low light iso question

Forgive the simple question, and it probably doesn't have a hard-fast answer, but here goes: what ISO setting should one use for low light photography? To try to answer this experimentally, I shot the same subject (stack of papers under just a 60 W bulb with no flash in an otherwise dark room) @ 200, 400, 800, and 1600 ISO keeping shutter speed constant (1/60) in shutter p. mode. Had to hand hold these but I braced the camera; I used my 50/1.8f for this experiment. Here are the stops the d50 selected @ different ISOs:

200, f/1.8
400, f/2.8
800, f/4.5
1600, f/5.6

I can see "grainy" effect in the lower light areas of the images @ 1600, but not too bad @ 800 and not detectable @ 400 and 200. My thought is that I should be using 800 since it seemed to give the best trade off between this grainy effect and f/stop. Assuming I'm not going for a DOF effect with my subject, am I correct in assuming that I want a medium stop value say 4-8 range?

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http://encoding.n3.net

your experiment seems ok.

A stack of papers may not be a neautral grey subject but your assumption about the grain might be influenced by your monitor.
In other words, how does a print look when done at a good lab.

Yes , you should always strive to shoot at a lower ISO to get better image quality, less noise, etc. but sometimes you have to go for a faster shutter speed or a smaller f stop.

Hey , why not try some pics of people in the same room at ISO of 400, 800, 1200 and see what the pictures look like.

Post some of your results for us to see.

Take care
--
Sam
http://www.samjsternphotography.com

Each situation requires a different setting.
As you know, F/stop, Shutter speed and ISO are all inter-related.

We talk about EV (Expoure Value), because you can choose different combinations of all 3, and still have the same EV

So, depending on what & where you are shooting, you choose different combinations

1. Fast moving subject, select higher shutter; with cooresponding larger f/stop and/or higher ISO

2. If you want to maximize DOF, select larger f/stop with slower shutter and/or ISO changes.

3. Low-light - You are generally gonna need to bump-up the ISO, but you must balance this against shutter speed (avoid blurs & camera shake) and larger f/stop (small DOF and physical limit of the lens)

ISO 200 is always preferred, if you can use it, but as you have seen, the noise is not that bad (IMHO) at higher ISO. You WILL see the noise in dark areas of the image, and especially as you enlarge and/or crop the image
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Warm regards,
Dad-of-four
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Hi running,

I have found that most camera's love the f8 to f11 range for sharpness. It does depend on the range of the lense aswell. For the 50mm 1.8, that range can be broadened from f4 to f11.

As for iso, I dont think you can generalize a iso for all low light conditions, as it depends on your subject. ie moving subject, backlit,subject lit with background,etc.

I will try and stay away, no matter what light condition, from any iso over 400. The higher iso's are just not needed for my style of shooting. In fact I cant remember the last time I have taken it out of 200...Plus I shoot 99.9% in manual operation, just so I can control the f stop and shutter for the effect I want or am trying to get.
Sorry for the vague answer, but I hope it may have helped you out...

Cheers,

Tin
--
If a tree falls in the forest...did anyone get a picture of it?

I, too happen to shoot a lot in low light, one of my reasoin for buying the dSLR after being disappointed by the SONY 828 in this department.

Following on the dead-on advise of dad_of_four, you have to be careful with the shutter speed and aperture you use. I have found the 50mm 1.4 produce too narrow a depth of field due to its large aperture under low light if you leave it to auto.

What I do now in low light situation is to leave the ISO on 200 in the menu, yet set it to Auto.

Then select the slowest shutter speed possible without producing camera shake, and the largest aperture possible without limiting your depth of field too much;

then VIOLA! the camera will automatically select the lowest(and least noisy) ISO for you!

After playing with this a few times you would get a feel for what ISO is probably appropriate for your lighting situation. Any noise produced can be cleaned up with software if desired and usually would not look too bad on prints.

I interpretted the orginal question in this way:

Is it best to sacrifice image quality by raising ISO and keeping the F-stop at point that maximizes the lens's sharpness? Or is it better to sacrifice lens sharpness by opening the lens to it's maximum aperature so that you can get the ISO(and noise) down?

Whether or not this was the orignial question, I'd like to know. Let's assume that we don't care about depth of field, but you do want a hand-holdable shutter speed.

Kelton

To answer you question, Kelton, I do want a hand-holdable shutter speed (about 1/80th with my 50 mm/f1.8 in my hands). Your first interpretation is more or less what I was asking with the caveat that I do care to minimize the DOF effect and allow for more of the image to remain in focus.

Does that answer your question?

Kelton Sweet said:

I interpretted the orginal question in this way:

Is it best to sacrifice image quality by raising ISO and keeping
the F-stop at point that maximizes the lens's sharpness? Or is it
better to sacrifice lens sharpness by opening the lens to it's
maximum aperature so that you can get the ISO(and noise) down?

Whether or not this was the orignial question, I'd like to know.
Let's assume that we don't care about depth of field, but you do
want a hand-holdable shutter speed.

Kelton

Click to expand...

--
http://encoding.n3.net

I think the biggest killer in a photo is motion blur, either camera shake or subject. So, if getting the shot in low light means sacrificing quality, the first parameter to throw out is optimum lens aperture, then noise from high ISO, then DOF. You can always correct noise issues in PP, and some focus error with USM, but risking motion blur for the sake of a little noise at ISO 800+ is not worth it to me. I shoot at 1600 @ f2 frequently for indoor sports.

Jim

Kelton Sweet said:

I interpretted the orginal question in this way:

Is it best to sacrifice image quality by raising ISO and keeping
the F-stop at point that maximizes the lens's sharpness? Or is it
better to sacrifice lens sharpness by opening the lens to it's
maximum aperature so that you can get the ISO(and noise) down?

Whether or not this was the orignial question, I'd like to know.
Let's assume that we don't care about depth of field, but you do
want a hand-holdable shutter speed.

Kelton

Click to expand...

I posted my "interpretted" question in the open forum and recieved some good responses there as well.

Which to sacrifice first:
Image quality with regard to noise?
Image quality with regard to the lens's optimum F-stop?

I guess the ultimate question is whether post processing can more easily recover damage from High ISO or from a less than idea F-stop.

Kelton

Well, here you get into the 'you get what you pay for' argument.

If you try and get an available light shot with a kit lens, you are going to get a lot of noise if you crank up the ISO to 1600 and still have a large amount of shadow. On the other hand, if you try the same shot with, say, an 85 1.8 and have to crop less, the noise will be less noticeable. I'll use the 85 or 50 1.8 over the 80-200 2.8 just to gain a little more light.

Jim

Kelton Sweet said:

I posted my "interpretted" question in the open forum and recieved
some good responses there as well.

Which to sacrifice first:
Image quality with regard to noise?
Image quality with regard to the lens's optimum F-stop?

I guess the ultimate question is whether post processing can more
easily recover damage from High ISO or from a less than idea F-stop.

Kelton

Click to expand...