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02-14-2011, 12:43 PM   #1
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looking for 300mm lens opinion

Hello Folks,

I currently use a minty Tamron Adaptall-2 SP 300mm f/2.8 LD IF (360B) which produces stunning results, even matched with the 2x converter (01F). My passion is wildlife photography - especially birds (which are often small and far away). I am considering selling this lens to finance the purchase of a Pentax SMCP-DA* 300mm f/4 ED (IF) SDM.

Is this a good idea?
Will I be sorry if I do this?

Tamron pros:
ability to use a good TC

Pentax pros:
lighter weight

Please help me decide! Thanks so much!


02-14-2011, 12:50 PM   #2
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That is a tough call

Personally, I would look for an SMC-F 1.7x AF TC and keep the tammy.

the reason is that 300mm is still too short, and you are giving up a full stop.

The 360B is reportidly pretty good against CA, (better than the 60B) so unless the weight is a real big issue, you are giving up a lot (In My Opinion) just to get AF.

There is no doubt the DA300 is a nice lens, but it won't do all you want if you still want to get to 500-600mm.

Using the AF teleconverter allows you to select a range of focus and the converter (with its own moveable elements) does the fine focus. you should note that there is no TC for the pentax line up which supports HSM so you are kind of stuck in that regard also. Many do report excellent results using the 1.7x AF TC with the lens, but that to me seems crazy in your situation, i.e. giving up a 300F2.7 for a 300F4 and still having to get the 1.7x AF TC on top.

However, if you are intent on selling, I am interested I have been looking for something faster than my K300F4, and the 360B is one of the candidates.
02-14-2011, 01:29 PM   #3
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Sorry? It would be a "cardinal" error IMO

QuoteOriginally posted by jon.partsch Quote
I currently use a minty Tamron Adaptall-2 SP 300mm f/2.8 LD IF (360B)
Same here regarding a 360B. I've never been tempted to exchange it for anything that I'll ever be able to afford.

Occasionally I wonder if the DA* 300 would be enough lighter to make a difference in use and whether AF would be useful, but each time I've tried long AF lenses for the stuff I shoot I've ended up using MF override to tweak 'em anyway. I just don't see that spending $400-600 more for a "better" 300-400mm lens would improve anything.

I have the same conclusion about the SP 90, SP 180 and SP 80-200 too - doubling the investment to get AF wouldn't change anything about the way I use 'em or improve the results. Tried an AF 1.7x TC with 'em all and decided AF didn't do a thing for me with these longer FLs. And I have a pretty good Tamron AF 75-300 for those non-critical occasions when a longer, lightweight AF lens would actually be helpful. (an $80 solution?)

And there's also a certain satisfaction in using these old friends that I don't get with the new kids. Besides, I'm still learning tricks to outwit 'em, too. Less than 2 1/2" of DoF trumps fidgety AF every time for me. Of course I'm probably missing the pleasure of worrying about FF/BF, SDM, and short lived warranties, but I can live with that.


K200D + 360B + 140F @ f5.6,

Incidentally, I suspect that AF would have hit on either the tip of the tail, the perch or the black band near the eye - and I couldn't have predicted or controlled which one without using MF mode anyway - but two of those choices would have produced a worse result with the limited DoF. I had to wait for the head to turn back over the perch/pre-focus point to make this work at all.

Last edited by pacerr; 02-14-2011 at 01:40 PM.
02-14-2011, 01:31 PM   #4
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Another vote for the F1.7X AF Adapter

I use this with my Tamron Adaptall 60B and it produces fine results at an effective focal length of 510mm. A little off-axis color, but not at all bad. You are probably going to have to pay a lot to get an autofocus lens with the same performance as the 360B and you will definitely miss going to f4 from f2.8.


02-14-2011, 01:37 PM   #5
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I am with Lowell... One stop loss is huge disadvantage compared to what you gain; AF and lighter weight. Add a 2x TC to the DA*300/4.0 and AF is no more. I am also interested in your 360B as Lowell is, but higher priority for me is the 63B.

02-14-2011, 07:56 PM   #6
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I had the 360B and the 1.7x afa and the DA300. I found with birds the fringing with the 1.7x and 360b had me stopping down to usually f5.6 on the lens so the DA is the one I kept as it was good even wide open with the 1.7x. Not an easy decision as the tamron was so darn good and well made, the focus ring felt like it was on ball bearings it was so smooth! Unfortunately with my eyes aging and the little viewfinder on my k20 I have a hard time manual focusing. I think auto focus is a good thing, especially for flying things. I would try the 1.7x on your 360B and see how you like it because you can always use it on the DA300 if you decide to try one. You could maybe rent one and see how you like it.
02-14-2011, 08:44 PM   #7
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I have the DA300 and the Bigma. I would suggest you try to get a older model Bigma if you can find one. I found the IQ with the DA300 marginally better than the Bigma but it is not as versatile as it is a prime. The pros for the DA300 are its size , weight , SDM, F4 and IQ. It is much better to do BIF pics and much easier to haul around .
The Bigma on the other hand has decent IQ and goes to 500mm without any converters. You can get great pictures with both but the Bigma is more versatile being a Zoom. IO had the Bigma first and have had some very good results with it. Just got the DA300 recently for a lighter easier to haul around lens. My outings with the Bigma usually include a monopod or tripod and are pretty much dedicated to that one lens. My K20d grip and the Bigma weighed close to 8 lbs without the monopod or tripod. The DA300 will be a nice relief sometimes and make BIF shots easier.

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