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In my backyard

docmoore

Subscriber and Workshop Member
IMO this is definitely colour shift and you can see it in the outdoors shots as well with the skies going Magenta.
You need to use a diffuser filter (normally supplied with the digital back) and to take a diffused image using the same f-stop/Aperture, then use a facility in the software to correct your images.

Some softwares will also let you correct vignetting at the same time.

Yair
I assume that I do have a large element of that in many of the pictures but thought that it would be mainly limited to the sides of the pictures. I attempted to use an Expodisc...screwed into the front of the lens and shot a capture at the same F stop but had to correct over 3 stops to see anything. Expodisc recommends to shoot a capture back at the camera as an incident meeter but this is counter intuitive for LCC. Am I able to correct exposure and then apply this for the LCC or do I need a different type of filter? This is an H3D 39 II so I pose this question to Hasselblad owners also.

The new Phocus has a white balance selection for LCC now and I am unsure if it will need corrections for all Fstops and focus distance combinations. Any ideas?

Thanks for the input.

Bob
 

yaya

Active member
I assume that I do have a large element of that in many of the pictures but thought that it would be mainly limited to the sides of the pictures. I attempted to use an Expodisc...screwed into the front of the lens and shot a capture at the same F stop but had to correct over 3 stops to see anything. Expodisc recommends to shoot a capture back at the camera as an incident meeter but this is counter intuitive for LCC. Am I able to correct exposure and then apply this for the LCC or do I need a different type of filter? This is an H3D 39 II so I pose this question to Hasselblad owners also.

The new Phocus has a white balance selection for LCC now and I am unsure if it will need corrections for all Fstops and focus distance combinations. Any ideas?

Thanks for the input.

Bob
You need an opaque White plexi filter which is thick enough to diffuse the image. It looses you about 2 stops which you need to bring back by pushing the exposure time.

The 45mm is quite forgiving just wait till you've tried it with a Schneider 35mm or 24mm with some shift....
 

docmoore

Subscriber and Workshop Member
Color Correction with Phocus and an Expodisc.

I had tried to capture a custom white reference file when I shot the pictures in the house but until prompted by Yair did not look at them closely enough. The following is the reference file.
 
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docmoore

Subscriber and Workshop Member
Uncorrected capture of ceiling fan...no color balance was attempted. Please look only at the colors ...like most of my stuff it is devoid of any artistic merit.
 
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docmoore

Subscriber and Workshop Member
Now the same capture after the reference file was applied in Phocus. Same workflow as the previous except for the reference file in Phocus.
 
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docmoore

Subscriber and Workshop Member
This is repost of Another Place from Above with the generic custom file applied in Phocus. I realize that even without shift nor tilt there is the potential for significant color casts with wide angle lenses. I knew this from my experience with the Leica M8 and CornerFix but now know the need to look for it in this setting. These files were corrected with a generic capture that was applied to different lighting situations, hence they are improved but still are not dead on correct.


So now I will begin to capture a reference frame for most of my Alpa work.

Thanks Yair - for pointing out what now seems all too obvious.

Bob
 
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J

jmvdigital

Guest
Bob-

The corrected image makes me sigh with relief... all is right in the world again. :)
 
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