Zoom to 200mm question

Discussion in 'Lens Lust' started by Maestrodawg1, Aug 21, 2005.

  1. Well, I own the 28-200G and the 70-200 VR.

    Here's the question. I put both lens on a tripod and extended both the lens out to 200mm. I also checked the exif data to make sure the lens were at the same focal length. Here's the wierd thing. It is very apparent that the 70-200 VR gives about a 1x times closer than the 28-200. Both lenses were set to f/8 and taken within moments of each other when I tested them. What's going on here? Any ideas?
  2. I don't wan't to be difficult, but 1X would be exactly the same as the first lens. Do you mean 2X?
  3. dbirdsong

    dbirdsong Guest

    Can you post examples?
  4. I suppose I mean that the 28-200 looks like 9x while the 70-200 looks like 10x. I am no mathmatican so I couldn't express exact numbers. I guess that first statement was a bit misstated. I'll snap a few quick ones tomorrow and put them up replicating it in the same way.
  5. JeffKohn


    Apr 21, 2005
    Houston, TX
    Make sure you're focusing at something distant, ie at or near infinity. Any claims about focal length of a lens are measured at infinity, and depending on the lens design the actual focal length can change considerably as you focus closer and closer.

    That said, it's not really that unusual for there to be a bit of a "fudge factor" in the actual focal range of zoom lenses.
  6. Don't have a clue but you have peaked my interest. Will be interested to see the images.