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11-07-2011, 04:55 PM   #1
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Best lens for the K-5 with ~500mm range

I am looking for good value lens with a 500mm range (minimun), it could be from 50, 100 or 200 to 500mm. I've been looking at the Sigma 150-500 (~$1K), seems to be a good lens but I've read that on the long end (close to 500mm) it's not very sharp, and had some firmware issues with the AF ??, and it would be a better option the Pentax DA* 300mm lens, and maybe use a teleconverter to get to the 500mm range ?, what are your thoughts ?, thanks

11-07-2011, 05:04 PM   #2
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the only teleconverter for the DA300 is the SMC-F 1.7x AF TC, you use the DA300 in manual focus and the TC has a small moveable element that works from the camera's screw drive. It gives very fast but "localized" af capability

The other option, perhaps sharper and better overall than the bigma, if you can find it used, is a Sigma APO 70-200F2.8 EX Non DG Non Macro. this is an old lens by current standards, having bought mine new in 2003, but it is by far the sharpest sigma 70-200 out there, and does very very well even wide open at 200mm. Using sigmna's 1.4x and 2xx TCs hardly degrades the immage at all, and the big benefit over the bigma is that if yo only need 70-200 you take off the TCs and shoot at F2.8, that is 1.5 stops faster than the bigma
11-07-2011, 05:41 PM   #3
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The Bigma is very nice as long as you're not shooting stuff that's very far away- because then the resolution really falls off.

Sigma 50-500mm F4.5-6.3 APO OS HSM - Review

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11-07-2011, 09:42 PM   #4
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My sigma 50_500 has the same issue as Adam. At 500 close range it is OK particularly in good light. from 10m to infinity the image becomes progressively softer. If the 150-500 performs the same way, then you might as well have the 50-500.

I am replacing my 50-500. I have the sigma 500 which is a great improvement (would need to be considering the cost). May buddy it with the pentax 60-250 but I have run out of money.

As far as I am aware there is no reasonable glass at a moderate cost going to 500mm other than sigma.

11-07-2011, 10:18 PM   #5
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I can't really agree that the 50-500 is so soft at a far distance. See this unaltered 100% crop from a day with a light drizzle. The building is 5.6 km (2.84 miles) away and you can still see the cables to the antennas. It is not a great picture but it is just an example of what this lens can do on a K5. Can post other pictures as well if you want to see.
11-08-2011, 06:40 AM   #6
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Just buy the best you can afford. IMHO you will be kicking yourself if you buy cheap.
11-08-2011, 03:17 PM   #7
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I have no problem at 500mm with my 150-500, even with a 1.5x converter...

11-08-2011, 03:45 PM   #8
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QuoteOriginally posted by fs999 Quote
I have no problem at 500mm with my 150-500, even with a 1.5x converter...
What Teleconverter are you using ?
11-08-2011, 08:02 PM   #9
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Long lenses get softer with distance because of atmosphere as well as optics. My longer glass -- cheap Spiratone 400/5.6 long tube, Sakar 500/8 mirror, Lil'Bigma 170-500, and Rubinar Makpo 1000/10 mirror -- are all crisp enough when the air is clear and cold and thin, and all soft-ish when the air is otherwise. The Lil'Bigma has good contrast under all conditions, and the others ain't bad.

What's best for you? Depends on your budget. That Lil'Bigma cost me 4x the price of the others total, and good long glass just isn't cheap.
11-09-2011, 03:02 AM   #10
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My blog has an article about the atmosphere issues and a table what focal lengths don't make sense at which distances and kind of weather.

-> Falk Lumo: LumoLabs: HowTo long range telephoto shots

About the lens itself: with very few exceptions, a zoom is a bad option. Because, at the long end it is softer than a prime to a degree that it may be better to crop.

There are some zooms which are stellar performers, like the DA*60-250. But I am unaware of such a 500mm zoom for the K mount.

So, between a DA*300 with crop, and a Sigma 500/4.5, I see little other options. BTW, AFAIK, the newer Tamron 1.4x TC work with the DA*300 and DA*60-250.

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