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Author Topic: Sinar 54H 16 shot files look soft  (Read 3011 times)
ynp
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« on: February 29, 2008, 11:38:03 AM »
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I have been using a Sinarback 54H on the Sinar-M for the last 2 months in 1 and 4 shot mode with success. 22 mpx. is more than enough for me and 4 shot is perfect  for copying artwork. No problems with the hardware. I am getting used to CS 5.5.1. and patiently wait for the eXposure.

I tried to shoot 16 shots several times and always  had some artefacts on the borders of the objects and in the areas of transition of colour in the 100% view in PS. The 50% image looks better. Downsizing helps, I do not output for the prints more than A3. Having the problem I tended to ignore it for a while being satisfied with my 4 shot images. Now I was asked to shoot Russian post stamps and I would like to use the 16 shot mode of the back.

I would like to understand whether  I have a hardware problem with my back. I have very limited experience with pixel peeping and for me the images look funny.

Thanks,
Yevgeny
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ynp
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« Reply #1 on: February 29, 2008, 12:51:08 PM »
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I am sorry, my computer crashed when I was downloading the 16 shot files on the yousendit·s.
I am attaching the 16 shot file.
Yevgeny
« Last Edit: February 29, 2008, 02:13:05 PM by ynp » Logged
brumbaer
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« Reply #2 on: February 29, 2008, 07:04:42 PM »
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Hello Yevgeny,

When you look closely you will see that there are "rogue" pixels in a fixed pattern (i.e. every 4 pixels in rows 3 pixels apart).

It looks like at least one of the shots has a different exposure than the others.
Whether this is a result of your lightning, a camera or back defect, just bad luck or whatever I can not say.

The shots appear also to be different in sharpness, so your setup is probably not stable enough.

The bottom right image has some very light areas which are not to be seen in most of the other images. Because of the way the images are interwoven, those "high contrasting" areas will shop up as high contrast dots in the final image.

And I assume these are the artefacts you see.



Regards
SH
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thsinar
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« Reply #3 on: February 29, 2008, 07:40:05 PM »
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hi Yevgeny,

Stefan is right: there seems to be an unstable environment.

Best regards,
Thierry
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Thierry Hagenauer
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« Reply #4 on: March 01, 2008, 03:24:45 AM »
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when i worked in 16 shot mode (  for a 250 page bookwork ) i faced a lot  of problems which seemed to be not very logic.
sometimes the environment seems to be not too stable ( opening or closing doors downstairs in the studio ) and the shots came out sharp.
sometimes everything was totally quiet and for hours not a single shot appeared which was free of artefacts.
finally i used a very short firewire cable ( 30cm ). with this short cable the results have been substantial better than with my longer cables. crazy? no idea, but with this cable everything worked 200% better. it seems as some of the issues which seem to be sharpness issues are created by completely other reasons as influences of the power source ( in the firwire connection ) or even delay offsets created by the cables. strange things.
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rainer viertlböck
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ynp
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« Reply #5 on: March 01, 2008, 04:11:56 AM »
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Dear Rainer, Thierry ans Stefan,

Thank you very much for your analysis , explanation and advice.
I think you are right, my problem has nothing to do with the lens resolution.
I was shooting in the studio with the concrete floor, on a FOBA stand with the new 4,5 m. cable and thought  that I covered all bases with that.
Now I realize I was wrong. I will try to tame the system over the weekend with no people in the studio, and I will use different lights. I think that a part of my problem was the small metal plate ( a sort of a spacer,  a Sinar part) which I had to install between the camera body and the ballhead. Without that adapter it was impossible to secure the camera on the stand because the H back (different here than eMotion) protrudes to the bottom more. The plate is too small. I will eliminate that with putting the camera in the vertical position without the spacer.

