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

[Andrea B.]

So it would seem that camera sensors can made a great deal of difference in the raw color outcome of a reflected UV photograph. I'm only having mild panic about this. Given the current state of the world, it seems ridiculous to have any panic at all over photographic trivia. But I am worried that quite a lot of what has been written here over the last 9 years about false colors and raw false colors in reflected UV photography might be, at best, incomplete, and at worst, erroneous or misleading.

 

In the past I've used converted Nikons, a Pentax, a little Lumix and a Sony. They all produced the same false color results whether raw or white balanced. Then along comes the S1R and all my false color facts have been upended. 

 

Well, so it goes.....

 

Here is an old photo of Spectralon under SB-140 flash (with its SW-5UV filter) made with a Nikon D600 conversion + UV-Nikkor + BaaderU.

 

 

Here is a recent Spectralon photo under filtered SB-140 flash made with a Panasonic S1R conversion + UV-Nikkor + BaaderU. It's about 49* different on the color wheel from the preceding. That's quite a lot of difference. 

 

 

 

So now what?

Should I wade through 9 years of topics looking for false color comments to update?

Seems rather daunting.

 

Maybe we should just start a new edition of the forum with new Stickies, etc. 

That seems kind of drastic. 

 

Any suggestions welcomed !!!

 

 

 

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By the way, anybody remember how upset I get when people try to make false color to wavelength correlations and don't realize or take into account how many variables are involved in producing false color? Refer to this topic for one more such variable.

 

 

I keep hoping I made some sort of stupy mistake. And once I discover it, the second photo will immediately flip into that nice 13* orangey-red.

[Andrea B.]

I should note that this false color difference between two sensors does not compromise the capture of UV signatures of any subject. 

Does it?

 

[dabateman]

I am glad you got the S1r first. If a different UV photography member had, it may have resulted in lengthy back and forth fighting and a loss of a user.

This is just a great example that not all the sensor color filter dyes are equal. 

Most are, but not all.

The S1R is just an other tool to get a different color pallet from uv, like a ug5 or ug2a filter. Will have a different colored look.

 

Now you have to compare some flowers and see which has the most pleasing false color uv. Some flowers may look best with one or the other camera. 

[JMC]

I'm going to throw another variable into this - the coverglass on the sensor, is it different between the D600 and the S1r? My guess is the S1R is like most modern sensors and quite drastically cuts the UV starting at 400nm. What was the d600 sensor coverglass like? If the d600 coverglass blocks less of the lower wavelength UV, I could see how that would change the colour balance of the image - Andrea were those colours derived from the Raw files (I'm assuming they were, but wanted to check) and was your coverglass left intact during the conversion, or was it removed and replaced with fused silica?

 

The d600 has been around for about 10 years now and I can well believe sensor manufacturing has changed since then. Perhaps Dan (MaxMax) or Kolari could comment on that.

[Andrea B.]

Thank you both for your comments!

 

David, yes I will be making those floral UV-signature comparisons. From what I have seen so far, the UV-absorbing/reflecting areas do not change between the two conversions. It is simply the false colour output which is different between the D610 and S1R comparisons. 

 

One small problem:  My D610 conversion seems to be broken. I suspect metering is failing, but I'm not entirely sure. The result is that I can no longer get a correct exposure. However ----- I still have the Pentax and Sony conversions. So I will get one of those going again for further tests, as they have always produced the same raw/false colours as did the D610.

 

*******

 

Jonathan, I unfortunately do not know anything about the coverglass on my two conversions. But I will try to find out what I can. 

 

As for the recently posted photos, they were all derived from raw files. The raw composites and histograms were made in Raw Digger and no white balance or camera color profiling was applied. I've always felt that was the best way to compare results because white balance tools and camera color profiles have some minor variances.

 

********

 

One small experiment I want to make immediately is to photograph the Spectralon outdoors in strong sunlight (which we currently have). I want to look at the raw color made with sunlight. I'll be back soon with that.

 

 

[Andrea B.]

Spectralon in strong sunlight (UV index currently at 9) with S1R.

Raw composite from Raw Digger - no white balance or camera profiles applied.

 

 

[Stefano]

If this pink raw color is due to limited sensitivity to shorter wavelengths, try to use your 340 nm bandpass filter, if you didn't do that yet. 340 nm light is recorded by (at least) most cameras as orange.

[Andrea B.]

Will do !!

[Andrea B.]

EDMOND OPTICS 340 BP 10 stacked with Schott S8612 (2.00 mm)

Raw composite. Sample looks quite orange to me.  

 

 

 

OMEGA 293 BP 10

And here is one just for grins. I need to redo this one with an IR blocker added. Be back soon with that.

Had to crank up the ISO here.

This sample is 3° clockwise from true red at 0°/360°.

 

 

OMEGA 293 BP 10 stacked with SCHOTT S8612 (2.0 mm)

Here is the result when the 293bp10 is stacked with an IR-blocker. Still red.

With the double filtration, I had to go to 60" at ISO-1600.

I really am not sure that this is UV light which I've captured, but it is not IR.

