Which entry level filter for UV portraits?

[Stefano]

1 mm of dichroic layers? It reminds me of a croissant.

[Andy Perrin]

David, noted, but to my knowledge only you have had major problems with this seller or this filter. It’s going to take more than a couple of bad examples to make me abandon something that has been high quality for so long. It wasn’t that long ago that Jonathan tested a bunch of Omega filters and found the lot to be nearly on spec with his spectrometer.

[dabateman]

1 mm of dichroic layers? It reminds me of a croissant.

 

Most likely 1mm thick fused silica glass with something a whole bunch of super thin layers of material to block visible and IR. As in single molecule thin coating.

 

Dichroic filters like the Baader venus U filter have to be handled with care. The Baader venus filter is 1mm UG11 glass with forty micro thin layers of IR blocking material. You don't want to wipe it hard, or scratch it.

 

Treat it kind of like an Astrophotography mirror. Very carefully.

[dabateman]

David, noted, but to my knowledge only you have had major problems with this seller or this filter. It’s going to take more than a couple of bad examples to make me abandon something that has been high quality for so long. It wasn’t that long ago that Jonathan tested a bunch of Omega filters and found the lot to be nearly on spec with his spectrometer.

 

Thats fine use at your own risk. Just letting people know my deteriorating experience with them over the last 2 years.

The first two filters I bought were excellent. After that its been down hill.

The 390bp25 is one of my favorite filters and would work perfect for the original poster. Just buy at your own risk.

 

[Nisei]

Ordered a 2mm ZWB2 first and see how it performs with my Kolari Vision Hot Mirror.

Looking at the graph it should work.

[JMC]

David, Andy, I've just seen the post about Omega filters. I wont comment here as it's not my thread, but I've had mixed experiences with them. I'll post something in a new thread when I get a big more time.

[Cadmium]

I like Omega. There are two eBay sellers from Omega, I especially like omegabob2, but that seller doesn't seem to have any listings now.

Right now "bjomejag" seems to be the active Omega seller. I think they are two different people who both work at Omega.

There are product differences sometimes between what they list and what they send. This is sometimes just due to copy//paste listing info, it happens when you are editing large amounts of listings.

They can be slow to respond to messages on eBay sometimes, after all, they have filters on Mars, so what you see on eBay is surplus, etc..

I got all my bandpass filters from them for my Sparticle bandpass array tester, back when those were less than half the price they sell them for now.

You may want to double check the specifics with them before purchase, just to make sure the out of band and transmission is what you expect.

They have some things that no one else has at prices that can be affordable. They are less expensive than going to mars with your socket wrench...

[Cadmium]

Now, about the Kolari Hot Mirror used for IR suppression g in UV-only stacks.

Bad idea.

Assuming the graph you have posted is T (transmittance) linear (instead of Ti (internal transmittance)), then the their filter is more or less kind of between BG39 and BG40.

Let remember that real BG39 has the same Red/IR suppressing as does S8612 (the best stuff this side of Mars), however BG39 also cuts off more UV than does S8612.

BG40 transmits a lot of UV as does S8612, however BG40 doesn't suppress Red/IR enough unless you use a ticker version which then also cuts UV.

So the best of both worlds is S8612.

So stacking that Kolari filter with any kind of U glass 2mm or less is going to result in some Red/IR leakage.

Then of course there is my usual warning about Chinese glass, because it is not reliable, and that can change the assumed graph for that product resulting in multiple differences in stacked transmission.

*** The important take away here is that 'hot mirror' has about the same Red/IR suppression as using BG40 2mm. Not good enough for UV stacking. ***

 

 

Here is a UG1 (similar to KWB2, but better) + BG40 stack.

This will work, but marginally, you will probably not see much warm IR leakage unless you look hard at the center of a Rudbeckia on a summer day, that should be your best test target, that or a dandelion.

Keep in mind that this stack using BG40 transmits more UV than the 'hot mirror' you have, your 'hot mirror' will cut much more UV,

not as efficient of a stack, lower amplitude peak UV transmission, longer exposure time, and less UV bandwidth than what this UG1 + BG40 stack shows here.

[ulf]

I would like to experiment with UV portraits so I went looking for a cheap UV filter, just to see if it's interesting enough to continue with.

Weighing in this as a strong factor for what to chose I think there is some latitude for risking some slight IR-leakage or quality issues, especially as there will not likely be any UV-black areas in the motifs.

Then it might be OK to take the risk with the lately potential problems with eBay Omega filters.

The only filters at really bargain prices are those.

[dabateman]

Ordered a 2mm ZWB2 first and see how it performs with my Kolari Vision Hot Mirror.

Looking at the graph it should work.

 

Sounds like a good idea. Test out what you have. Don't jump into anything yet.

 

Remember that we all have our own biases based on what we mainly like to and actually photograph. You want to do art with people. Great. Test out the hot mirror and your UV filter. See if the skin is still too plastic smooth, and glowy. Than you do have too much IR leakage.

 

I think (my own bias) men photography well in UV. Makes them look rough, tough textured. Women photography well in IR. Smooths out skin, adds a glow.

 

Depending on the look you want you may actually want an IR leakage balance, not too much details, some glow.

 

Have fun and play around. If you want more hard contrast than look into going strictly UV and black and white.

[Nisei]

Thanks

Yes, this is not about getting scientifically perfect results but about results I like.

I know now that the stack I'm going to try is not ideal so if I'm disappointed with the results I can always take the next step and buy something better.

[Andrea B.]

We have both "types" of UV photography happening here on UVP art and scientific. And indeed sometimes we see a mix of both in one photo. Making artistic photographs - which please you - is one of the most satisfying aspects of this unusual photography we all enjoy. Go for it! And please do show us your results.