Manual lenses: Color cast workaround for SD1 (Merrill)

Started Oct 30, 2013 | Discussions thread
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oz75
oz75 Forum Member • Posts: 91
Manual lenses: Color cast workaround for SD1 (Merrill)
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Greetings everybody,

as many SD1-users might already know, it is quite difficult to use manual lenses on the SD1 without getting terrible color casts. No matter which lens is being used, magenta-greenish color casts occur.

As far as I know, Sigma has calibrated its SPP-Software (and the camera-internal firmware) with lens profiles for the whole actual Sigma lens product line to remove any color casts from pictures taken with these lenses.

But unfortunately there is nothing similar available for old manual lenses (M42, etc...) which worked so perfectly with old SD cameras...

I would like to show a workaround for this issue. The only thing necessary for a successful color cast correction is a tool like gimp (or similar) and a piece of frosted glass (or an "expodisc" as I used for the following exercise).

1) Take a normal picture with the manual lens.

Example: (Helios 44-2 58mm @ f/5.6; SPP-Development with "zero"-setting)

2) Take a photo with the frosted glass in front of the lens against the bright sky (or similarly with the "expo disc", which I have used here).

The result: (Here: Helios 44-2 58mm @ f/5.6; SPP-Development with "zero"-setting)

Let's call this one "lens calibration shot".

3) Now load the original picture into gimp.

4)Then load the "lens calibration shot". Load it as a"new layer", not as a separate image...

5) Now use the layer operation "extract grain" (or "faser extrahieren", as it's called in German;-))

6) REDUCE the brightness of the "lens calibration shot"-layer by approx.  80-90%. (Simply test, which setting fits best...)

7)  Save the picture and enjoy the view.

Btw: As some of you might have already observed, this method not just removes the color cast but also (almost) all sensor dust stains from the orginal picture.

Regards,

Oz

 oz75's gear list:oz75's gear list
Canon EOS 5D Mark II Canon EOS 1000D Sigma SD9 Sigma SD10 Sigma SD14 +6 more
Sigma SD1 Sigma SD1 Merrill
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