRO Nikkor lens:

Nikon 100mm f2.8 Repro-Nikkor 100/2.8 Macro

[MEPER]

Ok, if is can perform that resolution on a very large image circle at full aperture it is probably very good.
Do you know the image circle of such a lens?     …...probably it can cover more than 24x36?

[Birna Rørslett]

Line pairs per mm:. It's tempting to invert the figure to get the dimensional resolution, however for a number of reasons one should  not.

The f number is important for the theoretical maximum resolution of any lens. In theory the larger aperture (small f number) will increase resolution and the lens performs best wide open, however only a few few specialist lenses e.g. a Ultra-Micro-Nikkor come anywhere close to that.

[MEPER]

It could look like this lens you got?
https://www.ebay.com/itm/Nikon-100mm-f2-8-Repro-Nikkor-100-2-8-Macro-Micro-Lens-ULTRA-RARE-Beauty-/293025984023

Something to look forward to.
Usually if image circle is large the resolution is lesser and if image circle is small resolution is higher like the Ultra Micro Nikkors where some has 1200 lp/mm resolution on a very small image circle.
So I think it is important to know the image circle of the lens?      …...my guess is that image circle is larger than to just cover 24x36 of this Repro-Nikkor. Else I would have expected a higher resolution of such a specialized lens.

I have also read that stopping down a lens will give lesser resolution but in most cases the contrast will be higher (at least the lenses I have) and then it looks like resolution is higher when stopped down a bit.

[MEPER]

There was some lens data included. It was very low geometric distortion. Sounds logical for a repro lens. Some experts can probably answer if resolution is exceptional.

[Birna Rørslett]

It's a  balancing act: stopping down at first reduces residual aberrations thus image contrast might rise, but eventually leads to a gradual loss of definition which itself lowers image contrast.

Each lens has an optimum aperture but one's requirements, the quality of the light, and the motif itself move that optimum to some degree. And what is considered "optimum" also depends on the post processing and what  later magnification the image will receive.

[Michael Erlewine]

It's a  balancing act: stopping down at first reduces residual aberrations thus image contrast might rise, but eventually leads to a gradual loss of definition which itself lowers image contrast.

Each lens has an optimum aperture but one's requirements, the quality of the light, and the motif itself move that optimum to some degree. And what is considered "optimum" also depends on the post processing and what  later magnification the image will receive.

I am told by Klaus Schmitt that this 100mm Repro lens is optimized for 1...2.5x or reversed for 0.4...1x, so not just 1:1 as the Repro Nikkor 85mm. And 0.4..1x is just what I seem to like. The Repro Nikkor 85mm has to have higher L/mm, because it is dedicated to just 1:1 (1x) range, while the 100mm I am going to try out has a broader range.

[Michael Erlewine]

I received the Nikon REPRO 100mm f/2.8. It is not little, but it is not too large and can rest easily on a DSLR or technical camera without needing any added support. It is a relay lens in that you can mount it using either end. I used a 40.5-to-52mm adapter ring and that to a 52mm-F-Mount. It works perfectly.

I am using on a Cambo Actus-Mini and will have to experiment with extension rings directly on a camera and mounting the camera on a focus rail. There is no internal helicoid. It does have a 12 blade aperture, which is nice. This is not going to be very difficult to learn to use, as I have many similar-style lenses that I am already familiar with.

I will have some work to do to see what magnification-range I can get out of it. With 160 l/mm, it seems sharp enough and we know it is well corrected as it was used in Hollywood. This particular lens is said to have once belonged to Donald E. Trumbull who was a major innovator/ technical engineer for companies such as Industrial Light & Magic and worked on effects for movies such as the Wizard of Oz, Star Wars, Close Encounters of the Third Kind, and other award winning movies as well (and father of Douglas Trumbull).

It is an odd lens, meaning I have never seen another or even one for sale. Thanks for Klaus Schmitt for pointing this copy out to me. I will be exploring how to best use this lens in my work, but so far so good, IMO.

Here is a first try.

[Michael Erlewine]

Got the Nikon REPRO 100mm APO Macro tracking right, so to speak. Unless the extension is just right, the sharpness is just not there.

This is an imagine of the first sprout for hundreds of Morning Glories ("Heavenly Blue"). The light changed in the stack, so that washed out the image quite a lot, but here is what I needed to see....that this lens works well.

[Dr Klaus Schmitt]

Just a correction: lppm (line pairs per millimeter) and lpm (lines per millimeter) ARE NOT THE SAME! lpm = 2 x lppm!!
So in other words the for onstance often quoted Russian resolution figures and in reality just HALF based on our most used line pair per millimeter standard.
Not sure what the resolution figures for Nikon are, as they are "lines per mm", so I would assume they are not line pairs per millimeter.

[Erik Lund]

I was under the impression that line "pairs" is one black line and one white line;
LPM=LPpM Line Pair per Milimeter

[rosko]

I am happy with the estimated 250l/mm of my Nikkor O 55mm f/1.2 CRT...

[bobfriedman]

for those interested.

https://schneiderkreuznach.com/application/files/4115/0781/8894/optics-for-digital-photography.pdf