Davethehiker Loc: South West Pennsylvania

I have a very high quality 300mm f/2.8 Sony lens that I use on my Sony A900. I discovered that when I add the 2X converter that was made for that lens my exposures were off. The histogram provided by the camera looked off! I changed the exposure compensation by minus 1.3 EV and everything started to look good. I'm confused by this. It seems like the camera's auto exposure does not work properly with all that glass attached to the camera. I would expect it to automatically correct for the loss of light, instead I need to "remove light" by dialing in minus 1.3 EV. Can anyone explain this to me, or experienced the same thing? Extreme care must be used with a lens this long. everything must be perfect, but if I take my time the 2X converter on the 300mm f/2.8 lens works remarkably well! There is some loss of contrast but that can be compensated for, post processing.

alann Loc: Virginia

I did when I used a Kenko but, with the Canon 2x III I don't. The keno has much less glass in it so that may be the reason.

Bigdaver

With a 2x you have a 300mm f5.6. Even though the camera won't indicate that in the viewfinder.
Exposures are 2x darker.
I think maybe you are mistaking darker for brighter. 1.3 is awfully close to 2.
Otherwise the world would be beating down Sony's door for their magic teleconverter that defies physics.
Glad it makes good images though.
For example an exposure of 200/f4 would become50/f4 or 100/f2.8.

BigDaveMT Loc: Plentywood, MT

I think you must have meant a 600mm not 300mm with the 2x converter.

Davethehiker Loc: South West Pennsylvania

Yes, but I knew what he meant. Actually the camera is smart enough to figger it all out. The metadata reports that I was using 600mm f/5.6 lens. The Sony A900 has a "preview" button that lets you see the picture and histogram without sending the image to memory. I made the 1.3 EV correction because of shape of the histogram was showing everything bunched up on one side. The minus 1.3 EV was a kind of "Kentucky-Windage" I added. It seems consistent. Maybe it just has to do with the kind of subjects I have been taking, wild deer in the woods. There is a lot brown dark wood and deer about the same color. It does seem like a magic lens. I need to gather a lot more experience to know if it's repeatable. I'm impressed that so many of you even my understood confusion/question. We seem to have some very competent photographers here on UHH!

I'm starting to think that maybe the auto exposure algorithm does not work well with very long lenses. Who know?

Thank you all for reading and understanding what I was saying.