Thank you again,
Yevgeny
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JerryReed
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« Reply #6 on: March 01, 2008, 06:02:54 AM »
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Quote
Dear Rainer, Thierry ans Stefan,

Thank you very much for your analysis , explanation and advice.
I think you are right, my problem has nothing to do with the lens resolution.
I was shooting in the studio with the concrete floor, on a FOBA stand with the new 4,5 m. cable and thought  that I covered all bases with that.
Now I realize I was wrong. I will try to tame the system over the weekend with no people in the studio, and I will use different lights. I think that a part of my problem was the small metal plate ( a sort of a spacer,  a Sinar part) which I had to install between the camera body and the ballhead. Without that adapter it was impossible to secure the camera on the stand because the H back (different here than eMotion) protrudes to the bottom more. The plate is too small. I will eliminate that with putting the camera in the vertical position without the spacer.

Thank you again,
Yevgeny
[a href=\"index.php?act=findpost&pid=178409\"][{POST_SNAPBACK}][/a]

I am a giclée maker, so all my work is copying original art, while waiting for the Hy6 (which only later learned will not support the SINAR H 54), I used the Mamiya 645.  I was not satisfied with the quality of the 16 shot mode, but the 4 shots was acceptable.  Later, upon learning that the Hy6 would not be a solution, I bought the SINARCAM 2, which has no mirror and the 16 shot mode is very acceptable.  I attributed the unsharp images to movement.  Like you I use a FOBA camera stand on a concrete floor.

Jerry Reed
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ynp
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« Reply #7 on: March 01, 2008, 06:43:40 AM »
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Quote
I am a giclée maker, so all my work is copying original art, while waiting for the Hy6 (which only later learned will not support the SINAR H 54), I used the Mamiya 645.  I was not satisfied with the quality of the 16 shot mode, but the 4 shots was acceptable.  Later, upon learning that the Hy6 would not be a solution, I bought the SINARCAM 2, which has no mirror and the 16 shot mode is very acceptable.  I attributed the unsharp images to movement.  Like you I use a FOBA camera stand on a concrete floor.

Jerry Reed
[a href=\"index.php?act=findpost&pid=178427\"][{POST_SNAPBACK}][/a]
Dear Jerry, thanks. I am no pro, my wife has a gallery, I am a collector and I have to shoot art for myself and for my family. Before I got a Sinar M, I was shooting artwork with my ALPA and Rollei lenses and sometimes Digitars. For me the M system is the continuation of the Simarcam line, and I do not understand why Sinar did not marketed the M as a modern Sinarcam.
I am back to studio/classroom to learn the trade

Regards,
Yevgeny
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brumbaer
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« Reply #8 on: March 01, 2008, 07:19:48 AM »
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As a reply to Rainers experience regarding the cable.

A back that uses firewire power will take the firewire power and convert it to whatever it internally uses and keeps this "internal" voltage constant.

Below a certain input voltage this regulation will not work any longer and changes of input power will cause changes in the "internal" voltage. Which will lead to all kinds of effects.

Every cable has some resistance and so a voltage drop accurs between the voltage source (firewire port of the computer) and load (back).

If anything else is the same, a cable twice as long has a voltage drop twice as big.

The voltage drop changes with the amount of current drawn by the load.

The current draw changes all the time with processing power used, cooling elements switched and so on.

The voltage drop on a short cable might be low enough so that a change of current will not effect the regulation of the "internal" voltage, while a longer cable between the same devices will result in greater voltage changes and will result in a voltage so low that the regulation fails and the internal voltage changes with changes in current drawn.

So if getting a "more stable" enviroment doesn't help, it is worth trying.

Regards
SH
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BobDavid
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« Reply #9 on: March 01, 2008, 10:11:33 AM »
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16-shot is fussy. Your issue looks like vibration in the environment during exposure. It is amazing how sensitive 16-shot photography is to enviromental factors. I've even had to turn off the music on my little stereo to cut back on vibrations during exposures. Even the force of flash upon a delicate surface, like a flower petal, can cause enough movement to degrade the image. Most of my business involves fine art copy work. I found that the best solution to mitigate the problem was to migrate over to a 39 megapixel 4-shot back. I also found that 16-shot mode had a tendency to reduce contrast in the overall scene.

As far as shooting macro goes, I wouldn't recommend 16-shot mode. Your reproduction ratio, for shooting postage stamps, doesn't warrant 16-shot. Unless color fidelity is of the utmost concern, I'd shoot it in one-shot mode.
« Last Edit: March 01, 2008, 01:55:58 PM by BobDavid » Logged
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