Long Exposure Noise Phenomenon

tigerminx

8

20 Nov 2006 - 4:47 PM

• Options
  • Report Error / Abuse

0

I had the opportunity this weekend to try out long exposures with the 30D, after a 10 minute exposure I noticed a really horrible looking blue gradient on the bottom edge of the frame. Thinking it was the lens I tried the 50mm F1.4 with the lens cap on and an exposure of 135 Secs @ F3.5 I noticed the same phenomenon. I took the camera back to the reseller today, and they had no clue. (The camera has since been sent back to Canon in Johannesburg.) Was wondering if anyone could shed some light on my dilemma?

I have attached a resized test image here:

Resized Image

And a 100% crop of the image here:

100% Crop

Exposure was 120 Secs @ F3.5 using an ISO of 1600. (Seems to happen on all ISO's)

I've heard of heat induced noise or "amplifier glow", but surely not after 120 secs and so severe?

Thanks in advance.
Bruce.

tigerminx

8

20 Nov 2006 - 5:00 PM

• Options
  • Report Error / Abuse

0

Camera was out in the cold Doug, I was wearing nearly 3 layers of clothing.

Strange thing is regular exposures (1 - 30 secs) are not affected. If the sensor is faulty, what is Canon's policy? The camera is still under guarantee.

Bruce.

tigerminx

8

20 Nov 2006 - 6:07 PM

• Options
  • Report Error / Abuse

0

If you read my post above I clearly state that it happens on all ISO's.

elikag

8

21 Nov 2006 - 11:57 AM

• Options
  • Report Error / Abuse

0

This happens on the bottom of the image, that means the top of the sensor.

Have you used the included rubber-thingy to block any stray light from entering the viewfinder? It seems like you get some stray light coming trough the viewfinder and fogging your images.

The blue tint may be due to some optical merits of the pentaprism.

HTH,
Ilia Kagan.

Tandberg

10

21 Nov 2006 - 1:41 PM

• Options
  • Report Error / Abuse

0

I do 10 minute exposures all the time

Try 10 minutes at 5.6 and a low iso!!

I use iso 50 on the 5d and no noise reduction on..

Make sure the camera is adjusted to the cold and you should have no problem..

Have a quick look at my night stuff and see for yourself
dave

tigerminx

8

5 Dec 2006 - 6:47 AM

• Options
  • Report Error / Abuse

0

All Canon's Sensor Calibration did was waste a couple days. 2 weeks now without the camera, and they have finally decided to replace the sensor? Should I be worried?

tigerminx

8

5 Dec 2006 - 11:24 AM

• Options
  • Report Error / Abuse

0

Thanks for the reassurance. I suppose It's either gonna work, or they will have to replace. It's just knowing that a 5 month old camera, has already had open heart surgery

Surely 10 minutes is not that long in terms of Digital SLR exposures? I remember on my 300D I managed an exposure of about 40 minutes. A bit of noise, but nothing near the likes of the image I posted above.

Thanks again.
Bruce.