BaaderU Raw Color with Nikon D600 and Panasonic S1R: Geez!! (Update: Edmond 340BP10)

[dabateman]

53 minutes ago, Andrea B. said:

I am now expecting that this stack [U-340 x 7.0 mm] will be black for the S1R

 

David, I'm not sure where you are getting that? I've already tested the S1R with U-340.

Some U-340 results are in this topic:  Panasonic Lumix S1R Conversion: An Exploration

 

The post there dated September 4, 2021 showed a bouquet photographed with 4 different UV-pass filters (including U-340 x 7.0) under the SB-140 UV-flash.

The post there dated September 13, 2021, showed the interesting differences in the raw color produced by the S1R and the D610 when using U-340 x 7.0 mm under the SB-140 UV-flash.

 

Also the S1R recorded something with that little Omega 293BP10. I posted that above. I was a bit unsure of that result though. Maybe because I was surprised I got anything at all.

You exposed that 7mm for 30 seconds,  with 2 to 5 flash bursts, which will be skewed to the upper UV end of the spectrum.  7mm u340 has 10-15% transmission at 370nm and the images are very monochromatic,  without false color. 

I think this indicates a high cutoff for that Panasonic S1R coverglass. 

[Andrea B.]

We have wandered way off topic....

I think it was originally about how the raw colors produced by the S1R seem to deviate from those produced by the D610 (which produces the "standard" false colors we are used to).

 

Then Jonathan got to wondering about the thickness of the sensor cover glass and whether that might affect the raw colors. I was reading somewhere that the S1R sensor cover glass is not as thick as some. I need to find that link.

 

Now we are talking about whether the S1R is UV-capable at under 7.0 mm worth of U-340 with SB-140 UV-flash illumination.

 

Anyway, to the last point, here are the raw versions of the 4 UV-pass filter photos all made indoors at f/11 for 30" at ISO-400 with the Panasonic S1R + UV-Nikkor with SB-140 UV-flash illumination.

For each filter, the SB-140 was fired 3 times during the 30": once on the left, once on the right and once in the middle.

 

To be fair, I'm thinking that this particular indoor exposure method does not allow for a proper assessment of these filters' speeds because no metering was used. I will try to get some metered shots outdoors in strong sunlight with these filters in order to be able to better make comparisons about how well they work on the S1R and how well the S1R works with a particular filter.

 

(whew!    )

 

 

 

[JMC]

3 hours ago, Andrea B. said:

Then Jonathan got to wondering about the thickness of the sensor cover glass and whether that might affect the raw colors. I was reading somewhere that the S1R sensor cover glass is not as thick as some. I need to find that link.

Andrea, the thickness isn't the issue (I don't think I mentioned thickness), it's the material its made from and/or any coatings present. With most sensors being made by one or two manufacturers, I suspect this is going to be more and more of a problem for UV imaging, especially with normal high street cameras. I go down the route of having the coverglass replaced mainly for my UVB work, but if you are starting to see 340nm being robbed, then this will start to have an impact on flower photography in sunlight and flash too.

[colinbm]

Yes sub 340nm is the problem 

[Andrea B.]

Andrea, the thickness isn't the issue (I don't think I mentioned thickness), it's the material its made from and/or any coatings present.

 

Jonathan, thank you for the clarification. As I indicated this topic wandered, and I lost track of it all. Wasn't on my game. 

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I am thinking that for a few years at least, we can make use of older camera bodies for UV photography if the newer models' sensor glass covers are blocking too much UV.  The primary problem is that we do not have a good way to know the specifications of the sensor glass covers. Perhaps narrowband filtration can help determine that, so I should probably try to get some useful 10 nm UV-pass filters peaking at 310nm, 320nm, 330nm (not U330 or UG5) and 340nm.

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[dabateman]

If you go down the narrow bandpass filter route. You will also need narrow band led light sources and excellent blocking on those filters. As any leak into visible will be pushed through. 

That is what I think you are seeing with the S1R. Too much leakage through your filter.

Stacking your 340bp10 with at least 2mm u340 or 4mm would definitely help to reduce the visible leakage through the 340bp10 filter. 

[Andrea B.]

Of course, for me, being able to test and shoot in sunlight is very important. I don't really want to get into narrow bandpass UV-LEDs at this time. I'll leave that to you all!! 

 

I do plan to try the 340bp10 with various things stacked over it after I finish hammering some plants into the hard clay soil we have here in the (so-called) garden. 

 

Anyway, I can't tell you how many times I have wanted to fling that dang-rabbity 340bp10 into a black hole. I can't understand why it would even be good for industrial use with that super-mirrored silver finish.

 

 

[colinbm]

Would the Baader U be a good cover to block the visible leak ?

[dabateman]

6 hours ago, colinbm said:

Would the Baader U be a good cover to block the visible leak ?

Depends on the version of the Baader venus u.  Mine has hard cutoff at 330nm I think. So not as good for the lower peak of the 340bp10 filter. It has two peaks if I remember correctly. The Baader venus would cut off some of the lower signal. 

The U340/UG11 filter wouldn't do that. Also you can stack 8mm of U340/UG11 to fully block all IR and still have a strong 340nm peak. Plus Andrea can sandwich the 340bp10 filter between U340/UG11 glass to avoid the horrible mirror problem she sees. Just add her 2mm U340 in frot and either her 1mm U340 or 2mm UG11 behind. That should block most IR and all visible leaks while still helping to remove the back mirror reflecting problem.