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12-15-2012, 01:25 PM   #1
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Pentax Km lens help: 400mm lens?


I was wondering if anyone could advise me if there is a suitable 400mm lens available for my Pentax Km?


12-15-2012, 01:35 PM   #2
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QuoteOriginally posted by Matt200 Quote

I was wondering if anyone could advise me if there is a suitable 400mm lens available for my Pentax Km?

I think that the only 400mm lens currently available new is this one:
Sigma 120-400mm f/4.5-5.6 DG APO OS HSM Autofocus Zoom 72A109

If you want to settle for older or manual lenses, here are a few options:
SMC Pentax-A 400mm F5.6 Reviews - A Prime Lenses - Pentax Lens Reviews & Lens Database
SMC Pentax-M 400mm F5.6 Reviews - M Prime Lenses - Pentax Lens Reviews & Lens Database
Sigma 400mm F5.6 APO Lens Reviews - Sigma Lenses - Pentax Lens Review Database

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12-15-2012, 02:07 PM   #3
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You could even go a little older with this one:
Tele-Takumar/Super-Multi-Coated TAKUMAR 400mm F5.6 Reviews - M42 Screwmount Extreme Telephoto Primes - Pentax Lens Reviews & Lens Database

Do you need a 400mm prime or just a lens that has that focal length? There are also a number of zooms that cover that range.
12-15-2012, 04:35 PM   #4

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Hi Matt,

Some others are:

SMC Pentax-FA* 400mm F5.6 ED [IF] Reviews - FA Prime Lenses - Pentax Lens Reviews & Lens Database

Sigma APO 135-400mm F4.5-5.6 DG Lens Reviews - Sigma Lenses - Pentax Lens Review Database

Tokina AT-X 80-400mm F1: 4.5-5.6 Lens Reviews - Tokina Lenses - Pentax Lens Review Database

These are all discontinued, and only available used. The recent market for the FA* 400 f5.6 puts them in the impractically pricey range (close to $2000 USD), IMO. From what I've seen they're very good, but not in the top tier of Pentax * class ultra tele lenses, IMO. Personally, I'd rather use an FA* 300 f4.5 + Tamron F 1.4x AF PZ MC4 TC to get 420mm f6.3, and in fact, that's exactly what I do. . .

I have the Tokina 80-400 f4.5-5.6 AT-X, and it's a competent lens with a very wide zoom range, but a bit soft at 400mm wide open. With stopping down a bit and some judicious sharpening in PP, I can get reasonably good results though.

When both the Sigma 135-400 and Tokina 80-400 were both available new, there was an on-going debate with Pentax users of each about which was better, and I don't think it was ever really resolved. User reviewers here seem to prefer the Tokina if you compare the ratings. I always considered them pretty equal, but have never shot the Sigma. From what I've seen, the current Sigma 120-400 is a better lens, and not as compromised at 400mm -- but it's a lot more expensive.

From what I've seen over the years, for the best bang for the buck in 400mm lenses in K mount, I'd say the Sigma 400 f5.6 APO is probably easily in a class by itself if you can find one.


12-24-2012, 11:07 AM   #5
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Hi guys,

Thanks for the replies, sorry for the delay in mine! To be truthful I'm rather new to the technical side of things and at least you have given me an idea on what area I should be looking at.

Had a Km for a 3/4 years now and had a 55-300mm lens for a year or so and whilst it's been good, it's more a case of being in the right place/right time to get a good shot with it. I'm into wildlife photography and would love to progress to better shots, more detail etc. I do like the camera and wouldn't like to change it, mainly due to cost of a new body!

Reading your advice and doing a little bit of research I've come across this on Amazon, I would be willing to pay that for a decent lens, does anybody have any thoughts on it? I know its a 500mm instead of 400mm but until this thread I didn't really have a clue on makes/costs anyway!

Sigma 150-500mm F5-6.3 APO DG OS HSM Lens for Pentax: Camera & Photo


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