24x36 Print
 

I am trying to crop a image shot with my Rebel XT to 24x36. When I open the image in Bridge the resolution is 240. I change it to 300 then open in CS2. When I make my crop there it change the resolution to 150 sometime less then that. How can I create a high res file that is 24x36 for printing on matte poster paper from my raw file. Any help with this would be apprecaited. Thanks

I suggest that you use Photoshop's Camera Raw function to open the RAW image keeping all of the Camera pixel data and in 16 bit mode if the RAW file offers you that option. When the RAW dialog box opens, don't worry about the resolution in DPI, just look at the image dimension in pixels and make sure you choose the highest. So, if your camera outputs an image which is 3000 x 2000 pixels, make sure that the image imported into PS is the full 3000 X 2000 pixels. From there, just use the Image > Image Size command to resize it. With the Resample box UNChecked, change the dimensions to 36 x 24 and look at what resolution you are shown. If that resolution is too low for your printer's requirements, then check the Resample Box and change the resolution to whatever you need.
Regards, Murray

Followed your steps and when I uncheck resample I ended up with a res of 133, but my pixel where over 3000x2000. So I checked resample and end up with a 6000x9000 pixel with a res of 258. What does resampling do to the image?

Let's say just for example that the image imported into PS is 3600 x 2400 pixels in size. If you tell PS to set the resolution to 300 dpi, then your picture will print at 12 x 8 inches (3600 divided by 300 x 2400 divided by 300). If you tell PS to set the resolution to 600 dpi, the image will be set to print at 6 x 4 inches. If you set the resolution to 100dpi, your image will print at 36 x 24, and so on. As you can see, as you raise the print size, the resolution drops. 100 DPI (or in your exact case 133 dpi) may not be sufficient to produce a "photo quality" image. This is where resampling comes in. When you set the size to 36 x24 and change the resolution from 100 to 300 by turning on resampling, youare telling PS to manufacture more pixels. PS does this by extrapolation of the pixel data. In the case where it goes from 100 dpi to 300 dpi, PS will in effect replicate each pixel 2 more times. When the ratio of up sampling is not even (like 133 to 300), the resulting image may look slightly softer than the original prior to up sampling. But generally you will get very good results when you upsample is 300%.
Hope this helps.
Regards, Murray

Trouble Printing
 

Thanks for your explanation of resample. I have meet another problem. After editing the file I tried to save as jpeg, but there was no option to save as jpeg. Which is odd. So I just took the psd file to copymax to have it printed and they couldn't get it to save as jpeg or pdf. What could be causing this problem?

You can not save the file as jpg if the Mode is 16 bit (must be 8 bit). It can not be in LAB mode (try RGB). It also can not be in indexed mode. Jpg does not support layers - you will need to flatten the image.
Regards, Murray

Ok so do I need to leave it 8 bit in Raw or leave it 16 bit? Then in CS2 how do I change it back to 8 bit. I did flatten the image and I didn't save as LAB.

To change the image to 8 bit, just go Image>Mode> 8 Biits/Channel.
I recommend that you archive your original RAW file out of the camera to a DVD or hard drive. You can save many edited versions of the file in other formats but it is always worth keeping the original. Or what I usually do is import the RAW files into PS without making any changes while acquiring the file. I will then archive the file as a TIFF or a PSD both of which are lossless. I do this in case a future version of PS will no longer read the proprietary RAW format of the camera maker.
Regards, Murray