I have another question about cropping in photoshop. 

Suppose, for example, that my objective is to create an 8X10 image.  ... and that after the crop operation, I will be able to resize the image to get the exact 8X10.  Assume for this example that there will be enough pixels ... or I can choose a reduced dpi for printing. 

What I would like to be able to do is to preset the crop to a specific aspect ratio (i.e. not necessarily a specific size) ... then as I drag the crop within the image, that aspect ratio (in this example, 8X10) would be maintained ... specifically, if I pull the lower right crop corner down, the left crop line would also move to maintain the chosen aspect ratio. 

What I'm thinking of is similar to the previsualization trick of looking at the scene through a frame.  Ansel Adams wrote, "11. Exploring with black cut-out card ... The card suggests possible compositions, creating 'configurations out of chaos' ... ".  Ansel Adams; "Camera and Lens"; ISBN 0-87100-056-3; pp 27 - 29, Figure 11.

So ... my Photoshop question ... Can the aspect ratio be preset? 

Thanks for any advice ...

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Martin

Do this with the rectangular selection tool.

Choose the selection tool
In the toolbar set STYLE to FIXED ASPECT RATIO and fill in the height-width ratio you fancy
Drag the size you want. The ratio is respected

When done choose Image>crop

done

I see that Tanchelyn advised,

Do this with the rectangular selection tool.

Thanks!  That is very good to know.  I tried it and see how it works. 

"click -> drag -> release" sets the selection size

"click -> drag -> release" then moves the selection as needed. 

Without starting over, is it possible to adjust the selection size (to a larger or smaller area with the same preselected aspect ratio) after the initial "click -> drag -> release"?

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Martin

Not that I know.

But you can start dragging and whilst keeping the mouse button down, you can hold the TAB key so you can temporarily move your selection to the exact spot you want it to. Then let go of TAB and adapt the size of your selection.

In case you know exactly where you want to start from - and you can drag from all four corners! - you can first draw guides ( view menu > rulers, or ctrl+r, then drag the guides out of the top or left side with the move tool ). Draw a horizontal and a vertical one, activate snap (view > snap, or Alt +v+n) and drag from the intersection.

In case you know the width (or height) draw your left and right (or top and bottom) guides and drag between them. Fixed ratio will give you your ratio.

To get rid of guides, drag the back into one of the sides (out of the canvas), or hide them with Ctrl+H.

Instead of Image > crop I usually prefer to use Alt+i+p

Martin, you can always adjust your selection by choosing Select -> Transform Selection. If you want to maintain the same aspect ratio, be sure to hold the Shift key while dragging any of the corner handles (not the side handles or you'll lose the aspect ratio). Hold Shift and Alt key together while dragging any of the corner handles and your selection will transform from the center point (all corners will expand or tighten simultaneously).

I simply use the Crop tool set it to he high/width you desire and drag i over the image until you are happy with what you get. Also gives you the option to set the resolution and black out the unselected area so you can see what your working area will be with out the distraction of the rest of the image. It is also possible to resize the crop selection with out starting over. This is the method I use to size all my work and I have not had an issue printing as large as 16x24

I see that girsempa 'put the icing on the cake' with,

you can always adjust your selection by choosing Select -> Transform Selection.

I tried that and it works exactly as you said. 

If you want to maintain the same aspect ratio, be sure to hold the
Shift key while dragging any of the corner handles

OK

All in all, this method will give me a way to visualize many possible ways to crop an image ... and, at the same time, select an image that will exactly match the paper size. 

BTW, this will also give me an easy way to create consistent square thumbnails for renderosity gallery uploads. 

Thanks for the help. 

--
Martin

I see that Tanchelyn had some good advice,

dragging and whilst keeping the mouse button down, you can hold the TAB key
so you can temporarily move your selection to the exact spot you want it to.

That would also work. 

guides ...

That is a possibility ... however, looking back to the reference picture from the Ansel Adams "Camera and Lens" Black cut-out frame concept ... please keep in mind that I would be trying to find a 'hot spot' (point of interest) in an image ... to maximize its value ... and to minimize inclusion of unwanted elements ... like waving the cut-out frame around before taking the picture. 

The 3-way control: (a) aspect ratio; (b) moving the selection within the image; (c) being able to change the size of the selection ... is what I was looking for, 

Thanks ...

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Martin

Thanks to viper for the advice to,

use the Crop tool set it to he high/width

Yes, that would help to get a final image that matches to paper size (or some arbitrary image size requirement). 

OTOH, I wanted to be able to select (crop) the image without knowing the image size in advance.  ... and still get a specific aspect ratio.  Up until now, My results depended on guess or aproximation of the aspect ratio when using the crop tool freehand (and estimating the height and width from the rulers) ... the advice I got in this thread will make my image selection(s) more effective ... more precise ... even easier ...

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Martin

Thanks to prixat for telling me that,

the Info Palette open it will display the size (and position) of the crop.

That will be a very handy way to do a freehand crop and obtain either a
target size or a target aspect ratio. 

(I'm beginning to get the idea that I should try to actually study and
really learn photoshop instead of just jumping in, using it, and
seeing how much trouble I've caused myself ... ya think? ... LOL)

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Martin

You'll find a ton of tips and tricks for PS here, I have learned a bundle of stuff from these videos :) http://www.photoanswers.co.uk/Video-Tutorials/