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04-19-2012, 06:08 AM   #31
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QuoteOriginally posted by oeriies Quote
Yes, I've used the Tamron TC with the DA*300. It works in good light with contrasty subjects but the autofocus hunts in conditions that wouldn't be a challenge without the TC, e.g. a bird among branches in a tree. As I indicated in a previous post in this thread, I prefer to use the DA*300 without a TC. It produces very sharp images that can be cropped 50% and still look great whereas a get fewer keepers with the TC attached.

Maybe this has been discussed somewhere on this forum already, but I've wondered whether the in-camera shake reduction is introducing blur when using the Tamron TC. With the DA*300, for instance, the camera thinks it is adjusting for shake for a 300mm lens when in fact with the TC attached it is a 420mm lens. I would think this would lead to an underadjustment. Anybody know the answer?
when using a TC that does not alter focal length, the camera is under compensating the vibration, so it is not so much introducing blurr, but undercompensating for it. I have this issue with my sigma 70-200F2.8 and the 1.4x and 2x TCs I think if you search the forum for TCs to use with the DA300, most members recomend the SMC-F 1.7x AF adaptor. The AF is very fast and quiet because it is moving only the small elements in the TC, and because on a long lens, the TC only works for a small focal length range, you get "selective focus" you can shoot through branches to your subject because they are outside the focus range.

I use this TC on my K300/4 and it works very well.

The other advantage of the pentax 1.7x adaptor is that it compensates for aperture, so when using P-TTL flash, for example, the exposure is correct, because the camera knows the true aperture.

the only down side I can see, is the price. I bought mine brand new in 1991 with my PZ-1 so I have not had to worry about getting one lately, but have seen posts suggesting the price is now about 500US

04-19-2012, 01:15 PM   #32
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QuoteOriginally posted by Lowell Goudge Quote
the only down side I can see, is the price. I bought mine brand new in 1991 with my PZ-1 so I have not had to worry about getting one lately, but have seen posts suggesting the price is now about 500US
The Pentax 1.7X makes sense the way you're using it, i.e. add AF to a MF lens. I haven't bought one for my A*300 because I hate having to switch from AF to MF on the camera, f/6.8 is too slow for much of my shooting, and price. I expect the value of the 1.7 TC will plummet once they release the 1.4X shown in the roadmap. If I decide to keep the A*300, maybe I'll try the AF 1.7.

On the DA*300, you lose WR and SDM, but the AF 1.7X seems to be the best compromise at this point.
04-22-2012, 05:31 PM   #33
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Thanks again guys for all the help. I love this lens its so much sharper and the colours seems so much better I am able to corp more now also I would still like a longer lens but I made the right choice in getting the 300 first as its not to heavy to carry around for a few hours. I also understand why people like Lower F stops going from F6-8 90% of the time to F4-5 makes a big difference and for wildlife it make the animals pop.

Thanks Again.
04-23-2012, 10:54 AM   #34
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QuoteOriginally posted by coreyhkh Quote
Thanks again guys for all the help. I love this lens its so much sharper and the colours seems so much better I am able to corp more now also I would still like a longer lens but I made the right choice in getting the 300 first as its not to heavy to carry around for a few hours. I also understand why people like Lower F stops going from F6-8 90% of the time to F4-5 makes a big difference and for wildlife it make the animals pop.

Thanks Again.
But that diffence is closing due to the improving high ISO performance of sensors. the real need today is for enough light to focus, and that's it, I think Pentax has it right with their newly announced 560/5.6 if it can produce ultra sharp wide open, there's no need for a faster lens

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