Photoshop perspective correction vs. movements.

[photographs42]

Originally Posted by amilne

I've been playing around with photoshop's perspective correction tool (in photoshop CS, I hear they're more advanced in CS3), and was just wondering what the drawbacks/differences are from using a camera with movements in the field?

I'm less concerned about image quality than ability to accurately correct or warp perspective, but if some horrendous degradation of image quality is involved I'll become concerned.


-Alex

Alex,
This is about the best (worst) example I can put my hands on at the moment. My purpose here is to show you how far you can go using PS CS and the skew command. I added the sky from another image but that is another issue. This image has been used in publications and I am sure no one knows how it began its life as a greatly distorted digital image.
Jerome

[paulr]

i haven't used the feature yet. i wouldn't be interested in using it as a substitute for camera movements (i'm just not into doing adjustments beyond tone and color in the darkroom/computer).

but i might use it to correct mistakes. every now and then i've been just a little off with the back of the camera. i'm ok with vertical lines that coverge significantly, or with ones that are dead parallel, but when they're a tiny bit off it can annoy me. especially if there are lines near the frame edge, that are almost but not quite parallel. if the ps feature works for cleaning up this kind of goof i'd try it out.

[Kirk Gittings]

My rule of thumb, especially with DSLR images. If you have to stretch the top of the image to correct perspective more than 1/3 the width of the image, you probably will be inducing too much interpolation for my tastes unless the top is nothing but clouds or blue sky.

[amilne]

Thanks everyone.

Originally Posted by sanking

This procedure is even more useful with medium format cameras that have no perspective control. Sandy King

This is precisely why I'm asking this question. I recently aquired a used Hasselblad 500 c/m, and am contemplating it's advantages over the view camera. I rarely, RARELY, enlarge past 8X10, and I rarely find myself photographing the empire state building or things needing extreme movements. With perspective tools, the 500 is becoming a viable contender (although the 4X5 won't be left alone).

I used to (I guess I still do) know an excellent B&W landscape photographer who used an Xpan. He wouldn't get too fancy but whenever he found severe converging verticals he'd just pop them straight with photoshop. This just never felt right, or fair for that matter, to me, and I've held off doing the same.

-Alex

[sanking]

Originally Posted by amilne

I used to (I guess I still do) know an excellent B&W landscape photographer who used an Xpan. He wouldn't get too fancy but whenever he found severe converging verticals he'd just pop them straight with photoshop. This just never felt right, or fair for that matter, to me, and I've held off doing the same.

-Alex

If you are doing documentary photography I could understand why you might be concerned about the distortion. However, for fine art photography pretty much anything goes in my book.

I definitely don't feel that there is anything at all unfair about using perspective controls in Photoshop for the type of work I do. However, compared to a view camera what you can do without showing digital artifacts is more limited.

Sandy King

[Wilbur Wong]

In addition to "perspective" control which was the question asked, a view camera also offers the ability to control the "plane of focus." I use photoshop abilities to correct perspective issues for quick and dirty work, but for serious photography I always use a view camera's abilities to select a plane of focus that is appropriate for my image. This use of the "Scheimflug" principles can be found on this forum as well as in many publications specific to learning to use the view camera.

The shifting of the plane of focus is something that must be done at the time the photograph is recorded and can not be simulated in any photo editing programs.

[David Luttmann]

Originally Posted by Wilbur Wong

In addition to "perspective" control which was the question asked, a view camera also offers the ability to control the "plane of focus." I use photoshop abilities to correct perspective issues for quick and dirty work, but for serious photography I always use a view camera's abilities to select a plane of focus that is appropriate for my image. This use of the "Scheimflug" principles can be found on this forum as well as in many publications specific to learning to use the view camera.

The shifting of the plane of focus is something that must be done at the time the photograph is recorded and can not be simulated in any photo editing programs.

Not entirely true...

It is fairly easy to have virtually everything in focus with a small sensor, and then selectively blur in software afterwards. In fact, because you can blur afterwards on a 23" screen vs a 4x5 ground glass.....the potential for more accurate selective blurring is fairly evident.

[Dakotah Jackson]

The biggest difference is in what you get in the final print. With film shot with the adjustable view camera you get what the film captured. With pixelography or scan and interpolate you do not get what the camera captured but what the computer added to make up for what was not there in the first place. If accuracy is what you want go with film and do it right.