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QB39+ZWB1: Possibly the cheapest way to get true UV? (~26€)


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I actually figured this stacking "trick" even before I came to this forum and I thought how clever and inventive I was.. Well turns out I'm no the only one doing such things, that's cool.

As I said, I'm stacking a QB39+ZWB1, both 2mm thick. I couldn't confirm the thickness on the listing for the ZWB1 but I assume it's 2mm.

I used the said stack, Canon EF 50mm f/1.8 and my Converted EOS 1100D.

Here are some results:

post-350-0-62087800-1620842774.jpg

post-350-0-89268000-1620842754.jpg

post-350-0-68832600-1620842741.jpg

post-350-0-59802600-1620842735.jpg

 

The last picture includes a small greenhouse, it was completely transparent to the naked eye but it looks like some sort of black hut with this setup. The filters combined cost me 26.61 Euros with shipping.

post-350-0-63278300-1620842936.jpg

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Andy Perrin
It does look UV, although results might vary depending on where you buy your filters. The Chinese glasses have a lot more batch-to-batch variations in their spectra.
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I think it does look mostly UV, the colors are OK (the lavenders seem a bit too red to me but that can depend on a lot of things), but I think you have some IR leakage because the nectar guides on the flowers in the first image are brown instead of black. Still, not bad for ~26 €. If you want 100% pure UV you can increase the thickness of either filter just a bit.

 

What lens are you using? If it passes little UV leaks appear more.

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I think it does look mostly UV, the colors are OK (the lavenders seem a bit too red to me but that can depend on a lot of things), but I think you have some IR leakage because the nectar guides on the flowers in the first image are brown instead of black. Still, not bad for ~26 €. If you want 100% pure UV you can increase the thickness of either filter just a bit.

 

What lens are you using? If it passes little UV leaks appear more.

As mentioned, I used a Canon EF 50mm f/1.8

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Sorry, I didn't see it. It is a modern lens as far as I understand, so unlikely to transmit much UV. This doesn't mean it is a bad lens, you can shoot UV with it, but your exposures will be longer and leaks can emerge.
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Yes Jason's Chinese filters are the only ones that I haven't had issues with. Also he can cut specific things if you ask.

I recently got a 77mm BG39 equivalent from him that is, but it just leaks a little 680nm peak with my zwb3 filter. Its perfect with other IR leaky UV filters as their IR peaks start at or past that point.

However it did let me get the nice orange in these dandelions.

 

https://www.ultravioletphotography.com/content/index.php/topic/4554-fun-with-zb1-filter-on-sigma-18-35mm-with-olympus-em5mk2/

 

I am waiting on a 365bp dichoic from him that I hope will be good. But he only promised 0.1% IR blocking, which isn't enough. But I will test it to see. The peak max was amazing.

 

My 52mm BG39 blocks all the IR from my UV filters, just the 77mm was a little thinner.

 

To give you an idea Jonathan tested the Csnon 50mm f1.8 here:

https://www.ultravioletphotography.com/content/index.php/topic/3232-canon-50mm-and-40mm-lenses-vs-50mm-cassar-s/page__hl__40mm__fromsearch__1

 

I know I have seen the spectrum for it but can't find it now. I have the STM Canon 50mm f1.8 lens, but haven't tried it in UV yet.

 

Bernard compared the STM 50mm Canon here:

https://www.ultravioletphotography.com/content/index.php/topic/4408-putting-values-against-performance-of-various-lenses-resolving-power/

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Andy Perrin
The lens seems fine from Jonathan’s test. If that filter seller is good then you have indeed found a winning combo. The white balance could explain slightly altered colors. Was it off PTFE?
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Sorry, I didn't see it. It is a modern lens as far as I understand, so unlikely to transmit much UV. This doesn't mean it is a bad lens, you can shoot UV with it, but your exposures will be longer and leaks can emerge.

Yes, I am aware, but I don't really have any better options on me at the moment. I'd love to get the Soligor but who knows when I find one.

