PK to m4/3 focal reducer

MohoWu · 11-16-2017, 06:47 AM

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Does anyone have any experience with using pentax lenses on m4/3 body using some of those relatively cheap focal reducers (like this)?

I know everything needs to be manual using these adaptors, but I'm curious how you change the aperture if your lens doesn't have a aperture ring.

It'd be great if anyone could share some sample images taken at different apertures to see how the sharpness compares with mounting the lens on a native Pentax DSLR.

With the new Panasonic G9 coming out soon with both great still and video feature in a relatively small body, I'm really considering moving to the m4/3 system. But I'm reluctant to completely get rid of my Sigma zoom lenses like the 17-50 and 50-150 f2.8 since they are pretty sharp. It would be ideal if these focal reducers can make these lenses somewhat usable on the m4/3 body.

Last edited by MohoWu; 11-16-2017 at 06:53 AM.

timw4mail · 11-16-2017, 06:57 AM

Originally posted by MohoWu

I know everything needs to be manual using these adaptors, but I'm curious how you change the aperture if your lens doesn't have a aperture ring.

You can't change the aperture without an aperture ring, when adapting a lens.

**UncleVanya** · 11-16-2017, 07:07 AM

I haven't used a focal reducer, but I do shoot m43 sometimes with an adapter and my k mount lenses. The adapter I have had a ring that says "open/close" and is labeled pentax DA to m43. The open close is an infinitely variable turn to operate ring. The effect is to full ofy open or fully close the aperture or any position in between. Shooting in any mode that meters and doesn't expect to change aperture for you works fine but you won't precisely know what aperture you have set unless you pre-calibrate an adapter for a particular lens and Mark the ring appropriately. It might be possible to make some paper bands to attach and remove to represent the marks but I haven't tried.
My read on the cheap focal reducing adapters is that they are very soft outside the very center and aren't usable until several stops stopped down. This isn't true of the very expensive original devices. Because of this I only use adapted lenses where the focal length makes sense. So my FA 31 as a fast semi normal lens. My FA 77 as a long portrait lens. My Rokinon 8mm as a very wide prime.
Largely however I use m43 lenses natively for the size and weight. Most of the ones I use are slow but have good image quality.

---------- Post added 11-16-17 at 09:13 AM ----------

This probably belongs in the non Pentax section.

thazooo · 11-16-2017, 07:35 AM

As others have said the cheap adapter don't work with DA or FAJ lenses. I like shooting with ST or PKA mounts on my m4/3. Simple in Av mode.
It wore off fast for me and I expanded my collection of m4/3 glass. If you go here.......... Forums | Mu-43.com - Micro Four Thirds User Group and look under adapted lens catagory you can see what others are using and the results.

11-16-2017, 06:47 AM	#1
MohoWu New Member Join Date: Mar 2016 Posts: 9	PK to m4/3 focal reducer Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here. Does anyone have any experience with using pentax lenses on m4/3 body using some of those relatively cheap focal reducers (like this)? I know everything needs to be manual using these adaptors, but I'm curious how you change the aperture if your lens doesn't have a aperture ring. It'd be great if anyone could share some sample images taken at different apertures to see how the sharpness compares with mounting the lens on a native Pentax DSLR. With the new Panasonic G9 coming out soon with both great still and video feature in a relatively small body, I'm really considering moving to the m4/3 system. But I'm reluctant to completely get rid of my Sigma zoom lenses like the 17-50 and 50-150 f2.8 since they are pretty sharp. It would be ideal if these focal reducers can make these lenses somewhat usable on the m4/3 body. Last edited by MohoWu; 11-16-2017 at 06:53 AM.

11-16-2017, 07:07 AM	#3
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,401	I haven't used a focal reducer, but I do shoot m43 sometimes with an adapter and my k mount lenses. The adapter I have had a ring that says "open/close" and is labeled pentax DA to m43. The open close is an infinitely variable turn to operate ring. The effect is to full ofy open or fully close the aperture or any position in between. Shooting in any mode that meters and doesn't expect to change aperture for you works fine but you won't precisely know what aperture you have set unless you pre-calibrate an adapter for a particular lens and Mark the ring appropriately. It might be possible to make some paper bands to attach and remove to represent the marks but I haven't tried. My read on the cheap focal reducing adapters is that they are very soft outside the very center and aren't usable until several stops stopped down. This isn't true of the very expensive original devices. Because of this I only use adapted lenses where the focal length makes sense. So my FA 31 as a fast semi normal lens. My FA 77 as a long portrait lens. My Rokinon 8mm as a very wide prime. Largely however I use m43 lenses natively for the size and weight. Most of the ones I use are slow but have good image quality. ---------- Post added 11-16-17 at 09:13 AM ---------- This probably belongs in the non Pentax section. Last edited by UncleVanya; 11-16-2017 at 07:12 AM.

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11-16-2017, 06:57 AM	#2
timw4mail Pentaxian Join Date: Apr 2017 Location: Driving a Mirage Photos: Gallery \| Albums Posts: 1,670	Originally posted by MohoWu I know everything needs to be manual using these adaptors, but I'm curious how you change the aperture if your lens doesn't have a aperture ring. You can't change the aperture without an aperture ring, when adapting a lens.

11-16-2017, 07:35 AM	#4
thazooo Pentaxian Join Date: Sep 2006 Location: Mississippi, USA Photos: Gallery Posts: 854	As others have said the cheap adapter don't work with DA or FAJ lenses. I like shooting with ST or PKA mounts on my m4/3. Simple in Av mode. It wore off fast for me and I expanded my collection of m4/3 glass. If you go here.......... Forums \| Mu-43.com - Micro Four Thirds User Group and look under adapted lens catagory you can see what others are using and the results.