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Hello from Czech republic!

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#1 Martin

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Posted 09 June 2020 - 05:18

Hello from Czech republic!

Hi, I'm forensic expert in digital image processing (photo & video) and digital data anlysis. I use UV photography for forensic purposes, f.e. corpses and evidence & traces investigation, so I can't show you the interesting part of my work, but I hope I'll share some non violent / harmless photos sometimes. I started practising UV recently and still looking for better lens, but now I have full spectrum modified EOS 80D with Helios 44-2, Nikon E 35/2.5, filtres U-340, S8612.
Martin
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#2 dabateman

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Posted 09 June 2020 - 05:23

Welcome to the forum.
Many might be interested in experimental setup photos, not of actual evidence, but rather the background tests that verify the technique.
Would be interesting to see some reference.

But also remember to have some photographic fun.

#3 colinbm

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Posted 09 June 2020 - 07:07

Welcome aboard Martin
Interested in what tricks you have to show please.....you might even learn some too...

#4 nfoto

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Posted 09 June 2020 - 08:19

Welcome to UVP !! We are eager to learn more abut your expertise and practical results. Any problems -- just open a discussion in a separate thread. UVP members pitch in to the best of their insights and knowledge.

And yes -- the fun part of photography should never be forgotten. For "invisible light" explorers, potential wonders are waiting everywhere.

#5 Bernard Foot

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Posted 09 June 2020 - 09:36

Hi, Martin.

Looking forward to seeing some of your less unpleasant forensic UV images and hearing how yhou make them.

I would expect the Helios 44 would be poor for UV, but I haven't seen any tests on it and will be interested to hear how you get on with it. I'm sure you have seen that there is plenty of advice and discussion on this forum about lenses that work well for UV/
Bernard Foot

#6 JMC

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Posted 09 June 2020 - 14:03

Welcome to the forum Martin.

With regards to lenses, as Bernard says, the Helios 44-2 is probably not ideal, That being said I have not seen anyone use it before, so it'll be good to see some pictures with it.

If you're after a longer focal length lens which is suitable for UV, the old style (chrome) 80mm El Nikkor enlarger lens is hard to beat, as it has both excellent UV transmission and low focus shift. Being an enlarger lens it does need a helicoid to give you some focusing, but is easy enough to adapt for SLR use. There is plenty on that in this forum.

Jonathan

Edited by JMC, 09 June 2020 - 14:03.

Jonathan M. Crowther

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#7 Martin

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Posted 09 June 2020 - 15:57

View Postdabateman, on 09 June 2020 - 05:23, said:

Welcome to the forum.
Many might be interested in experimental setup photos, not of actual evidence, but rather the background tests that verify the technique.
Would be interesting to see some reference.

But also remember to have some photographic fun.

Actually I do have some, but poor quality because of borrowed equipment (EOS 550D, Helios 44-2, Andrea UV). I'm super excited to share it, but it was highly recommended to me wait until I pulish my "research" on Web of Science, Scopus and mainly in my bachelor thesis and forensic methodology. So be patient please, the day will come :-)

View PostBernard Foot, on 09 June 2020 - 09:36, said:

Hi, Martin.

Looking forward to seeing some of your less unpleasant forensic UV images and hearing how yhou make them.

I would expect the Helios 44 would be poor for UV, but I haven't seen any tests on it and will be interested to hear how you get on with it. I'm sure you have seen that there is plenty of advice and discussion on this forum about lenses that work well for UV/

Yes indeed, Helios 44-2 is not the best option, but I've tested it on blood, sperm, sweat and saliva in daylight and hey, it works, so I've bought one for me for future comparison. No false-positive results on water, juice, chorine and mineral-containing fluids. Nothing super cool, but works for me.

View PostJMC, on 09 June 2020 - 14:03, said:

Welcome to the forum Martin.

With regards to lenses, as Bernard says, the Helios 44-2 is probably not ideal, That being said I have not seen anyone use it before, so it'll be good to see some pictures with it.

If you're after a longer focal length lens which is suitable for UV, the old style (chrome) 80mm El Nikkor enlarger lens is hard to beat, as it has both excellent UV transmission and low focus shift. Being an enlarger lens it does need a helicoid to give you some focusing, but is easy enough to adapt for SLR use. There is plenty on that in this forum.

Jonathan

Actually, I do need to capture crime scene (walls, furniture, floors), traces and evidence such as clothing, bed linen, arms with tatoo, old scars. 80 mm and also Helios are kind of too much for me (more photos needed for inspection), so I've ordered Nikon E 35/2.5 (being shipped now from Japan). I'm reading UVP more than 6 months, so I've already learned something from you :-) As soon as I will have some extra money, I'll need help to find some more suitable lens ;-)

Edited by Martin, 09 June 2020 - 16:01.

Martin
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#8 dabateman

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Posted 09 June 2020 - 20:40

For Canon, surprisingly the really cheap 40mm f2.8 STM lens is excellent for UV and will auto focus. I got one for $80 US dollars. See if you can find one. That might out perform the other lenses you have mentioned.

#9 Martin

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Posted 09 June 2020 - 23:19

View Postdabateman, on 09 June 2020 - 20:40, said:

For Canon, surprisingly the really cheap 40mm f2.8 STM lens is excellent for UV and will auto focus. I got one for $80 US dollars. See if you can find one. That might out perform the other lenses you have mentioned.

Oh, really? I did not hear anything about it before. Do you have any further information, especially internal transmittance peaks, samples etc.?
Martin
Forensic expert in digital photography, digital video and digital data analysis fields.

#10 dabateman

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Posted 10 June 2020 - 13:23

Here is my quick spectrum of my copy of the Canon 40mm f2.8 STM lens:
https://www.ultravio...__fromsearch__1

This is a much better controlled spectrum by Jonathan:
https://www.ultravio...dpost__p__19599

This was Jonathan's flower test:
https://www.ultravio...__fromsearch__1

This was my flower test:
https://www.ultravio...__fromsearch__1

Edited by dabateman, 10 June 2020 - 13:23.


#11 JMC

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Posted 10 June 2020 - 14:37

Here's a more up to date, direct scan of transmission for the 40mm Canon.

https://www.ultravio...dpost__p__29227
Jonathan M. Crowther

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#12 colinbm

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Posted 22 June 2020 - 01:02

Hi Martin
Do you know this filter, KODAK INFRARED CUT OFF FILTER NO. 301A, is there a transmittance graph, Please ?
Cheers

Col

Edited by colinbm, 22 June 2020 - 01:03.