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UltravioletPhotography

Discussion of Collodion Emulation


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Editor's Note: I split off the discussion of the Collodion emulation from OlDoinyo's original 2014 topic Ultraviolet as a Tool for Faux-Vintage Effects.

 


good morning, after a year I return to update you.

 

I bought a full spectrum A7; my idea was to use it with Schott BG25 filter to emulate the wet collodion spectrum that "sees from 325> 510nm"

 

But there is a big problem ... the sensor sees many I.R. so I ordered a BG39 (similar to s8612) I hope it works ... to have a preview of the result and the right exposure when I take pictures with the collodion.

 

I have a doubt. Will BG25 + BG39 be enough?

 

in the graph of the schott that I have elaborated, you can see the green part that is cut

however there is a zone that I have marked in red from 1300 to 3000 nm that exceeds 1 percent.

I ask you: do you know how far you see the sensor of the sony A7 F.S. ?

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The best IR response I have seen from Sony silicone sensor is 1050nm. Above 1100nm will not be imaged, so you don't have to worry there. Unless you want to image there. Then you have to spend a boat load of money on a SWIR sensor.

 

I look forward to seeing some of your images. I was inspired by this blog:

http://www.philwarrenphotography.com/recreating-1850s-vintage-photography-and-ir/

 

But have yet to jump in with images. Surprised that was almost 2 years ago.

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sorry, I can't insert the image

 

Should be no problem. Open the Full Editor (or click 'More Reply Options') and there is a section for uploading and attaching images to your post.

 

If you already have posted without your image(s), then you need to enter Edit mode by clicking 'Edit' ....

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The best IR response I have seen from Sony silicone sensor is 1050nm. Above 1100nm will not be imaged, so you don't have to worry there. Unless you want to image there. Then you have to spend a boat load of money on a SWIR sensor.

 

I look forward to seeing some of your images. I was inspired by this blog:

http://www.philwarre...ography-and-ir/

 

But have yet to jump in with images. Surprised that was almost 2 years ago.

 

thanks Da Bateman

the link leads to a conclusion ... a question I was looking for before 2019.

now I have a full spectrum, I have to figure out how to make it work (set well)

The tests I did with BG25 put me in confusion

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I've been thinking about replicating collodion for ages, but never got around to do it.

 

How thick is your BG25 filter Photoni (and is it real BG25 or an 'equivalent')? Some of the ones I have seen are 2mm. I was thinking 3mm BG25 combined with S8612 (1.5mm or thereabouts). By going to 3mm for the BG25 you get rid of most of the 500nm-700nm light from that shoulder, and reduce the degree of long wavelength red and IR contamination.

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Here is Toni's Collodion Spectrum posted from a screen shot.

(I am not sure how to link a photo directly from Flickr??)

 

Screen Shot 2021-03-15 at 10.31.06 AM.jpg

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I've been thinking about replicating collodion for ages, but never got around to do it.

 

How thick is your BG25 filter Photoni (and is it real BG25 of an 'equivalent')? Some of the ones I have seen are 2mm. I was thinking 3mm BG25 combined with S8612 (1.5mm or thereabouts). By going to 3mm for the BG25 you get rid of most of the 500nm-700nm light from that shoulder, and reduce the degree of long wavelength red and IR contamination.

 

JMC, I saw your site is very professional, you have some crazy cameras (D850 mono etc) and space equipment and filters that I can only dream of.

 

As I told you, my research was parallel to the 1854 photograph that I still use. Everything ... with this method is variable and questionable, everything changes even with small variations, such as the type of chemical formula that uses different chemical elements to combine with the silver nitrate and become sensitive to light.

Speed (sensitivity) and contrast; change with time and formula. there are recipes that are ready after a few hours and last a week at most, others that take at least 10 days to "mature" and then be ready for 6 months.

 

For collodion emulation the simplest thing is a very narrow (exaggerated) filter like the UV Kolari Vision, which only sees from 340 to 380nm approximately. the collodion has a wider range, that's why I got the Schott BG25.

