Out of curiosity, I was wondering whether this is typical behavior. I bought a used 200-400mm VR from another Nikonian and just purchased a used TC14EII from KEH. The teleconverter just arrived so I was testing it out before heading out in the field. When taking photos with the 200-400mm lens zoomed all the way to 400 mark, my camera (D300) reports an effective focal length of 550mm. By my calculations 400 * 1.4 = 560. When I try the teleconverter with my 70-200mm VR, the D300 reports 280mm effective focal length when the lens is zoomed to 200mm setting.
Is the discrepancy (only a reported 10mm difference) anything to worry about? I have checked that the 200-400mm is recording 400mm to the EXIF when zoomed to that setting.
Joshua, Maybe I wasn't as precise with my terminology as I should have been. I believe the EXIF should report the focal length of the lens + any teleconverter attached, at least that's what my D300 has always done with my Sigma 1.4x. It doesn't to my knowledge report what I erroneously referred to as the effective focal length. IF it was reporting the crop factor of the sensor then with the 200-400mm lens, I would expect it to report 600mm when zoomed to maximum magnification. Also, given that it reports it correctly for the 70-200mm zoom at 200mm (reports 280mm = 200 * 1.4), I'm at a loss. Unless there is something wrong with my 200-400mm. That or else I just live the mis-reporting and don't worry about it.
Neil, Thanks for your reply. That was my suspicion but I didn't find any mention of it when I ran a search with that combination. Interesting that I just came across a post by Richard over in the Wildlife forum where his 600mm and 1.4 report the incorrect focal length as well.
I was basically being paranoid having just purchased the lens and teleconverter. I won't worry about the missing 10mm anymore Thanks, Tim
Ah, yes. It appears that Richard got your missing 10mm! And really, he doesn't need it with that monster.
Perhaps you should demand a partial refund from one or both sellers. You are due a 10/560 = 1.785% refund of the total cost
Just as an aside, I have seen some reports that actual tests suggest most lens focal lengths are not exactly as marked. It is very likely that the actual focal length is more along the lines of 550mm because the long lenses are usually short of spec.
But that is not the intent of course, or the norm. It is strange that the camera/lens firmware can not always get that number right. Seems simple.
What does your camera report for the 200-400mm without the TC? If I remember correctly, there is an industry standard for focal length measuring errors. The 550mm with the TC suggests a 392mm without the TC. 2% is probably within the accepted error range.
---------+---------+---------+---------+---------+ Joseph K Seattle, WA, USA
Joseph, My camera report 400mm when zoom ring shows 400. I presume this is just a calculation error as suggested by Neil. Although, if I had to accept a 2% error due to the computer while doing my statistical modeling, I wouldn't be happy. Evidently Nikon and maybe the camera industry has a much different standard than I have as a scientist. I just find it interesting that this is my only lens + tc that shows this "error". Thanks, Tim