Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
05-14-2017, 11:31 AM   #1
New Member
philodragon's Avatar

Join Date: Apr 2015
Location: San Diego, CA
Photos: Albums
Posts: 22
Double Lens Adapter Question (Canon to Pentax)

Hello all,

I am trying to find a way to use my Rokinon 8mm Canon Fisheye lense with my Pentax K5 (I switched from Canon to Pentax some years back). I have learned that there are no adapters for Canon lenses that would make them compatible with my K5. However, a friend mentioned using a Nikon adapter and then using a Canon adapter on top of that in order to make it compatible. Has anyone seen this work? Any drawbacks?

Happy shooting,



05-14-2017, 11:48 AM   #2
amateur dirt farmer
Loyal Site Supporter
pepperberry farm's Avatar

Join Date: Dec 2014
Location: probably out in a field somewhere...
Photos: Gallery | Albums
Posts: 28,645
wouldn't it be easier to sell the Canon lens and purchase a Pentax-mount lens?
05-14-2017, 12:02 PM - 1 Like   #3
Loyal Site Supporter
Loyal Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: North Syracuse, NY
Photos: Gallery
Posts: 16,058
Just buy it in K-mount...We're not talking about an exotic lens...
05-14-2017, 01:41 PM   #4
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 41,478
To answer your question...it will not work for the same reason why a Canon-to-K adapter will not work.*


Steve

* Yes, they do exist, but Canon has a short registration distance meaning that an auxiliary glass element is required to attain infinity focus on cameras having a longer registration. This is true for both Pentax (M42 and K) as well as Nikon F.

05-14-2017, 02:57 PM   #5
Forum Member




Join Date: May 2017
Location: Dublin, Ireland
Photos: Albums
Posts: 79
Adapters can be had for Canon mounts that pre-date the EOS line. I have an adapter that will let me use lenses designed for the Canon Pellix and AE-1 lines.
I used to know why the EOS lenses couldn't be adapted.. but can't remember right now. The information is out there on the 'net somewhere.
05-14-2017, 03:02 PM   #6
Site Supporter
Site Supporter




Join Date: Nov 2012
Location: North Wales
Photos: Gallery | Albums
Posts: 2,556
It's not just the registration distance. Canon bayonets are wider than the others - the camera has a bigger "throat". Thats why other mounts (PK, CY, Nik F, OM) easily adapt to canon. The canon reg distance in shorter, and the other bayonets fit "inside" the canon bayonet. Just doesn't work the other way round.
The only way to go in these cases (other than getting a PK mount example of the lens, as already recommended, is a mount swap.
05-14-2017, 03:34 PM   #7
Loyal Site Supporter
Loyal Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: North Syracuse, NY
Photos: Gallery
Posts: 16,058
QuoteOriginally posted by Heebie Quote
Adapters can be had for Canon mounts that pre-date the EOS line. I have an adapter that will let me use lenses designed for the Canon Pellix and AE-1 lines.
I used to know why the EOS lenses couldn't be adapted.. but can't remember right now. The information is out there on the 'net somewhere.
EOS has a wider mouth, shorter registration distance, and electromagnetic aperture. A corrected adapter would be pointless on an UWA or Fisheye because it is a short TC...

07-19-2017, 03:30 AM   #8
Senior Member




Join Date: Jul 2010
Posts: 273
Tell me more pls as I have some bunch of Canon FD lenses. Were you successful to mount FD glass on Pentax body?


-----
QuoteOriginally posted by Heebie Quote
Adapters can be had for Canon mounts that pre-date the EOS line. I have an adapter that will let me use lenses designed for the Canon Pellix and AE-1 lines.
07-19-2017, 06:23 AM   #9
Site Supporter
Site Supporter
timw4mail's Avatar

Join Date: Apr 2017
Location: Driving a Mirage
Photos: Gallery | Albums
Posts: 1,669
QuoteOriginally posted by Prakticant Quote
Tell me more pls as I have some bunch of Canon FD lenses. Were you successful to mount FD glass on Pentax body?