I don't know if mine is an original or Chinese filter :) it is ø 75mm bare rimless, 2mm thick which I got on Ebay in germany at affordable price.

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JMC, Probably as you say it would be better for the BG25 a thickness of 3mm, maybe even 2 by 2mm.

Would be better than the BG39 that I ordered the Schott S8612, but I only found it in USA, ø52 with customs fees and shipping costs too much.

Maybe tomorrow I will try to do a test with BG25 + Kodak Wratten 80A, using the Elichrome flash generator and some old lights with the tube without anti UV treatment.

 

As lenses I have a Nikkor D 50 f: 1,8 a micro Nikkor 60 f:2,8 and three old Nikkor-H 24 f:2,8 - 35 f:3,5 and 50 f:2 ... I then have one ApoGerogon 150 f:9 and one ApoRonnar 240 f: 9. What do you advise ?

 

You who have a lot of experience can you confirm to me that the old Sony A7 FS does not see beyond 1000nm?

Thank you

Toni

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[nome citazione = "Andrea B." timestamp = '1615826953' post = '43594']

Toni, le tue foto sono fantastiche !!

[/ quote]

 

Grazie Andrea. non è in linea con quello di cui parliamo ... ma per realizzare queste stampe utilizzo solo lampada abbronzante UV

Toni

post-141-0-61570400-1615833143.jpg

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Che strano vedere commenti italiani qui...

La lampada abbronzante emette anche raggi UVB, quindi dovresti aver catturato pure quelli, forse. Strano che i fiori siano bianchi.

 

[En]

It's so odd seeing Italian comments here...

The tanning lamp you used emits also UVB rays, so you should have captured them too, maybe. Odd that the flowers are white.

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Che strano vedere commenti italiani qui...

La lampada abbronzante emette anche raggi UVB, quindi dovresti aver catturato pure quelli, forse. Strano che i fiori siano bianchi.

 

[En]

It's so odd seeing Italian comments here...

The tanning lamp you used emits also UVB rays, so you should have captured them too, maybe. Odd that the flowers are white.

 

Yess .... it is strange that I write with google translated. i am an old 1956 school :)

 

anyway yes, the photo was taken with 8x10 inch panchromatic film 100 ISO. but the flowers were white with a little pink shades in the center

 

the thing about UV is that many antique techniques prints such as the cianaotype, Van dick, platinum / palladium need a UV light to be exposed in contact with the negative. I have some collodion negatives but they are very soft, after the development I had to do a "reinforcement" which I didn't do.

 

si è strano che io scriva con google traslate :)

comunque si, la foto è stata fatta con pellicola pancromatica 8x10 inch ma i fiori erano bianchi con sfumature rosa al centro

la cosa relativa a UV è che le stampe antiche molte tecniche come il cinaotipo Van dick platino palladio hanno bisogno di una luce UV per essere esposte a contatto del negativo. Io ho alcuni negativi di collodio ma sono molto morbidi, dopo lo sviluppo dovevo fare un "rinforzo" che non ho fatto .

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It's so odd seeing Italian comments here...

 

Sometimes I try to practice Italian a bit so I won't forget what little Italian I know.

I can read it and hear it much better than I can write or speak.


 

the thing about UV is that many antique techniques prints such as the cianaotype,

Van dick, platinum / palladium need a UV light to be exposed in contact with the negative.

 

And this is also why many (most?) enlarger lenses are UV-capable (some more than others).

This has been a useful discovery for UV photographers. :lol:

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Hi Toni,

Thanks, I'm lucky enough to be able to fund my research with the work I do, which is why I have some interesting stuff.

With regards to your question about sensitivity beyond 1000nm, yes it will have some between 1000nm and around 1100nm, but the sensitivity drops rapidly above 1000nm. Easiest way to check, get a 1000nm IR filter and try imaging with and without that in combination with the BG25/BG39 combination you are using. That'll give you a rough idea if whether it is an issue.

I've seen one of those 75mm BG25 filters on ebay, so good to know you are using one.

