Yes, that is a problem. My tests with SR and the wrong focal length have led me to believe it is not desired. So in reality, all zooms pre-F don't work very well with SR.
This was on factor in driving me towards the DA* lenses. For my wedding work I was using a combination of DA 16-45/4 (no problems, just a little dim), A 35-105/3.5 (no SR) and A 70-210/4 (no SR). I did some tests where I put in the middle focal length of the zoom and then did shots at the wide, mid and tele ends. Then I input each specific focal length shot on the zoom. I tried this multiple times with both zooms and got similar results each time - wrong focal length is not good for SR. So a TC on a zoom like the 100-300/4 is going to have a similar effect. The focal length will come through while you zoom, but it will be wrong. -- Bruce Wednesday, August 22, 2007, 8:35:47 AM, you wrote: PG> Hi Bruce, PG> Does the fact that the lens is reporting the wrong focal length render PG> the S/R system on the K10D useless ? PG> I can't see myself inputting the focal length everytime I zoom PG> especially if i;m following action (sports/nature). PG> Regards PG> Patrick PG> On 8/20/07, Bruce Dayton <[EMAIL PROTECTED]> wrote: >> 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 >> PG> -- PG> Regards PG> Patrick Genovese -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
