long exposure

please have a comment on my long exposure shot
using my 50mm f/1.8 lens and 50d body.
exposure: 30secs
iso: 100

is it grainy?
how can i minimize the graininess of this kind of shot?
i didn't use the "long exposure noise reduction" on the camera body.
http://backup.cambridgeincolour.com/...e109108c_b.jpg

Hi Isabelo,

It does look pretty noisy, especially in the shadow areas. My guess is you've either under-exposed it, or used a very high ISO setting.

Isabelo,

It might sound stupid, but is/was your lens dirty when you took this shot? Because I had similar shot last night and I am sure it was because of the smudge on the lens. (I have lost my lens cover and can't find a new one :( ) Otherwise long exposure shots come out pretty neat. Or check out with the ISO again. Sure it is 100?

this is the unedited image,
yes i'm sure that it is iso 100 and 30 secs exposure. im 90% sure also that my lens is clean.
is it the factor of the sensor being hot? i said this because this shot is my 9th time consecutive shoot a 30 secs long exposure and i can feel the body is rather warm after many long exp shoots. (my only pause in shooting is when i check the image in the lcd). ...could these be the reason?
http://backup.cambridgeincolour.com/..._5919538_n.jpg

When I said a similar shot, I meant every word of it. ;)
Looks like you also kept you camera on an embankment along the lake/Sea. Mine also got blown out ;)
I have no clue about the sensor getting heated up and ruining the shots.

http://i39.tinypic.com/303da1z.jpg

Quote:

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Originally Posted by belong

this is the unedited image,

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There's the problem ... it's grossly under-exposed; you probably needed something like a 4 minute exposure or ISO 800. What's happening is there is very little light reaching the sensor and so what is recorded is mixed in with a LOT of noise, which is revealed in post-processing. I'm assuming you shot RAW?

These types of scene are difficult to capture because of the extreme contrast - my rule is to simply expose for the mid-tones; the highlights are going to blow anyway - this example "kinda" shows what I'm meaning ...

http://backup.cambridgeincolour.com/...8979/large.jpg

Although the glare from the lights in the distance is going to blow badly. The other option is to expose the sky by an extra stop or so - expose the bottom by an extra 3 to 4 stops - and then combine them into a composite. It's for that reason that I often bracket this kind of shot to give me options afterwards.

yes i shot it in raw,
thanks colin, at least now i know the problem with that kind of shot.
it's totally dark out there in the shot that you cannot literally see the person behind 3 meters, all that is visible is only the lights out there.
:)

Quote:

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Originally Posted by belong

yes i shot it in raw,
thanks colin, at least now i know the problem with that kind of shot.
it's totally dark out there in the shot that you cannot literally see the person behind 3 meters, all that is visible is only the lights out there.
:)

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No worries :)

I actually had the same issue with this shot. THis one is 12 minutes, but on an earlier attempt I had to abort the exposure when I tripped over a tripod leg ... as you say, pitch black ... only the lights of the horizon.

http://backup.cambridgeincolour.com/...124/medium.jpg

Quote:

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Originally Posted by Colin Southern

No worries :)

I tripped over a tripod leg ...

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Yay, I'm not the only one :)

Thanks for the question Isabelo and for the useful words Colin, these threads are very helpful.

big thanks to all...

If the problem is because of overheating from multiple shots you should see a difference between the first and ninth shot, if the noise is consistent then the problem could be heat from the long exposure.

Quote:

---

Originally Posted by belong

this is the unedited image,
yes i'm sure that it is iso 100 and 30 secs exposure. im 90% sure also that my lens is clean.
is it the factor of the sensor being hot? i said this because this shot is my 9th time consecutive shoot a 30 secs long exposure and i can feel the body is rather warm after many long exp shoots. (my only pause in shooting is when i check the image in the lcd). ...could these be the reason?
http://backup.cambridgeincolour.com/..._5919538_n.jpg

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Very interesting. I enjoy shooting at night and this is all helpful. I show you the results when I get something good.

By the way I think the original looks much more interesting than the edited, despite being too dark.
it just shows off the "night" a bit more.
It's more natural.