360 Panoramic Technique

[NathanO]

Hi all. I'm having problems taking 360 degree panoramic pictures. I read the tutorial on the main page but it's a bit too general. I'm confused on where to auto focus, if I even should..where to expose, how to get a bright foreground without blowing out the sky....

I want to take a 360 degree panoramic at a park. When I pan around on my tripod,,,the center focus hits the sky on some views, buildings on others, hills on other views....

Here are the settings I use. Canon XSI with kit lens: Manual Mode, manual focus, Image Stabilization Off, exposure times and aperture don't change. Here's what AUTOMATICALLY Changes: the EV values. Some shots are +1/3, others are -1/3, some are at 0.... so here are my questions...

How in the world do I expose? Do I halfway click on the foreground ; Re-compose and then shoot that view; Rotate and do it again? Is there any way to lock the exposure so the sky or grass doesn't change? What time of day should I be shooting. Is it bad to get a sunset panoramic?

Thanks for your replies.

[dcclark]

First, a question -- why are the EV values automatically changing? If you're in full manual mode, nothing should change between shots -- which is exactly what you want. You should check your modes -- I don't think Canon has an "Auto ISO" mode yet, but I know that on my Nikon, even in full-manual, "Auto ISO" will still change the ISO, trying to correct my exposure, unless I explicitly turn it off.

That should answer your question about exposing. Your exposure should not change between frames -- this will cause infinite touble when stitching. Pick your exposure by taking several sample photos in some sort of auto mode (I would choose Av, and fix your aperture at wherever you want it to be in the final product). Average out the shutter speeds which your camera chooses. Switch to M (full manual exposure) mode, choose your settings there, and shoot.

Now, doing this, your photos will look different from angle to angle, because some will have more light coming in than the others. This is why you need to average the shutter speeds: hopefully, your exposure will be close enough to "correct" in all situations that none of your frames will be utterly over or under exposed. If worse comes to worse, after stitching your panorama, you can apply local exposure fixes, and blend them in with the photos next to them.

I hope that helps!

[Gulpa]

Originally Posted by dcclark

I don't think Canon has an "Auto ISO" mode yet,

I've got a Canon Powershot S3 IS and it has Auto ISO - I assume that the newer cameras would have it too.



The rest of the tips sound really good - I need to practice panoramic shots as well

[fletch]

Originally Posted by NathanO

Here are the settings I use. Canon XSI with kit lens: Manual Mode, manual focus, Image Stabilization Off, exposure times and aperture don't change. Here's what AUTOMATICALLY Changes: the EV values. Some shots are +1/3, others are -1/3, some are at 0.... so here are my questions...

How in the world do I expose

The EV value doesn't 'automatically' change, in manual mode the EV the camera displays is the metered exposure vs the settings you have given it. 0 EV means it would have chosen the same expsoure (aperture/shutter/ISO) as you + or - means it would have been different. I.e. its just acting as a light meter. When taking a 360 panorama the light will be very different for each shot so the camera wants different settings for each picture. However using manual forces the camera to use what you say not wants.

The trick with a panoramic is to pick the average settings and force the camera to use them. That way the brightest shot will not blow out and there will be detail in the darkest shaddows. Each individaul shot will have the same exposure (apertrue/shutter/ISO) but may be brighter or darker than the last,when you stich them togther they will have the same relative brightness as the original scene.

If you took each photo at a different exposure the individaul shots may look OK but when stiched you wont be able to match up the edges and you will get banding.

[OsmosisStudios]

Dont worry for a second about focusing: manual focus and use a deep DoF.

Gulpa: The S3is has a setting to set the ISO to a specific point. Use that.

[inkista]

Originally Posted by NathanO

How in the world do I expose?

.. and this is why 360° pano shooters were using HDR about a year before everybody else started to. My personal technique is to meter the brightest and darkest shots (usually facing the sun and with my back to the sun), and then averaging out exposure between the two scenes, or deciding if there was a dominant part of the scene I wanted to have most properly exposed, or if I should be shooting bracketed exposures for HDR.

Do I halfway click on the foreground ; Re-compose and then shoot that view; Rotate and do it again?

Hell, no. Your first instinct was actually right: go into Manual mode and stick with the same exposure settings for all the images, so you get consistent exposure across the scene. If you vary the exposure with each individual image, you're going to have a heck of a time getting the sky to match.

The one setting you forgot to lock down, though, is white balance. Make sure you're not in auto white balance mode, because that can also create color casts between images, the way automatically exposing can. Or, you can shoot the images in RAW, and then make sure they're all set to an identical white balance adjustment in post processing.

Some software (enblend) may be able to compensate for these shifts up to a certain point, but it's always better to play it safe. The version of Hugin that can deal with all these problems is, iirc, still in development.

Is there any way to lock the exposure so the sky or grass doesn't change?

Nope. It's the nature of the beast. When you change the scene, you change all the values in the frame, and you change the metering. It's just what happens. It's not a bad thing.

What time of day should I be shooting. Is it bad to get a sunset panoramic?

Nope, although it can be tricky, since the light changes over time, and each of your frames is going to be taken a little bit later than the one before. If you're shooting during sunset--try to work fast. Don't bungle it or rush, but don't linger, either. For me, the absolute worst time of day to be shooting panos though is noon, or when my shadow is going to be causing stitching problems.

The other error you may have is parallax causing havoc with your stitching--try to avoid scenes that have nearby objects unless you know that you can spin the camera at its no-parallax point. You usually need a special panohead on a tripod, or lots of practice and special techniques (like a Philopod) to do this handheld.

One more little note: rotating the camera into portrait mode will get you more vertical coverage if you're doing a single row.