[Harri]

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Hi all. I've had my K10 for nearly 10 years now and it is still going strong. The lens that lives on the K10 is an old manual 75-150 which I use mainly for motorcycle events - enduro, road racing e.t.c. Sometimes the 150 isn't quite long enough and I was thinking about getting a longer lens that reaches up to 200-300. Also AF would be a luxury! I kinda know what is out there after answers I got to another post. But someone has mentioned that to use some lenses I might need to upload firmware? Anyone know if this is true and what lenses would this apply to?
The pentax 55-300, the Sigma APO, these are the price bracketed lens I have been looking at.

[twilhelm]

I have an original 55-300 that I bought with my K10D all those years ago. It's a great combination, the DAL version should work fine also and be cheaper. As far as firmware, I updated mine when it was available, so I really don't remember what that was for. Part of getting old

[Adam]

The SMC or HD Pentax 55-300mm F4-5.8 will probably give you the best image quality at its price point for an autofocus zoom. However, the autofocus with this lens may not impress you much (even compared to MF) since the lens is both a little slow in terms of aperture, and it has a long throw. The Sigma 70-300mm APO is another great choice, though I don't believe it's available new any more.

The DA* 60-250mm (mentioned in the review above) would focus faster and deliver even better image quality, but it's of course expensive at around $1000. You would need firmware 1.3 or newer to use that lens, but chances are you already have this installed (press the menu button while turning the camera on to check the current version).

Pentax Firmware Update Guide - Tutorial Videos | PentaxForums.com
Latest K10D Firmware Update : Software Downloads | RICOH IMAGING

If you decide to upgrade the body later on, any of these lenses should still work really well.

[Not a Number]

The last firmware update had to do with SDHC stability. Indeed SDHC support was added at some point and is not in some of the earlier versions as I recall. I don't remember what the SDHC card size limit is on the K10D.

[i_trax]

The SMC or HD Pentax 55-300mm F4-5.8 will probably give you the best image quality at its price point for an autofocus zoom. However, the autofocus with this lens may not impress you much (even compared to MF) since the lens is both a little slow in terms of aperture, and it has a long throw. The Sigma 70-300mm APO is another great choice, though I don't believe it's available new any more.
If you decide to upgrade the body later on, any of these lenses should still work really well.

in Australia there are still two versions of Sigma 70-300 still available new:
Items in dcxpert store on eBay !

[Skodadriver]

I am assuming you are not talking about buying new which may be wrong.
I have recently bought a Pentax DA L 55-300mm used and rate it as slightly better than the budget 70-300mm zooms I have from Tamron and Sigma.
If you are not fazed by using manual focus lenses, the Tamron SP 60-300mm (Adaptall model 23A) I rate as better than the budget Tamron and Sigma too.
If you are buying new and are looking at the PLM version of the 55-300mm lens then you may require a software update, someone will know, as it is not a screw drive AF.
If you find the older pre PLM HD and WR versions (and I think I have seen them for just less than £300) on sale, it might be a very good option too.