This sample is 7° counter-clockwise from true red at 0°/360°.

 

 

So I'm beginning to think that the sensitivity of the converted S1R is OK. 

[JMC]

Andrea, absolutely, these types of comparisons should be done with Raw files. I assumed you did, but wanted to double check.

 

Here's a quick test. Try both cameras with the UV Nikkor. With your Edmund Optics 340 BP 10 stacked with Schott S8612 (2.00 mm), on the same subject and in the same lighting, how do the images from both cameras look in terms of overall exposure, when you take images with the same ISO, shutter speed and f stop?  If possible do the same comparison with the SEU or a bandpass filter around 400nm.

 

If the coverglass on the S1R is absorbing more UV at 340nm than the one on the D600, this should show up as a difference in exposure. Using something like a 400nm bandpass or the SEU will give you a reference point higher in the UV / around the Uv/vis border where I'd expect the coverglasses to be behaving similarly (as there may be differences in actual ISO between the cameras).

[Andrea B.]

Andrea, absolutely, these types of comparisons should be done with Raw files. I assumed you did, but wanted to double check.

 

I always want folks to check stuff I do! Sometimes we get distracted, etc. 

 

*****

As mentioned above, my D610 is failing. So I will try your suggested experiment using the Sony which I have pulled out of storage. Charging its batteries now.

[Andrea B.]

Haven't forgotten. Getting set up to do this one.

 

Camera 1:  Panasonic S1R (full spec)

Camera 2: Sony A7R (full spec)

Lens:  Asahi Ultra-Achromatic-Takumar 85/4.5

UV-Pass Filter 1: Edmund 340bp10 + S8612 (2.0mm)

UV-Pass Filter 2: SEU Red

Exposure: f/8 @ ISO-400 for n seconds, where n is to be determined.

 

It is crazy windy here, so a landscape probably is not feasible.

I'll try shooting the usual spectralon and color checker card first.

[Andrea B.]

I will have to reshoot this Test because a couple of things cropped up during shooting that caused difficulties.

 

So I do not think it is safe to judge yet whether or not the S1R and A7R have any exposure differences which might be attributed to a thicker coverglass in the S1R.

 

SET #1 All at f/8 for 1/6" @ISO-400.

 

For the SEU (Red Version) UV-pass filter my Sony A7R seemed to have a bit of difficulty measuring the in-camera white balance while the Panasonic S1R did ok, but not perfect. Given that this is false color, I cannot say which of the following 3 photos has the "correct" white balance, but the S1R is probably closest.

 

The left side of the Spectralon has a tiny amount of blue cast, but the middle/right side is white.

I have no explanation for this.

 

 

The Sony in-camera white balance measurement did not produce white on the Spectralon. There is a uniform cyan cast over the Spectralon area. You have heard me mention before that sometimes in-camera WB measurements are not accurate when made through UV-pass filters. 

 

 

I used the Sony Imaging Edge Edit.app to set the white balance by using the white balance marquee tool over the Spectralon.

This did not entirely remove the cyan cast on the Spectralon, but there was an improvement over the preceding version for the Spectralon area. This consequently seemed to produce a pinkish cast over the CC card. Net result: a mess.

 

 

 

SET #2 All at f/8 for 5" @ISO-400.

 

Here are the results for the Sony A7R and Panasonic S1R when using the Edmund 340BP10 + S8612 (2.0mm) UV-pass filter stack. Neither camera handled the white balance measurement well for this filter stack, but this time the Sony A7R did better than the Panasonic S1R. The WB result from the S1R is really strange.

 

The 340BP10 stack is tough to use. It is very mirrored (silver) so tends to cause a kind of veiling flare. I get better results from this stack when using UV-flash. And it is not always easy to focus through it.

 

With most UV-pass or IR-pass filters, a white balance measurement on the white Spectralon also makes the first row, left-most CC patch become black. That did not happen here. The black patch is dark blue. However, the Spectralon area is neutral with no color cast although it needs a bit of brightening to look white.

A 10 nm width probably does not give enough data variation to get the usual WB results.

 

 

 

Somewhere up there I mentioned we were having a very windy day. So this last one is a bit OOF and tilted.

 

The WB measurement is completely pie-whackety. The S1R was not handling it well at all. I am thinking that I should try making the WB measurement at a much higher ISO and with the lens wide open (sorta) at f/4.5. Then the measurement time will be considerably shortened, so I might get a better result?

 

[Andy Perrin]

Those last two results look almost like they have visible light leakage?

[JMC]

I agree with Andy, those last two look like visible light image. For the Edmund and Thorlabs band pass filters I only ever use those in controlled environment and lighting (filtered light sources etc). If you have that with S8612 in sunlight, visible light leaks are highly likely. The only time I use those types of bandpass filters in sunlight is in combination with something like 4mm U-340.

 

[Stefano]

I agree. I would use that filter like Jonathan described. With such a narrow bandpass filter you should expect little to no color variation in your images. Also I don't understand the point in white-balancing them. That's really forcing false colors, normally images do look weird if you do that. For example, out of curiosity I tried the same with my BrightLine 340/26 filter + 2*2 mm ZWB1, and I had a noisy blue channel and almost no color.

