Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-16-2010, 03:24 PM   #1
Forum Member




Join Date: Aug 2007
Location: Dublin, Ireland
Posts: 84
K-Mount to Micro 4/3 adapters

I'm considering buying a Panasonic GH1 for filmmaking purposes.
I love my K20D so I have no plans to change to Micro 4/3 for everything.
My FA 35mm, Sigma 24-60mm f/2.8 and Tammy 70-300mm would all come in handy for films.

Do the cheap adapters on ebay have any impact on the focal length or aperture of the lenses?
I've noticed from the FD mount adapters that it increases the distance from the lens to the body quite a bit so I'd imagine it does something to the image.

09-16-2010, 03:35 PM   #2
Pentaxian




Join Date: Sep 2007
Location: Boston, MA
Posts: 7,411
The cheapest adapters don't have a mechanism to stop down the aperture on DA-series lenses (or other lenses without aperture rings). There's a more expensive version that does.

The better adapters have better protection against light leaks and are more precise with regard to preserving infinity focus, but all of them do the job well enough. The m4/3 sensor/mount has a crop factor of 2x, so your FA35 will be a 70, your 24-60 will be a 48-120, and your 70-300 will be a 140-600.
09-16-2010, 03:36 PM   #3
Veteran Member
wlachan's Avatar

Join Date: Sep 2006
Location: Canada
Photos: Albums
Posts: 2,626
The focal length & aperture won't be affected because there is no glass between PK-4/3 adaptors. However, some adaptors might be a little shorter or longer which will affect the infinity setting. Also, such adaptors might impact the edge/corner image quality of IF lenses because the non-linear glass movement is optimized based on a specific film plane distance.
09-16-2010, 03:44 PM   #4
Veteran Member




Join Date: May 2009
Location: Twin Cities, MN
Posts: 2,869
I have two adapters; one is strictly the mount extention, the other has an aperture control ( This is the ebay link - runs about double the non-aperture control adapters ).

The aperture control one isn't as solid a build as the metal ones found on ebay, but it will control the aperture (by moving the pin, purely mechanical in nature, not automatically!) for newer DA lenses which don't have aperture rings.

As Wolf said, the crop factor is 2x with m4/3 rather than 1.5x on Pentax's aps-c sensor.

The adapters don't have an affect on focal length, that is only based on the sensor size; they also don't affect the aperture as there is no glass involved, it is only setting the proper distance between the lens and sensor.

02-05-2011, 09:50 AM   #5
Forum Member




Join Date: Aug 2007
Location: Dublin, Ireland
Posts: 84
Original Poster
Does anyone have experience of this aperture control adapter? - link

I've already bought a basic model for my older lenses, but this will be used on the Tamron 17-50mm.
02-05-2011, 10:20 AM   #6
Veteran Member




Join Date: May 2009
Location: Twin Cities, MN
Posts: 2,869
Skip it. I had that one, and it is absolutely terrible build quality - thin plastic all around. I got it, played with it, and ended up never using it again.

The one I linked to above controls aperture, and is a much better build for almost half the price. When checking out, they have a $2 express shipping option; it arrived from Hong Kong to the US in about a week - well worth it, and much better than the one you linked to.

Edit: I guess the link to that auction is dead. Here is a current link to the same item:

http://cgi.ebay.com/Pentax-K-lens-MICRO-4-3-M4-3-adapter-GH1-E-P1-E-P2-/3704...item5640282ead

The seller's name is terence_camera (in case that link goes dead too!).
02-07-2011, 03:54 PM   #7
Forum Member




Join Date: Aug 2007
Location: Dublin, Ireland
Posts: 84
Original Poster
QuoteOriginally posted by pxpaulx Quote
The one I linked to above controls aperture, and is a much better build for almost half the price. When checking out, they have a $2 express shipping option; it arrived from Hong Kong to the US in about a week - well worth it, and much better than the one you linked to.
Thanks for the link! Looks like great value.
Silly seller doesn't clearly state it controls aperture.

