[Nass]

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Check out this widget: Fotodiox Lens Mount Adapter Pentax K AF Lens to MFT (Micro-4/3, M4/3) Mount Mirrorless Camera (such as OM-D E-M10, Lumix GH4, and BMPCC) w/ Aperture Control Dial - Adapters

This is a m4/3 <=> pk adapter, with an "aperture control dial" that lets the user stop down the lens. What the lever seems to do judging by the comments is push the aperture open and closed as you adjust it. So first of all my guess would be that this piece of apparatus is useful for more modern Pentax lenses that don't have an external f/stop ring. If you wanted to reverse and use one of those it might be useful - just use it as a reverse aperture controller, forget that it's a m4/3 thing. "Although the lens will fit physically, automatic diaphragm, auto-focusing, or any other functions will not operate correctly while using this adapter. In this case "stop-down mode" will need to be used when metering since the lens does not have the ability to have its aperture controlled by the camera body. You can shoot with manual mode or aperture priority mode micro 4/3 body. Infinity focusing is guaranteed." A macro cheat for folks who have modern lenses without aperture rings who want to use them reversed... and don't want to use a piece of rubberband/paper/whatever to keep the aperture closed.

BUT

What I'm after is a tad different, a bit more. What I'd like is a piece of apparatus that is like the one above, but with the added feature that it stops down the aperture when taking the pic. I don't have the skills to make it myself. I believe that all it would require some sort of tiny transmitter firing off a flash signal (ie sitting in the flash shoe) to some small battery operated servo on the adapter that'd push that aperture pin closed during the actual shot. Surely can't be that hard - and would mean you wouldn't have to try and focus with a stopped down aperture (which is a pain).

If I buy the component and parts, is there anyone on this forum with the skillz neccessary?

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Last edited by Nass; 10-14-2016 at 11:10 AM.

[Nass]

Here's the Chinese copy, even cheaper: Pentax PK K mount DA AF lens to Micro 4/3 Adapter M4/3 E-P5 OM-D G7 GX7 GH4 MFT | eBay - the advert says "With aperture control ring" so I assume you rotate it to stop down or open the aperture. Anyway I'll buy it and see if that's what it is, I'll post here when I get it

[grahame]

Here is the mechanical way of coupling shutter and lens aperture on an adapter.

[Nass]

Here is the mechanical way of coupling shutter and lens aperture on an adapter.

Very cool

[pacerr]

Try it the easy way first. Given a suitable adapter for the lens (registration distance) simply place various "disks with a hole in it" near the mid-point of the extension. Some experimentation on hole size and placement will be in order.

Look for the adapters and macro DIYs in the Q sub-forum for examples. A 10-20% step-down from wide open aperture would be a good starting point.

[UncleVanya]

I have discussed this quite frequently lately. I have done this multiple times with da lenses. (with no automation)

[BrianR]

I've eyed these up for the same purpose. I'm not sure about the ones you've linked to, but I think some of the Fotodiox models have click-stops for selecting the aperture, which I'd think would help with consistency. I'd also love a stop down mechanism like you're describing. Add in a few small LED's to help with focusing and I'm in for one

[UncleVanya]

I've eyed these up for the same purpose. I'm not sure about the ones you've linked to, but I think some of the Fotodiox models have click-stops for selecting the aperture, which I'd think would help with consistency. I'd also love a stop down mechanism like you're describing. Add in a few small LED's to help with focusing and I'm in for one

Are you sure the k mounts have click stops? Given the fact that A series and older series use different amounts of movement between f stops it would be at best consistently wrong on one or the other.

[BrianR]

Are you sure the k mounts have click stops? Given the fact that A series and older series use different amounts of movement between f stops it would be at best consistently wrong on one or the other.

No click stops on the lenses, but if the adapter has them you'd always know the amount you had turned the adapters dial and thus could be consistent with the same lens from shoot to shoot. Each lens would get a different page in the notebook, but the point would be more easily repeatable results.

[UncleVanya]

No click stops on the lenses, but if the adapter has them you'd always know the amount you had turned the adapters dial and thus could be consistent with the same lens from shoot to shoot. Each lens would get a different page in the notebook, but the point would be more easily repeatable results.

Interesting, I've never seen a k mount adapter like that, all I've seen have the clickless kind. I will seek it out as I agree that would be easier too get consistent results from.

[BrianR]

Interesting, I've never seen a k mount adapter like that, all I've seen have the clickless kind.i will church it out as I agree that would be easier too get consistent results from.

Since I can't seem to find a clicking Pentax adapter on the Fotodiox website it's possible I imagined it using wishful thinking or I just can't find it or they're hiding it since they know I'm looking for it. Either way, it was too expensive to be an impulse buy for me, so I don't have one. Even an imaginary one. Sorry if I got anyone's hopes up, unless it actually exists somewhere