 

Can you see the colored squares in the raw images?

[JCDowdy]

Andrea, there does appear to be a lot of visible in your 340BP10 images.

There are two 340nm CWL 10nm bandpass filters listed on the Edmund Optics website:

   340nm CWL, Hard Coated OD 4.0, 10nm Bandpass Filter.  Minimum transmission in passband ≥85% and average out of band OD ≥4.

and

   340nm CWL, Traditional Coated 10nm Bandpass Interference Filter.  Minimum transmission in passband ≥25% and average out of band OD ≥3.

 

With a rather low passband of ~0.6 OD the traditional coated filter has on average less than 2.5 OD residual blocking. 

If your 340BP10 is the traditional coated version then one would expect to see a fair amount of visible light imaged, especially with such a narrow bandwidth.

[Andy Perrin]

I think hers is hard coated but even OD4 is probably not enough when the 340nm light is so dim, especially in that narrow band. 

[JCDowdy]

Andy,

That is entirely possible even in Andrea's sun soaked territory. 

I also assume Andrea fully appreciates the difference between the two filters, but rather perhaps she did not receive the intended filter.

[dabateman]

Its possible her 340bp10 filter is fine. She has had it for a long time.

The problem might just be the cameras.

Vivek lyer scanned the A7R coverglass and it only transmits 20% at 350nm and very little at 340nm.

The Panasonic S1R might be worst, seeing what looks like more visible light than the A7R.

Bernard also so nothing with a Sony A7R and returned it for a A6000, after his first A6000 broke. 

 

Too bad your D610 is broken it looked to be slightly better than the A7R at 340nm from Vivek's cover glass plots: 

 

The Sony A7:

 

 

For Deep UV imaging we might just be limited to the Sony A7, Sony A6000,  Olympus Em5mk2, Olympus Em1mk1 and one of the Canon M-mount APS-C cameras. 

[Andrea B.]

I hear ya, guys! I mentioned above that the results from the 340BP10 were bad.

 

I make it a point to I *always* post the results which are goofy or otherwise "off", so that we can all learn from them. (If there is indeed anything to learn.)

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My Edmund 340BP10 is the silver-mirrored, hard coated version. Without the addition of some kind of over-filter, the 340BP10 is unusable because the mirroring creates all kinds of flare and reflections.

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Why did I set white balance before shooting? Well, we have to choose some kind of white balance to use when shooting. And using a correct white balance makes it easier to set exposure variables and get the proper exposure.  However, when the WB does not work out well or cannot be set, then what? With the old D610 I had nudged the camera WB setting I used for UV into a useable place by attempting to set a uniWB (uniform white balance for which the WB coefficients R=G=B=1.0 or very close to it.) UniWB makes UV or IR exposures easier. Also sometimes I set the LCD to monochrome if I cannot use a correct WB. Even though the camera histogram is for JPGs, it is still useful when shooting monochrome UV or IR to ensure the result is not too dark or too bright.

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I had forgotten that the A7R was shown to be not so great for UV. But the S7R did better with the 340BP10 than the S1R.

I am *really missing* my D610 conversion. The last time I had a Great Debate (in my head) about what conversion to buy to replace the ailing D610, I got the Panasonic S1R because it looked very promising. But we miss the familiarity of a camera style we have used for years. So I'm thinking again about another Nikon conversion.

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I'm thinking about stacking the 340PB10 with the BaaderU.

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Anyway, I'm going to try again with that 340bp10.

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[dabateman]

Do you have more than one 4mm U340 filter?

If you do than using 8mm of u340 would be better than the 340bp10 filter.  Or stack the 340bp10 with whatever thickness of U340 you have, at leastyour 4mm one. That will be better than stacking it with a Baader venus filter.

I am now expecting that this stack will be black for the S1R, and very dim for the Sony A7R. Its possible the color cast we have been seeing all along for the Panasonic S1R isn't due to different color filter dyes,  but due to a coverglass with nearly no UV depth.  As in the S1R might be limited to only 380nm. That would make sense based on these results. 

[Andrea B.]

I'm just now going out to try the Panasonic S1R with a variety of 340 glass. And I'll try the A7R again. why not....might as well as long as it is all kitted up a ready to use again.

 

I was going to stack the narrowband 340bp10 with the BaaderU because I was hoping to suppress any visible leak. 

If I stack 340bp10 with U340, I will still get the vis leak, maybe.

 

I'll be back with some results by evening I hope.

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I have the following U340 glass:

U340 x 4.0 mm

U340 x 2.0 mm

U340 x 1.0 mm

which obviously adds up to a 7mm thick stack with some air gaps.

 

I could add some UG11 to the stack. Thoughts?

UG11 x 0.75 mm

UG11 x 2.0 mm

 

 

[Andrea B.]

OF COURSE THE SUN JUST WENT AWAY.

dang-rabbity.....FOO !!!

 

I was outdoors until around 2PM and it was sunny the entire time with no clouds and no smoke from the New Mexico wildfires.

[Andrea B.]

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.