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Thread: Alpa and H3d11-39 back - pinky poos

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    Alpa and H3d11-39 back - pinky poos

    "The H3D II ... Nevertheless, please be aware of a possible firmware glitch still existing today (last tested as per May 2008) and potentially with all Hasselblad backs (also the CF types). If you use your back together with a mechanical shutter you might face sharp but reddish or pinkish colored pictures (across the whole image) with shutter times shorter than 1/60 sec. This is not a classical color cast or aberration but rather an artifact of a wrongly timed synchronisation of the back. Please ask your Hasselblad dealer as this is NOT a problem of the mechanical Copal shutters we use."

    I have been scratching head over the issue of a pink caste in my shots with the Hasselblad back and Schneider lenses...for anyone else shooting with similar rig I came across this (by accident) on the Alpa site.

    Apologies as in a previous thread I indicated that this colour caste issue was a wide angle lens issue - apparently I was wrong..

    As I dont have any other back mounts for my Alpa I can't try my Sinar back to see if this is a common issue.

    I would appreciate any feedback from a Hasselblad rep or anyone else familiar with the situation on this issue and suggested work around..

    I am usually shooting between 1/8th and 1/125th max with a 35 digitar - and yes hahahah too many times on 1/15th - although I haven't really tested for sharpness loss on 1/15th yet..




    This is an example of what I mean by pinky poo..a straight tiff export no adjustments just ersisized and saved for web..and it takes a lot of mucking around to fix...

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    Re: Alpa and H3d11-39 back - pinky poos

    Hey Peter,

    Sorry I didn't know about this before - we could have fixed it!

    I have sent you a PM. But for the benefit of other readers...

    Some copal shutters deliver the flash sync pulse too early for the way we flush the sensor. Most of the time it is not an issue but it seems in your case it is.

    We flush the sensor in a particular way to avoid the 'wake-up' release that is necessary on some Phase One backs for instance.

    However, in your case Peter you will need to do something similar with your setup.

    H camera electronic release into the H3D unit + standard release to the lens. Release the back first, then immediately the lens, making sure you have enough exposure time on the back to 'cover' the shutter exposure.

    Ie, if you were shooting at 1/15s you could set 1 second on the back and it wouldn't matter. You are still only getting 1/15s worth of light... unless you have a leaky shutter. ;-)

    David

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    Re: Alpa and H3d11-39 back - pinky poos

    Quote Originally Posted by David Grover / Hasselblad View Post
    Ie, if you were shooting at 1/15s you could set 1 second on the back and it wouldn't matter. You are still only getting 1/15s worth of light... unless you have a leaky shutter. ;-)
    Out of curiousity, then I presume the EXIF would record 1s, even though the actual exposure was 1/15s? Wouldn't this mean that some raw developers would deal with the file wrongly?
    Carsten - Website

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    Re: Alpa and H3d11-39 back - pinky poos

    Quote Originally Posted by carstenw View Post
    Out of curiousity, then I presume the EXIF would record 1s, even though the actual exposure was 1/15s?
    I think the Exif data comes from the camera (with lens, aperture...). But if you use a tech camera you actually have no Exif - at least a Phase back attached on a view camera just shows the ISO... no aperture, no exposure, no lens. It's basically connected with the copal shutter via flash sync... so there is no channel to send Exifs.
    Regards, Thomas

    edit: and of course the LF lenses have no ROM (might be different with electr. shutter lenses... I don't know).
    Last edited by thomas; 4th June 2009 at 12:35.

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    Re: Alpa and H3d11-39 back - pinky poos

    Quote Originally Posted by thomas View Post
    I think the Exif data comes from the camera (with lens, aperture...). But if you use a tech camera you actually have no Exif - at least a Phase back attached on a view camera just shows the ISO... no aperture, no exposure, no lens.
    Phase One P+ series backs record the shutter speed (as measured on the shutter) on tech cameras.

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    Re: Alpa and H3d11-39 back - pinky poos

    Quote Originally Posted by David Grover / Hasselblad View Post
    Hey Peter,

    Sorry I didn't know about this before - we could have fixed it!

    I have sent you a PM. But for the benefit of other readers...

    Some copal shutters deliver the flash sync pulse too early for the way we flush the sensor. Most of the time it is not an issue but it seems in your case it is.

    We flush the sensor in a particular way to avoid the 'wake-up' release that is necessary on some Phase One backs for instance.

    However, in your case Peter you will need to do something similar with your setup.

    H camera electronic release into the H3D unit + standard release to the lens. Release the back first, then immediately the lens, making sure you have enough exposure time on the back to 'cover' the shutter exposure.

    Ie, if you were shooting at 1/15s you could set 1 second on the back and it wouldn't matter. You are still only getting 1/15s worth of light... unless you have a leaky shutter. ;-)

    David
    Thank you very much for the information David - much appreciated. The issue has been bugging me for a while now as it wasn't a 'constant' in any equation - sometimes I got pinky poos sometimes I didn't. At least now I know what to do - much appreciated.

    btw - I now know what the speed settings on teh back are useful for as well!


    Pete

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    Re: Alpa and H3d11-39 back - pinky poos

    Quote Originally Posted by carstenw View Post
    Out of curiousity, then I presume the EXIF would record 1s, even though the actual exposure was 1/15s? Wouldn't this mean that some raw developers would deal with the file wrongly?
    The "actual" exposure is 1 second though, as the back has recorded it. For noise removal purposes, the file should be treated as a 1 second file.

