i'd love to see it in a pentax mount. it's a lens that i'd like to use as a general purpose telephoto which i'd keep in my bag, so i'd like to spend some time getting everything *perfect*.

that's 1mm extra space should be salvageable.

if i get it done, i'll be sure to share the results here

the sony alpha mount is about 1mm less than pentax, if i recall correctly, which seems like much less of a daunting task. it's worth it to me, since i've craved an stf for a while!

hi all,

has anyone ever tried to get a sony lens on pentax? i understand that it would involve removing the lens mount, so you'd lose af etc.

i'm looking specifically at the 135/2.8 stf, which is a manual focus lens anyway, so i think the functionality loss would be minimal. i'd love to get one of these onto a pentax mount.

even if no one else has done it, does anyone know of any engineer/shop that i might be able to contact within europe that might be able to help out?

i know that others have done similar things with a minolta mc/md mount, but the alpha mount.

thanks for the help!

i think that i'd generally have no reason to use it.

but, i can think of one scenario, and only one, where it might be useful.

imagine that you're working in very poor light, that you need to bounce your flash of a very distant wall, and you really need to milk it. i'd want to set the iso up high, and the aperture as wide open as possible.

but still, it's the one camera mode that i've never used.

i don't mind pentax's high prices for the da limiteds and da* lenses. they are quality. and, in the case of the da-limiteds, utterly unique.

@ Mike-P

i take the 60-250mm to be way too big. i did mention the 180/4 cv as an example of what i want.

@ Tyr

i want an actual 180mm or 200mm lens at a speed about f/4. i don't want to start confusing things by talking of crop factors etc., so i always talk in terms of the actual focal length of the lens.

i already own a 200/2.8. taking one stop away would bring the bulk down very considerably. something like a modern version of the old 200/4 m-series, or the 150/3.5 type size. that sort of thing as a limited would be great.

not only is it what i want, but it is consistent with a large part of pentax's design philosophy with what they started with the da limiteds. it just makes a lot of sense to me for them to release such a lens.

a longer telephoto da-limited.

something like the voigtlander 180/4, but with autofocus. compact, well built, excellent optics, and with a bit of speed taken off to keep the bulk down. it would be in keeping with their current strategy with regards to their primes, and i'd certainly be among the first to preorder one if it were announced.

anyone else think the same?

i had one, just because it was meant to be one of the must-have pieces of pentax equipment. i found i didn't use it, and sold it on.

i'd agree with your decision to sell. it's a fine piece of equipment, but it's always best to have stuff that you use.

i had a 35mm da limited macro that couldn't focus all the way to infinity. it needed some readjustment due to some loose bits inside.

if you grab the focussing ring and try to wobble it, is there any play? i.e. not if you try to turn it, but if you try to push it up and down in the way that it's not meant to go. it should be pretty sturdy and stable. it should hardly move in that direction. if it does move, then you likely have the same problem that i did, and your lens needs to be repaired.

to answer your first question first:

the 40/2.8 and the sigma 50/1.4 are very very different lenses. the 40/2.8 is probably the smallest lens you will ever use, especially if you count hood sizes. it will not add any weight to your kit, and is excellent optically. i had one, sold it, and regret it a little bit (but only a little bit, since now the gap is very nicely filled by the excellent 31/1..

the 50/1.4 is an excellent lens. but it's heavy. the two stops is a big deal, but so is the weight. so, it's up to you. is background isolation very important? is low light important? then the 50/1.4 is a better bet. is lightweight more important? are you going to be using this mainly for landscapes with a deep dof, then the the 40/2.8 is the one to go for.

lots of people above have suggested excellent alternatives. the 30/1.4 that smeggypants suggests is an excellent lens. the focal length is slightly better suited to me as a walkaround lens than the 40mm or the 50mm. i could walk around with the 40mm, but the 50mm is pushing it one step too far. the 55/1.4 da* is also an excellent lens. the 50/1.4 fa is a good fifty too (pentax has only ever made 50s of the highest calibre—you can't go wrong with any of them), the 50/1.4 pentax fa is also much smaller than the sigma, which you might bear in mind if you want something that fits the bill between the 40/2.8 and the 50/1.4.

lenses, as with most camera equipment, serve different purposes. which one you get should mainly be driven by what you value in a lens; not what other people think.

everyone here has recommended decent lenses. i'd just think about what it is that you want, and then choose the lens accordingly.