[Filter Test] AndreaU-MkII, BaaderU, Hoya U340 x 4.00 mm: Raw Colors

[Andrea B.]

Recently I was shooting a sunflower for the botanical section using an SB-140 UV-flash. As a side note I made these raw composites in Raw Digger in order to see the non-white-balanced colors for the three UV-pass filters I was using.

 

I've made lots of posts before about raw colors for different filters. I will try to find the links and post them here in case anyone is interested in this. I am rather fascinated by the idea of the non-white-balanced colors our cameras are actually recording under different UV, IR or UV+IR filters, but it might be total Boresville for some (many?).

 

LINK:

This is a link to photos showing the non-white-balanced colors of 36 UV/IR filters. It does not include raw colors for two filters in this current topic (U340 x 4.0mm and AndreaU Mk-II).

https://www.ultravio...white-balanced/

 

 

 

ADDED LATER: I was not going for a comparison, per se, between filters using the photos shown below. I only intended to post some raw color illustrations for the filters I was using during the sunflower shoot. See Cadmium's Post #4 below for a comment about comparability of filters. I agree with that comment.

Also I don't think the raw color for the AndreaU Mk-II had ever been posted before, so there's that too.

 

 

 

The AndreaU-MkII for this flower was about 15° which I would call red-orange if you accept orange as being at 30°. The BaaderU was at aboug 19° which is a little bit more orange. And the unblocked 4mm thick U340 was almost entirely orange at 28°.

 

 

 

 

 

[Andrea B.]

The background here is Spectralon.

 

Peak: 360 nm with 75% transmission

Full Width Half Max: 346 nm - 386 nm

 

 

Peak: 350 nm with 78% transmission.

Full Width Half Max: 320 nm - 380 nm

 

 

I like the unblocked U-340 x 4.0 mm which passes a smidge of IR.

Heresy, I know, I know.......

 

 

No flash used for this stack.

[Stefano]

I noticed that (talking about raw colors) 365 nm light is almost pure red, and 340 nm light is orange (I think almost every camera sensor sees colors this way), so a shift towards orange with deeper-peaking filters is what I would expect.

[Cadmium]

U-340 alone would not be in the same category as Baader U, etc.. You would need to stack U-340 with S8612 to make them comparable.

U-340 is seldom used alone with no IR suppression. It can be used as a dual band filter, but there are better choices for dual band usually.

To me, it doesn't make sense to compare U-340 4mm with UV pass filters when the IR isn't suppressed.

 

U-340 4mm is not enough to suppress the IR, you really need 6mm or 8mm.

[Andrea B.]

I really like that U-340 x 4.0 mm with no blocking. That is why it was included.

 

But I totally agree with you that if I were trying to compare filters, then the leakage should be blocked.

 

I'll add something to the original post or refer to your post.

[Cadmium]

That's OK, just pointing it out for those who might get mixed up.

If you want pure U-340 then I recommend using 8mm, (or two 4mm stacked). You could also stack U-340 4mm + S8612 1mm, but that looses the UV band width that pure U-340 8mm retains.

[dabateman]

Yes looking forward to testing one piece solid 8mm zwb1. I have a bunch of 2mm thick that I have stacked and look good.

 

I was expecting more color comments from Stefano. He seems to be holding back.

 

But you are only using a flash which will be skewed to the upper UV wavelengths.

[Andrea B.]

The transmission through 8 mm of U-340 is higher than I though it would be.

[ulf]

The transmission through 8 mm of U-340 is higher than I though it would be.

Steve's graphs shows the internal transmission without the surface transition losses.

Those cause about 9% less transmission for a solid 8mm thick U-340.

[Cadmium]

Jonathan has a nice spectrometer scan of those same thicknesses on here somewhere, I tried to search for it, but I wasn't able to find it.

[ulf]

Jonathan has a nice spectrometer scan of those same thicknesses on here somewhere, I tried to search for it, but I wasn't able to find it.

I found a spectrometer scan I made some time ago of my 2 x 4mm U-340 stack.

It has a peak transmission of 51% at 329nm and a FWHM of 66nm

[Cadmium]

Here are the scans Jonathan did:

https://www.ultravio...9186#entry19186

[dabateman]

Andrea,

Back to the point. If you still have that flower and all the filters available. It would be nice to see how those colors change when you illuminate it with a 365nm Led torch/ flashlight, like the convoy or Nemo.

 

The raw color results should be significantly different than from the flash, which is a broader spectrum and favors the upper UV.

 

You could also try your deep UV flashlight, but I don't know if you ever got that working.

 

[Cadmium]

I would guess the opposite, given the LED torches have a rather narrow even monochrome illumination, compared to a UV flash which is more broadband.

 

If you are doing more of these then maybe try a U-360 2mm + S8612 2mm stack, to see how the colors of that stack compares to the Baader U.

[Andrea B.]

Here is a raw color filter test which includes the U-360.

https://www.ultravio...__fromsearch__1

 

 

And this link - which has nicer looking test results - includes the U-360.

https://www.ultravio...__fromsearch__1

[Andrea B.]

This is the best raw color filter test of all time.

 

[Filter Test] AndreaU MK II with BU, SEU, U-360 :: Bouque...

 

I want another bouquet like that!