problem with sigma 400mm 5.6 prime lens
I was woundering if anyone has ran into this problem i have older sigma 400mm prime auto focus lens. I bought a 1.4 SIGMA telecoverter to use on the lens i read in the chart that it would work but only on manual so i said ok so i put the thing on and it worked fine but when i took the teleconverter off and put the 400mm on and switch on the Autofocus on i started to get this strange grinding noise and now the thing will not auto focus right but works in manual and sticks. It has made me upset to think that i follow directions and the thing screws up my lens. Woundering if anyone has had this problem or any other problems with this lens and its gears.
SIGMA ... it is all in the age
No, I am not saying that. Eric. The older SIGMA lenses were designed for a different kind of focus drive source. The Minolta cameras had LESS torque to the lens. Putting them on the higher-torque SONY's could be asking for trouble.
The newer SIGMA lenses have been re-designed for this problem ... and that's how I suggest you roll. My personal issues with SIGMA dated back to anything under $500 and earlier than 2008. They have made some improvements ... and the reduced number of returns is quite indicative of that.
Bottom line, older SIGMA is a roll of the dice. I hope that clears it up.
Not every lens made a clean migration to SONY. In fact, I still have a rare Ozunon AF 70-210mm f/4.5 lens that works just fine on my Minolta 7000 and Minolta 9000 bodies, but does not work on any SONY body I have had. The point where the screw drive blade meets the focus drive on the lens ... you know, that slot in the lens. It is actually too narrow to meet up and lock, so the camera's screw drive just noisily spins away against it, when the lens is cleanly mounted, and the focus does not work. It's like using a #2 Phillips head screw driver on a #1 Phillips screw. No good ... and an awful racket, to be sure.
I apologize if I sounded like a SIGMA-basher. I used to be ... but, they have definitely improved their product, where it comes to SONY, and it is what I now use for most of my stuff. I would say that is a significant change in posture. If you take a moment and check my gear list, you will note that I have four (4) significant SIGMA lenses, and a variety of others. Most of my SONY manufactured glass is prime lenses, of which only a few other manufacturers even make these lenses, but then again, most of the third parties are represented in my collection.
I invite the other members to relate their experiences, too ... to get a true feel to this unfortunate issue of yours. I hardly want to be the only canary in the coal mine.