what made this picture so grainy?

the day i took these, there was heavy overcaste. could it be the white balance or something? im' new to photography, just lookin for some help

Byte size: ZERO | Content warning: NOT AN IMAGE

You shot it at ISO 1600, so what you are seeing is noise because of the high iso

The exposure is all wrong. 1/1600 of a second, F/18 and ISO 1600

You need to do some research in to how shutter aperture and iso relate to one and other.

Yup, what he said, High ISO.

ISO should be left on 100 unless its too dark to get a photo. All increasing ISO does is amplify the signal received by your sensor. Increasing it does lead to higher shutter speeds but at the cost of higher noise as it is an artificial factor in the photo.

Secondly, F/18 (actually f/16 and above) should only be used when you want extremely high depths of field. In this range the very high apperture value (which means a very narrow opening for light to pass through) actually starts to degrade image quality. It will also cause diffraction effects around point sources of light.

I'm all for using iso 1600 if its called for, just wasn't needed in this shot. If you have understood the relation between shutter aperture and iso you could have used a different exposure

Take a look at Virtual Camera for some instant feedback: Cameras Interactive aims to help novice photographers grasp the main concepts of SLR photography.
http://www.camerasinte​ractive.com/index.php#

Enjoy! Digital SLR Cameras - a Canon beginners guide.
http://web.canon.jp/Im​aging/enjoydslr/index.​html

Exposure explained: Three gateways for light.
http://www.canon.co.jp …ng/enjoydslr/p_​2_005.html

Exposure = Aperture + Shutter Speed.
http://www.mir.com.my …phy/fototech/ap​ershutter/

Exposure - Low Tech Tips
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SimCam
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It's the high ISO that caused the noise, as others have said. The 20D and 30D are less noisy than the Digital Rebel at ISO 1600, but you didn't need to use ISO 1600 for this shot anyway.


Firstly - you need to learn the relationship between depth of field, focal length and distance. It's best to avoid apertures smaller (higher f/number) than f/11 on a 1.6x camera unless you need them for sufficient depth of field - that's around the point where diffraction begins to affect image detail.


Secondly - as others have said, use the lowest ISO possible to get the shot. f/8 would have probably sufficed - which is 2 1/3 stops faster than the f/18 you used (the EXIF says this picture is 1/1600s, f/18, ISO 1600).

I think the picture is maybe a touch underexposed, so we'll go for 1/3 stop greater exposure, and an ISO two stops slower than the ISO 1600 you used. In other words, 1/1600s, f/8, ISO 400.


I'm no expert on this sort of shot - it's something I need plenty of practice with. However, 1/400s, f/8, ISO 100 (shutter speed two stops up, ISO two stops down) should have been possible with good technique - pan the camera before and as you fire the shutter. The use of AI Servo and Custom Function 4 set to 1 or 3 could help - though I know the Digital Rebel has some limitations with in this area - I'm a 20D owner.

David

Not as many as you might think, David!
Radio Controlled Boats - 6 shots
https://photography-on-the.net/forum/showthre​ad.php?t=101101

Formula cars - Waterford Hills POTN Race Weekend
https://photography-on-the.net/forum/showthre​ad.php?t=95303

Would this be reciprocity failure?

No. That only applies to film where the exposure is very long or short.
Most lenses have a sweet spot where they're sharpest. Usually 2-1/2 to 3 stops down from max aperature. Things go downhill from there 'till you start to see the diffraction effects.

No - there's no significant reciprocity failure with digital anyway. Reciprocity failure is where exposure doesn't behave linearly with long exposures, especially with film.

The effect that Citizensmith and I mention is diffraction. There's a good explanation of diffraction here. A 350D, 20D or 30D begins to be diffraction limited at f/11 (you'd see the first effects of diffraction at 100% crop at around f/11).

David

I think I've finally found someone who types slower than I do, David!

Actually, I'm about 90wpm. I'd lost the link to the site with the good explanation of diffraction and took some time to find it. I then got distracted by a phone call, and didn't finish the post until I came back to the computer.

David

Have you tried running it through a noise reducer like noise ninja or neat image?