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12-02-2008, 06:13 PM   #1
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Tamron 70-200mm issues

Has any other owners of this lens noticed that at F2.8 at any range, it seems like the image is slightly brighter overall and just lacks contrast compared to 1 stop down. I don't know if this is the "ghosting" effect that's talked about elsewhere, or that the camera is getting the exposure wrong...

Also, my copy seems to have the same issue as the one tested by DPReview, namely, AF is just so unreliable, especially for distant objects. When it's spot on, I'm amazed by the sharpness, but I'm more often disappointed and frustrated when focus is off.

Other than that I don't mind the focusing speed, though it hunts more than any of my other lenses, the bokeh is buttery and colour and contrast as I expect, except @ F2.8.

Anyway, I've decided to give the Sigma a try.

PS. I'll try to post some pics when I get home

12-02-2008, 06:29 PM   #2
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Supa, please post pics.

My Tamron is due in tomorrow afternoon so I'll put a post up about my thoughts on the lens when I get it.
12-03-2008, 09:23 AM   #3
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The Sigma will probably have the same issues you have. It's a bit soft wide open, but sharpens up very nicely when stopped down. Focusing at 70mm can be slightly off, so when that happens I usually zoom in, focus, then zoom back up and the problem is fixed.
12-03-2008, 09:41 AM   #4
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On long-range shots, my Tammy 70-200 would sometimes lock on high-contrast background instead of the subject - I needed to refocus a couple times to hit the subject. My DA 50-200 and a couple other long zooms I've had did the same thing.

12-04-2008, 04:26 AM   #5
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Both 100% crop @200mm, top f/2.8, bottom f/3.5
Subject approx 1km away
f/2.8 just look softer with less contrast, f/3.5 much better

It seems focusing problem is predominantly for distant objects, perhaps infinity focus is not calibrated properly... That's my guess anyway

Consolation is that when AF gets it right, I'm very impressed by the resolution, colour, contrast.

I've had replies on other forums where a number of Tamron owners reported the same findings as me. Guess my copy isn't bad after all... Maybe I should just keep it or at the most send it with my camera to get calibrated.

12-04-2008, 11:04 AM   #6
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All,

My Tamron 70-200 was delivered last night. I didn't have a whole lot of time to play with it, but I did do a few low-light shots and the results were... interesting.

Here's a few observations:

1.) AF

Two things jumped right out at me about the AF. The first thing is that it's LOUD. Loud enough that I had to put the lens away at 10pm because I was annoying my fiancee who was working on the computer on the other side of the room. Her exact words were "I hope you never photograph a wedding with that thing because they'll kick you out"

The second was tha it does hunt in VERY low light (like 1/2s, f2.8 ISO1600 territory). The lens has a heck of a time focussing at that low lighting.

With that said though, in better light (1/60s, f2.8, ISO1600) it focuses with no real problems. It's pretty fast, finds contrast well (although it won't focus on a flat white wall at 200mm under that lighting) and doesn't back/front focus at all.

2.) IQ

The lens is really sharp across the frame. Maybe just a little bit (and I mean very little) soft in the corners at f2.8 but not noticable in a real life picture. The DOF is pleasing and colors are really good.

3.) MF

I hate the MF on this lens. Here's the deal. It's got that 'feature' where you pull the focus ring back to engage MF, buuuuuut on the K10D you also have to switch the camera body to MF also or you just end up turning the screw drive in the camera when you spin the focus ring... very bad. The good news for me is that I almost never use MF, so it's a rather moot point.

4.) Build

This thing is a big lens. Especially with the hood on it, it can be very ominous looking. It's pretty high quality though and lighter than it looks. It doesn't balance incredibly well on my K10D w/ BG, the weight is a little front of where I like to hold it but I'm sure I'll get used to that.


Now for pictures:

Like I said I didn't take many and a few came out blurry because it was dark and I was hand holding at <1/60s for a lot of shots.

Here's a 'good' f2.8 shot, ISO400 and a crop of it. Natural lighting for this shot (a lamp in the room).



and a crop of that shot. Sharpened and leveled in PS.




I'll update this after I have a chance to really try out the lens this weekend and put my thoughts in the lens review database.
12-05-2008, 04:24 PM   #7
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More testing, this time AF vs MF

Seems like infinity focus calibration is the culprit.

100% crop @200mm f/2.8, top MF, bottom AF, subject >500m away

MF achieved incredibly sharp image whereas AF struggles with inconsistent focus, quite often not hitting focus spot on.

12-05-2008, 06:25 PM   #8
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That's definately out of focus.

i'm finally going to have mine out during the daytime tomorrow. I'll take a few near infinity shots and let you knowwhat happens.

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