28mm and shorter lens for UVA - what and why?

[JMC]

Coming back to the opening question - have you considered the 25mm Zeiss Luminar?

 

It has a very deep UV transmission, but is obviously more aimed at macro work - https://www.ultravioletphotography.com/content/index.php/topic/3878-macro-uv-with-the-zeiss-luminar-25mm-f35/page__view__findpost__p__35273

[Guest]

Coming back to the opening question - have you considered the 25mm Zeiss Luminar?

 

It has a very deep UV transmission, but is obviously more aimed at macro work - https://www.ultravio...dpost__p__35273

 

I am interested, but I need a solution for the UV pass sensor location without having it pancaked onto the sensor.

 

Btw, what is the working distance for the 25mm Luminar?

[Guest]

Anton,

 

What about the Orion-15 for standard distance work?

[JMC]

I am interested, but I need a solution for the UV pass sensor location without having it pancaked onto the sensor.

 

Btw, what is the working distance for the 25mm Luminar?

Yeah, filter use is an issue. I was using it on a camera which had the UV filter directly on the sensor.

 

There's some good info here on Enrico's site, including working distances at different magnifications - http://www.savazzi.net/download/manuals/Zeiss_Luminars_3.pdf

[diant]

Anton,

What about the Orion-15 for standard distance work?

 

Orion-15 should be a good performer in UVA. According its optical scheme 4/4 with SK (TK-16) external crowns and very thin internal SF (TF5) flints it should have internal transmission around 60% at 360nm. Simple chemical coating may give a real UVA transmission around 40-45% at 360nm. But F/6 is very dark for me. I need a more open lenses.

 

Now I bought Vega-7Э (2/20) and plan to test it soon. It has such scheme (5/4):

 

SK (TK14) - 2.2mm on axis

air

SK (TK14) - 2.4mm on axis

F9 - 0.5mm

air

SK (TK14) - 2.8mm on axis

air

SK (TK14) - 1.5mm on axis

 

Its transmission calculated without regard to balsam in 2-3 elements but with regard to simple surface coating should be around 30-40% at 350nm.

But balsam may decrease it more or less... I'll compare it with T43 lens.

[Andrea B.]

I have a question.....don't get offended, but why the need for a wide-angle lens?

 

Couldn't you just stitch images made with 60mm or 105mm? Granted that is an extra task, but at least you could be assured of the UV-ness of the image from a UV dedicated 60mm or 105mm lens. These days the stitching apps are really quite good.

 

I'm just curious, as always.

 

Of course, there is always the joy of the search.

[Stefano]

A wide-angle lens will give you wide-angle images directly, plus I guess it could be useful for videos.

[diant]

Andrea, dedicated lenses are a something costly for me - firstly.

And secondly I often need to take a shot of fast processes, so I have no time to do several images for stitching.

[diant]

Some my late tests show me that Vega 2/20mm can see 360nm and may be even a little 350nm. And it have a circle of coverage around 2/3-1".

 

Meanwhile I was given by my friend the enlarger lens Mikar 4,5/55mm.

In spite of some hazy rumours on the web (that it is allegedly tessar-type lens) it proves to be a true triplet!

And may be it will take its deserved place among the cheapest UVA-capable lenses.

I mean that lens. It sell here (in Russia) for a fanny $3-4. It have a coverage no less Full Frame.

 

[diant]

Example of the work of Mikar S 4,5/55mm lens - solar spectrum in vicinity of Ca doublet (393 and 397 nm).

It was made by my hand-made spectrograph and of course reflect a combine UVA-capability: film Grate, camera sensor and Mikar transparency itself.

"экв. ширина" = equivalent wide