An SD15 Full Spectrum with Filters comment

Although a blue sky is said to be considerably darkened by such as yellow or orange filters on the lens, that is not my experience with the SD15. Instead, it remains at around mid-tone and changes color, usually to something ugly like cyan or greenish cyan or a yukky brown.

I put this down to the blue sky having plenty of emissive energy above the peak of 450nm or so, even including hefty amounts of near-IR. So, although these filters are said to "block" a blue sky, plenty of energy actually passes through these normally quite soft filters and is detected by all three Foveon F13 layers.

The following curves tell the tale:

At right, the middle one of the green curves is the Tiffen Yellow #12 that I received yesterday.

Here is a yellow #12 shot opened in RawDigger and shown in RGB mode:

It lacks contrast, has no vibrant Kodak reds or dark blues and does not smite my eye at all.

On the other hand, a brief play in RawTherapee produced this in-your-face image:

Not many will like this over-the-top rendition. However, it is posted to show the efficacy of post-processing with the goal of producing impressive images albeit not necessarily emulating Kodak Aerochrome or Ektachrome EIR.

In RT, I played with many functions but the main benefits [?] were from:

Haze Reduction, 3-channel Color Mixer and the White Balancer. The White Balance adjustments (temperature and two tints) were particular effective after messing with the Mixer! Continuous adjustment of the brightness, highlight compression and shadows was needed as stuff kept getting clipped or bottomed in the histogram.

RT Users can download the sidecar file from here (right-click then Save Link As ...):

http://kronometric.org/phot/ir/SDIM0825-RGB.pp3

It is a text file and non-Users can open it and have a guess at what was done (search on "Enabled=true").

Hope this is of some interest to a few of us ...

To be more clear, the Workflow itself is:

Shoot in full spectrum with the filter of choice on the lens (or no filter at all).

Open in RawDigger and export as RGB.

Open the RGB in RawTherapee and load a previously-created** sidecar file.

Adjust further to taste.

Save result.

** I envisage a set of "base full spectrum" sidecar files for each filter or no filter for each desired effect. RT is just plain incredible for what can be done ...

Still researching the "Aerochrome look" on the Internet, maybe the bar isn't that high:

Observe the dull cyan sky and the orange-brown foliage ... for $96 !!!

I'm sure that the cognoscentihere can beat that for nowt (nada).

SigmaTog wrote:

Thanks Ted
The graphs are too small for me to read ?

Hello 'Tog,

Did you view them in original size and then click once on the image?

The magenta, to me it is indicative of over-exposure.....

"Exposure" means many things to many people.

I can assure you that none of the raw data was clipped in that shot, ergo, the sensor was not over-exposed. But in RawTherapee, I did do some pretty drastic slider action.

Did anyone try different cold mirror and hot mirror filter?

Here are 3 shots with my filters i got some years ago on ebay. Most of them are all 52mm but the 18-50 is 58mm so i just held them in front of the lens. I played in RawTherapee, too. I had to make other settings for the orange filter.

Yellow #12 should be Y52.

I used the X3F Files in RT, was not able to get usable outcome with RGB Tiffs from RawDigger.

Orange (G) Filter, same RT Profile than Y44/Y48

Orange (G) Filter (other RT Settings)

Yellow 48

Filter

sambaba wrote:

Yellow #12 should be Y52.

I don't understand. I bought this - it says number 12 on the box, not 52:

there are some more systems for color filters. Perhaps not so much technical.

Most of my (old) filter don't have Wratten Numbers.

https://photobutmore.de/vintagephoto/filter/filtervergleich/

https://filterfind.net/Data.html

sambaba wrote:

there are some more systems for color filters. Perhaps not so much technical.

Most of my (old) filter don't have Wratten Numbers.

https://photobutmore.de/vintagephoto/filter/filtervergleich/

Nicht sprecken zie Deutsch

https://filterfind.net/Data.html

Yes, of course I know that there are different systems, but you said "Yellow #12 should be Y52."

Does that mean I should have bought a Nikon Y52?

xpatUSA wrote:

sambaba wrote:

there are some more systems for color filters. Perhaps not so much technical.

