Long Exposures

[spides]

Hi, just a quick one. I'd like to get more into long exposures, like stars at night, but remember reading ages ago, that the internals can get hot and create condensation. Is this true

[jjphoto]

Yes. The camera can get warm but this causes sensor noise but not condensation. I think you may have misunderstood something you've read as people often fit electric lens warmers to stop condensation forming on the cold front of the lens. The camera warming up is not a concern except for the effects on sensor noise, as per below.

This is a one hour exposure on Canon 20D with lens cap on and at ISO100. This is a straight RAW conversion, no tweaking at all.
http://www.johnjovic.com/temp/Noise/1_hour_IMG_1142_1000px.jpg

100% crop of the above image, no tweaking at all.
http://www.johnjovic.com/temp/Noise/1_hour_100percent.jpg

JJ

[spides]

Thanks, I'll give it a go

[dannat]

Winter is a good time for night shots becausevthe ambient temp keeps the noise down, how long of a shot r u thinking about?

[nightbringer]

Now to just wait for a clear night.

I've also heard there is a method where you have your camera take many pictures in even intervals, and then merge it all together in one picture. That's how I figure I'm going to try my hand at star trails - I fear my D3100 would die if I left the bulb open for too long.

[OzzieTraveller]

G'day NB

have a sqwiz in the Astro forum - there's been lots of info on star trails posted there in recent months

Regards, Phil

[spides]

Winter is a good time for night shots because the ambient temp keeps the noise down, how long of a shot r u thinking about?

Was thinking about light trails but then there was an amazing star trails shot in the local paper that apparently was over about 18 minutes. It got me thinking about ones I've seen and heard about that last hours

[dannat]

Therebisba piece of software that joins short shots together to form one image, It's called startrails & will make the stars appear much longer when you join the shots. If you want to increase the signal but have the stars still appear round, you need some different software called deep sky stacker. ( both software Is free)

[koguchi]

Is the photography version of noise the same as a photoshop noise effect, e.g. image gets grainy?
sorry for my lack of knowledge, I am yet to get to the photography terms and meanings section of the forum.

[ricktas]

Is the photography version of noise the same as a photoshop noise effect, e.g. image gets grainy?
sorry for my lack of knowledge, I am yet to get to the photography terms and meanings section of the forum.

Yes, basically! Noise is the side effect of increasing the voltage to the camera sensor, more voltage means the sensor is more sensitive to light, but noise is the result. Same as film, remember the grainy black and whites of old? Film grain/noise is caused by the size of the silver oxide crystals used to make film faster (higher ISO), digital noise is caused by increasing voltage to the sensor to make the sensor faster (higher ISO).

Photoshop noise is basically creating, or removing, the noise using software.

[JBuz]

Does anyone know the max length the shutter can stay open on the d3100 before it gets too noisy? Just wondering how far I can "push" the camera before it pushes back :)

[etherial]

Does anyone know the max length the shutter can stay open on the d3100 before it gets too noisy? Just wondering how far I can "push" the camera before it pushes back :)

As with many questions in photography, the answer is "it depends"