D70s Noise Problem

Anubis · May 31, 2009

Hi,

Can anyone explain why I get noise in the second image please. I've noticed this happening on a lot of my photos lately. Both taken with the following settings; ISO250, f4.5, and 70mm focal lenth. The first image was 1/250 sec and the second image was 1/640 sec. I have another shot the same as the second taken at 1/125 sec with just as much noise. Both shot in RAW.

If anybody could shed some light on the cause it would be much appreciated!

Cheers,

A.

Pure · May 31, 2009

Anubis said:
Hi,

Can anyone explain why I get noise in the second image please. I've noticed this happening on a lot of my photos lately. Both taken with the following settings; ISO250, f4.5, and 70mm focal lenth. The first image was 1/250 sec and the second image was 1/640 sec. I have another shot the same as the second taken at 1/125 sec with just as much noise. Both shot in RAW.

If anybody could shed some light on the cause it would be much appreciated!

Cheers,

A.

You may want to check your statement again. There is no way that the second picture is ISO250 f4.5 1/640.

Assuming you took these two pictures within a few minutes of each other, then the second picture should be really dark, underexposed, compared to the first.

Despite that, it is extremely clear that the second picture looks noisey due to using a high ISO to capture the picture. Higher ISO typically means more noise.

Check your EXIF data, and you will find you shot the second at something like ISO 1250 f/4.5 1/640 assuming exposures were exposed dead center.

1/125 to 1/640 is 2 and 1/3 stops, so applying that to ISO 250, you get ISO 1250.

Anubis · May 31, 2009

Thanks for the reply, but that is the exif info ...I shoot on full manual so it shouldn't have changed by itself.

manaheim · May 31, 2009

I haven't seen a case where the exif has lied before... that would be odd.

And I can't really see any other reason why the image would look that noisy. Maybe a HAIR underexposed, but that noise is kinda extreme.

D70 is an old old camera now... maybe it just wigged out on one shot?

Anubis · May 31, 2009

I've done a bit more reading and it does seem to be an issue caused by underexposing. I might start bracketing in future, I was just messing around yesterday but I'd hate to lose a good shot because it was a little underexposed.

Thanks for the replies!

Dwig · May 31, 2009

Anubis said:
...Both taken with the following settings; ISO250, f4.5, and 70mm focal lenth. The first image was 1/250 sec and the second image was 1/640 sec. ...

...making the second shot 1 1/3 stops underexposed relative to the first. Adjusting such a shot to get similar tonal reprouction will expande the shadow information making the noise more significant. Its just like shooting at higher ISOs except that there is a tendency to increase the local contrast in the shadows more making the noise even more pronounced.

gsgary · May 31, 2009

Anubis said:
I've done a bit more reading and it does seem to be an issue caused by underexposing. I might start bracketing in future, I was just messing around yesterday but I'd hate to lose a good shot because it was a little underexposed.

Thanks for the replies!

I have the classic 1D Canon, if i over expose a touch i get less noise

JerryPH · May 31, 2009

I just tried 2 different EXIF viewer programs and though I know the camera, lens used , program used to create/modify the file (Elements 5), and create date and some more useless info... basic info like ISO, shutter and what not are not shown using Opanda and Kuso EXIF viewers.

Strange.

Garbz · May 31, 2009

Anubis said:
Thanks for the reply, but that is the exif info ...I shoot on full manual so it shouldn't have changed by itself.

Full manual implies controlling both the shutter speed and aperture. If your camera is set to AUTOISO then it would adjust the ISO to centre the exposure even if you shoot on full manual. At least that's how it happens on the D200 and D40.

Anubis said:
I've done a bit more reading and it does seem to be an issue caused by underexposing.

Both of those photos look like they were exposed equally. Did you push one in photoshop? If not then it's not underexposed. Which is what leads to user error. There's no way that that image is on the same ISO as people already have said the exposure value is quite different. 2.3stops lower on the second one. So it should definitely not be darker.

gsgary said:
I have the classic 1D Canon, if i over expose a touch i get less noise

You also get less dynamic range when you adjust the exposure afterwards. This is not the right solution to the problem.

Anubis · Jun 2, 2009

Garbz said:
Full manual implies controlling both the shutter speed and aperture. If your camera is set to AUTOISO then it would adjust the ISO to centre the exposure even if you shoot on full manual. At least that's how it happens on the D200 and D40.

Both of those photos look like they were exposed equally. Did you push one in photoshop? If not then it's not underexposed. Which is what leads to user error. There's no way that that image is on the same ISO as people already have said the exposure value is quite different. 2.3stops lower on the second one. So it should definitely not be darker.

By full manual I mean I control the settings for shutter, aperture, ISO, white balance and focus. The only thing I did to the images was to export them from RAW to JPEG in Elements 5. They are absolutely both shot at the same ISO. The only difference is the shutter speed. I wonder if the camera is trying to adjust the exposure itself after the shot is taken? (Nikon D70s)

gsgary · Jun 2, 2009

Anubis said:
Garbz said:

Full manual implies controlling both the shutter speed and aperture. If your camera is set to AUTOISO then it would adjust the ISO to centre the exposure even if you shoot on full manual. At least that's how it happens on the D200 and D40.

Both of those photos look like they were exposed equally. Did you push one in photoshop? If not then it's not underexposed. Which is what leads to user error. There's no way that that image is on the same ISO as people already have said the exposure value is quite different. 2.3stops lower on the second one. So it should definitely not be darker.

Click to expand...

By full manual I mean I control the settings for shutter, aperture, ISO, white balance and focus. The only thing I did to the images was to export them from RAW to JPEG in Elements 5. They are absolutely both shot at the same ISO. The only difference is the shutter speed. I wonder if the camera is trying to adjust the exposure itself after the shot is taken? (Nikon D70s)

Well that means the second shot was under exposed if you didn't adjust the aperture, what do you expect if you under expose this test is a total waste of time

Anubis · Jun 2, 2009

gsgary said:
Well that means the second shot was under exposed if you didn't adjust the aperture, what do you expect if you under expose this test is a total waste of time

What I would expect from an under exposure would be a dark image, not the grain that appeared. As stated originally, I did not know the source of the grain. I wouldn't say it was a waste of my time since now I have an answer.

Garbz · Jun 3, 2009

You have an answer? I'm still confused. The image doesn't appear underexposed at all.

Can you please export them and post them with the EXIF data intact so I can make sense of this all?

Anubis · Jun 3, 2009

Garbz said:
You have an answer? I'm still confused. The image doesn't appear underexposed at all.

Can you please export them and post them with the EXIF data intact so I can make sense of this all?

I'll export them tonight when I get home and post them again. Though I don't know why it would be missing in the first instance :S maybe elements needs something checked to export the exif data in the JPEG!?

NateS · Jun 3, 2009

I'm waiting to see the ones with exif. I bet if you checked your settings you'd find that auto iso was accidentally clicked on. If both have the same exposure (which they do) with the different settings you posted, either one or two things happened. 1. Auto ISO is enabled and it's adjusting it for the right exposure, or 2. It was underexposed and had to be bumped up in post....either one will cause the same exposures with higher noise in the second shot. I used a D70s for a couple years until recently and it will not adjust your exposure in full manual unless auto iso is enabled.....or possibly your camera needs repairing.