Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-24-2017, 09:10 AM   #16
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 31,435
QuoteOriginally posted by pathdoc Quote
True, but it may be viable for the person who desperately wants to shoot Nikkor against Asahi glass on a DSLR (e.g. with a split focusing screen fitted) and needs everything else (sensor, processor, etc) to be held constant.
Then "force fit" is the answer. Pentax Forum user @carpents used this approach in his famous Normal Lens Shoot-out with the K10D.

the Normal Lens Shootout Photo Gallery by Sean Carpenter at pbase.com


Steve

03-24-2017, 09:49 AM   #17
Veteran Member




Join Date: Dec 2016
Posts: 532
I have 2 Vivitar AI F-mount and a 28-85 AF Nikkor..On a K30 all 3 fit, but the Nikkor doesnt twist enough and it falls out with a slight strike, the Vivitars fit pretty in, no problem
But on a K5iis, they will not bayonet.
As for the infinity focus, you can try to readjust the front element, but you will close focus..lens focus ranges are set and cant expand
03-24-2017, 10:38 AM   #18
Site Supporter
Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: North Syracuse, NY
Photos: Gallery
Posts: 14,026
QuoteOriginally posted by Jeff Lopez Quote
I have 2 Vivitar AI F-mount and a 28-85 AF Nikkor..On a K30 all 3 fit, but the Nikkor doesnt twist enough and it falls out with a slight strike, the Vivitars fit pretty in, no problem
But on a K5iis, they will not bayonet.
As for the infinity focus, you can try to readjust the front element, but you will close focus..lens focus ranges are set and cant expand
AF F-mount lenses have the electrical contacts. They are out for force fitting. AI F-mount lenses can be force fit, but the aperture ring works better if you get rid of the AI part...
03-24-2017, 10:55 AM   #19
Veteran Member




Join Date: Dec 2016
Posts: 532
QuoteOriginally posted by boriscleto Quote
AF F-mount lenses have the electrical contacts. They are out for force fitting. AI F-mount lenses can be force fit, but the aperture ring works better if you get rid of the AI part...
The AI vivitars are already grinded, per RioRicos example, but they wont bayonet on a K5iis..

03-24-2017, 02:16 PM   #20
Veteran Member




Join Date: Nov 2012
Location: North Wales
Photos: Gallery | Albums
Posts: 1,868
As already mentioned the PK and nikon F bayonets are very similar, and it is possible to force fit an F mount lens onto a pentax, usually in an upsidedown position. two wee points not mentioned as to why there isn't a simple F to PK adapter:

1. only older lenses are F mount, most are AI mount, bayonet is the same but now there are aperture linkages protruding that prevent the lens sitting flat against a Pk if you try to force fit it.
2. the throat sizes are too similar. Canon is good for adapting other lenses eg PK, OM, CY Nikon because of its larger throat ie eos bayonet is larger across, so there is easily sufficient space for the other bayonets + adapter.

Last edited by marcusBMG; 03-24-2017 at 03:41 PM.
03-24-2017, 02:53 PM   #21
Loyal Site Supporter
Loyal Site Supporter
WPRESTO's Avatar

Join Date: Aug 2010
Location: Massachusetts
Photos: Gallery | Albums
Posts: 35,964
QuoteOriginally posted by THoog Quote
No, no, I understood you perfectly, and agree on all points - I was only correcting the math. (46.5-45.46 = 1.04)
Mea culpa
03-25-2017, 04:29 AM   #22
Loyal Site Supporter
Loyal Site Supporter




Join Date: Mar 2015
Photos: Gallery | Albums
Posts: 6,273
So in other words, the only Nikon lenses that go on a Pentax K mount smoothly are... what? Takumar era?
03-25-2017, 05:03 AM   #23
Loyal Site Supporter
Loyal Site Supporter
WPRESTO's Avatar

Join Date: Aug 2010
Location: Massachusetts
Photos: Gallery | Albums
Posts: 35,964
QuoteOriginally posted by pathdoc Quote
So in other words, the only Nikon lenses that go on a Pentax K mount smoothly are... what? Takumar era?
More or less, BUT, do not casually dismiss those lenses. Some were the best of their era, and some old SFL Nikkors stand up very against modern zoom lenses. Look back at great, iconic images taken from say 1960 to 1980 and see how many were taken with SFL Nikkors.