Most of my (old) filter don't have Wratten Numbers.

https://photobutmore.de/vintagephoto/filter/filtervergleich/

Nicht sprecken zie Deutsch

https://filterfind.net/Data.html

Yes, of course I know that there are different systems, but you said "Yellow #12 should be Y52."

Does that mean I should have bought a Nikon Y52?

i have Y44 and Y48 here, your #12 Filter should be (compare to) Y52 (so a bit darker than mine).

(better?)

sambaba wrote:

xpatUSA wrote:

sambaba wrote:

there are some more systems for color filters. Perhaps not so much technical.

Most of my (old) filter don't have Wratten Numbers.

https://photobutmore.de/vintagephoto/filter/filtervergleich/

Nicht sprecken zie Deutsch

https://filterfind.net/Data.html

Yes, of course I know that there are different systems, but you said "Yellow #12 should be Y52."

Does that mean I should have bought a Nikon Y52?

i have Y44 and Y48 here, your #12 Filter should be (compare to) Y52 (so a bit darker than mine).

(better?)

Now I understand ... thank you!

Meanwhile, I've just tried today with no filter and only using the RT 3-channel Color Mixer:

X3F embedded JPEG at right.

Very bright blue sky around 10am solar time reflecting a lot of IR from the dirt road, maybe why some people prefer the Hoya X1 filter which only transmits low amounts of IR

I myself am leaning heavily towards no filter at all. Here's none versus Hoya X0 green versus Tiffen Y12 yellow:

Ted why are you going through Rawdigger?

Does it natively support the x3f from sd15, I don't know.  I know most programs support the sd14 as the last Sigma camera.

Is this just a quick and dirty way to get to a tiff to edit in RawTherapee?

dbateman wrote:

Ted why are you going through Rawdigger?

I find that RawDigger's RGB export preserves channel detail far better than SPP.

RawDigger:

SPP 3.5.2:

Observe how SPP crushes the green channel in the selected area. The foliage comes out quite similar. That means that using a 3-channel color mixer is far less effective on an SPP image than it is on a RawDigger RGB export.

Does it natively support the x3f from [SD15], I don't know.

RawDigger supports all X3F files from the Polaroid up to the last Quattro.

I know most programs support the [SD14] as the last Sigma camera.

Remember that RawDigger is not an editor. What you see is what your sensor captured.

Is this just a quick and dirty way to get to a tiff to edit in RawTherapee?

No.

HTH ...

did you try to open the x3f directly in RT? Works with my SD1M Files

sambaba wrote:

did you try to open the x3f directly in RT?

RT has been able to convert X3Fs for a good while, they use LibRaw.

Works with my SD1M Files

Yes. They also have a couple of SD14 profiles.

Thanks, what version of raw digger do you own? The max, medium or basic version?

I will have to see if Art supports x3f files. I like its interface better than Raw therapee

https://bitbucket.org/agriggio/art/wiki/Home

dbateman wrote:

Thanks, what version of [RawDigger] do you own? The max, medium or basic version?

I bought the Research Edition, currently V 1.4.2

I will have to see if Art supports x3f files. I like its interface better than Raw therapee

https://bitbucket.org/agriggio/art/wiki/Home

Good luck with ART ...

xpatUSA wrote:

dbateman wrote:

Ted why are you going through Rawdigger?

I find that RawDigger's RGB export preserves channel detail far better than SPP.

...

Observe how SPP crushes the green channel in the selected area. The foliage comes out quite similar. That means that using a 3-channel color mixer is far less effective on an SPP image than it is on a RawDigger RGB export.

SPP is rendering a daylight/natural light image: the channel gain and white balance matrix are not meant for infrared. And that remains true even if you capture a Custom WB off an 18% grey card, you'd need to capture it off an infrared reflective target − which I believe that the SD14 could... ?

Have you tried injecting your RT 3x3 colour matrix into an X3F for SPP to handle? I'd expect the results to be far superior. Then again, am I just wading into an ad for RawTherapee?

BBC disclaimer: other image editors and compositors with similar and/or extended toolsets are also available.