High ISO verses Long Shutter Speed

[Dirt_Bike_Ryda]

I was out trying to capture some star trails tonight, and i set the camera up and what not. and worked out the shutter speed by cranking up the ISO and opening up the aperture till i got a picture like what i wanted, then i worked out the time as i work backwards on the ISO and aperture. And the result affter an HOUR was surprising... Have a look...

This is the "test shot"
ISO 6,400
F/8
30seconds




This is "the shot"
ISO 200
F/22
3,402 seconds (about an hour)



They are both very noisy. but i thought this would be a good example to illustrate the different types of "noise"

[FoG]

ahhh bkles the bulb setting !!!! nice shot that first one I have yet to try this as need a remote

[andrecb]

Hi,

have you try low iso, like 100 or 200, and not so long shutter speed, like 15min to 20min only, instead of an hour ??

try and post back the results

Like the photographs tho, specially the first one

[Heaterguy]

Interesting, but noisy.

[DivemasterDoug]

I've experimented with the same type of shot. I've found that I've gotten better results with low ISO 100-200 and multiple short exposures (30 secoond). I then composite them in photoshop.

[equilution]

I've been having issues too trying to catch night trails w/o noise...no luck so far. Too bright in the area I'm in. Thanks for sharing your tips!

Jim

[Dirt_Bike_Ryda]

Yeah.. well for the longest shot i was using the Lowest ISO... 200... (i could go to LOW.1 AKA iso 100 but im under the feeling that this adds a little noise, but allows for a slower shutter... if you follow).

I might try it again tonight using a larger aperture and go for 30 minutes. i was honestly not expecting so much noise.

[CaptainNH]

I have had the best success in capturing star trails shooting multiple shots wide-open for shorter periods. The combine them in PP.

Were you using such a small aperture to get the shed and stars in focus, or to get longer exposures?

If you need to get a close object in focus, providing you have solid tripod, you might try focussing on the shed and exposing with flash then, quickly, refocussing to infinity for the remainder of your long exposure to capture the trails.

Hope that makes sense - I'll see if I can dig up an example.......

[Dirt_Bike_Ryda]

actually.... that is a very good idea..

Yes i was using a small ap for the DOF purposes.

And yes i have a sturdy tripod lol.... $1,000 sturdy LOL !

[Dirt_Bike_Ryda]

Heres the one that i took last night.

ISO 100
F/16
Shutter 1327 seconds (around 20 minutes)



Still VERY noisy. i lit the shed up with my flash, hand held it and just pressed the flash button. i did this twice once from either side at about 45 degree to the shed.

Im going to try again friday night.. im going to try the multiple exposure thingy that my D90 has. see if that can help. then ill start playing with "long exposure noise reduction" awrful slow and pain full though