Compression settings for S1

[scott1120]

I know this has been asked and answered in several other topics. What I am having a problem understanding is: When I change the compresion to S (superfine) the number of pictures goes to a smaller number. From all the other threads I have read here it seems everyone says that superfine makes a larger pic, where as the manual says it is larger.

Anyone make sense in laymans (I mean beginner) terms?

[Jon]

The number of pictures will go down as you increase the size in pixels or decrease the compression, becoaus either of those choices will make the file larger.

[scott1120]

Maybe what I meant to say: The manual says you can save aprox 308 pics at L and S, where as 552 at L and F. If superfine is compressing more why is file size larger? To me by the definition the larger the file the more detail, so to me more compression means smaller size file.

Totally confused.

[RossW]

Let's consider the two factors that determine image quality, picture size, and the file size of that image. You haven't asked about what is usually called resolution, which is the physical number of pixels that make up an image. It's pretty straight-forward; more pixels makes a larger image (and a larger file) and in general will give better quality because you have more pixels to work with when printing or displaying the image. (That's a somewhat over-simplified statement, but I don't want to bring in more esoteric aspects of resolution because they won't add to the discussion.)

Compression, which you asked about, is a scheme to mathematically treat the data that makes up a digital image to reduce the size of the file. It has no effect on the size of the image... just the size of the file, and the quality of the image. If the data is compressed more, the file size is smaller, and the image quality can suffer. Conversely, less compression yields relatively larger files, and higher image quality. Again, no change in image size. As you note, less compression = larger files = fewer pictures that can be stored on a given memory card or disc.

Perhaps some of the confusion is with Canon's terminology for the compression settings:

"Superfine" refers to quality (best), which indicates the least compression. Therefore, larger files, fewer pictures stored.

"Fine" is the medium setting for quality, middle amount of compression, middle-range file sizes, etc.

"Normal" is the lowest setting for quality -- (who'd call it poor?) and applies the most compression. Therefore, smallest file sizes, most images stored on a card.

Again, compression doesn't affect the image size. Resolution does that, and when you combine three (or four) resolution settings with the three compression settings, you get nine (or twelve) different size ranges of the files.

Hope that helps.

[Jon]

Maybe what I meant to say: The manual says you can save aprox 308 pics at L and S, where as 552 at L and F. If superfine is compressing more why is file size larger? To me by the definition the larger the file the more detail, so to me more compression means smaller size file.

Totally confused.No, Superfine is compressing less. Note that Canon's specs for the camera give a typical size of Large / SuperFine 1,602Kb and 2,048 x 1,536 pixels and Large / Fine 893KB and 2,048 x 1,536 pixels so you can see that the resolution doesn't change. But SuperFine doens't compress the file as much, so less detail is lost where there are subtle tonal gradations.

[scott1120]

Yes, I finally got it. To me the words "superfine" meant more compression. If I am not doing alot of post processing would the "fine" setting be enough? Hard drive space is not an issue.

[Jon]

Yes, I finally got it. To me the words "superfine" meant more compression. If I am not doing alot of post processing would the "fine" setting be enough? Hard drive space is not an issue.I think you'll find p. 32 of your manual will clarify the relationship between the various settings.

I recommend saving the best quality possible; cards are cheap, and getting cheaper. You never know how big you'll need to go or how tight a crop you'll want to make. Unless card space is really an issue, I'd use SuperFine.