03-25-2017, 05:19 AM   #24
Loyal Site Supporter
Loyal Site Supporter




Join Date: Mar 2015
Photos: Gallery | Albums
Posts: 6,273
QuoteOriginally posted by WPRESTO Quote
More or less, BUT, do not casually dismiss those lenses.
I wasn't trying to be dismissive - I was merely putting them into their temporal context. Take a look at the lens inventory in my signature and you will divine in short order EXACTLY what I think of Takumar-era lenses.

(I am sometimes tempted to try ancient, pre-AI film Nikons or even Olympuses, but my half of the library is crowded enough with film cameras already, and if I get into another film-era ecosystem I think my wife will probably brain me with a skillet in my sleep.)
03-27-2017, 10:54 AM   #25
Loyal Site Supporter
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 14,702
QuoteOriginally posted by marcusBMG Quote
As already mentioned the PK and nikon F bayonets are very similar, and it is possible to force fit an F mount lens onto a pentax, usually in an upsidedown position. two wee points not mentioned as to why there isn't a simple F to PK adapter:

1. only older lenses are F mount, most are AI mount, bayonet is the same but now there are aperture linkages protruding that prevent the lens sitting flat against a Pk if you try to force fit it.
2. the throat sizes are too similar. Canon is good for adapting other lenses eg PK, OM, CY Nikon because of its larger throat ie eos bayonet is larger across, so there is easily sufficient space for the other bayonets + adapter.
In nikon lingo F mount is the entire collection of various types of the F mount. There is no "AI mount" but this is not really different from the fact that there is a Kaf and Kaf2 and a Kaf4 mount but all are called K mount etc. The point you have made is reasonable. The purported fix which is used in more than just this situation is to thin the AI tab from the rear - this supposedly allows it to slip past the Pentax mount and still be used on Nikon AI cameras. I have seen this claim online but I have not tested it. I know this is also what some adapter users in the mirrorless world say that they have done if they don't have a true AI compatible adapter (usually too cheap to buy another adapter). You can also butcher the lens by completely removing the AI tab but that's not nice to the future users of the lens who might be Nikon users.
03-27-2017, 11:00 AM   #26
Loyal Site Supporter
Loyal Site Supporter




Join Date: Mar 2015
Photos: Gallery | Albums
Posts: 6,273
QuoteOriginally posted by marcusBMG Quote
Canon is good for adapting other lenses eg PK, OM, CY Nikon because of its larger throat
Is this also why Canon, alone (IIRC) of all the manufacturers, is able to offer an f/1.0 lens for its DSLRs?
03-27-2017, 11:03 AM   #27
Site Supporter
Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: North Syracuse, NY
Photos: Gallery
Posts: 14,026
QuoteOriginally posted by pathdoc Quote
Is this also why Canon, alone (IIRC) of all the manufacturers, is able to offer an f/1.0 lens for its DSLRs?
If you are willing to pay the price you too can turn it up to 11...

Canon 50mm f/1.0 Review
03-27-2017, 12:21 PM   #28
Loyal Site Supporter
Loyal Site Supporter




Join Date: Mar 2015
Photos: Gallery | Albums
Posts: 6,273
QuoteOriginally posted by boriscleto Quote
If you are willing to pay the price
Pass.
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, bayonet, bayonet mounts, bodies, camera, diaphragm, fit, focus, infinity, k-mount, lens, lenses, mirrorless, mount, nikon, pentax, pentax lens, plate, registry, replacement, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Travel If there were no pastor, if the sheep were left without shepherds.. zztopd Post Your Photos! 6 07-26-2018 03:21 PM
Is FD lens on K-01 (without glass adapter) and focus to infinite possible? dmb video Pentax K-01 19 01-25-2013 01:35 PM
Prescription Corrective Lenses and Focusing Carson Photographic Technique 13 12-03-2012 02:34 AM
May 1st, 2012 A Day Without the 99% No Work No School No Housework No Shopping jogiba General Talk 4 05-02-2012 02:48 AM
GIMP Photo Manipulation - Corrective Rotation dosdan Digital Processing, Software, and Printing 3 06-16-2008 05:32 AM



All times are GMT -7. The time now is 08:51 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