Serious Heat/Hot pixel Problem

[gMaster]

Hi guys
Was trying to shoot some star trails last night for the first time. But my first image (18min exposure) come out like this


Is there a way to avoid this? My camera wasn't used extensively before take that shot. Or I just got a bad batch of D70s, if that is the case, I will go get my camera warrantied while it is still in warranty.

Thanks for any tips.

[MattC]

The magenta blooming is normal for extended exposures. Is NR on?
I cannot say that I have ever seen this first hand (but have read plenty). My longest exposure has been around 30s with the norm around 8s.

[birddog114]

As MattC said, NR should be off, when shooting long exposures.
This has been seen in few threads on this board.

[Oneputt]

When I did this out in the desert I used a 30 minute exposure (make sure that your battery is charged though.)

[gstark]

This is normal. The sensor heats up during prolonged exposures, and this is the result.

Sadly, the D70 isn't an ideal camera for shooting this type of subject.

[gMaster]

Yeah noise reduction is off.
Damn, ok ... doesn't look like any extra long exposure for me until i can afford a D2x.

[digitor]

You could try a dark frame subtraction using Photoshop, or one of the tools like this one - http://www.mediachance.com/digicam/blackframe.htm

This would probably make most of your "amp glow" disappear.

Cheers

[Flyer]

As MattC said, NR should be off, when shooting long exposures.
This has been seen in few threads on this board.

Yeah noise reduction is off.
Damn, ok ... doesn't look like any extra long exposure for me until i can afford a D2x.

Sorry, but I disagree.
Long Exp NR should be turned ON to eliminate this problem.
Also have a look here.

Cheers.

[sheepie]

I think you'll find if you turn Noise Reduction ON, you may have better luck You may also find other side-effects of NR, but overall at least you'll get your picture

This one was a ten-minute exposure with 12-24dx. Unfortunately, you start getting other bits of noise take over, and I also found that the star trails were too narrow, so became somewhat jagged - perhaps a result of using the 12-24 (too wide / not enough pixels ). So overall, I'm still not really happy with it - next time, I'll try with the kit lens...


(Also looks a lot darker here than the original for some reason, but you get the idea )

So - what you are trying to do is possible with the D70 - however, as Gary said, it is NOT ideal for this purpose

There have been a few others with varying levels of success - try Killakoala, and I think Darb may have posted a few. I also seem to remember a POTW at one stage having star trails, but can't find it right now.

EDIT: Found the POTW thread - http://www.dslrusers.net/viewtopic.php?t=6633&start=0

[MattC]

I should have been a little clearer. I would go with NR switched ON for these extended exposures.
As Digitor mentioned, you could use dark frame subtraction. Dark frame subtraction would probably be the better method if you do not want to be doubling your exposure times. One dark frame can serve multiple images providing that the exposure times are all the same.

I have no idea if or how well the above will work. As previously mentioned, I have never taken a shot with exposure times long enough to see this effect.

[kipper]

I definately think the D70 isn't the best camera for this kind of work. From what reports I've seen there always seems to be problems with noise or magenta/purple haze introduced to the image. I haven't experimented myself with this kind of photography but would like to at some stage. From what I've seen Canon's are really good for this kind of thing. Here is a photo that won POTW on NSN, it's the Milky Way in Cygnus by a guy called Jeff Hapeman. Now before the copyright police come to whisk me away. I have spoken to Jeff and asked him for permission to repost this image.




Jeff's Website can be found here:

http://www.pbase.com/jhapeman

Also if you wish to contact Jeff at all please let me know and I can pass the message on.

[Flyer]

Nice shot.
Although not as good as Jeff's here's my attempt at Milky Way.
Composite of two images.



Cheers.

[digitor]

Here's a link that shows the glow at various long exposures: http://www.nies.ch/tech/nikon-d70/noise.en.php

Cheers