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The lens seems fine from Jonathan’s test. If that filter seller is good then you have indeed found a winning combo. The white balance could explain slightly altered colors. Was it off PTFE?

What do you mean PTFE?

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Yes, I am aware, but I don't really have any better options on me at the moment. I'd love to get the Soligor but who knows when I find one.

Ulf found mine on eBay, if you search you may find one (or other UV-capable lenses). I got mine for 61.61 GBP (shipping and customs included).
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What do you mean PTFE?

He means polytetrafluoroethylene (Wikipedia). It is a material with some interesting properties, including a very flat reflectance in a broad range of wavelengths, including UV. In other words, it is white in a broad sense. It is perfect for white balancing photos.
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He means polytetrafluoroethylene (Wikipedia). It is a material with some interesting properties, including a very flat reflectance in a broad range of wavelengths, including UV. In other words, it is white in a broad sense. It is perfect for white balancing photos.

Ah, I see, I just white balance my UV photos off of things that look like they should be grey to me, much like I would do with other photos.

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Ulf found mine on eBay, if you search you may find one (or other UV-capable lenses). I got mine for 61.61 GBP (shipping and customs included).

60 GBP is unfortunately quite an investment for me at the moment, I get that I shouldn't have picked such a hobby when I'm this low on funds but what can you do, I'm a student so I don't really get paid monthly and I still live with my parents (I'm 18). I want to get a part time job in the summer and buy some gear then, but it will take a while.

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I am just a bit older than you, and it took me about two years to improve my gear to where I am now. It is normal to do it slowly, and my funds are limited too. I have so many projects I would like to do, but are far too expensive for me.

 

Your setup is fine, you can always improve it in the future.

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Andy Perrin

Ah, I see, I just white balance my UV photos off of things that look like they should be grey to me, much like I would do with other photos.

For quick-and-dirty photos (or ones where colors are not that important to you, or arty photos), that will do, but if you want to make your photos understandable/analyzable by the board, you need a proper white balance standard. PTFE is relatively cheap and works very well.

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The cheapest way to make a PTFE standard is get some ptfe tape, called plumbing tape or thread seal tape. Then just wrap a couple layers around a card and keep that in your pocket. That should cost you less than a dollar.

 

Or buy a block of virgin white PTFE from Ebay.

 

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I think it does look mostly UV, the colors are OK (the lavenders seem a bit too red to me but that can depend on a lot of things), but I think you have some IR leakage because the nectar guides on the flowers in the first image are brown instead of black. Still, not bad for ~26 €. If you want 100% pure UV you can increase the thickness of either filter just a bit. What lens are you using? If it passes little UV leaks appear more.
I agree with Stefano that the brown areas hint about some IR-leakage.

One possible reason for seeing this can be the transmission of the lens.

I do not own and have not measured the EF 50/1.8, but as it is a relatively modern design with modern glass types and coatings.

With ten air to glass surfaces I expect a rather poor UV-transmission.

https://global.canon...duct/ef451.html

 

Lenses with a poor UV-transmission gives a much higher demand on IR-attenuation.

My guess is that the same filters will perform better on a lens with a more proper UV-transmission.

 

Edit:

OOPS I should have refreshed the thread before writing my answer.

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Andy Perrin

Ulf, I want to see it with a proper white balance before making assumptions about the colors and leakage. Remember when I photographed the birds-foot trefoil and we all got different colors and it turned out to be a white balance issue?

https://www.ultravioletphotography.com/content/index.php/topic/2746-birds-foot-trefoil-an-interestingly-boring-yellow-flower/page__view__findpost__p__21004

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You are right, but the very first image do really look properly white balanced and still show brownish flowers.
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The cheapest way to make a PTFE standard is get some ptfe tape, called plumbing tape or thread seal tape. Then just wrap a couple layers around a card and keep that in your pocket. That should cost you less than a dollar.

 

Or buy a block of virgin white PTFE from Ebay.

Thanks! I'll see where I can get my hands on some.

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