-----
They still require a glass element, and that leads to quite a cut in image quality. ( I have an FD to PK adapter, and a Canon 50/1.8)

So, not really worth it.
07-19-2017, 07:47 AM   #10
New Member




Join Date: Jun 2016
Posts: 14
Some possible options:

Replace the mount on the lens:
Leica & Pentax & Nikon | Leitax

Replace the mount on the camera:
Pentax K+ Multi Mount - Adaptist
07-19-2017, 09:03 AM   #11
Loyal Site Supporter
Loyal Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: North Syracuse, NY
Photos: Gallery
Posts: 16,058
QuoteOriginally posted by Prakticant Quote
Tell me more pls as I have some bunch of Canon FD lenses. Were you successful to mount FD glass on Pentax body?


-----
The FD to K adapter is a short teleconverter (1.43x). It has a single corrective element and is just about useless wide open...If you take the corrective element out it becomes a short extension tube.

adapters for non-K-mount lenses to Pentax K-mount DSLRs: new dimensions for LBA - PentaxForums.com
07-19-2017, 12:27 PM   #12
Senior Member




Join Date: Jul 2010
Posts: 273
THX, might be worth giving a FD 300mm/4.0L + K-3 a try, at least for fun


-----
QuoteOriginally posted by boriscleto Quote
The FD to K adapter is a short teleconverter (1.43x). It has a single corrective element and is just about useless wide open...If you take the corrective element out it becomes a short extension tube.
07-19-2017, 02:41 PM   #13
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 41,478
QuoteOriginally posted by altis Quote
Replace the mount on the lens:
Leica & Pentax & Nikon | Leitax

Replace the mount on the camera:
Pentax K+ Multi Mount - Adaptist
Neither will work with Canon FD or EF (the mounts under discussion on this thread).


Steve

Last edited by stevebrot; 07-19-2017 at 04:50 PM.
07-19-2017, 05:55 PM   #14
Site Supporter
Site Supporter
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 16,918
QuoteOriginally posted by timw4mail Quote
They still require a glass element, and that leads to quite a cut in image quality. ( I have an FD to PK adapter, and a Canon 50/1.8)

So, not really worth it.
I have tried optically corrected canon FD to PK and Nikon AI to PK , depending on the optics quality they have quite a lot of color blooming at wide apertures, and are essentially teleconverters, the Nikon has a 1.25 X magnification ratio the canon about 1.45x from memory.

If you want soft blurry low contrast portrait lens it does the job but not much else
07-19-2017, 07:14 PM   #15
Forum Member




Join Date: May 2017
Location: Dublin, Ireland
Photos: Albums
Posts: 79
QuoteOriginally posted by Prakticant Quote
Tell me more pls as I have some bunch of Canon FD lenses. Were you successful to mount FD glass on Pentax body?


-----
I've not had any issues with them. I'm sure there's degradation, as it's a relatively inexpensive adapter, but it's still reasonable. I did recently get "native" Pentax glass to replace the Canon lenses I was using. I could try shooting a few examples of K vs. FD adapted to K if I have the time and anyone would be interested.
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!
adapter, adapter question canon, canon, k5, lens adapter question, pentax, tripod
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Looking for a focusing rail that can double up as a nodal point adapter for 645D / Z r4heim Pentax Medium Format 4 03-23-2016 07:36 AM
Double Exposure: Canon vs. Nikon interested_observer General Talk 3 12-23-2011 06:35 AM
Pentax to Canon EF adapter question thorir Pentax SLR Lens Discussion 13 11-14-2011 11:07 PM
Nature Double Double-banded plover groom Kailash Photo Critique 3 02-04-2011 01:20 PM



All times are GMT -7. The time now is 04:26 PM. | See also: NikonForums.com, CanonForums.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