low ISO and Long exp OR short exposure and and High ISO

[jwind]

Recently I've been doing quite a bit of shooting* at* night. I shoot with a 20D and occasionally the 1ds Mark II though this question goes ou to all -brand users. we know that longer exposures create noise and we know that higher exposures create noise. My question is that of the subject field. I been hooting around 30 secods are 200 ISO ( se image below.)

Does anyone have anyone prefer on setting to the other? A couple thoughts. Higher ISO has noise no mater what but often I find the noise to be a little more uniform ( much like film grain) where long exposures can often cause chunky and colored noise.

I'm very interested to see what others have to say on this subject.

[metalstorm]

I don't do a lot of long exposure shooting but have you experimented with stacking a series of shorter exposures?

[fuentes]

6 of 1, half dozen of the other. just kidding. i haven't done any comparisons myself. just thought i'd say that that's some great color in the shot. its the closest i've seen to reciprocity blue in digital.

adrian

[jwind]

Originally Posted by metalstorm

I don't do a lot of long exposure shooting but have you experimented with stacking a series of shorter exposures?

No, but I think that that's going to be my next step. It's just that you have to have (more) patients to shoot at night especially multiple shots at the same place :P

[jwind]

Originally Posted by fuentes

6 of 1, half dozen of the other.* just kidding.* i haven't done any comparisons myself.* just thought i'd say that that's some great color in the shot.* its the closest i've seen to reciprocity blue in digital.

adrian

Yes, kinda figured it was 6 or 1 and so on.... as for the blue, I generally shoot in "k" mode (color temperature) and I did have to change in a wee bit in post production.

[fuentes]

Originally Posted by jwind

Yes, kinda figured it was 6 or 1 and so on.... as for the blue, I generally shoot in "k" mode (color temperature) and I did have to change in a wee bit in post production.

love the post production. so much control. wish it worked on people.

[metalstorm]

Originally Posted by jwind

No, but I think that that's going to be my next step. It's just that you have to have (more) patients to shoot at night especially multiple shots at the same place :P

I think noise can be controlled through stacking. Not sure if it actually exceeds the the single exposure in time.

[SensorDust]

For night I have used 100 ISO and long exposure only, using tungsten white balance too.

I have not tried higher ISOs yet and I have not checked for pattern noise. I use the lowest ISO that would get an exposure under 30 seconds or use manual mode and bulb.

I guess my answer would be that a shorter exposure high ISO might be preferred if there is a fast moving very bright source of light on any part of the frame (like the moon.) To prevent light trails from stars for example. Or when people are on the picture and their exposure is done by flash and the background by slow sync. People can't stand still for the time of a long exposure. Other than that, I don't see the need for higher ISO when the camera is on a tripod (for my particular use)

I have heard of astrophotography done by stacking pictures but the technique is unknown to me.

[mikej]

I have done multiple exposures and stacked them when doing star photography as well as some normal daytime scenes and it does work to reduce noise and also hot pixels in the night shots.

With the start shots, I take about 5 or more 30 second exposures at ISO 100 and about f8. I use the f8 to limit my shots to the center of the glass, even though my "L" glass is pretty consistant from wide open to smallest fstop. If the center is a little sweater, I want to use that. Later, in photoshop I will stack image 1 and 2 (it's been last winter that I did the last ones and can't remember if I used multiple, but I think so), flatten the image and then stack this new one with image 3, do the same thing, then stack image 4, etc., till the last image. It brings out detail that you can't see in just one image and any hot pixels (they look like red stars) are gone since they happen in random spots and the merge will cover them up.

This also works in regular shots taken with normal exposure as well. I've only tested it a couple of times, but it does reduce noise and give more detail in the shadows. This is different than merging two images, one exposed for the highlights and one exposed for the shadow. I do that on a regular basis. With multiple images like the star fields, the images are all exposed correctly and then merged.

There is a program that will merge stacked images a lot easier than I can do it that I'm going to get when I start doing start photography this winter. That will do the process a lot easier and quicker than I can do it manually. But you can try taking 3 or 4 exposures of your night scenes and merge those together manually and see if it works for you. If you google stacking images, you will find a lot of information on it.


Mike

[Rokcet Scientist]

The colors are absolutely gorgeous, jwind.
Maybe even more amazing is that you got a 428KB jpg posted. How did you do that? As I was hitherto – including this pic – limited to 128KB jpg's. Which sort of seriously 'cramps my style' and doesn't allow me to appreciate my fellow-members' photos in their full glory. (Apart from yours, of course).
This forum IS about photography, isn't it?

RS

[badpickev]

it looks like Jwind posted his pic as a link and you posted yours as a file. I have the pic hosted and the click on insert an image, then past the link to the pic so it looks like this. ]url[

[Rokcet Scientist]

Originally Posted by badpickev

it looks like Jwind posted his pic as a link and you posted yours as a file. I have the pic hosted and the click on insert an image, then past the link to the pic so it looks like this. ]url[

That's right, bad, I forgot. Thx for pointing it out.

RS