Light Modifiers for UV Sources

[Toby]

Does anyone have any experience with using light modifiers for UVIVF photography?

 

I've been thinking about ways to soften the light sources and it seems like most traditional modifiers (softboxes, diffusers, etc.) would be impossible to use due to their fluorescence under UV. The only thing I could think of that could have a chance at working would be something like a bounce.

 

Looking forward to hearing people's thoughts on the topic.

[dabateman]

I am not sure what your light source is.

 

If you want to kill the central hot spot of the convoy. We had a thread about that. The best thing to do is wrap a small piece of plumbing tape (white ptfe) around the refector. It works amazingly.

[Toby]

I am not sure what your light source is.

 

If you want to kill the central hot spot of the convoy. We had a thread about that. The best thing to do is wrap a small piece of plumbing tape (white ptfe) around the refector. It works amazingly.

 

Thanks for the advice, that'll come in handy. But my curiosity more has to do with sources like flashes at short distances and eliminating hard shadows.

 

Maybe it's a stupid question but I was interested in the techniques that people have been using to get light to behave since some traditional photography techniques don't seem like they'd work.

[Andy Perrin]

I think traditional photo methods would work just fine, but you have to choose materials that work for wavelengths in question. In this case why not use virgin PTFE (which is reasonably inexpensive on ebay) as a diffuser or to bounce the flash off of it? It doesn't fluoresce as far as I know, and it reflects UV pretty evenly across the spectrum. You could build a box out of it even, and put UV LED strips around the top.

 

Also didn't someone find a translucent UV diffuser material that worked really well awhile back? Let me look for the thread.

 

ETA:

 

Mark had a thread:

https://www.ultravioletphotography.com/content/index.php/topic/3202-a-diffusion-filter-to-remove-uv-hotspots/page__view__findpost__p__26679

 

Jonathan had a thread:

https://www.ultravioletphotography.com/content/index.php/topic/2629-potential-uv-diffuser-roughened-pmma-plates/page__view__findpost__p__19786

[nfoto]

Aluminium foil can easily be arranged to provide efficient reflectors.

 

If you use studio flashes, you can attach a huge variety of light modifiers. Be aware that many of these are not very effective for close-up work as they are designed for longer working distances.

[dabateman]

Yes for flashes I found that Lee 750 works best. Transmits the full UVB and up spectrum.

 

First mentioned here I think:

https://www.ultravioletphotography.com/content/index.php/topic/3201-uv-transmission-photography-with-african-violet/page__hl__%2Blee+%2B750__fromsearch__1

 

This was my test with the convoy:

https://www.ultravioletphotography.com/content/index.php/topic/3510-paint-torch-reflector-black/page__view__findpost__p__30500

[Andy Perrin]

Yes for flashes I found that Lee 750 works best. Transmits the full UVB and up spectrum.

 

First mentioned here I think:

https://www.ultravio...__fromsearch__1

 

AH, yes that was what I was looking for!

[dabateman]

I think traditional photo methods would work just fine, but you have to choose materials that work for wavelengths in question. In this case why not use virgin PTFE (which is reasonably inexpensive on ebay) as a diffuser or to bounce the flash off of it? It doesn't fluoresce as far as I know, and it reflects UV pretty evenly across the spectrum. You could build a box out of it even, and put UV LED strips around the top.

 

Also didn't someone find a translucent UV diffuser material that worked really well awhile back? Let me look for the thread.

 

ETA:

 

Mark had a thread:

https://www.ultravioletphotography.com/content/index.php/topic/3202-a-diffusion-filter-to-remove-uv-hotspots/page__view__findpost__p__26679

 

Jonathan had a thread:

https://www.ultravioletphotography.com/content/index.php/topic/2629-potential-uv-diffuser-roughened-pmma-plates/page__view__findpost__p__19786

 

Andy your first Mark thread is my thread talking about the Lee 750.

[Andy Perrin]

Andy your first Mark thread is my thread talking about the Lee 750.

Ooops! His was the post that the search engine found...

 

Anyway, sounds like the options are:

 

-Lee 750 diffuser on the flash

-Aluminum foil as a reflector

-Virgin PTFE as a diffuse reflector for a variant on a soft box idea

[Toby]

Thanks all,

 

This has been really helpful. I was not expecting to find a non florescent gel!

[Adrian]

I know that most of the discussions have centre around the use of flash for UVF, I wonder if I can put in a word for UV torches, such as the Convoy S2+UV.

Yes it has a very distinctive hot spot, but I use it with a technique known as "light painting". Arrange for a 20 - 30 second exposure, and then, with the shutter open (in a completely dark room) move the torch around the subject to completely light it. Paint it from the top, the side and bottom to fill in all shadows. If you want to get a bit "creative" then give more exposure from top left than bottom right for example. Although this works best with solid subjects, I use it all the time with flowers and other plant materials (holding my breath during the exposure!). The main issue is consistency - no two images are rarely there same.

The image below, of fluorescing lichens, was shot with a 30 second exposure at f/16 with a single Convoy torch

[colinbm]

Nice Adrian

Removing the reflector can remove the 'hot spot'.

Did you have a UV pass filter on the Convoy ?

[Adrian]

Yes I use a Hoya U-340, but always struggle with the "correct" colour of the fluorescence!

[colinbm]

Thanks Adrian

[dabateman]

Nice Adrian

Removing the reflector can remove the 'hot spot'.

Did you have a UV pass filter on the Convoy ?

 

I think its actually best to carefully wrap the refector with a layer of PTFE tape (plumbing tape) that increases the brightest without the hotspot. Thats what I found from my test.

Cadmium saw the same thing with UV meter measurements. That the PTFE was diffuse but very similar intensity. Much better without reflector or with it painted black.

 

Adrian,

The blocking filter on camera will alter the color. I used to stack 2A with S8612. But it cuts out too much red. I now find it easier to use a UV/IR blocking filters that has harder edges to let in more red.

The Baader UV/IR is very expensive. So I use a modified Sigma SD15 filter. A 2A or 2E stacked with an older BW486 might work though. I have found all the newest 486 since I bought after 2016 seem to leak more IR.

 

One is so bad I get a lot of signal stacked with a #87. I may use it for 730-780nm isolation.

[enricosavazzi]

Aluminium foil can easily be arranged to provide efficient reflectors.

 

If you use studio flashes, you can attach a huge variety of light modifiers. Be aware that many of these are not very effective for close-up work as they are designed for longer working distances.

Aluminium is in fact an extremely good reflector for NUV, and perfect for use as a reflecting light modifier for UV imaging. The only "trick" is to use aluminium devoid of coating films (especially plastic) and of anodized surfaces (especially pigmented ones).