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Old Apr 3, 2011, 11:29 PM   #1
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Default Initial Impression of DA 60-250mm with Pentax AF 1.7x Combo

About a week ago, I was wondering whether the DA 60-250mm and Pentax Af 1.7x combo was good enough for birding, or do I really have to get another lens e.g. Sigma 50-500mm just for that purpose. The weight of the equipment has always been a concern to me because of my shoulder and back problem, so I was hopping that I do not need to get the Bigma.

My first quick test yesterday in church was quite discouraging. As some of you have seen, the CA seems to be quite bad, something that I have never seen before when I was using another system. But I felt that perhaps the problem may have to do with the hash lighting condition at that time, which was about mid-day

So this morning, I tested the 60-250 and 1.7x combo again in the morning. The results seems to be acceptable, for which I feel relieved.

f6.7, 1/400, ISO800


f10, 1/400, ISO800


A newly discovered Sunbird Nest, 1/6.7, 1/320, ISO1600
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Old Apr 4, 2011, 1:05 AM   #2
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Hi calvinlo,

These are very nice!

For something longer, I would seriously consider the DA* 300/4. Granted there's not much difference between what you have already and 300mm, but the lens would give you 510mm with the 1.7x AFA and weigh about the same as your zoom. Thi Bigma weighs about 800g (28 oz more) and extends to a very long lens at 500mm which throws the balance off more.

The Bigma is f6.3 max aperture at 500mm, (some say it's actually more like f6.7 in reality). This limits it's ability to use TCs with AF since the effective max aperture would be f8.8 with a 1.4x and f10.7 with the 1.7x AFA.

If you desire more reach than 510mm, then it might be practical to get a 300/2.8. Used Sigma ex 300 f2.8 APOs can probably be found for a few hundred $$ more than the Bigma, but the faster max aperture gives you more room for TC use. I use a Tamron 1.4x TC stacked on a 1.7x AFA with 300 mm f2.8 lenses quite a bit, and this gives 714mm f6.7, 420 f4 with just the 1.4x, and 510 f4.8 with 1.7x AFA.

There's a current thread on DPR where someone is using his DA*300/4 with stacked TCs, and he says it works, but I'm always leary about testimonials like this. My experience with my new-to-me DA 55-300 is that it's not necessarily reliable focusing, but my f5.8 lens is not as sharp and is a hair slower than his stacked combo, so that may make the difference. I concluded that somewhere @ f9.5 is probably the marginal AF cutoff for the K-5, but I haven't used it enough to say conclusively.

BTW, I'm not seeing much if any PF or CA in these shots, and there are a few areas where they could appear, so I don't think you should concern yourself with this as a problem. . .

Scott
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Old Apr 4, 2011, 2:30 AM   #3
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Thanks for the encouragement!

Yes, now that I've acquired the Pentax 1.7x adapter and have use it, I'm beginning to realise that it is probably meant for a prime lens. So the DA 300mm f4 will be a good option, considering that it is pretty light compared to the Bigma.

Will be saving up for that.
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Old Apr 23, 2011, 6:13 AM   #4
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Shot the Magpie Robin this morning at the Singapore Botanic Garden with the DA 60-250mm and AFA 1.7x.

After playing with it for a while, I realise that I have to stop down to at least f8 to attain satisfactory sharpness. Fortunately, I can push my ISO all the way up to 1600 without worry with my K-r. It'll be a different story if I'm using my older system.

ISO400, 1/125, f8


It seem that without a monopod or tripod, the lowest shutter speed I can go at max zoom ~638mm is around 1/125. What about you guys? Any tips to share?
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Last edited by calvinlo; Apr 23, 2011 at 6:40 AM.
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Old Apr 23, 2011, 9:37 AM   #5
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I recall reading in the Pop Photography review that this lens was a good one. However, your assessment of this lens as being "acceptable" or "satisfactory" does not make this lens sound like an outstanding piece of glass. For what it costs, descriptors should range from "thrilled" to outstanding"....just my $.02 worth!
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Old Apr 23, 2011, 10:00 PM   #6
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Quote:
Originally Posted by jelpee View Post
I recall reading in the Pop Photography review that this lens was a good one. However, your assessment of this lens as being "acceptable" or "satisfactory" does not make this lens sound like an outstanding piece of glass. For what it costs, descriptors should range from "thrilled" to outstanding"....just my $.02 worth!
Don't get me wrong - The DA 60-250mm is definitely a wonderful lens by itself. It's sharp enough that I can shoot wide open without worry.

However, the problem comes when it is coupled with the 1.7x adapter, which I feel is more suitable for prime lens e.g. DA 300mm f4.
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