rufus1 Loc: Winter Haven, Florida

I need some opinions about this lens. Purchased the 170-500m, 1:5/6.3 used and have been struggling with it ever since. Most of the photos are soft or just plain out of focus whether they are shot hand held or tripod, infinity or not.
Ask local photo store about problem, cost about $400.00 to clean and recalibrate. Actually have never gotten a tack sharp image since purchase. Do not want to waste money or anymore time if it's a lost cause.

MT Shooter Loc: Montana

The Sigma 170-500, 150-500 and 50-500mm zooms all have repeated excellent reviews for sharpness, albeit a little slow due to the aperture rating. I have used one on a tryout and was impressed with the sharpness, but did not buy it as it did not improve the image over the 400mm F5.6 Sigma prime I was already using.
I notice you bought this particular lens used, hopefully from a dealer such as B&H, KEH or Adorama who all give you at least 30 day money-back guarantee. If you bought it from an individual I would have hoped you had tried it out before buying it.
In either case, to give any USED lens a bad review is hardly objective as you typically have no history as to the use or abuse of that lense. Buying a used lense is the same as buying a used car, you get what you got unless it comes with some sort of guarantee from a reputable dealer. I am sorry you got a bad deal but due diligence in any used purchase is a buyers best asset.
You might try setting up on a tripod and zooming on a high contrast subject and taking several shots at wide open aperture and manual focusing in very small adjustments, you may find a nice "sweet spot" in the focus range that way. This will tell you that the cameras AF is out of synch with the lense and that it WILL take good, sharp shots, but that you will definitely have to get it cleaned and adjusted for your camera. Hope you got a pood price on it.

rufus1 Loc: Winter Haven, Florida

Took it for a test drive but was urban (LCD did not show flaws), most of what I shot is landscape and wildlife. Even had my eyes checked because it was getting so bad. My 70-200mm seems fine. It isn't a major loss of cash but sure has shaken my confidence

MT Shooter Loc: Montana

I shoot wildlife also, here is a shot with my Sigma, don't think you can fault the sharpness here.
Good luck with the lens, its a good bright sunlight lens if you get the focus working for you.

rufus1 Loc: Winter Haven, Florida

Thanks for your interest, let me show you the problem

Within 20 feet


Focus on Heron about 500 feet

MT Shooter Loc: Montana

I have to agree, they are definitely out of focus. It almost appears in both photos as though the actual focal point is in FRONT of the object you are focusing on. Have you tried spot focus? If so, the the AF sensor is definitely off and manual focus, or recalibration by a good shop, might be necessary. Some of the branches in front of the cardinal are in better focus than he is, and it looks like the duck in the water is in better focus than the heron. Low level shots like the heron are often tough on the multipoint AF anyway, as is the multitude of small branches with the jay.

rufus1 Loc: Winter Haven, Florida

Thanks MT you are seeing the problem. Now it is decision time to repair or replace. Take care. Allen

MT Shooter Loc: Montana

Glad to help when I can. Good luck.

MtnMan Loc: ID

I agree that the stuff in front of the Cardinal looks pretty sharp in this thumbnail. Can't tell on the other one with the thumbnail.

You may want to check this out:

http://www.dofmaster.com/dofjs.html

Please note the info below the input changes as well when you do the calculation.

I was surprised to see how narrow DOF can be in some situations. Perhaps more careful spot focusing could help?

sinatraman Loc: Vero Beach Florida, Earth,alpha quaudrant

check with keh.com they have an inhouse repair center, suposed to have a quick turnaround time. if you go to the website click on repairs answer a few questions they'll give you a "ballpark estimate"

rufus1 Loc: Winter Haven, Florida

Thanks for the calculator-may have been off on the jay, but the heron and ducks in flight should have been fine. Before I break the bank, think I'll backyard test tomorrow.

rufus1 Loc: Winter Haven, Florida

Heard of them before on UHH, if I decide to repair will look them up. Thanx

sinatraman Loc: Vero Beach Florida, Earth,alpha quaudrant

no problem, havent used them for repair but am a enthusiastic customer of their used gear. all of which comes cleaned and looking good so i assume some of it has been repaired by them.

rufus1 Loc: Winter Haven, Florida

Well, thanks for that, I'll check repair and/or purchase.

tomfr Loc: Brevard N.C.

If the intention of the purchase was to shoot landscape and wildlife, testing it in an urban setting was rather useless. You are the buyer, it is your money going over the counter. Take it out in the country, or, in a local park to shoot whatever wildlife may be there. Would you buy a used car driving it around the dealer's lot. Too many times consumers are intimidated by the people behind the counter. They are simply supplying a service, they are not the god's of photography.


tomfr