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06-11-2016, 04:57 AM   #16
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Interesting what some people accept from third party lenses. No live view AF with a new lens and changing focus shift make for a lens not worth considering.

06-11-2016, 05:32 AM   #17
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QuoteOriginally posted by zapp Quote
Interesting what some people accept from third party lenses. No live view AF with a new lens and changing focus shift make for a lens not worth considering.
Well, I can tell you why I'm prepared to consider accepting it...

(1) Live View is of no use to me given the focal length range of the lens and what I'll be using it for... If it was a problem with just my copy of the lens, I wouldn't accept it, but if it's a compatibility limitation then I'm OK with that
(2) It is very common for AF zoom lenses suffer from some degree of AF accuracy differences at various focal lengths, and common practice to fine adjust AF for the best compromise at all lengths
(3) There is no other Pentax mount AF 70-200 f/2.8 at the same sort of price point that is optically comparable (Sigma's offering and the Pentax 50-135 f/2.8 are both considerably more expensive, while the 60-250 is way more expensive again and slower)

Not worth considering? If I can make it work for me (and many, many others have to their satisfaction), I disagree

Last edited by BigMackCam; 06-11-2016 at 07:15 AM.
06-11-2016, 06:36 AM   #18
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I can only agree with BigMackCam on this, I barelly use LV with AF lenses. I had used the sigma 70-200 HSM zoom, and sorry, but on modern screw drive models(k-3 and above), it has slower AF, and its not as sharp as tamron is( in my opinion tammy also is better in harsh light, no flares etc). I had to adjust all my lenses for every body I got in this system(both 3party, and genuine), its normal thing-never had any vari-foccal zoom issues like FF on wide, and BF on tele, only static FF or BF in some part of the range,or constant, both thing in most cases that could be removed with build in AF adjust.
My tammy 70-200, brand new, was sent in same week I got it along with body to Tamron service centre just in case, it was returned not more than week later, with my previous body K-30, on that one it was adjusted it was SPOT ON, on almost every picture after that, but on my newer- K-s2, it is prone to small front focus on 200/2.8 setting bellow 4meters distance, as far as I know, its just the way this lens behaves with AF. I'm considering sending it again if BigMackCam unit will get rid of any 2.8 focus issues.

Last edited by Reed; 06-11-2016 at 06:43 AM.
06-15-2016, 02:17 AM   #19
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For @Reed and anyone else following the thread, my 70-200 arrived back at the supplier yesterday. They are out of stock right now, but have more coming in later this week, so I should have the replacement in the next 5 - 7 days... I'll report back on the AF adjustment and consistency...

06-15-2016, 03:20 AM   #20
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To the OP and everyone else might be interested, just take a look here: https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/289608-u...rs-needed.html

What is more important is here: https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/289608-u...ml#post3216782

The 70-200/2.8 remains a great lens with excellent optical performance (I'm very satisfied with mine) despite all the various restrictions - that are quite expected if you consider the asking price from Tamron.
06-15-2016, 03:47 AM   #21
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QuoteOriginally posted by redpit Quote
To the OP and everyone else might be interested, just take a look here: https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/289608-u...rs-needed.html

What is more important is here: https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/289608-u...ml#post3216782

The 70-200/2.8 remains a great lens with excellent optical performance (I'm very satisfied with mine) despite all the various restrictions - that are quite expected if you consider the asking price from Tamron.
Thanks for that, Pete - very useful indeed. If my second copy still won't adjust within +/-10 then I'll keep it and send with my camera to Tamron for calibration. Even with my first copy I was impressed with the lens and if it means I need Tamron's service to get one within acceptable parameters, I'm OK with that
06-15-2016, 04:42 AM   #22
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QuoteOriginally posted by BigMackCam Quote
Thanks for that, Pete - very useful indeed. If my second copy still won't adjust within +/-10 then I'll keep it and send with my camera to Tamron for calibration. Even with my first copy I was impressed with the lens and if it means I need Tamron's service to get one within acceptable parameters, I'm OK with that
You're welcome. Exactly what I would propose! I have nothing more to add.
06-27-2016, 03:30 AM   #23
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Well, at long last my replacement 70-200 arrived today! Casual calibration (focusing on objects in the garden and chimney stacks in the distance, rather than my SpyderLensCal) suggests that it is best at -7 adjustment at 200mm... I may be a little off on that, but by -9 it is definitely worse, and same by -5. I haven't tested the other focal lengths yet. What I have noticed is that it seems to front focus a little more with very close subjects - have any other users have found this? That said, -7 seems to be a good compromise. By f/4 any slight inaccuracies are gone. I'll do more formal testing later, but so far it's looking positive. Woohoo!

06-27-2016, 03:59 AM   #24
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Well this seems to behave like mine piece after service centre calibration, now I have this issue only around 200mm and at F2.8 when focused on minimal to 2-3meters distances. Other lenghts/distances/apretures works fine.
06-27-2016, 04:41 AM   #25
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Yes, that's exactly what I'm seeing. 70 - 150mm+ is great, but at 200mm it front focuses a bit at close distances - as you say, 2 - 3 metres, and only really noticeable wide open. I'm satisfied with that - especially given that it's behaving like yours. I don't expect any lens to be perfect, so long as it's performing to the best of its ability. I'm quite happy to work with any minor idiosyncrasies
06-27-2016, 01:41 PM - 1 Like   #26
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UPDATE: Well, I spent some time this afternoon calibrating the AF fine adjustment for the replacement lens. In fact, it seems to work best at -10 fine adjustment - right on the limit, but it's now giving me identical results to very careful manual focusing. At 5 metres plus, AF is pretty much spot on at all focal lengths. At very close focusing distances (2 to 3 metres or so) it front focuses at the long end, but is close to spot on at 70 through 150mm+. General optical performance of the lens appears to be very good based on my initial tests. I don't think I'll be using it wide open at 200mm as there is some softness even when focused perfectly, but stopping down to f/3.5 or f/4 improves things considerably, while f/5.6 and beyond is excellent.

I'll use the lens for a little while and see how I get on with it, but might still send it to Tamron for calibration with my K-3. It may be that it can't be (or doesn't need to be) improved beyond its current state, but I'd be interested to see if they feel it needs any further fine tuning... For now, though, I'm happy
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