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Old May 28, 2006, 3:37 PM   #1
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Hi all, I've just been looking through some photo's taken yesterday at a charity football match and noticed a few shots with quite bad banding. This only happened after the light got too low for the standard ISO range (200-400) so I had to up it to 200-1600. The images were much brighter and noiser (as expected) but what was not expected was the banding.

The attached image is reduced to 1024*768 for posting and has had no processing.

JPG
ISO 1600
F4
1/250th second.

Any thoughts, or is this a known issue that I'm just going to have to get used to.

I can see the EXIF data in PaintShop Pro but can't save it as a file as yet. If it helps I will get some software from the net to do this.

Thanks for your time.

Dave
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Old May 28, 2006, 4:26 PM   #2
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My monitor and eyes leave a bit to be desired at times.

But, this image is very underexposed. So, you can expect problems to be worse with it, especially noise related banding, just as if you were using an even higher ISO speed (especially if you try to brighten an underexposed image using software).

Judging from the EXIF, you were shooting in Tv (Shutter Priority) Mode with a shutter speed of 1/250 second at f/4 and ISO 1600.

I can't see what the largest available aperture of the lens was in the EXIF. But, chances are, you ran out of Aperture (it couldn't open up any more than f/4) causing the underexposure. I also can't see the focal length reported in the EXIF (either because your editor stripped it out, or you were using some kind of Teleconverter that didn't report it properly). If you were using a TC, you'll also have light loss (around 1 stop for 1.4x TC or 2 stops for a 2x TC).

Most cameras will let you know via a flashing shutter speed or aperture indication when you exceed the capabilities of the camera (for example, trying to shoot at shutter speeds that are too fast for the largest available aperture of the lens, for the selected ISO speed and lighting conditions). That's what appeared to have happened here (you tried to shoot at shutter speeds too fast for the lighting and largest available aperture of the lens).

With a properly exposed image, your image problems would probably go away.

You may want to shoot in Av Model instead, choosing the largest available aperture (smallest f/stop number). Then, the camera would pick the appropriate shutter speed for proper exposure. You would not have gotten shutter speeds anywhere near as fast (because of the amount of underexposure that image had). But, at least you'd have a properly exposed image without the issues associated with underexposure at higher ISO speeds.

For night sports, a lens that can maintain f/2.8 throughout it's focal range is a good idea, even at higher ISO speeds. Otherwise, you'll be faced withmotion blur from subject movement, and/or blur from camerashake, and/or high noise with unwanted image artifacts, and/or underexposure trying to shoot at shutter speeds too fast for the lighting and lens. Even f/2.8 may not be good enough in some lighting. But, that's the preferred type of lens most sports shooters use in a night game, even shooting at ISO 1600 to 3200.


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Old May 28, 2006, 5:21 PM   #3
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we've got the exif.
the problem with the higher ISO is even if you shoot in raw your exposure needs to be right on because PP will just enhance the worst of the image..
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Old May 28, 2006, 6:14 PM   #4
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Thanks for both of your replies. The lense I was using was a Tokina SZ-X210at 210mm (315mm on the DL) and the aperature on 4 which is the maximum on that lense.

I was using Tv and the camera did complain about the aperature size, as 4.0 was flashing in the viewfinder. I would have gone to a higher ISO but having heard of the problems with excessive noise at 3200 I decided to go for a lower one as I thought I could "squeeze" more out of it back home.

That all makes sense now. I had heard of problems with banding in the *ist DS and thought it was that rearing its ugly head. Looks it is a case of me blaming my tools for a bad job...



Thanks for your help.

Dave
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Old May 28, 2006, 6:36 PM   #5
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dave,
forgot to say, welcome to the forum.. is the tokina a manual focus lens without the A setting?? that would explain why the exif doesn't report it.. even the i have 2 A lenses. one report the aperture the other does not.. go figure.. the pentax is great at higher ISOs but your exp has to be better than at the lower ones.. just enjoy.

roy
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Old May 28, 2006, 6:58 PM   #6
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Thanks forthe welcomeRoy, It's nice to be a part of such a friendly and knowledgeable forum.

It is a manual focus with the "A" setting of which I always keep it set. It is one of the main reasons I bought the DL as I used to use a Ricoh KR10 years ago (still have but don't use anymore) and bought the lense new in '93/'94.

It was in my opinion a good lense then, so I was quite pleased to hear that the DL took all the "K" mount lenses. It was the deciding factor in choosing between the Canon 350D and Nikon D50 and the Pentax *ist DL.

I'm off to bed as it's12:58am in the UK at the moment and I need my sleep...:whack:



Thanks for all your help.

Dave
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Old May 28, 2006, 7:22 PM   #7
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it takes all the screw mount lenses also..

roy
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