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Author Topic: Striations in P45+@800 ISO normal ?  (Read 20851 times)
eronald
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« on: November 14, 2007, 03:21:27 PM »
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Hi Guys,

 I have lengthwise striations in my P45+ images at high ISO, attached a pushed ISO 800 which shows them clearly. Is this usual for this back, or should I send it to Phase for repair ?

Edmund
« Last Edit: November 14, 2007, 03:37:15 PM by eronald » Logged

Edmund Ronald, Ph.D. 
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« Reply #1 on: November 14, 2007, 03:43:18 PM »
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You should not push (I reckon you mean you have underexposed and pushed up via curves or levels?) a file that has been shot at ISO800. Nasty stuff happens. Not sure whether it is usual with the P45 but I have had it on all the backs I used. Never bothered to send them back. Fact of life, I figured. Maybe I am wrong?

With the Leaf I got weird greenish funky stuff, lines & patterns when lifting an underexposed file on ISO400. With the Hasselblad it is mostly magenta funky stuff.

Not sure how you took this and how far you needed to raise the exposure slider?
« Last Edit: November 14, 2007, 04:06:51 PM by Dustbak » Logged
jpjespersen
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« Reply #2 on: November 14, 2007, 03:50:32 PM »
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Looks pretty bad.  Somethings wrong with it.
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filmless
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« Reply #3 on: November 14, 2007, 04:26:41 PM »
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Hi Guys,

 I have lengthwise striations in my P45+ images at high ISO, attached a pushed ISO 800 which shows them clearly. Is this usual for this back, or should I send it to Phase for repair ?

Edmund
[a href=\"index.php?act=findpost&pid=152818\"][{POST_SNAPBACK}][/a]


Hi Edmund,

Is the image you posted representive of the processed image or the preview?  The noise reduction and other "clean up" functions do not take place until the processing takes place.

Also... very important.... was this image viewed/processed in Capture One software or with another program?

Tim

Tim Palmer
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eronald
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« Reply #4 on: November 14, 2007, 05:25:52 PM »
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Tim,

 I'm posting the image processed with C1 below. Above it was Photoshop CS3. The image in each case has been resized for the web. You will note the C1 version too has striations.

 I actually like the rendition of the back at this Pushed ISO a lot, and would love to be able to use it for available light and night photography as it holds the highlights nicely- the random noise in itself does NOT pose a problem to me for this type of imagery, in fact I find it quite limited, but the striations wreck the pictures.

Edmund

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Hi Edmund,

Is the image you posted representive of the processed image or the preview?  The noise reduction and other "clean up" functions do not take place until the processing takes place.

Also... very important.... was this image viewed/processed in Capture One software or with another program?

Tim

Tim Palmer
Techncal Services
Capture Integration
tim@captureintegration.com
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« Last Edit: November 14, 2007, 05:26:42 PM by eronald » Logged

Edmund Ronald, Ph.D. 
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« Reply #5 on: November 14, 2007, 05:53:04 PM »
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Looks Pretty Bad...
Can you maybe answer one of the question someone ask, which was did you underexpose then push the curve up to "normal" or was metering on...?
Looks like you over developed it from an under exposed file?
Snook
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eronald
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« Reply #6 on: November 14, 2007, 06:27:16 PM »
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Looks Pretty Bad...
Can you maybe answer one of the question someone ask, which was did you underexpose then push the curve up to "normal" or was metering on...?
Looks like you over developed it from an under exposed file?
Snook
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 The image I show is manually underexposed -to get the picture- , and then pushed by pushing the exposure slider up.

 Unfortunately, now that I know what to look for I am noticing the same striations in dark areas of ISO 400 images. I have just developed the FIRST picture I took with this back, the one of the gentleman who sold it to me. It's 400 ISO, and when processed then curved slightly in PS, with the same curve I always use, and sharpened, clearly shows striations in the dark areas (see reduced crop).

 I guess I have answered my own question, this back is probably broken.

