Found a new cheap lens for reflected UV-Photography

[ForenSeil]

Today I tried nearly all my lenses for UV-transmission with 365nm LEDs, filtered through Shott UG1
Rodagon 50/2.8, Rodagon 135/5.6, some Russians like Jupiter 8M, Helios 44-2, Helios-103,... and many more.
All showed slight to strong haze in contact with UV-light. Some even strong fluorescence.
The only lens I found to be perfectly clear in UV-light was the Rodenstock Trinar 75/4.5



Straight JPEG modified NEX-5N
Light 365nm LED, filtered through Shott UG1


Crop:


No flare, no haze, very usable contrast and sharpness,... the lens seems to work very nice for UV-light. At least for 365nm. Unfortunately I have no Baader-U etc. filter to test it outdoors and no flowers to test it on something more interesting .

[Minolfan]

Looks very interesting indeed.
A humble triplet enlarger lens, isn't it?

[jjphoto]

Maybe it's the case that the fewer elements the less UV is attenuated.

Anyone try UV pinhole pics?

[kds315*]

You could have save quite some time by simply reading my BLOG uvir.eu as I have tested hundreds of lenses and the ones that do work, I have written about (right side link list). There is even a SEARCH function...

That Trinar I know but did not find it sharp enough for my work.

Pinhole I tried, also shown on my BLOG with examples. Only good for large format, not digital UV.

[Alex H]

It may be sharp with narrow-band LED but how will it perform with the "broad-band" Baader U2 and how deep in UV does it transmit?

[ForenSeil]

[ForenSeil]

VIS (cheap chinese UV-IR-Cut filter)


Schott UG1 + small UV torch light


crop:


A B/W conversion


Lens is not exactly as sharp as El-Nikkors or dedicated UV lenses but produces a perfectly clear picture without any flare, haze etc.. while having a usable transmission.
I think it should also work outdoors with Baader U or similar as there's only a tiny focus shift between VIS, UV and IR.

Need some more interesting subjects

[kds315*]

That bw converted last UV image look pretty good to me!

[mo]

I like the B&W version,and the crisp whiteness of the first.

Can I ask ForenSeil, what made you want to explore the UV world?

[ForenSeil]

[JCDowdy]

[wuxiekeji]

A lot of materials absorb UV -- more than you think. Most polycarbonates also do a fantastic job at killing UV. With all the wacky materials they use in making lenses and coatings, it's not surprising that some UV gets absorbed, scattered, or excites fluorescence leading to more scattered light.

I would guess (haven't tested) that likely most old, cheap uncoated lenses made of fused silica and nothing else might all do reasonably well for UV.

[kds315*]

[JCDowdy]

[kds315*]

That wasn't the criteria, I was referring to lenses that reach to about 320-340nm and having a transmission at 365nm of at least >50-60%

[BrianS]

People might look into old spectrum analyzers, those being surplused. Ones with optics in and that go down to the UV are good candidates.

I found an old Quartz lens, sent it to Klaus years ago. The salt lenses had deteriorated. One of the optical engineers at the lab told me that BK7 was good for near-UV.

http://www.schott.com/advanced_optics/us/abbe_datasheets/schott_datasheet_n-bk7.pdf

[sammo]

Spectrometers more often use mirrors instead of lenses to avoid CA.

[BrianS]

Some used optics. I'll try looking into which ones used optics. Unfortunately, both of the senior optical engineers that knew the old equipment have retired. Was nice to get immediate answers on everything from UV to thermal IR.