*istD banding

What would one say are acceptable levels of noise banding? Took some moonlit shots the other night. Cloud in sky/ reflection off sea etc. Even at iso400 and noise reduction on, there is some banding 20seconds/f8-ish

Also at iso1600 2secs - awful! the picture is pretty well striped. The banding is horizontal.
Any insights etc welcome
Thanks
Andy

The only level I would accept is none. If it were an insurmountable design defect I guess some subjects would go back to film.

Is there a problem, *istD Users? :

I hope this works - an example of what I mean is in my epz portfolio
here


2.5sec f6.3 iso1600 Noise Reduction ON;

Andy

Ouch! Definitely not the type of 'flaw' one only picks up on by zooming in on the image. No suggestions from my quarter though but a note of empathy!

Doesn't look right at all.

I regularly take images at ISO1600 and ISO3200 with the *ist-D and have never had any perceivable banding.

If your RAW image was correctly exposed (ie you're not trying to pull out deep shadows from an underexposed image), then I'd say it's a repair job - quite likely a CCD problem.

Matt

Matt,

If by correctly exposed you mean no post-processing, that is what the image is. Ie a night-time, moonlit shot converted from RSP with no additional tweaks - just some sharpening

Looks like I ought to send it back - got about 10days left on warranty!

Andy

What I meant was whether you were having to ramp up the exposure compensation in the RAW convertor.

For instance, in Capture One, there is the "EC" control (Exposure Compensation). If you've set that to +1, +2, or even +2.5 then you will get a serious amount of "grunge".

For instance, I took a 10s shot with the lens cap on at f22, ISO1600. There is some background noise at EC+0, but set EC+2.5 and I can see some kind of banding amidst all the terrible CCD noise.

With a RAW file, the shadows have noise. The further into the shadows you go, the more noise. So, 1stop under will be noisy, but 2stops under will be twice as noisy. That's one of the reasons people say "Expose To The Right" when shooting RAW (because CCDs have a linear response, whereas film and our eyes are logarithmic).

Another question to ask is: has this always happened?

Matt

Not sure - but suspect it has. I remember a few shots taken several months ago where I think banding occurred.

A thought - re another thread and batteries/ battery grip etc and the use of Ni-MH batteries - could it be a low voltage problem causing internal supply around the sensor to 'wobble' a bit? The banding is not fixed - ie on the previous shot to the one posted the bands are in a different position to this

Andy

It's more likely to be temperature related. CCDs are not very good for long exposures. CMOS sensors are much better since they have a much lower operating current.

The noise will increase with the temperature, therefore the longer you have the camera running, the more noise (and possibly banding) will occur. Banding does occur (in CMOS sensors too), and Capture One has a banding suppression that can help.

The other thing is that the higher the ISO, the more significant the noise becomes.

Also, watch out for devices nearby that emit EMI (such as mobile phones). It is possible for these to affect the CCD, especially when using long exposure/high ISO settings.

To be honest, I've never really tried long exposures at high ISO, though I wouldn't have expected much at ISO400... I'll see if I get a chance to take some long test shots to compare.

(You could email the RAW if you want. Shove it through Adobe DNG convertor to shrink it first though!)

Matt

Matt,

I don't have the Adobe DNG converter - is it compatible with Elements 2? or can it stand alone?

Andy

Ps I wasn't near any EMI stuff - just on a beach with nearest street lamps about 150metres away - unless the guy fishing had something txing!

Andy,
The DNG convertor is stand-alone.
http://www.adobe.com/products/dng/main.html
Matt

Thanks, Matt.
File has been e-mailed to you
Andy