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    Re: Alpa and H3d11-39 back - pinky poos

    Quote Originally Posted by carstenw View Post
    Out of curiousity, then I presume the EXIF would record 1s, even though the actual exposure was 1/15s? Wouldn't this mean that some raw developers would deal with the file wrongly?
    Not a significant amount of difference to matter.

    And as Eric states for Black Cal purposes the 'correct' exposure is 1 second.

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    Re: Alpa and H3d11-39 back - pinky poos

    Quote Originally Posted by PeterA View Post
    Thank you very much for the information David - much appreciated. The issue has been bugging me for a while now as it wasn't a 'constant' in any equation - sometimes I got pinky poos sometimes I didn't. At least now I know what to do - much appreciated.

    btw - I now know what the speed settings on teh back are useful for as well!


    Pete
    No problem. It will vary depending on the shutter speed, if there is an issue.

    You could also use the One Shot cable from Kapture group but it is a bit bulkier.

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    Re: Alpa and H3d11-39 back - pinky poos

    Not trying to throw a spanner here but the image to me shows a typical case of colour cast with WA lens on a technical camera (I can see Magenta & Green shifts there). The combination of the Digitar 35mm and the Kodak sensor is the cause and the solution should be a calibration/ Shading/ LCC/ Gain shot taken through a diffuser filter and correcting it with your software.
    I would not blame it on the copal shutter.
    Peter see if you can try that and let us know the outcome.

    Yair

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    Re: Alpa and H3d11-39 back - pinky poos

    Hi Yaya thanks - yes ..it was my first conclusion...only way to tell is to see if a slow shutter gives consistent magenta/green tinge..

    I am not familiar with shooting a white calibration shot with Hasselblad back...

    I am hoping it is a white calibration issue because the whole idea of using two cables or special cables is a nuisance.

    .

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    Re: Alpa and H3d11-39 back - pinky poos

    Quote Originally Posted by PeterA View Post
    Hi Yaya thanks - yes ..it was my first conclusion...only way to tell is to see if a slow shutter gives consistent magenta/green tinge..

    I am not familiar with shooting a white calibration shot with Hasselblad back...

    I am hoping it is a white calibration issue because the whole idea of using two cables or special cables is a nuisance.

    .
    Change aperture + displacement and you'll see the shifts shifting their location

    Yair

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    Re: Alpa and H3d11-39 back - pinky poos

    Quote Originally Posted by PeterA View Post
    Hi Yaya thanks - yes ..it was my first conclusion...only way to tell is to see if a slow shutter gives consistent magenta/green tinge..

    I am not familiar with shooting a white calibration shot with Hasselblad back...

    I am hoping it is a white calibration issue because the whole idea of using two cables or special cables is a nuisance.

    .
    Peter,

    Real simple process...use any semitransparent white sheet of plexi or plastic or a commercial product like expodisc or CBL lens. Expose at a couple of usually used F stops....F4 F8 with a slight overexposure plus 1 or 2.

    In Phocus under lens corrections there is a custom white choice and you can create and save this choice...so open up your shot process the custom white and then apply it to your picture. Then save this correction immediately and apply it to the subsequent pictures you open then you can process them cast free. The cast will change shape and position based on F stop mainly so it will correct most of your pictures easily.

    This may be the source of your problem...check out this prior thread...http://forum.getdpi.com/forum/showth...3435#post73435

    Worked for me. Now some insist that the Expodisc works less well than a simple sheet of plastic....

    I will be interested in your findings.

    Bob

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    Re: Alpa and H3d11-39 back - pinky poos

    The white frame will only work for the shutter issue if the shutter calibration generates the exact same color pattern in every shot... Lens cast does for a given lens and shift and why white frame works for that. So doing the white frame may actually help you isolate the issue to lens cast or something shutter delay related.
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    Re: Alpa and H3d11-39 back - pinky poos

    Bob - thanks for that info much appreciated
    Jack - yes I must check out the shutter speed issue and whether it is limited to speeds < 1/60th OR whether it is a general issue requiring white calibration shots at various speed and aperture settings...
    btw
    I will also be making a detailed comparison between the Alpa with H39 and the arTec with Sinar 75LV backs next weekend in Sydney - something I am very much looking forward to as I will be shooting with a fantastic photographer - who also happens to be the Australian Sinar dealer.

    I shall post a thread if I discover anything intersting.

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    Re: Alpa and H3d11-39 back - pinky poos

    Quote Originally Posted by PeterA View Post

    I have been scratching head over the issue of a pink caste in my shots with the Hasselblad back and Schneider lenses...for anyone else shooting with similar rig...
    I have a similar problem with an older 132C on my Rollei, but haven't managed to get to the bottom of it yet. I initially thought it was when the sun was directly in the image, but that has proven not to be the case. I also am using flash sync, as the din connector caused more problems than it was worth. There are a lot of times when the camera fires but no image is captured; I was assuming it was a dodgy sync cable, but I suppose it could be caused by a timing issue.
    There is a delay setting on the back, I thought it was related to camera model - or does this only apply if using the din cable?

    I guess after reading this I might have to try random delay settings and see what happens...

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    Re: Alpa and H3d11-39 back - pinky poos

    Quote Originally Posted by yaya View Post
    Not trying to throw a spanner here but the image to me shows a typical case of colour cast with WA lens on a technical camera (I can see Magenta & Green shifts there). The combination of the Digitar 35mm and the Kodak sensor is the cause and the solution should be a calibration/ Shading/ LCC/ Gain shot taken through a diffuser filter and correcting it with your software.
    I would not blame it on the copal shutter.
    Peter see if you can try that and let us know the outcome.

    Yair
    I agree,
    looks like some of the images I took with my technical camera and Rodenstock35mm before applying the wide shading correction.

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