I've already bought an ultra cheap non aperture one, which has yet to arrive.
02-07-2011, 05:55 PM   #8
Veteran Member




Join Date: May 2009
Location: Twin Cities, MN
Posts: 2,869
Yep, it looked like it did control aperture (with the open----close written on the side), and I had to ask. I am kind of guessing the design is probably a copy of a nicer adapter, so they don't put the full description in order to avoid a take-down from ebay.

02-07-2011, 07:20 PM   #9
Forum Member




Join Date: Aug 2007
Location: Dublin, Ireland
Posts: 84
Original Poster
QuoteOriginally posted by pxpaulx Quote
Yep, it looked like it did control aperture (with the open----close written on the side), and I had to ask.
I've seen the open/lock ring on Canon FD-m4/3 adapters I've used.
I assumed it was just used to lock the lens in position.
02-08-2011, 02:33 PM   #10
Forum Member




Join Date: Aug 2007
Location: Dublin, Ireland
Posts: 84
Original Poster
My cheapo lens adapter arrived today.
The quality is actually surprisingly good. It's very solid and mounts snugly to both the body and lens.

The only thing I didn't realise was that my DA lenses all stop down to minimum aperture.
I'd assumed they would stay wide open, as they do on an old film body.

Is there a way to get them to operate wide open on this cheap adapter?
02-08-2011, 02:40 PM   #11
Veteran Member




Join Date: May 2009
Location: Twin Cities, MN
Posts: 2,869
Not any kind of way I would recommend, no. I would say it is worth it to have both anyway for the following reason: the one with the aperture control FORCES you to use that aperture control - in other words, I can't know exactly what aperture is being used, even with the lenses I have which do have an aperture dial. I would suggest buying the one linked above to use your DA lenses with any sort of good results.
02-08-2011, 05:52 PM   #12
Forum Member




Join Date: Aug 2007
Location: Dublin, Ireland
Posts: 84
Original Poster
QuoteOriginally posted by pxpaulx Quote
Not any kind of way I would recommend, no. I would say it is worth it to have both anyway for the following reason: the one with the aperture control FORCES you to use that aperture control - in other words, I can't know exactly what aperture is being used, even with the lenses I have which do have an aperture dial. I would suggest buying the one linked above to use your DA lenses with any sort of good results.
I ordered the aperture control model yesterday.
I'm happy to have 2 adapters anyway, it means I can share my lenses with the other GH1 camera guys I work with.
02-28-2011, 06:26 PM   #13
Forum Member




Join Date: Aug 2007
Location: Dublin, Ireland
Posts: 84
Original Poster
QuoteOriginally posted by pxpaulx Quote
Mine arrived today. A little late considering I paid for the faster postage.

Not a bad adapter. It's solidly put together, although there's very little travel in the aperture ring.
Probably as a result of the design of the DA lenses.
03-01-2011, 06:58 AM   #14
Veteran Member




Join Date: May 2009
Location: Twin Cities, MN
Posts: 2,869
RichyX, I think that since it is actually turning the aperture lever (which doesn't have much actual travel), that results in the small amount of turn in the ring itself.

I didn't notice this at first but it is worth mentioning - if you turn the ring softly, you should notice that it actually has slight stopping points - upon reviewing where the aperture stops it appears it approximates full stops (i.e. on my 43mm LTD it is open to 1.9, then stops at 2.8, 4, 5.6, 8 etc). I say approximate as it is seems that way based only a visual measurement (comparing the actual aperture ring stops of the 43mm).
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
adapters, k-mount, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
adapters for non-K-mount lenses to Pentax K-mount DSLRs: new dimensions for LBA Douglas_of_Sweden Pentax Camera and Field Accessories 151 11-01-2014 09:26 AM
Lens mount adapters macdaddy Pentax Camera and Field Accessories 10 08-24-2010 09:20 AM
Screw to K mount adapters wildman Pentax SLR Lens Discussion 59 01-12-2009 08:47 PM
Question Regarding T-Mount Adapters Mikhail Pentax Camera and Field Accessories 4 01-30-2008 07:56 AM



All times are GMT -7. The time now is 12:11 AM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top