Don't know if the 10D has a removable focus screen, if so take a look at the grid screen, that helped me (I use the hot shoe bubble as well).

I had a lot of problems too until I got a grid focusing screen for my 1D. A level wouldn't help me much (unless it was visible in the VF) because I'm often not on a tripod.

- DL

Fixing the horizon always leaves me with less image real estate and sometimes ruins my composition.   I'd rather get it right the first time.

Either that or get a 1Ds MK II and crop to my heart's content...

Not the first time I've been outsmarted by Photoshop.
Incidentally, Jonathan, did you come by your Photoshop expertise in the same somewhat haphazard way as most of us seem to be doing or did you take some sort of really organized intensive course at some point?

I use ACR's upsizing to enlarge the image to the maximum pixel dimensions. When the image is upsized, the artifacts introduced by rotation and perspectgive adjustments affect thing less overall, espesially if you downsize before printing.

ACR interpolates to get from a Bayer matrix to a bitmap image. The point of upressing in ACR is that the upressing and the conversion are all done during the same interpolation pass - only once - reducing degradation buildup.

Any tricks to keep those bloody things level?   Seems like I'm having more trouble with this since I got the 10D, perhaps due to the smaller viewfinder...

???

Alternatively, Really Right Stuff have a tripod clamp that has a spirit level on it. If you are using a quick release type tripod head (Kirk/Arca), then you can remove the clamp and replace it with the Really Right Stuff one.

A bubble level and on a tripod  works most all of the time.
however, I took a quick shot at a sailboat in the sunset. (it was behind me and I swung the camera around, on the tripod, and quickly shot)  I didn't have time to level so the end result was a horizon slanting to the right at about 6 degrees.

In photoshop  I used the rotate option at about 5 degrees. then cropped out of that image.  It worked great and now have the image with level horizon.

Hey even better for leveling the horizon, after the fact.

I did it by trial and error using the rotate/arbitrary  option.

PS is a bit smarter than that. If you make your line reasonably vertical, PS will fill in the rotation amount required to make the line exactly vertical. This is useful when shooting architecture. I also used on my new avatar to make sure the pistol was not tilted.

What's ACR?

You can always get a small level and use that to level the tripod when shooting.

I once saw one of those buble in water things which you attached to the hotshoe. I often wish that I bought it as it would be quite usefull.

You're using digital so it's easy to fix a crooked horizon in Photoshop or any other imaging software.

You can buy those things anywhere; any big photography store, any mail order dealer (Adorama, B&H, etc).

Guess I'm getting too conservative in my old age.  I like my horizons horizontal, not vertical.  Just personal taste, though

It has to be said...

If you rotate in PS, you are applying an interpolation algorithm. That will degrade the image. It might be very small and not the least bit significant, but it is not the same as the lossless approach of getting the horizon positioned properly "in-camera".

That being said, when I need to, I also rotate in PS (or even adjust perspective). But I know that interpolation is being applied and set my expectations accordingly.

Yeah, that and the little loss of "real estate" from the cropping after the rotation is why I now keep a little bubble level in my hot shoe all the time.  I usually got horizons good enough without it, but when the light is the best and you know it'll be gone in a few minutes or seconds, shooting fever can make you a little hasty.

Adobe Camera Raw - has an upsizing capability (a limited # of steps).  Interestingly one of the options gives me exactly the up rez I need to take 1DMKII file to 17x25 @ 240 dp.  which is were I like to be for a max size "normal" aspect print on my 4000.

You can get really cheap levels with bubbles at right angles that fit in the hot shoe. I always carry one as a second check on true horizontal.

Do your out-of-level errors have a pattern?  Mine did.  I found that my D-70's sensor was out of alignment with the VF.  It's easy to test.

Peter

I learned a technique from some article (probably on this site), but can't remember who wrote it to give proper credit. Anyway, use the Measure tool (buried under the eyedropper) to draw a line along your horizon. Then go to Image > Rotate Canvas > Arbitrary and the correct amount of rotation will be automatically filled in for you.

If you use the Measure tool (same toolbar slot as the eyedropper) you can draw a line along the horizon or something supposed to be vertical and when you go to rotate canvas arbitrary, the correct value will already be filled in for you.

It's a combination of learning by doing, reading the help files, and hanging out on internet photography forums. I picked up that particular trick on Rob Galbraith's forums.

It may seem simple enough, but if you are leveling in PS via trial and error, undo the error before the next trial so you won't be interpoling the next trial with previously interpoled data.

I assume the reason to use ACR uprez is that it doesn't interpolate, and thus is why not to use PS uprez in this particular case?