Anyone own this filter?

[Fandyus]

https://www.pnta.com/expendables/dichroics/rosco-permacolor-dichroic-filter-3660-double-coated-uv-pass/

Seems really cheap for having basically no IR leaks. I wonder how good could it be for actual UV photography though, given that it basically only goes down to 360nm-ish.

[Andrea B.]

I've never seen that Rosco filter before, so thank you for the link.

 

There is a *lot* of good imaging between 360 - 400 nm. Indeed, I would say that most of the photos you see on UVP lie within that range. This is because our lenses typically work best in that range. It is only a few lenses which dip below, say, about 330 nm. And there are some very sweet UV-pass filters with peaks between 360 - 400 nm.

 

The important thing is that this Rosco filter has (we hope!!!) no IR leaks. However, it is not a pure UV-pass filter. It seems to be a UV + Violet + Blue filter. That is interesting. I do not know just how much the visible Violet and Blue would affect the UV reflectivity/absorption portions of the photo. I'm thinking that perhaps there would be a "wash out", but I don't know for fact.

 

 

There have been some Rosco filter tests on UVP. I can't recall whether this filter was tested though. Search around.

[Fandyus]

I've never seen that Rosco filter before, so thank you for the link.

 

There is a *lot* of good imaging between 360 - 400 nm. Indeed, I would say that most of the photos you see on UVP lie within that range. This is because our lenses typically work best in that range. It is only a few lenses which dip below, say, about 330 nm. And there are some very sweet UV-pass filters with peaks between 360 - 400 nm.

 

The important thing is that this Rosco filter has (we hope!!!) no IR leaks. However, it is not a pure UV-pass filter. It seems to be a UV + Violet + Blue filter. That is interesting. I do not know just how much the visible Violet and Blue would affect the UV reflectivity/absorption portions of the photo. I'm thinking that perhaps there would be a "wash out", but I don't know for fact.

 

 

There have been some Rosco filter tests on UVP. I can't recall whether this filter was tested though. Search around.

 

Thanks! And no problem, was glad to link.

[Andy Perrin]

Some thoughts:

1) That spectrum stops before the 800nm range and we don't know what's happening there. Cameras are still quite sensitive in the 800nm's.

2) Like Andrea pointed out, there's loads of blue in there and it may out-shine the tiny amount of UV in sunshine, so it will behave as a mostly blue filter.

 

All that said, it would be quite interesting to do some tests with this thing!

[colinbm]

Yes I have one.

I'll post a picture soon....

[colinbm]

Rosco Permacolor Dichroic Filter, #3660 Double Coated UV Pass.......

 

What they don't want you to know....

 

 

 

Does the addition of an S8612 help any....?

 

[Andy Perrin]

Hah, as they used to say on Mythbusters, “THAT’S a result!”

 

It seems my suspicion that the filter might pass IR in the 800s was justified.

[Andy Perrin]

I would love to see some photos with and without S8612 Colin.

[Fandyus]

Thank you, that's really disappointing though, I had my sights on the filter but now I know better.

[Stefano]

You can expect most materials and filters to become more transparent in IR. IR-blocking filters are not so common.

[Fandyus]

One thing I do have to ask tough, how do the photos taken with it look? Is it like all the other UV/IR bandpass filters?

[colinbm]

Rossco 3660, both CWB in camera

 

First Rossco 3660 alone.....

 

Second Rossco 3660 with S8612....

 

 

[eye4invisible]

https://www.pnta.com...coated-uv-pass/

Seems really cheap for having basically no IR leaks. I wonder how good could it be for actual UV photography though, given that it basically only goes down to 360nm-ish.

 

Yes, I have one, and like colinbm stated, it leaks IR like crazy.

 

Also, pnta.com's customer service leaves a lot to be desired. I called them (left a voicemail) and emailed them, and nobody ever got back to me to confirm if they ship to non-US addresses. I ended up sourcing one from B&H Photo instead (https://www.bhphotovideo.com/c/product/1164556-REG/rosco_120336607495_2_round_uv_pass.html)

[Fandyus]

Rossco 3660, both CWB in camera

 

First Rossco 3660 alone.....

 

Second Rossco 3660 with S8612....

 

 

 

Thank you for showing me, that's pretty disappointing, could be useful with orthochromatic film though.

[eye4invisible]

Rossco 3660, both CWB in camera

 

First Rossco 3660 alone.....

 

Second Rossco 3660 with S8612....

 

 

Nice captures, colinbm!

 

I need to dust off my 3660 and take some more shots with an S8612.

[Cadmium]

Problematic to most dichroic coated filters is the color shift from center to sides, and/or the color shift when viewing the filter straight on or at an angle.

Below examples of that.

 

DB850 straight on and at an angle.

 

Lee C47 dichroic straight and angles.

[colinbm]

Nice captures, colinbm!

 

I need to dust off my 3660 and take some more shots with an S8612.

 

 

I need to disassemble the camera & de-dust some internal glass...

[Cadmium]

A BG3 2mm + S8612 2mm stack would transmit about the same with no IR, with no dichroic color shift tendency.

[Andy Perrin]

Thank you for showing me, that's pretty disappointing, could be useful with orthochromatic film though.

 

That situation, where the manufacturer's spectrum doesn't show a leak that's just beyond where they end the graph, is really common, so when you shop for filters, learn to look for it. Basically if you don't have a spectrum that goes all the way to 1000nm or so (the 1000-1100nm part usually doesn't matter because the camera isn't that sensitive there) then you don't know if it leaks IR or not. Be suspicious.

[colinbm]

Thank you for showing me, that's pretty disappointing, could be useful with orthochromatic film though.

 

 

The S8612 goes all gooey & sticky in a bit of humidity & you have to continually clean it with hydrogen-peroxide.

[Andy Perrin]

I’m still not sure how humid it has to be for that to be an issue, Colin. I’ve had my S8612 for a few years and never seen any oxidation, but I would say my storage conditions are typically 20C and about 20-40% humidity.

[colinbm]

Dave has the same problem & Ulf is very aware of it.

[Andy Perrin]

I don’t deny it happens, but I think it must be much more humid where you are! Anyway you can just store it with those little desiccant packets, the kind that say “Do Not Eat.”

[colinbm]

I don’t deny it happens, but I think it must be much more humid where you are! Anyway you can just store it with those little desiccant packets, the kind that say “Do Not Eat.”

 

 

40% humidity is considered very dry weather here....

There has been plenty of discussion on the science & habits of this phenomena on this forum, to fill an encyclopaedia with the knowledge.

It is real & it is not prevented by using silica gel, in fact S8612 absorbs moisture better then silica gel.

[Alaun]

The S8612 goes all gooey & sticky in a bit of humidity & you have to continually clean it with hydrogen-peroxide.

 

 

??? The S8612 is Schott glass and Schott is quite clear about the pros and cons of the properties ?