I have a question about lens selectors like


They don't enable to add extension tubes in the parameters. So for a given sensor size, a given working distance, and a given extension tube width, to know the good focal length I need, I just compute it with a lens selector and I add it with the width of my extension tubes ? Or is it more complex ?

  • If you are talking about "extension tubes", they don't change much to this, they just let you focus closer... – xenoid Dec 1 at 18:22
  • What do you mean by rings, or ring width, or "lens adapter"? – scottbb Dec 2 at 2:11
  • Yes sorry, by ring I meant extension tube, I edited – Alfred Dec 2 at 11:26
  • The line of camera equipment your link points to seems to be video equipment aimed at computer vision, product inspection, etc. That stuff really isn't on topic here. FWIW, that manufacturer appears to have lenses that focus as close as 5mm, so it's not clear what benefit you'd get from extension tubes even if available for that system. If you're talking about something more general, perhaps you could give a better example. – Caleb Dec 2 at 14:26
  • I want to use a zoom lens (17mm to 102mm) lenscraze.blogspot.com/2014/07/… on a 1/3" sensor, I tried several extension tubes but they do not fit... I wanted to be able to compute theoretically what extension tube length I should use – Alfred Dec 2 at 15:07