Testing the Carl Zeiss 60mm f/4.0 UV-Objektiv

[JMC]

This thread will contain any testing I do on the Carl Zeiss 60mm f4 UB-Objektiv lens (lens shown here - https://www.ultravioletphotography.com/content/index.php/topic/3942-carl-zeiss-60mm-f40-uv-objektiv-exakta-mount/page__view__findpost__p__36259).

 

The lens is a triplet construction, and my copy is in Exakta mount. As I have an adapter for Exakta to Canon EOS, I'll be using this on my Canon and Sony cameras. If I get a Nikon adapter in future, I'll also try it on those.

 

How does it behave in UV? Here's some initial test shots, taken on multispectral Sony A7III, using both the Baader U filter, and a combination of the Baader U and a 365nm 10nm band pass filter from Edmund Optics. It was a windy day but sunny, so I cranked the ISO up to 10,000 to try and spot the movement, and the exposure times were between 1/30s and 1/100s. White balanced in Darktable using a Baader U image of a PTFE disk. Pictures of Buttercups and my garden.

 

 

 

 

Definitely some good strong UV rendering of the Buttercups with the lens. There's also some swirl in the background which reminds me a bit of the Helios 44 and 58mm Biotar lenses.

 

When the focus ring is turned all the way to close focus, the lens shows evidence of some pretty horrendous light leak. Although this disappears very quickly as the focus moves away from closest distance. Shot below was taken at closest focus distance.

 

 

As I do more testing in the future, I'll add to this thread with the results.

[JMC]

Transmission measurement from 280nm to 420nm

 

Below is the lens transmission curve for the Carl Zeiss 60mm f4 UV-Obektiv lens between 280nm and 420nm.

 

 

The lens shows good UVA transmission although it drops quickly below 340nm. It still shows some transmission at 300nm and below, although I suspected it drops to practically zero just below 280nm. This is very different to the UV-Nikkor, Asahi Ultra Achromatic Takumar 85mm and UV Sonnar, which show no evidence of this drop in transmission around 300nm. The transmission behavior of the Carl Zeiss 60mm UV-Objektiv is closer to that of the 60mm f4 Jekoptik / Coastal Optics lens with its drop at around 300nm.

[Andrea B.]

I'm going to look at my UV-Objektiv at close focus to determine if it also light leaks like that.

Try a shot with a small towel or other cloth wrapped around the lens.

 

It's great to have a transmittance curve for the UV-Objektiv. Thanks.