Edmund
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Edmund Ronald, Ph.D. 
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« Reply #7 on: November 14, 2007, 06:40:41 PM »
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edmund...if i understand this correctly (and after reading your email) you expect the files to be clean when shot at 800 and underexposed 2 stops (which really means you are shooting at 3200)....it's just not going ot work....my P30 behaves at 100, i can really open the shadows, use all sliders in LR and everything stays clean, but the higher up you go the uglier it gets and the less you can do to the files....i am sure the P+ files give you an extra stop, the P30+ would give you better performance then the P45+ but either way you are asking too much....
BTW someone here mentioned the canons...don't even try underexposing 2 stops with any canon even at 100....the little detail that is in the shadows with a correct exposure will be totally gone....

you can shoot the pshase backs at high asa, i love the "grain" but you have to be much more careful with your exposure....
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« Reply #8 on: November 14, 2007, 06:53:25 PM »
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Paul,you hit the nail on the head!
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Willem Rethmeier
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eronald
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« Reply #9 on: November 14, 2007, 06:58:47 PM »
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Actually, I wondered whether the P45+ Phase backs can be shot at 1600. You only know if you try. So I shot a set of images in available darkness to test the back and my ability to focus.  And the answer seems to be yes, for lifestyle stuff 1600 is ok and probably 3200 barely IF your back is ok.

 My back appears to have a defect so that even properly exposed 400 is damaged a bit. As far as file quality is concerned (without striations) 400 ISO when well exposed is good enough for anything I plan to do with the back. I now need to get that striation problem sorted out.

 I do realize that my point of view is different from that of most members of this forum. However, most of the shots I've had run in magazines have run at quarter-page size, full page max, and some grain is acceptable in my catwalk shooting as it is essentially photojournalism. As for the arty stuff which I mostly do for my own amusement, grain is really not a problem.

Edmund

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edmund...if i understand this correctly (and after reading your email) you expect the files to be clean when shot at 800 and underexposed 2 stops (which really means you are shooting at 3200)....it's just not going ot work....my P30 behaves at 100, i can really open the shadows, use all sliders in LR and everything stays clean, but the higher up you go the uglier it gets and the less you can do to the files....i am sure the P+ files give you an extra stop, the P30+ would give you better performance then the P45+ but either way you are asking too much....
BTW someone here mentioned the canons...don't even try underexposing 2 stops with any canon even at 100....the little detail that is in the shadows with a correct exposure will be totally gone....

you can shoot the pshase backs at high asa, i love the "grain" but you have to be much more careful with your exposure....
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« Last Edit: November 14, 2007, 07:02:21 PM by eronald » Logged

Edmund Ronald, Ph.D. 
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« Reply #10 on: November 14, 2007, 07:01:21 PM »
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Actually, I wondered whether the P45+ Phase backs can be shot at 1600. You only know if you try. So I shot a set of images in available darkness to test the back and my ability to focus.  And the answer seems to be yes, for lifestyle stuff 1600 is ok and probably 3200 barely IF your back is ok.

 My back appears to have a defect so that even properly exposed 400 is damaged a bit. As far as file quality is concerned (without striations) 400 ISO when well exposed is good enough for anything I plan to do with the back. I now need to get that striation problem sorted out.

Edmund
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I think PSS was right on...
and I am sure if you go to the Moyen Format shop he'll tell you the same.
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eronald
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« Reply #11 on: November 14, 2007, 07:06:21 PM »
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I think PSS was right on...
and I am sure if you go to the Moyen Format shop he'll tell you the same.
[a href=\"index.php?act=findpost&pid=152905\"][{POST_SNAPBACK}][/a]

David,

 My impression after spending the evening looking at these shots is that my problem appears at ISO 400, where it is NOT supposed to happen. The ISO 400 shot already has problems, and that one is well exposed. I expect usable ISO 400 from this back, grain is not a problem, lines are a problem.

