Distance meter
May 29, 2010 6:43 AM   Subscribe

Is there a range finder / meter that is particularly good for photography?

I have recently gotten into creating gigapans, which involves taking hundreds of photos with a telephoto lens and then stitching them together into one large image, which allows zooming in and out of the image and look at details. I find that I get the best results if I set my camera (Canon 40D, typically with 100-400 L lens) to manual focus and exposure settings. In order to ensure the resulting image is sharp across the entire image and make the right aperture decisions for a specific focal length I need to know the distance to the objects I am taking photos of. Although the camera does autofocus, it does not give me sufficient level of detail to allow me to calculate depth of field as it does not, for example, distinguish between 50m and 500m.

There are laser rangefinders out there that may do the job, such as the Nikon 1200S, but they seem to particularly focus on golfing or hunting, are quite an expensive option and seem to not provide any other features for photographers.

Are there any affordable (less than 300 USD) range finders or other distance meters out there that are more specific for photography? Ideally, it would be great to have some other features such as measuring the average light cross an scene.

For my purposes, the distance has to go up to minimally 1km / 1,000 yards as there is a big difference between 500m, 700m and 900m when shooting with a 400mm lens.
posted by eurandom to Media & Arts (3 answers total)
First of all, I assume that you're going to be on a tripod and that you're going to be stopping down to f/8 since you're worried about image quality. If your main subject is 500 feet away and you're at 200mm, your depth of field is roughly 800 feet, starting at 300 and going to 1100 feet. Once you've AFed onto something that is 500 feet away, even if your camera is off and is actually AFed onto something 450 feet away, that's fine, it will still be in focus.

Why do you need to know down to the foot how far away something is when you cannot even lock that in using MF since your lens' focussing scale isn't that precise?

What I'm saying is, even if you found something for $10 that told you down to the foot how far away something was, what good would that number do you since you cannot accurately set your lens to that reading and even if you could, would it matter when your DoF is 800 feet?

Alternatively, focus stack.

As for light across a scene, do what those who shoot slides do when they're worried about exposure since slide shooters have such limited dynamic range, get a spot meter and meter various parts of the scene and then figure out what parts will be outside of your exposure latitude and adjust your exposure accordingly.

Alternatively, bracket your exposures and merge them, but please non of that overdone HDR crap.
posted by Brian Puccio at 9:29 AM on May 29, 2010

Just a heads up, the hyperfocal distance for a lens at 200mm at f/8 on a crop body is 864 feet or 288 yards. Focus at this and everything from 431 feet to infinity will be acceptably in focus. Stop down a bit more as long as you don't run into diffraction. I'm not sure what this will be on your body.

Also, shoot primes if you're going to pixel peep and compare sharpness. 200mm f/2.8 vs 100-400mm @ 200mm.
posted by Brian Puccio at 9:35 AM on May 29, 2010 [1 favorite]

Brian Puccio, I never said I needed to know to the foot how far something is, an estimate is good enough. And yes I use a tripod, I wouldn't know how else to take a gigapan, I tend to stop down to at least f/8 and know what a DoF calculation looks like.

The problem is that I appear to be doing terribly at estimating distances. Something that I think is 200m away has turned out to be be 500m meters away or something that I estimate as being 300m away may only be 100m away. These are big differences that give a totally different DoF calculation, particularly when shooting at 400mm. Knowing that a scene will be in focus 431 feet to inifinity is doing no good if my subject is unexpectedly at 100m. My lens shows anything over 20m as being varying degrees of "infinity" and is therefore no help in finding out a good estimate of how far something is.

Case in point this gigapan which I took recently. I had estimated the abbey was at about 500m and the barn in the front was at about 300m, so I thought I would be fine with a 400mm focusing on the front of the abbey with f/11. However, when I came home I was surprised that the barn was out of focus and when I checked google earth, I found out why: the barn was a mere 120m away and was therefore out of focus. I have had similar issues with other photos.

I ended up going out and buying a laser rangefinder so I know better how far things are away when shooting as I could not identify any other solutions.
posted by eurandom at 10:07 PM on June 2, 2010

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