Modifying Pentax mount lenses for SA mount cams?

Started 1 month ago | Discussions thread
eFilm Senior Member • Posts: 1,836
Re: Modifying Pentax mount lenses for SA mount cams?

SteveNunez wrote:

As for the question "why modify" for me the answer is simple. I no longer have my Pentax K1II (FF) and have a bunch of old manual lenses lying around

...which could be sold or traded for other gear, like SA-mount lenses. Saving the K-mount lenses for some other user who appreciates un-mutilated K lenses.

and recall reading Pentax K mount is physically the same


(or near)

Is near good enough / worth it? S'pose that's the (rhetoric) question.

and can be mounted on Sigma cameras with minimal modification. Since I received my Quattro yesterday and only have the 150-500 lens and am awaiting a few other lenses I ordered,

So basically the actual motivation is impatience, right?

I figured this Pentax 50mm f1.7 lens is a great candidate to modify to use on the Quattro as I only paid $20 and tons are available on eBay. I now have a manual 50mm f1.7 lens I can shoot with and it's small and light and is very sharp: all for $20! All I had to do is snip off a lever and trim off a little bit of plastic and it works flawlessly. It snaps into place and doesn't spin just like a native lens and comes off easily when the lens release is used- all like a native lens.

How about the difference in flange distance? Looks like you can indeed focus fairly well on fairly near subjects, like that lovely model of yours (apparently she was around 4 to 6ft or less away), but what about the rest of the focus range?
I didn't know the lens will

I know what the 'mod' would entail, I've got a fully functional Pentax SLR body and a K lens or two, as well as a Sigma SDQH, but I haven't had either the 'heart' or the motivation to mutilate the len(es) to 'fit' the SA mount, for some apparent and some rather obvious downsides. Regardless of the (next to nonexistent) resale value of the lenses.

I've also got the SA to M42 adapter and a couple of M42 lenses, but I very rarely use them with the SDQH. I didn't use them that much with the SD15, either.
The M42 adapter does move the lens forward to compensate with the 1.46mm difference in the flange distance. Without any need to "mutilate" the lens.

Why wait when you can use them now on a sd Quattro!

I can think of two or three valid reasons, as described in my previous comment. For example, they work as both stills and video with nearly all mirrorless cameras, but for video they work better in their original aperture lever intact. YMMV, of course.

If you're in a desperate need for native SA lenses, I've got an old but unused 28-105mm Sigma SA mount (FF) lens, complete with original box, which I might even give away to someone in need for the price of shipping, or for a small contribution, depending on the case.

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