how do I control exposure for panorama photos?
November 16, 2009 11:10 AM   Subscribe

I just bought a new Canon digital camera, an SX110IS, and have discovered that it doesn't have the stitch assist mode. I may yet return it, but I'm wondering what would I need to do to still do a decent panorama without the assist? Obviously I have to frame the photos for overlap, but the real benefit of stitch assist mode was the exposure control. What should I do, manually, to get good panoramas as a result?

I love making panoramas while traveling, and the stitch assist mode in my older Canon A720IS was great for this. Besides guiding you on the image framing for overlap, it would hold the exposure settings across the series, so that they'd blend well later when you stitched them.

Frankly I just assumed that all Canon digital cameras came with that feature now, but I see now that the lower end SX110IS and SX120IS don't have it. Once you step up to the more expensive SX200IS and up, you get the feature. Bah!

So, do I need to put the camera in some sort of manual mode, and which exposure parameters exactly should I control? Aperture? ISO? I'm not much of a photographer.

I'll give it a shot during travels next week, and if it doesn't work so well for me then I'll return the camera, but I'd like to avoid that hassle.
posted by intermod to Technology (10 answers total)
Best answer: Take a shot containing part of what you'd like to panorama. Now review that shot in "verbose" mode (whatever it's called), and note the ISO, shutter speed (usually a fraction) and the aperture (usually a number with one decimal, i.e.11.2). Then go back into picture shooting mode, in MANUAL, and go to town with those settings.

Alternately, set up in picture-taking mode, verbose style, and note the shutter speed/aperture. Take one shot. On the next shot, use under and over exposure to get the same shutter speed (the aperture will usually take care of itself).
posted by notsnot at 11:19 AM on November 16, 2009

notsnot's suggestion is what I'd do too, or I'd use Autostitch to correct for the different exposures after taking the pictures in auto mode.
posted by zippy at 11:28 AM on November 16, 2009

I'm not trying to be argumentative here, but as a heavy user of Autostitch type software (PTGui), I still make sure every shot I'm going to stitch is the same exposure, or tweak the hell out of it before stitching so things mostly line up, luminosity-wise.

If you've got any bright spots in a stitch (n>2) it's going to throw that one photo off, and it's going to be noticeable in the stitch.
posted by notsnot at 11:43 AM on November 16, 2009

Response by poster: Thanks for the advice. I do actually use Autostitch, in Linux (originally via package, then via hugin) and it works great. But I've always been spoiled by the camera's stitch assist mode, so I don't know how well it will handle the uneven exposures.

More advice welcome. Thanks again!
posted by intermod at 12:06 PM on November 16, 2009

Best answer: I'm going from memory here (can check later if needed) but you can lock the exposure for a shot on the Canon cameras - You have to half-press the shutter then press either the cursor right or the cursor up at the same time. This will lock the exposure for all subsequent pictures until you reset the setting (or cycle the power).

It's 'AEL'/Auto Exposure Lock if that helps you find it in the manual

I use Autostitch and have had great results from it.
posted by azlondon at 12:14 PM on November 16, 2009 [1 favorite]

( I wasn't knocking Autostitch...I was knocking the look of widely variable exposures forced together....see my Flickr stream for lots of examples of stitched panos)
posted by notsnot at 12:16 PM on November 16, 2009

The manual on page 110 appears to be what you're after - 'Locking the Exposure Setting'
posted by azlondon at 12:23 PM on November 16, 2009 [1 favorite]

Best answer: You can load the CHDK firmware for even more control.
posted by djb at 1:45 PM on November 16, 2009

Response by poster: Thanks folks. To summarize, A) I can try the exposure lock, or B) just shoot and Autostitch might deal with the exposure variations just fine. The latter is put forth on the net as a reason why pano assist modes are dropping off cameras.

Another thing I liked about the stitch assist is that it would name the photos differently, so I could quickly identify a series (STA, STB, STC,,,) that was intended to be stitched. Without it, I have to guess whether I'm looking at a series or not.

I'd forgotten about CHDK, which is a really cool prospect. However it doesn't seem to have a stitch assist mode. I sure would like to have those long exposure times for night shots though ...
posted by intermod at 6:20 PM on November 18, 2009

Response by poster: Followup:

Exposure lock was too much of a pain. I am typically taking these panaromas very quickly, so as not too annoy the wife too much ("Ugh, another panorama? Cmon!"). So I don't have time to do the exposure setting steps. Literally, I bang-bang-bang through the panorama as fast as the memory card will absorb them, and taking the camera out of auto mode and remembering and firing the button sequence is just too much time.

The stitching software did NOT do an adequate job of matching photos, without the stitch-assist or exposure lock. Blue skies not matched at all.

There were a couple other things about the camera that I didn't like (bulk, slow shot-to-shot times), but this was the biggest one. And you know what? I decided that if I'm going to be unhappy with the camera, it might well be one that is cheaper and fits easily into my back pocket.

So I returned the camera and will buy a cheaper and smaller Panasonic Lumix next month. Canon, you really blew it by removing the stitch assist feature from your pocketable compacts.
posted by intermod at 9:47 PM on December 17, 2009

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