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03-03-2009, 12:21 PM   #1
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Manual focusing on the DA 55-300

I have a Sigma 70-300 APO DG lens which many have faulted for being soft above 200 mm, and indeed in many of my pictures taken at that length it is. I am convinced, however, that much of that apparent softness is due to auto-focusing the lens with my K10D rather than an inherent quality of the lens itself, because occasionally I'll get one taken at 300mm and f/8 that is quite sharp even at 100%. (Understand now, I'm not talking razor sharp like a prime but comparable to most zooms I've used.) I've experimented with manually focusing this lens, and can occasionally nail "perfect" focus, but it's very difficult because the difference in being in focus and out of focus is only a fraction of a mm in rotational travel of the focusing ring.

This rather lengthy lead-in brings me to my question about the Pentax 55-300 which has been highly praised and, in my opinion, rightfully so. How easy is it to manually focus? As auto-focusing lenses with the same apertures is more a function of the camera than the lens, it seems reasonable to assume that my camera would be no more able to focus satisfactorily on a songbird 50 feet away with the Pentax lens than with the Sigma, so purchasing the Pentax would not necessarily give me consistently sharper images. I realize that the Pentax is not going to have the manual focusing properties of a dedicated macro. I'm just wondering if it's definitely easier than the Sigma. In other words, is the connection between the focusing ring and the lens elements geared as high, so to speak. I'm seriously considering purchasing the 55-300, but see no point in doing so unless I can expect a definite improvement in the sharpness of my images, and have convinced myself that that depends on the ease with which the 55-300 can be manually focused. Thanks for your response.

CN

03-03-2009, 03:51 PM   #2
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auto focus 55-300mm

Attachment 29482
Attachment 29481
Hi,just thought id show you a few results from auto focus on the DA 55-300MM.
To be honest ive never manuel focused in my life but i do intend to try soon.Im
waiting for the footy season to start here soon to see how the lens performs at sports and would like to be able to manuel focus if needed but im hoping auto focus will do the job.It does have the quik shift focus i tried a couple of times but never realy needed just tried it for the hell of it.Just wanted to say im sure the 55-300 will do a good job for you in manuel or auto.
Thnx Paul
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Attachment 29480

Last edited by trumpyman; 03-14-2009 at 07:01 PM.
03-03-2009, 04:48 PM   #3
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QuoteOriginally posted by Clem Nichols Quote
This rather lengthy lead-in brings me to my question about the Pentax 55-300 which has been highly praised and, in my opinion, rightfully so. How easy is it to manually focus?
CN
Save money and get a DA* 300. My 55-300 cost me $0, so for its IQ, it's great. My copy has a rickety manual focus ring (is it because it rolled onto the floor from my couch once? ). It sounds like a dentist drill and will chase bears away.

Raccoons don't seem to mind the noise or the flash! (note: pentaxforums degrades IQ significantly):
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03-03-2009, 05:10 PM   #4
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Trumpyman:

Very sharp images. I ordered a 55-300 today from B&H. I guess that's the only way to find out for certain. With their return policy, if I'm not satisfied that it gives better service than the Sigma, I can always return it for a full refund. Thanks.

CN

03-03-2009, 05:13 PM   #5
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QuoteOriginally posted by asdf Quote
Save money and get a DA* 300. My 55-300 cost me $0, so for its IQ, it's great. My copy has a rickety manual focus ring (is it because it rolled onto the floor from my couch once? ). It sounds like a dentist drill and will chase bears away.

Raccoons don't seem to mind the noise or the flash! (note: pentaxforums degrades IQ significantly):
I have the Tamron 70-200 f/2.8 and the Bigma, but those two suckers are simply too big and heavy to carry along comfortably on a hike. I want something with decent telephoto capability that's reasonably lightweight, and I think the 55-300 fits the bill.

CN
03-03-2009, 05:23 PM   #6
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QuoteOriginally posted by Clem Nichols Quote
I have the Tamron 70-200 f/2.8 and the Bigma, but those two suckers are simply too big and heavy to carry along comfortably on a hike. I want something with decent telephoto capability that's reasonably lightweight, and I think the 55-300 fits the bill.

CN
Yeah, I was half-joking about saving for the DA* 300. It's a lens I'd like to own, but 55-300 provides me with loads of cheap fun.
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