Megapixels? What to shoot at?

[jdvass]

I have both a Canon Rebel XT (350D) and a Rebel XSi (450D). I have been shooting at the highest mega-pixel setting on both, 8 and 12 mega-pixels respectively.

What I'm wondering is this, is shooting images of this size necessary or is there a kind of sweet spot between image size and quality? Generally the biggest prints I will make is 11 X 14 inches.

[Gonzo13]

I have an XTi and I have always shot at the largest size or RAW. With RAW on mine I only have the option of shooting at 10 mp. I thought that there was another option on the XSi for a smaller RAW file but I might be mistaken I was doing research on cameras for my Dad around the time that it came out so I might be confusing it with another camera. From what I understand though for high quality prints you want to have an image at 300 dpi which would be 4200 x 3300 for a 14 x 11 print which the XSi doesn't completely reach at 4272 x 2848. I would say keep shooting at 8 and 12 mp.

Curiously why are you asking about a smaller size? Are you running out of space on your hard drive? Or do you just want a smaller file to work with?

[jdepould]

Shooting smaller jpgs isn't going to change your image quality at all, so there's no sense in shooting smaller unless you're desperate for card space.

[candleman]

always shoot max resolution. one day you'll get a shot you'll think is awesome.. and if you han't got the resolution its not going to be much use.

quality is not dependant on resolution, that is the product of ISo and the cameras sensor quality.

[Doug Pardee]

Originally Posted by jdepould

there's no sense in shooting smaller unless you're desperate for card space.

There are other reasons to use reduced resolutions (not that they are likely to apply here).

Because the files are smaller, lower resolution photos are faster to deal with. Faster to download, faster to backup, faster to process, faster to transmit/upload. Time is money. Or at least it can be.

Not all kinds of photography demand top resolution. Not all kinds of photography have the potential of giving you that "once in a lifetime" shot.

If you're taking pictures of product to accompany the weekly supermarket advertisement, there's no reason to "go big". If you're taking passport photos, there's no reason to "go big". Those are just a couple of the uses for images whose value is practical rather than artistic and where small size is all that's required.

To answer the original question from jdvass: the maximum resolution of printing equipment is about 320 pixels per inch. Assuming that you're not going to crop except to crop down to the 11x14 aspect ratio, you'll need 5280x3520, or 19 megapixels, to assure maximum quality results. So shooting at 8 or 12 megapixels is reasonable.

Speaking in very approximate terms, 300 pixels per inch is considered "the gold standard", 250 is "pretty darned good", 200 is "good", 150 pixels per inch is "passable for personal shots", and 100 pixels per inch is "rough". So just do some simple math to convert between capture size and print size.

[jdepould]

Originally Posted by Doug Pardee

There are other reasons to use reduced resolutions (not that they are likely to apply here).

Because the files are smaller, lower resolution photos are faster to deal with. Faster to download, faster to backup, faster to process, faster to transmit/upload. Time is money. Or at least it can be.

Not all kinds of photography demand top resolution. Not all kinds of photography have the potential of giving you that "once in a lifetime" shot.

If the difference in file size is enough to translate into appreciable time/money, then you might need to invest in better computer gear. The difference between raw and jpg is pretty big, but jpg L and M or fine and norm, shouldn't really be noticeable.

Originally Posted by candleman

always shoot max resolution. one day you'll get a shot you'll think is awesome.. and if you han't got the resolution its not going to be much use.

quality is not dependant on resolution, that is the product of ISo and the cameras sensor quality.

Yep, always shoot in max res!

[jdvass]

Thanks for the info. I never really had a problem with the sizes of the files. I have lots of storage space and my computers are more than capable of handling the files. I'll just keep clicking away at the max resolution.