I kind of doubt that very many people have both lenses to compare with. When you say the 100-300 - I have to assume that you are meaning the Sigma 100-300/4 EX lens. If so, I have that lens and can give you a one sided report. I also have the Sigma 1.4X EX TC and have used it many times with the lens.
First of all, the TC attached does not adjust the focal length transmitted to the body - it is just as if there was no TC there. So if zoomed to 250mm that is what gets trasmitted - TC or not. My reading and viewing of information indicates to me that the 100-300/4 is a better lens than the 50-500. One would guess that at a similar price the shorter zoom range would be optically better. Also it is f4 throughout the zoom range where the 50-500 is a variable aperture changing as you zoom. I was looking at this very issue when I got my lens and it really came down to how often would I be out towards the 500mm end. The only time the 50-500 has any advantage is when you are at the long end. The 100-300/4 is faster and arguably has better optical quality. Putting the 1.4 on causes some losses. First, you are now at F5.6, second there is a slight contrast loss (can be made up in PP), third is focusing - I can tell the difference in speed and locking on to subject with and without the TC. The 100-300/4 can be shot wide open and net excellent images - don't really know if the 50-500 is good wide open. So for me, it came down to speed and optical quality. I decided that the 50-500 was too slow for a good percentage of my shots. If you would be spending most of your time zoomed out beyond 300mm, then the 50-500 might be the better choice, otherwise I think the 100-300/4 EX is the better lens. As far as ruggedness, I have shot somewhere between 20,000-25,000 images with that lens (making it the most used lens I have) and it has held up. -- Best regards, Bruce Sunday, August 19, 2007, 10:26:19 AM, you wrote: PG> I'm going to be needing a long telezoom approx 400mm at the long end PG> for nature photography ... the 50-500 seems to be very popular for PG> this type of photography. How does it compare with 100-300 + 1.4x TC PG> combo ? PG> Regards PG> Patrick Genovese -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
