What is parallax error in photography?

BBW

Administrator Emeritus
Jul 7, 2010
123
betwixt and between
BB
Since we've got at least one thread which mentions parallax, and I'm sure we may have more, I thought it would be helpful to have a thread that explains what parallax error is and how one can either avoid it, or maybe not even have to worry about it.

Here is a link from dpreview's glossary entitled "Viewfinder" that explains a bit about the differences in viewfinders and the possibility of parallax error.
...The optical viewfinder on a digital compact camera consists of a simple optical system that zooms at the same time as the main lens and has an optical path that runs parallel to the camera's main lens. These viewfinders are small and their biggest problem is framing inaccuracy. Since the viewfinder is positioned above the actual lens (often there is also a horizontal offset), what you see through the optical viewfinder is different from what the lens projects onto the sensor. This "parallax error" is most obvious at relatively small subject distances. In many instances the optical viewfinder only allows you to see a percentage (80 to 90%) of what the sensor will capture...
I'd welcome your explanations and thoughts about parallax issues with regard to photography.
 

WJW59

New Member
Feb 20, 2011
3
If you are viewing through the lens that actually takes the image then parallax is a non-issue. When you have different lenses for viewing and taking, such as a TLR, rangefinder, or when using a separate optical finder, it can be an issue. The closer the subject is to the camera the larger the problem.

A good example is a TLR (Twin Lens Reflex) with different shooting and viewing lenses. The upper lens is your viewing lens and is mounted about 2 inches above the lens for the film. If you focused on something 50 feet away, the difference in height between the lenses makes little practical difference. If you are focused on something 3 feet away, the height is a big difference. There were devices made specifically to adjust for this (Mamiya Paramender) by allowing a tripod-mounted TLR to be raised by the difference in lens height just before taking the photo.

Rangefinders had to adjust for both vertical and lateral parallax as the optical center of the rangefinder view was both above and (usually) to the left of the lens. Many of them had a moving line, frame, or mark that showed the actual area that would appear on the film. The better the camera, the more accurate this frame would be. In most cases, the marked area would usually only cover about 90% of the film so small errors would be covered.

The EVFs for the compacts all use the image coming through the lens so there is no problem there. The optical finders will present the same problem as the TLR since you will be above the lens and not viewing through it. If the hot shoe is also offset, then you get in to the rangefinder-type problem. Once again, if your subject isn't close, no problem. If you around the minimum focus range for your lens, it could be a real problem. This is one reason I decided to order a VF-2 since I know I'll get a 17/2.8 at some point.
 
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bilzmale

Super Moderator Emeritus
Jul 17, 2010
124
Perth, Western Australia
Bill Shinnick
A simple way to experience parallax is to hold a finger aabout 40cm in front of your face and look at it first just with just your right eye and then with just your left. The finger appears to jump from side to side.

Go on, try it - no-one's watching. :)
 
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BBW

Administrator Emeritus
Jul 7, 2010
123
betwixt and between
BB
Appreciate your responses, WJW and Bill!

I practice my parallax error quite often as I try to see which eye works best with my glasses while I'm reading.:wink:
 
Sep 8, 2010
123
London UK
Andy
Isn't Parallax error in photography when you miss the shot because you are too drunk to focus on the subject........ or is that Parallex error? :laugh1:

Sorry...silly mood!!:biggrin:
 

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