theory and practice of basic UV lenses

[photoni]

theory and practice of basic UV lenses

having no measuring tools, I took as an example the graphs of the objectives tested by ULF and the graphs of the filters of Jason / Tangsinuo
it is a pragmatic and basic test that “seeing” theories and non-certified graphs.

after the first tests I realized that in order to focus correctly with different lenses I needed a filter that let through part of the visible.
i used the QB29 (it should be similar to the BG25) This is the light band I am interested in to emulate wet collodion (325 ~ 510nm) To "see" the depth of the UV I added to the QB29 a ZWB1 (similar to UG11) all 2mm thick
contamination of IR in this case does not disturb, on the contrary it helps to read the spectrum of emission of light.
NOTE: I didn't add IR cut filters like QB39 ~ BG39 ~ TSN575 because they cut the lower part of UV (= green)
Unfortunately I don't have an S8612 which seems to be the only filter that lets 325nm pass and cuts red and IR

[if someone wants to give it to me is welcome]

For all images i used same aperture f:11 the power of the studio flash was always 1000w with a clear flash tube, the ISOs set were the same. The filters were applied to the end of the cone of light ø52 (not on the lenses) the Raws were developed with Capture One, with white balance with a Teflon ball.

Conclusions: the best 35mm is the Soligor KA, the Prinzgalaxy is the poorest of the three, but much better than others tested.
I only tried two 50mm the Meritar sees green well… so it should reach 325nm
my Helios 44-2, considered by many to be good… is very dark.

Unfortunately I cannot find information on the jagged IR spectrum of the flash light,

I asked the Italian distributor, but he has no news.

Any of you have any idea if the emission peaks in IR have an atomic element and nm signaled?

Thank you Antonio

 

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[dabateman]

Interesting,  your Helio 50mm is clearly the worst for UV depth. 

I also think your Asahi is worst than the Princgalaxy.

Looks like you have a relatively cheap testing method now.

[Doppler9000]

Very interesting - thank you for this.

 

I would be very interested to see how the Imagon performs in the comparison.

[photoni]

6 hours ago, Doppler9000 said:

Very interesting - thank you for this.

 

I would be very interested to see how the Imagon performs in the comparison.

 

imagon is a strange photographic lens for large format ...
to understand it is difficult to focus
it is an achromatic doublet (a group of 2 lenses) so it lets a lot of UVs through.
it has a very strong "flare", with a very marked color shift,

if you use it with blue - UV light it probably works in a soft but acceptable way.
it has a length of 200 - 250 - 300 mm with a very narrow telephoto angle.

it has holes in it to regulate chromatic aberration ... creative flare like in the old days of pictorial photography

 

this is its rendering with ZWB1+QB29 and QB29
the white balance is with a teflon ball, according to the CADMIUM table, it sees green, so good up to 340 nm

 

 

[photoni]

@Andrea B.  there is a problem
I have confused QB29 with QB39
QB29 ~ BG25
QB39 ~ BG39
I should put the RIGHT IMAGE and description back, but it's not possible.
is a limitation that is not on flickr, why can't I delete and edit my posts here?

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in my post ... clearly NOT INTERESTING the image is wrong and no one noticed the QB 39 does not see (or sees little) IR

[Doppler9000]

Thank you so much.  The Imagon is quirky lens indeed, but excellent reach.