Railfan Technology > Image Noise

Here are 3 photos taken last September at Shawmut, AZ during the monsoon season, and I am wondering if the noise level in these photos is excessive or normal. Shot at ISO 2500, auto exposure, camera mounted flash (to bring out the reflective stripes).

The first two photos are the entire frame, while the 3rd photo is about 1/5 of the original frame and then enlarged to the standard TO size.

Thanks...

Ted

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Excessive noise? Really hard to say. What's the camera, and how were these shots processed? Are we looking at jpegs right out of the camera, or a RAW image that's been run through some editors? exif info would be helpful.

John.

Yep - I screwed up and forgot the basic info :). Camera is a Canon 5D3, lens the 24-105 zoom, image is from the .CR2 file processed in PS6, saved as a .tiff file, then resized to TO specs and 'saved for web' in PS6. I am not sure how to show the exif data though?

Thanks!

Ted

The colors look pretty good considering the ISO. You can probably adjust the noise reduction slider a bit to smooth things out.

Ryan Wilkerson
Fair Oaks, CA

You can screenshot the EXIF data of any of the photos and post it here as well. I would recommend getting a lens more suited for low light photography, if you don't have one already. Something like the 50mm F1.8 or F1.4 will suit you really well. The 24-105 isn't a great low-light lens and I speak from personal experience. I'm not certain if the 5DM3 has it, but if you're shooting in manual mode, see if it will allow you to select Auto ISO so you won't have to worry about that. The camera will usually select the appropriate ISO when you're shooting and you just worry about the shutter speed and aperture.

I have not used the 5D Mark III enough to be an expert but my opinion is that is a lot of noise for Canon's most popular Full Frame camera.

As is, I would recommend using a noise reduction program to make these images more pleasing. Neat Image is perhaps the most popular out there.

I would like to suggest, however, that you reduce the possibility of noise before you even shoot.

You already have one of the greatest tools to lessen noise available, a superb Full Frame camera.

Next you need to go Manual. Letting the camera make the all important exposure decision is like letting a 5 year old select their own career path.

If you allow the camera to figure out the exposure, it's meter is going to assume what it is looking at is a nice sunny day. Bu it's so dark, it thinks "Oh my, this is very dark! I need to brighten this up a lot. So I will crank up the exposure so this dark scene looks like noon!" This action, will make any Auto ISO go through the roof and create the noise you are seeing.

When the sun goes down, I look at my meter and deliberately underexpose 1 stop. Later, I'll go 2 stops under. Why? Because I want it to look dark like what I am seeing, not over-exposed, grey and milky.

What I do is balance the ISO, the shutter speed and the aperture while I am there.

I think with your 5D Mark III, now try ISO 2000 and see how that works. Go lower if you possibly can.

Can you get away with a slower shutter speed? Maybe the train is stopped or you are not doing a 3/4 action wedgie. Perhaps it's a straight on shot where you can get away with 125th, f/4 and 1600 ISO.

I of course I appreciate a lens that goes f/2.8 or faster. But with usable ISO's 5 times the speed of dear old Kodachrome, you can do pretty well even with a f/4 lens.

Below is a low light shot I did. EXIF is Canon 40D, 320th, f/5.0, ISO 800, 127mm lens.

http://goo.gl/1KXXQy

Dennis Livesey
New York, NY

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Thanks for the info Dennis! I meant to say that the camera was set for shutter priority, and the auto part was the f stop and the flash duration. I am somewhat new to digital and I am still learning my way around PS6 and looking at some of the first digital slide shows I made I can see that some of the photos need to be re-done. I may also be over-sharpening a bit...

The train in these photos was moving along at about 25 or so - its tail end was still coming out of the siding. By the time the DPU came by he was up to about 40 or so.

Ted

As mentioned above, a fast lens is a good thing :-) You like to start with the bar as low as you can get it: bigger aperture means easier shooting.

And I agree with setting the camera on manual for the exposure. I also shoot RAW, and have since I got my first Nikon D70 back in 2005... Well, actually, I shot jpeg for three or four months and got really tired of the results, so I went RAW.

My technique it to aim for f8, or at least two stops faster than the base aperture of the lens, set the shutter speed according to the subject (moving or stationary) and then adjust the ISO. If the ISO is too high, I'll open the aperture up. I set the actual exposure by taking a test shot, running home and developing it, examining the negative... Wait! That was years ago, and it didn't work too well. I take the test shot, and then examine the image using the camera's histogram, making sure that I'm not over exposed. A person can always bracket if in doubt.

I don't hold to 'smoothing' more than just a very small amount. If it's got noise, that's just the patina with a very difficult shot, lightwise; my noise reference is tri-x developed in microdol-x at 1:3. I notice that smoothed shots are often shots with missing detail... I can get that effect with a much cheaper camera.

John.

First of all, these are super images with some rather subtle colors. The camera side of the discussion has been well covered, and the program 'Neat Image' was mentioned. I ran one of your photos through my free & basic version of NI, and this is the result. I used the default settings and it took as fast as I could move the mouse!! I've found the basic version excellent, particularly for scanned slides, where grain is grain!! Chris UK.



Edited 1 time(s). Last edit at 07/03/14 01:01 by 55002.

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Thanks Chris - that program really did make a difference! I'll give it a try and see how it works.

Ted

I have used Neat Image for years and could not live without it. It's good on old grainy scanned slides and pictures to.

Marty Bernard

Sooo, it sounds like there is noticeable noise, which I keep thinking of as 'grain'. Sounds like the ISO is a bit high.

I keep thinking of ISO as ASA, I never had access to ASA over 400. But it's digital and it seems to be working fine. It's a lot more fun using those ISO's that we never had with film.