Jonathan

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Hi again Toni,

Sorry, I didn't reply about the lenses. All glass lenses will cut off some of the UV that your filters will be letting through. The more complex the lens, with more coatings and adhesives, the more the UV will be cut. This would of course also be an issue when using Colloidon - just because it is sensitive, the light still needs to be able to get to it. Unfortunately it is difficult to give definitive answers about the best lens without testing them. However, they should all be good from around 380nm upwards, with some of them even going a little lower. You may seen minor differences between them in terms of whitebalance, and exposure times for a given f stop, because of this. So the choice some down to the effect you are trying to produce.

Good luck with your work. I'm interested to see how you get on. Reading what you are doing prompted me to go and get a few filters to test (BG3, BG23, BG25, and BG28 in 3mm).

Jonathan

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I think a stack consisting of UG5 or U-330 in a suitable thickness together with a suitable IR blocking BG-glass would be the proper way to go.

BG39 would work well for this, even if the S8612 would be even better

 

If the collodion is as UV-sensitive as the thick blue graph in Andrea's image above the visual portion of the spectra must be attenuated as the image sensor has much less sensitivity in UV.

 

A cheap way to experiment if proper filter glass is outside a realistic budget might be to get some of the better Chinese filter-glass

The glass type from china with similar characteristics to UG5 is called ZWB3

This seller is a good source for this simpler glass:

https://www.ebay.com...34619&_bkw=zwb3

 

It might be possible to get custom made thicknesses if you ask them.

Naturally customisation will cost extra, if they accept making them for you.

 

A few years ago I got 52mm filters ZWB3 in 2mm, 2.5mm and 3mm from them.

I do nor recall how much those filters costed, but it was not painfully expensive.

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I think you are safe with the IR using either BG39 or S8612, the camera sensor is probably not going to be sensitive to higher IR.

You gain some UV depth with S8612, but if this is all you use it for, I don't think you will see much difference from the UV depth.

However, you may see some difference using BG25, UG5/U-330, that is hard to say.

 

post-87-0-06021500-1615947752.jpg

 

post-87-0-87346700-1615947779.jpg

 

post-87-0-80518000-1615947799.jpg

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Thanks Cadmium for those graphs!

I hope it is OK for you that I borrow your graph for some added annotation.

/U

 

Compare the black curve in the last graph-image in the regions 300nm - 400nm (UV-A) and 400nm - 500nm (B & G),

post-150-0-76338800-1615969944.jpg

with sensitivity curves for image sensors:

post-150-0-99653200-1615969868.jpg

(Image found here: https://www.dpreview.../thread/4535813)

 

In UV the sensors have a lower sensitivity that would be balanced by the peak in the filter-transmission.

 

For the filter-transmission the ratio between the UV-peak level and the level of the BG-plateau can be varied by changing the UG5 filter thickness.

Increasing the thickness attenuates the BG-plateau more than the UV-peak.

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If you've not seen it there is a link to how the collodion spectrum was captured on Lunds website - https://www.lundphotographics.com/index.php/blog/technical/capturing_solar_spectra_on_collodion_film.html

 

Personally, after watching that, given the plate was scanned to get the curve, not sure how close it is to a 'true' spectral response. However I think it is fair to say that the response is between 300nm and 500nm with a peak in the low 400nm region.

 

Ulf - interesting, I hadn't thought too much about camera sensitivity with this. Be interesting to see the BG25 and UG5 approaches compared at some point.

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Cadmium you did a magic ... putting composite curves. your second graph (BG25 + BG39) is much clearer than mine which I created with photoshop.

I hope the BG39 - ø52mm that I ordered from AliExpress from Tangsinuo Store arrives soon ... she write April 16!

Today I tried all the old filters I had at home with the standard Nikon Z5 and the Sony A7 full spectrum ... with flash light and that of the tanning lamp. below I put the result.

Today I have prepared some collodion with Rhen formula with lithium (sometimes I use the New Guy recipe with Cadmium :-)))

Tomorrow I try to do a practical test, but I doubt that the comparison with Sony A7 is useful.

Thank you

Toni

post-141-0-13232100-1616009121.jpg

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