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08-15-2011, 09:09 AM   #1
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Tamron 300mm f2.8 60B soft at further focus distances?

I finally got around to figuring out what was up with this lens. I would get soft results, but then I'd go and shoot a chart and get great results. But I figured it out:

20110626-IMGP0168 - Minus

You can click view original. Turns out it's the focusing distance. 50+ feet and it seems pretty bad. Closer and it gets better. One day I got really lucky and a fox came up close to me and it was amazingly sharp. Unfortunately, all my birding shots, moon shots, mountain shots at far distances are very soft, which was the main reason I got the lens.

Mostly similar results with rear filter in, out, front filter in, out, tripod, mirror lock up, cable release, etc.

Does anyone else have similar issues with this lens?


Last edited by Eruditass; 08-15-2011 at 09:32 AM.
08-15-2011, 10:53 AM   #2
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I've had similar struggles with this lens, I think I have narrowed it down to focusing error on my part. The lens focuses far past infinity, so actually finding the exact point where the lens is focused is difficult - AF confirm of the camera is not reliable.

If I put the lens on a tripod and use the magnified live-view to focus, I can usually get a good result.
I have the infinity point detented based on that test, however the detent knob seems to move a bit on its own over time.

Another problem: the focus ring on my sample of the lens moves backward and forward, if I push forward on it while I focus, the action is smooth, if it's pulled back, focusing is very rough - almost locked. I don't know if this is normal. The focus changes when the ring moves back and forth, this is a serious problem if I have to shoot upwards. I could focus on a bird in-flight, let go of the ring a bit, and it will fall out of focus.

Last edited by Mock; 08-15-2011 at 11:13 AM.
08-15-2011, 12:01 PM   #3
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I have found a similar issue with both my Tamron Adaptall II 200-500F5.6 and with my SMC 300F4 when used with the 1.7x TC


I also believe focus error is the issue,
08-15-2011, 12:54 PM   #4
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QuoteOriginally posted by Eruditass Quote
I finally got around to figuring out what was up with this lens. I would get soft results, but then I'd go and shoot a chart and get great results. But I figured it out:

20110626-IMGP0168 - Minus

You can click view original. Turns out it's the focusing distance. 50+ feet and it seems pretty bad. Closer and it gets better. One day I got really lucky and a fox came up close to me and it was amazingly sharp. Unfortunately, all my birding shots, moon shots, mountain shots at far distances are very soft, which was the main reason I got the lens.

Mostly similar results with rear filter in, out, front filter in, out, tripod, mirror lock up, cable release, etc.

Does anyone else have similar issues with this lens?
I had a problem with a pentax FA*300mm f2.8 like that. It was pretty good under about 30' , but at the distances you would normally use the lens, it was soft. The lens wasn't any sharper stopping down, or manually focusing and it wasn't any less sharp with the 1.7x TC. I think it had an element in the focus group that may have been out of alignment. My 360B was sharper and since pentax wouldn't fix it (under warranty even) I got a bad attitude and got a Canon out of spite.

08-15-2011, 01:15 PM   #5
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I had a similar problem on my 60B. It turned out that the retaining ring holding the front element had backed off slightly. A little judicious tightening got my infinty focus back.
08-15-2011, 01:30 PM   #6
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I've gone all throughout the range, past infinity, well before infinity, and the mountains never came in focus.

QuoteOriginally posted by Derek Quote
I had a similar problem on my 60B. It turned out that the retaining ring holding the front element had backed off slightly. A little judicious tightening got my infinty focus back.
Can you show me some pictures of what the issue was?
08-15-2011, 05:51 PM   #7
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My copy does not have these problems. I bought it almost new (old stock) from another forist. I paid 920 plus 120 for normal filter. I love lens. You can preset focus and lock it. That is what I do with infinity focussing.
08-15-2011, 06:12 PM   #8
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QuoteOriginally posted by Eruditass Quote
I've gone all throughout the range, past infinity, well before infinity, and the mountains never came in focus.



Can you show me some pictures of what the issue was?
Sorry, I can't show any examples but everything from about 50 feet and further went to mush. It pretty much ruined about half the shots I had taken at a local rodeo. After I tightened down that retaining ring everything was fine and has remained that way.

It's easy to check. As I recall I just held the lens between my knees (objective lens facing up) and gently torqued on the retaining ring with a couple of small flathead screwdrivers. A pair of steak knives would probably work just fine.

08-17-2011, 04:17 PM   #9
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Sorry, I'm not familiar with optics terms. Which part is the objective lens? And which is the retaining ring?

08-18-2011, 02:37 PM   #10
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To use the sample image of a 60B that you just posted, the objective lens is the large (aprox. 112mm) glass lens element at the far left. It is recessed in the "female thread" lens barrel and is held in place by the "male thread" retaining ring.
The retaining ring has two very small notches located 180 degrees apart, one of which is visible in the 60B image near the bottom of the objective lens. To tighten the ring you could place the tips of two screwdrivers or knives, holding one in each hand, into these notches and turn the ring in a clockwise direction.
Be very careful that one of the tools does not slip. You might gouge up the retaining ring, or in a worst case scenario, the lens element itself. This wouldn't be the end of the world, or even the end of your 60B's usability. Just really annoying if you ever went to sell the lens.

Last edited by Derek; 08-18-2011 at 02:42 PM. Reason: Didn't fully type the word "direction".
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