Comparison Olympus 30mm Macro vs Sigma 30mm Art vs Olympus 14-42R2 in UV

[ulf]

David,

 

Yes, you are right about the UV-Nikkor and likely the UAT too!

 

The UV-Nikkor is specified to have a transmission >70% from 220nm - 900nm.

With 6 groups of 6 elements and no coating or glass losses it could only reach around 62%, assuming it is built with Silica and CaF₂ elements

The coatings might also be intended to protect the CaF₂ elements that are more sensitive to the environment.

 

In my text above I just wanted to convey that uncoated, older simple AR-coatings (and specialised wide band coatings) can allow UV passing, but that highly optimised modern AR-coatings likely block much UV.

 

Also many modern optical glass types have a low UV transmission.

If thick lens elements of such glasses are used in a lens design they will have a big impact on the UV-transmission.

Just as with filter glass, the thicker the more attenuation.

[rfcurry]

Ulf,

 

Two excellent posts from you, above. Most BBAR (Broadband Anti-reflective coating) that I have been offered for UV has given a 0.02 improvement in transmission over the typical 0.92 reflection factor. This is in line with the UV-Nikkor case you mentioned: The standard 0.92⁶ = 0.6063 becomes 0.94⁶ = 0.6898, which is close to the 70% advertised.

 

https://www.edmundoptics.com/resources/application-notes/optics/anti-reflection-coatings/ has a simple summary of the AR issue.

 

I, personally, favor pre-1970 German lenses for UV The quality is usually quite good and the prices, especially in Exakta mount, is low. Just one opinion.

 

Cheers!

[Timber]

I had the Sigma 30mm f2.8 on my Sony NEX6 and it was one of my favourite UV portrait lens as it has AF. It's definitely usable with a 365nm setup... unfortunately... APS-C only :'(