3:2 ratio...pixels...dimensions...help!

[MTG]

I received a CanonA630, and PSE 6.0 for Christmas. I finally went to print some pictures this week and came to the following road block that I'm hoping is just a misunderstanding on my part. (I hope I get all the terms in the right places...)
I've taken all my pictures at the highest resolution on my camera 3648 x 2736 ppi. When I open a photo in PSE it tells me the image size is 15.2 x 20.267 inches (at 180ppi)
Not wanting to end up with really big photos I thought I'd try cropping and see what happens. A crop set at the 3:2 ratio ends up cropping off a portion of all my pictures. Which led me to further investigation.
All of the settings in my camera have a 4:3 ratio, not 3:2.
The manual says to use the postcard setting to get the 3:2 ratio, but then my pixels drop to 1600 x 1200 (which in my math is still 4:3) I really don't want to drop to 2MP when I own a 10MP camera.
If I took my memory card to develop pictures without using PSE first would all my pictures end up being randomly cropped by the store? or have I "missed the math" somewhere?
Thanks in advance!
TG

[V8Rumble]

Yes, they would be cropped at the store, and you will have no control over it. It's best to allow room for cropping when taking a picture, then do it yourself. 2:3 camera users have to do that if they will be printing 8x10's, 4:5 ratio.

[tonylong]

One thing you're confused on is the need to crop to get a "smaller picture". If you are satisfied with your composition, and you have a 2:3 aspect ratio, you don't need to crop your pic to print, say, a 4x6 or a 12x18 pic. You might resample the image to the exact size you want, though, to fine-tune image sharpness, for example, but no cropping will be necessary. Resample to the exact size of the print at 300 ppi, check and adjust sharpness, then save as a high-quality jpeg (checking your color space -- if PS is using Adobe RGB you'd want to convert to sRGB to ensure a "safe" color space unless your print outfit explicitely uses Adobe RGB).

Diffent printer operations will handle things differently. Some places have more human involvement and may not require resampling, they may be happy to determine what is the best treatment of your full-size jpeg. I'd always run some batches of test prints with an outside service before entrusting them with large orders, especially large orders of large prints!

If you are going to print to a different aspect ratio, such as an 8x10 print (4:5) you want to do your own cropping. If PSE has a preset for 4:5/8x10, then it should have a "constrain" option to let you resize the crop but keep the aspect ratio. You then just drag the corners to change the boundaries of your composition. Make it as large as you want, but you will lose some of your shot. But better that you design your crop rather than a machine.

I print at several sizes -- 4x6 if I want to mail some "snaps" off to a friend, 8x10 or 8.5x11 "full bleed" for more "portfolio"-type prints, 12x16 for a bit of a cropped "portrait-style" frameable print, and 12x18 for a frameable "landscape-style" print. These are ones I do at home, I control the cropping and the printing as well. For larger prints, I'd use a lab, but I'd still maintain control of all my cropping and any need for resampling/sharpening, etc, and I'd request proofs from the lab before I threw a batch order of, say, a bunch of 16x20 prints. Eventually, I'll replace my B-size printer so that I'll be able to print my own 16x20 pics...

[Jon]

I'm afraid that almost no camera has a "perfect" aspect ratio (the ratio of the image's height and width) for all prints. Your 4:3 will give perfect uncropped 6x8" prints; my 3:2 will give perfect 4x6" or 6x9" prints. Both of us will have to crop, or leave some blank space on the paper, for any other commonly-used print size. Depending on who you take your images to, you may be able to specify that they use the full image, even though that means leaving white space. The fast, "bulk rate" or drugstore processors will probably not be able to manage this.

The size PSE gives you is using the ppi setting embedded in the file (180) and the total pixels to give you a size. However almost no printers pay any attention to that value; they use the specific dimensions you provide them; if you say you want that 3648 x 2736 pixel image printed on an 8x10" piece of paper, that's what they'll print it on ("bleeding over" the edges or leaving white space depending on your directions).

[tracknut]

have I "missed the math" somewhere?

Nope!

Dave

[tzalman]

Because almost all P&S type cameras, as well as one brand of DSLRs use the 3:4 ratio, many labs offer what they call the "4X" size which is 4.5x6 inches. But as Jon said, for anything larger we are all pretty much in the same boat.

[MTG]

Thank you all so much for your help! Guess I'll go get friendly with my cropping tool!