5Dmk2 Long exposure articfacts/noise

W

wavefront

Suspended / Banned
Messages
160
Name
Mark
Edit My Images
Yes
Hi all,

I've some funny noise / rgb artifacts appearing in a long exposure shot I took last night and hope some of you could shed some light on what happened?

I was out taking pix of the starling murmurations at Brighton pier, and spent the best part of an hour taking stills and lot of video on the 5Dmk2. After the (absolutely amazing) display, I took a 429sec long exposure which shows some very bad noise/artifacts - see the unprocessed 100% crop below, and the complete shot to show how they are all over the image.

6658724477_9f49bc85d5_o.jpg


6658765465_775e5ff8d6_o.jpg


Do you what happened? It was taken with a 10stop ND, at 800iso, f4, and the long exposure noise reduction wasn't enabled.

My 5D has been behaving completely fine, and I've never seen this on it's long exposures before. It's not the usual noise , as you can see that 'normal' noise in shadow of the pier hitting the water in the crop above.

I've tested for hot pixels with a 120sec exposure at iso50 with the lens cap on. The image is completely fine, and a 429sec exposure I have some hot pixels bit Lightroom ACR copes with them fine so not worried about hot pixels as such.

Any thoughts why this happened? Do you think it was just because I was filming/or using Live view for the best part of an hour and the sensor was quite hot (though is was bloody cold on the seafront!)

Thanks in advance,

Mark.
 
Looks like movement blur to me was is windy at that length of exposure could have been move don't need much movement But like mark says you want to be using iso 100-200 IMO
 
429 seconds will show up any hot pixels. Those look like a worse version of the pixel problems I had on my 5d2.

I doubt Canon would do anything as 429 seconds is way out of there spec range. You dont actually state thats how long the first picture was, but in my case 10 seconds showed 165 knackered pixels and Canon changed the sensor under warrenty.
 
As said earlier, you really need to be at the lowest iso possible whenever possible, which easily is at that length of time....

I have a 550D and I see noise at 400 iso, so 800 seems way to high....
Looked like interesting shots though.
 
You've done the hot pixel check at ISO50, have you tried the same at ISO800?

+1 for the ISO being the problem, although it's perhaps a secondary problem.. a 4-stop or 6-stop ND filter might have been better for the conditions. You could then have closed-up the aperture a stop or two and dropped the ISO without affecting the overall exposure.
 
What's your workflow? I was doing long exposure stuff recently and had this on images from my 5D1 when I looked at them in the Library module of LR3, soon as I changed into the Develop module they were gone, LR sorts it automatically. Think Bridge can do it too or it might be something to do with Adobe Camera Raw.

I was shooting at iso 1600 so was left with some noise but the hot/stuck/dead pixels were all sorted automatically.

Have you cleaned up any dust marks or is your sensor just that clean?
 
Thanks for the replies so far :)

markmullen

I reckon it is just long exposure noise, coupled with ISO800 noise.

Out of interest why ISO800? As you're on a tripod and in for a long haul anyway I'd have used ISO100 and just left it even longer.
Click to expand...

MADDOGHARPER

As said earlier, you really need to be at the lowest iso possible whenever possible, which easily is at that length of time....

I have a 550D and I see noise at 400 iso, so 800 seems way to high....
Looked like interesting shots though.
Click to expand...

At the time, I used ISO800 because it was the lowest ISO I could use without drastically increasing exposure time. If I'd gone to ISO400/200/100 I'd have been waiting 14/28/57 mins and my wife would have served divorce papers ;)

If I'd not used the ND110 I would have had to have been at ISO50, at F16-22, and at the time thought I'd only be able to get a 2 min exposure and for some reason thought I'd want about 5mins. However in hindsight I think my calcs weren't exact, and I realised I had my 1/2/3 stop ND's with me :bonk:

ChrisH
429 seconds will show up any hot pixels. Those look like a worse version of the pixel problems I had on my 5d2.

I doubt Canon would do anything as 429 seconds is way out of there spec range. You dont actually state thats how long the first picture was, but in my case 10 seconds showed 165 knackered pixels and Canon changed the sensor under warrenty.
Click to expand...

Thanks Chris, I checked for hot pixels and my camera seems fine, tho as Alastair said I should maybe check again as ISO 800.

fixedimage
What's your workflow?

I was shooting at iso 1600 so was left with some noise but the hot/stuck/dead pixels were all sorted automatically.

Have you cleaned up any dust marks or is your sensor just that clean?
Click to expand...

I take all my images through Lightroom which usually does a very good job with hot-pixels, but even it's brilliant Noise Reduction module won't help here!

I'm now even more worried, my sensor is clean? It's not usually ;)

Alastair
a 4-stop or 6-stop ND filter might have been better for the conditions.
Click to expand...

Yup, shame I'd forgotten about my other ND's in my bag! However, I didn't think ISO800 would have been an issue, as ISO800 is very very clean on the 5D and I regularly take 30sec-1min exposures at ISO800/ISO1600 and have never seen issues as bad as this. Does the ISO performance at very long exposures (5 mins +) really degrade that quickly?
 
"I didn't think ISO800 would have been an issue, as ISO800 is very very clean on the 5D and I regularly take 30sec-1min exposures at ISO800/ISO1600 and have never seen issues as bad as this. Does the ISO performance at very long exposures (5 mins +) really degrade that quickly? "

That's a fair question, I'm not taking into account the 5D mkii's performance, I was talking from my own experience with my 550D which shows the introduction of noise at iso400 so as you can imagine iso800 seemed like madness to me. If I'm going to use a long shutter speed I set my camera to the lowest iso which is iso100 and then pick the ND filters required to suit the time I have in mind, ie; I last used my ND filters a few weeks ago in south wales, I knew I wanted the effect of a 30 second exposure but only had an ND4 and 8 but it was still a little over exposed, so I cheated by reducing my aperture to f.22 which evened the the exposure with the added bonus of a greater depth of field and keeping everything infocus.
 
What's the best settings to look for hot pixels? ISO3200 (forgot flash w/ me), f1.4 1/40 found few white pixels. Should I be concerned?
 
You must log in or register to reply here.
Back
Top