Comparison of five different Leitz 50mm Focotar lenses

[ulf]

Finalized: Work in progress.

Last Update:

Note: Additional information or links about this lens are welcomed and will be incorporated into the first post as time permits.

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Comparison of five 50mm Focotars

 

For more information of the individual lenses:

https://www.ultravio...-focotar-2-f45/

https://www.ultravio...-f45-from-1952/

https://www.ultravio...-f45-from-1964/

https://www.ultravio...-f45-from-1969/

https://www.ultravio...ocotar-f45-lfe/

 

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Spectral Transmission Graphs

UV-NIR, Focotar 50mm f/4.5

The transmission measurement accuracy into the end of NIR range is less good due to limitations in the light source.

 

UV, Focotar 50mm f/4.5

[Andy Perrin]

What year is the Focotar-2 from?

[ulf]

What year is the Focotar-2 from?

1975, as stated in the post about the lens, the first link above.

 

For more information of the individual lenses:

https://www.ultravio...-focotar-2-f45/

[bvf]

Ulf - where is the serial number on the lens? I can't see it on my lens, and not in the photos of your copy either.

 

Edited - OK, I've found it!

[Andrea B.]

This is a *very* useful comparison of the Focotar 50s. Thank you, Ulf.

 

Now I need to go find mine and see where it fits on your charts.

[ulf]

Thank you Andrea.

 

I am beginning to find the UV Lens Technical Data section a bit cluttered.

When working with the raw data for my entries I keep information for each lens in a separate folder and have seen the same problem for the folder I keep each lens-folder.

Remember that I already have data for many more lenses to work with, even if it is not complete.

 

To improve the overview I have separated the folders in sub-groups:

1. Lenses for bellows, enlargers and microscopes without any focussing mechanics.
   
2. Normal not extreme lenses with reasonable focus lengths and ability to focus.
   
3. Extreme lenses like super teles and fisheye lenses
   
4. Lens comparisons.
   

Maybe there should be another group for dedicated UV-lenses too.

Then my Fused silica DIY lenses might be there together with special lenses like the UV-Nikkor I do not have.

 

I think that the UV Lens Technical Data section would be easier to navigate if it got subsections like the ones I use.

Would that be difficult to implement and do you see that as an improvement too?

[Stefano]

I don't understand the colors. What is the lens with the purple curve and that awesome transmission?

[Andy Perrin]

Ulf and Andrea - HARD AGREE on the suggestion for subsections.

[Andrea B.]

Let's try out the subdivisions and see how it works. I will try to get to that tomorrow.

[dabateman]

Great comparison. From the curves the 1960s looks to be a good uv transmission year.