Recently I saw two questions pop up that didn't jump out as photography themed: What does "distortion <XX%" mean in lens specs? and How to read a lens spot diagram?. After a response from the poster, it looks like they are on lenses that are used for machine vision. I am unfamiliar with this, but this brings up the discussion point - are questions about lenses uses for industrial applications on topic?

2 Answers 2


I think we should apply the same rule as for video:

Can I use this information in still photography?

If it's very specific to machine vision — about optics, techniques, or terminology not applicable to still photography? Then it's probably not right for here.

I don't know about theses particular questions, but I'd love to see them answered in a way that relates these technical diagrams to those more typically used in photography. That way, I'd learn something.

  • I agree. I don't know enough about machine vision, and the poster hasn't given enough supporting details - for me to really decide if these relate to photography at all. We will see I guess.
    – dpollitt
    Jan 13, 2012 at 3:53
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    I think it's reasonable to ask for a lot more background than these questions have.
    – mattdm
    Jan 13, 2012 at 12:23
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    I think when it comes to answering questions about optics, the results can always edify photographers. The lens in question was used for machine vision, however the question was not about machine vision...it was about the nature of optics and a photographic lens (i.e. something that projects a virtual image, with the ability to adjust aperture, focus, and maybe zoom. The lens design looked VERY similar to a DSLR lens.) If the question had been about how to use the lens for machine vision processing, I would agree, its off topic...that was not the case. Machine vision only came up in a comment.
    – jrista
    Jan 18, 2012 at 2:23

My thought process is this:

  • If we consider a question like this on topic, would we not be inviting any and all questions about optic and optical devices to be asked and answered here?
  • Wouldn't the questions given as examples fit better on a physics or engineering stack exchange site?

If we open up to all optics questions, are we prepared and willing to answer questions about microscopes, telescopes, etc? I only have a general understanding(if that) of machine vision, so I could be way off, but I am leaning towards off topic.

  • Questions about microscopes and telescopes should indeed be on-topic, as people use both devices to do photography quite frequently. I myself am a huge fan of astrophotography, and if I had the time and money, photographing the microscopic world would probably also be a hobby. I don't think either of those should be off topic when the questions are about optics or photography in relation to them. If people cannot come to PhotoSe with questions about optics, even when its marginally related to photography (machine vision is on the border), where else can they go?
    – jrista
    Jan 12, 2012 at 23:37
  • How lenses project images is something the people on this forum seem well qualified to answer. Discussions about the virtual image projected by a lens, be it for machine vision, a DSLR, or a telescope, are all discussions about the same exact thing, and all the same physics apply.
    – jrista
    Jan 12, 2012 at 23:39
  • I think the Pee-Wee Herman Rule might apply here as well. The asker of that question came to this site hoping it would be a place he could get an answer, and while he may be the nerdy suit, he isn't playing way, way out of bounds. I feel inclined to give him the benefit of the doubt for now, rather than chase him off right away and eliminate any chance he could become a welcome, contributing member of our community, particularly given that his question is something we are qualified to answer.
    – jrista
    Jan 12, 2012 at 23:50
  • "where else can they go" I was suggesting either the physics site or an engineering SE site. I haven't looked to far into it, but I think we have some of these. I don't want to chase off contributing members either.. but keep in mind I tried asking him a question yesterday on one of the questions and still haven't heard a response. The other, as you already agreed with - we are left with open questions still. If we are following mr. hermans rules - I don't see a large potential for contribution. Maybe the user has great knowledge that no one else here does though, so there could be that too.
    – dpollitt
    Jan 13, 2012 at 0:09
  • It doesn't need to be a "large" potential, just a potential. We could close and migrate the question to either the physics or engineering site, however before we do, I think we should at least give it a chance here. I guess my point is, when it comes to marginally off-topic questions, we should give askers the benefit of the doubt first, rather than just closing without a chance. We have had a variety of "science of optics and image processing" questions here on PhotoSE, from color theory to aspects of human sight. I think such questions are beneficial in small amounts.
    – jrista
    Jan 13, 2012 at 1:42

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