I agree with all that is said, and the film guys out there can correct me if I am wrong but I believe film is/was often cropped at printing time to do exactly what we do by cropping in PS.  man if I couldn't crop to straighten my horiszons and eliminate stuff on the edges I would have to give up.

When you select the 1:1 it will zoom to 100%

Gerhard 

i don't think there is or ever has been any rule against cropping an image. We all do that with most images that we take. If you can shoot the image and not have to crop than great. The limiting factors are going to be technical and will stress the equipment that you are using. By that I mean if you are using a lower megapixel camera such as a 4 to 6 Mega Pixel camera than the amount of cropping that you can do will be limited as the image will be degraded as you over crop it. It is that degradation of the image that is the limiting factor and the "rule" since it will not be as sharp. Having said that not all pixels are created equal. If you use a point and shoot camera that is lets say 10 or 12 megapixels the image produced by these will not standup to much cropping since the sensor in these cameras is very tiny when compared to a DSLR. One of my DSLR's is the Nikon D2Hs which is a 4 megapixel camera but because the sensor is the same size as my 12 megapixel D2X the ability to withstand cropping is much better than the point and shoot and the image is not degraded as much. In comparing the D2Hs and the D2X the higher megapixel sensor will withstand a greater amount of cropping before the image is degraded.

Hopefully this makes sense.

I think that cropping an image is quite acceptable since the image was still taken by you. You are just taking what you feel is the best part of the image to display. With the tundra swans there were so many of them you pretty much have to crop the image to make it interesting as it would be far too busy without cropping the area of interest especially when shooting them on the pond or landing.

Bob 

I tend to agree with Gerhard.  By putting the camera to your eye you are already "cropping" or printing on various size papers.  I cropped a few of my swan photos as the focal lengtht needed to get a tight shot is beyond what I have in my camera bag. 

It's best to try to get the best image that is closest to what you want directly in the camera but there can be times when you just can't get an image framed exactl they way you would like it (ie not long enough zoom or when someone steps into the edge of a good frame).  Also many DSLR do not show 100% view many are 95% so you cannot always see what is on the edges of your image.

Gehard is correct for 100% crop.  Most digital cameras now greatly exceed the number of pixels that are normally displayed on a computer monitor which are typically only 1 - 1.5 mega pixels. A 100% crop is a crop of the image is a portion of the image where t 1 pixel from the image is equal to 1 pixel on the screen.  It is usually used to see the detail in an image because when you look at a large picture resized to fit a computer monitor you cannot see the fine detail that is contained in the full size image.  It also helps to see noise or other problems inside large images.

Bryan 

I would not worry what others think about cropping, if the results are pleasing to you go for it.  Cropping certainly is necessary when you print to different sized paper and I don't see anything wrong cropping to improve composition.  There are purists out there that will disagree with me but I think the majority of people crop.

100% crop is when the pixels displayed on the screen are the same density as those recorded by the camera, usually to fit a picture on your monitor the pixel density is decreased.

Gerhard 

With all the wonderful photos from the swan shoot and the need for very long focal lengths to get up close and personal shots, I'm wondering about a couple of things. In general with photography, when is it acceptable to crop a photo to get a closer look and when is it discouraged? If you crop a photo, is it expected that you identify that you've done it? I'm trying to make my way through the photography etiquette handbook. 

Another question I have is what does '100% crop' mean? Does it mean that what you see is what came out of the camera ie no cropping was done? I see the term a fair bit and would like to know what it means.

 Many thanks again for all those sharing their expanse of knowledge. I appreciate it so much.

~patti