Which supertelephoto?

879 on amazon for that lens, and 939 on amazon for the 50-500, its a toss up at this point, 8.8 on FM for the bigma, 9.1 for the 200-500

Don't forget about the rebates out now on the Tamy.

Tamron Lens Mail-in Rebates
OFFER
Purchase any of the Tamron lenses listed below between September 1 and December 31, 2006 and receive the corresponding rebate via mail from Tamron.

• AF11-18 F/4.5-5.6 Di-II LDAspherical (IF): $30
  
• AF17-35 F/2.8-4 Di LDAspherical (IF): $10
  
• AF24-135 F/3.5-5.6 ADAspherical (IF)Macro: $30
  
• AF28-75 F/2.8 Di LDAspherical (IF) Macro: $30
  
• AF28-105 F/2.8 LD Aspherical (IF): $200
  
• AF28-300 F/3.5-6.3 XR Di Aspherical (IF) Macro: $30
  
• AF55-200 F/4-5.6 Di-II LD Macro: $30
  
• AF200-500 F/5-6.3 Di LD (IF): $30
  
• AF14 F/2.8 Aspherical (IF): $200
  
• AF90 F/2.8 Di 1:1 Macro: $40
  
• AF300 F/2.8 LD (IF): $500

Tokina 80-400 AT-X D thread with pictures: https://photography-on-the.net/forum/showthre​ad.php?t=206338

If you don't want the wider end, the Tamron is a good deal. Most versatile is the Bigma.
The dust pumper and the Sigma OS lenses are all good. Optically the Sigma OS and the Tamron maybe the best, but not by a large margin (check photozone.de). If you want the cheapest 500, then I'd go for Tamron, if you want the biggest range and don't mind the weight, the bigma. If you don't mind the 400 and want OS/IS, then either Sigma OS or the dust pumper.

I think Im narrowed down to this..

Sigma 50-500
Tamron 200-500

I mean, ill still have the 70-200, 50 1.8, so i really dont need the range..

As far as AF speed, motors, quietness, which is better?

I think you will find the Bigma wins hands down on the AF speed as it's HSM. IMHO I'd also go as far to say that the IQ on the Bigma is as good as the Tamron. The build quality is slightly better also from memory. I think you will find when you look at review ratings such as those on FM you will find that part of the overal rating is for price.

Have a better look over the net at more reviews so you can be more informed on your choice. IMHO I think if you look at IQ, AF speed (HSM)-FTMF, focal range and lastly build quality the Bigma will win easily. The Tamron seems to have good IQ (IMO I would say it's equal with the Bigma's IQ at best) and is lighter and a slightly lower price.

I would base my choice between the EF400 5.6L, EF100-400L or the Bigma 50-500DG. The EF400 has the best IQ of the 3 by far but is a prime so it has limitation of use. The fact that you said you are planing on going to a FF body and want as much reach as you can afford I'd give the Bigma good thought. But you have to make your own choice in the end and work out what works best for you.

Fureinku wrote in post #2074505
I think Im narrowed down to this..

Sigma 50-500
Tamron 200-500

I mean, ill still have the 70-200, 50 1.8, so i really dont need the range..

As far as AF speed, motors, quietness, which is better?

Bigma is better in terms of AF speed, AF quietness. It also has HSM motor and FTM focusing, and a better build feel.
Tamron is a touch better in terms of shaprness.
Bigma is much better in terms of versatility.

How about the Sigma 120-300 f/2.8?

JuZ wrote in post #2076469
How about the Sigma 120-300 f/2.8?

great lens, but if hes struggling to pay for the 100-400, i think its out of his price range.

Im also not in tghe market for anything that stops at 300mm... 400+

My biggest problem with the Tamron 200-500 was the placement of the focus ring. How often do you plan on doing manual focus? If so, do hold one before buying. It is kinda unbalanced for manual focus.

If you can wait a few days I just bought the Tamron 200-500 from another POTN member. It's coming from Canada so it's taking forever and a day, but I'll let you know how it performs and post some examples of birds and the like.

I'm a new owner of the Bigma and recently I tried panning for the first time (with limited success...) But here's a shot at 500mm, ISO 400 (on the XT), 6.3, 4000, just resized.

I think the 100-400 is the way to go. I realize one can not make up their mind based on several sample photos, but the zoom gives you decent quality with little effort and practice, really easy to use. These are uncropped shots, no pp, very typical of the lens axtended to 400mm.

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wow that tern shot is great. what timing.