Hoya U-340 8mm

[Cadmium]

This topic is related to a previous discussion/topic:

https://www.ultravioletphotography.com/content/index.php/topic/3634-some-ideas/page__st__40

 

Quick test of Hoya 8mm thick filter, and compared to Baader U.

This is not a stack it is just U-340 alone (see graph).

Weather = all clouds. These are full frame marquee white balanced in CNX2.

Much more testing ahead.

D7000 UV/IR, UV-Nikkor 105mm.

 

Hoya U-340 8mm (no suppression)

 

Baader U

 

Schott UG11 8mm (no suppression), and Hoya U-340 8mm (no suppression)

Here is another graph: https://www.ultravio...dpost__p__19190

[Andrea B.]

Wow, an 8mm thick filter. How long was the exposure?

 

Interestingly (or not?), when diff-stacked the tonality of the two photos is very nearly identical.

[Cadmium]

ISO 200, f/8, Aperture Priority, Matrix.

Exposure U-340 8mm = 8s

Exposure Baader U = 1.6s

 

At peak (~85%), the Baader U is much stronger and obviously (violet/blue) has stronger 320nm-400nm content exposing much faster.

[Cadmium]

U-340 8mm, WB in CNX2 from RAW (full frame marquee WB)

 

 

This version below was white balanced from RAW in Photo Ninja (full frame WB).

[Andy Perrin]

When I try white balancing the 8mm one in PN, it looks pretty much like the Baader.

[Cadmium]

Full frame WB from RAW in CNX2 and Ninja look a little different. I WB in CNX2.

Full frame WB from the JPG above in Ninja looks much different, and much more lavender, not yellow like from RAW.

I think the big difference for you is you are WB from the JPG. I tried both, and it is dramatically different from RAW or from JPG.

[Andy Perrin]

Ideally from RAW, yes, but I don't have the RAW, so I did the best I could. By clicking around rather than doing full frame (which is pretty arbitrary, as you mentioned...) I can make the colors look quite similar to the Baader.

[Cadmium]

The first U-340 8mm JPG photo at top, re-WB from JPG in Photo Ninja.

 

U-340 8mm RAW file WB in Photo Ninja.

[Andy Perrin]

The bottom does not look white balanced. If you want to do this rigorously, put some PTFE in there and white balance the RAW off that.

[Cadmium]

I prefer the bottom one myself, has more differentiation in it than the first one at the top of the topic.

I will try some PYFE at some point, this was just a quick test.

 

It looks promising to me.

It reminds me a little of the PrimaLuceLab U that Enrico posted about some time back on his page.

http://www.savazzi.net/photography/images/P1030193s.JPG

http://www.savazzi.n...alucelab_u.html

(about half way down the page)

https://www.primaluc...ltraviolet.html

Unfortunately the PrimaLuceLab U has a pretty bad IR leak, and some of its color may be the result of the IR.

This U-340 8mm seems to have a similar mix of colors.

[dabateman]

That looks like what I would expect, green. You really have a 340nm filter there. The amount of higher UV wavelengths is really low. A Baader venus filter allows in much more of the 380nm than your U340.

 

[Cadmium]

Indeed, and that is why most people with lenses that are not capable of a lower UV reach should stick with UV filters that cut off at 400nm rather than 380nm

This has a different color mix, which I find interesting. It is not suppose to look like a Baader or a U-360 stack, I don't want it to.

When white balanced in Photo Ninja, it takes on a much more variegated color palette.

 

Wait till I shoot the dandelions that I found late today. Yep, dandelions in January.

[Cadmium]

I forgot to include these links.

First off, this thick U-340 filter was inspired and discussed here previously:

https://www.ultravioletphotography.com/content/index.php/topic/3634-some-ideas/page__st__40

 

And here are Jonathan's scans of various thicknesses of thick U-340 which should be the best. Thanks Jonathan.

https://www.ultravioletphotography.com/content/index.php/topic/2383-good-practice-and-setup-for-spectrometer-measurements/page__view__findpost__p__19186

[Stefano]

Oh, nice! You did it! So it is simply a lower cut off filter than the usual UV-pass filters, which renders differently some things (I made a recent topic about the differences between these two kinds of filters). It suppresses IR to OD 5+, which I think is required in deeper UV.

[Stefano]

Schott UG11 8mm (no suppression), and Hoya U-340 8mm (no suppression)

Here is another graph: https://www.ultravioletphotography.com/content/index.php/topic/2383-good-practice-and-setup-for-spectrometer-measurements/page__view__findpost__p__19190

As I previously said, the U-340 is better than the UG-11, both in UV transmission and in IR rejection.

[Cadmium]

Oh, nice! You did it! So it is simply a lower cut off filter than the usual UV-pass filters, which renders differently some things (I made a recent topic about the differences between these two kinds of filters). It suppresses IR to OD 5+, which I think is required in deeper UV.

 

Yes, it suppresses to OD5, and I think it probably has a 55% peak UV, like Jonathan's graph shows for 8mm. I probably don't have the correct reflection factor entered for the U-340 in my calculation, so I trust his scan.

https://www.ultravioletphotography.com/content/index.php/topic/2383-good-practice-and-setup-for-spectrometer-measurements/page__p__19186#entry19186

[Cadmium]

As I previously said, the U-340 is better than the UG-11, both in UV transmission and in IR rejection.

 

Unless you are using thinner U-340, like under 2mm or especially under 1.5mm, then it can leak more than UG11 in the 500nm range.

[Cadmium]

Hoya U-340 8mm thick non-glued air-gaped stack from today, actual sunshine.

Late afternoon sun, this shot is pointed west by northwest.

Nikon D-7000 UV/IR, UV-Nikkor 105mm. ISO 200, f/8, 2s.

White balanced using Spectralon in Photo Ninja.

My neighbor moved his truck.

[Cadmium]

Here is the U-360 2mm + S8612 2mm version of the same scene, also individual Specralon WB/PN.

[colinbm]

Much more nice Steve....;-)

[dabateman]

Interesting, the dry grass and the side of the TV seem to have a slight blue or purple in the U340 shot to my eyes. But the dry grass not at all in the U360+S8612 shot.

However that Winnebago is clearly most purplish in the 360.

 

Also did you blur out the license plate or is that a cover?