Edmund
« Last Edit: November 14, 2007, 07:08:16 PM by eronald » Logged

Edmund Ronald, Ph.D. 
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« Reply #12 on: November 14, 2007, 07:07:17 PM »
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My P25 (not +) looks much better than that at 800.
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david o
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« Reply #13 on: November 14, 2007, 07:17:10 PM »
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David,

 My impression after spending the evening looking at these shots is that my problem appears at ISO 400, where it is NOT supposed to happen. The ISO 400 shot already has problems, and that one is well exposed. I expect usable ISO 400 from this back, grain is not a problem, lines are a problem.

Edmund
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have you tried long expo to see what you get...
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« Reply #14 on: November 14, 2007, 07:26:13 PM »
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That is the classic result of gross underexposure, coupled with boosting the exposure slider in processing the raw file.

Were you at the limits of open aperture, and long shutter?  (IE: f1.8 and 1/30s)

If so, you've simply exceeded the capabilities of the sensor.

I get the same results when I push an underexposed Canon 1Ds image by 3 stops (and the majority of the image is still in the bottom 1/4 tone).
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eronald
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« Reply #15 on: November 14, 2007, 07:40:19 PM »
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have you tried long expo to see what you get...
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David

No, I haven't tried it. My only real "exceptional" need is for filmlike 400 ISO for fashion (and the grain on this back is ok for me if the striations weren't there). With Canon I have done exposures of 2 mins in the past for interior design catalogs, but I have no imperative need to go there again.

Edmund
« Last Edit: November 14, 2007, 07:44:48 PM by eronald » Logged

Edmund Ronald, Ph.D. 
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« Reply #16 on: November 14, 2007, 07:43:28 PM »
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No, I haven't tried it. My only real "exceptional" need is for filmlike 400 ISO for fashion (and the grain on this back is ok for me if the striations weren't there). With Canon I have done exposures of 2 mins in the past for interior design photos, but I think I will leave that to specialists in the future.

Edmund
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may be it worth to try long expo low iso to see how it behaves.
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eronald
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« Reply #17 on: November 14, 2007, 07:47:22 PM »
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may be it worth to try long expo low iso to see how it behaves.
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David,

On second thoughts, I guess you're right. I'll dig out a tripod tomorrow and let down the blinds

Edmund
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Edmund Ronald, Ph.D. 
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« Reply #18 on: November 15, 2007, 06:50:34 AM »
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These lines shouldn't be there, sure an incorrectly exposed file will have certain noise problems but lines, I dont think so. When you pay 30 grand for something you deserve to have it work correctly. And by the way, I heard from a little birdy in one of the major phase one dealers that strange lines on high iso files with the plus backs is a known issue. I'd demand a refund or a back that didnt have the problem, the non plus backs dont have this issue I heard, mine certainly doesnt, what a great upgrade eh?
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eronald
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« Reply #19 on: November 15, 2007, 07:13:11 PM »
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I have seen my dealer and given him example images. He is sending reports to Phase One. We will see how they answer.

Gotfred sent me some images he made with his back @ISO 800 (Thank You!), I haven't yet fully checked them out.

One unfortunate fact is that once you have noticed the lines your eyes pick them out on every image that has them. I guess if an AD gets one really bad image she might then start to get picky even about the acceptable ones.

Based on some conversations I have had with industry insiders, I am starting to wonder whether this is not a signal processing issue linked to the speed at which the CCD is clocked in the new P+ backs. I don't think it's really a sensor issue. Pure conjecture of course.

The good new in this story is that the current generation of non-microlens sensors with the current electronics in the P+ backs appear to be capable of images processed to at least 1600 ISO if you were happy with the grain of 1600 ISO film and if they fix this striation/banding issue.


Edmund

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These lines shouldn't be there, sure an incorrectly exposed file will have certain noise problems but lines, I dont think so. When you pay 30 grand for something you deserve to have it work correctly. And by the way, I heard from a little birdy in one of the major phase one dealers that strange lines on high iso files with the plus backs is a known issue. I'd demand a refund or a back that didnt have the problem, the non plus backs dont have this issue I heard, mine certainly doesnt, what a great upgrade eh?
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« Last Edit: November 15, 2007, 07:15:25 PM by eronald » Logged

Edmund Ronald, Ph.D. 
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