184mm F/.9 Industrial CRT Lens by Lenzar Optics

Lou Jost · Post by **Lou Jost** » Wed May 30, 2018 8:27 pm

I'll watch my tongue...And I will be sure to report on this lens. It seems unique. I also have some Lenzar and ReproMaster large-format lenses waiting for me which may make good tube lenses. Hope springs eternal...

Lou Jost · Post by **Lou Jost** » Sun Nov 18, 2018 10:28 am

Reporting back on this strange lens. It is perfectly telecentric at 1:1. There are some CA in the brightest highlights but overall it is a nice lens. Will post some examples one of these days when I have more time.

JohnyM · Post by **JohnyM** » Sun Nov 18, 2018 10:59 am

Telecentric you say... how about coverage and working distance?

Lou Jost · Post by **Lou Jost** » Sun Nov 18, 2018 1:03 pm

WD was 47mm, coverage perfect on MFT (no corner degradation at all); I think it covers FF, will check in the future.

Ratio of consecutive Zerene scale factors near mid-stack, with step size 35microns, was 0.99998.

JohnyM · Post by **JohnyM** » Sun Nov 18, 2018 2:01 pm

Seems like a good replacement for Nikon MM 1x which struggles with APS-C. And aperture is much better.

JohnyM · Post by **JohnyM** » Sun Nov 18, 2018 8:52 pm

Btw, im using Repromasters all the time. Oddly 135mm F9, when focused @ infinity (via my eyeballs) is providing 7x with Nikon 10x, but covers A7RII sensor very well and works in Zerene with alignment and scaling @ OFF, so i assume "telecentric enough". Today's work:

Lou Jost · Post by **Lou Jost** » Sun Nov 18, 2018 9:01 pm

That looks very good. I have some Repromasters but not that one.

However, since you are using it as a tube lens, in a fixed position, it has no relevance to the telecentricity of the system. It would be the 10x objective that is making the system telecentric. This happens also with the 10x Mitutoyo, for any 200mm tube lens.

Macro_Cosmos · Post by **Macro_Cosmos** » Mon Nov 19, 2018 4:50 am

It's a pretty fun toy to have, field curvature is probably going to be significant, since the CRT screen is curved as well.

Just like the CRT-Nikkor 55mm f/1.2 lens, it is probably extremely poor outside the dedicated magnification. The Nikon one is extremely sharp wide open, a fun lens to play with. It is optimised for 1:4 (or was it 1:5?) reproduction ratio.

Lou Jost · Post by **Lou Jost** » Mon Nov 19, 2018 5:36 am

This doesn't behave much like that CRT lens. The telecentricity is remarkable, and I did not notice strong field curvature. Lots of more modern CRT screens were flat, unless my memory is fooling me. An internet rumor says these replaced the Repro-Nikkor, not the Nikkor CRT lens, in the oscilloscope-photographing application.