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04-17-2011, 07:46 AM   #1
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Fitting Nikon lenses on Pentax body

Sorry if the title seems a bit provocative, but it's not, really
See, I have a friend that own an arsenal of Nikon stuff. Well, I'm a true Pentaxian, like anyone here as a matter of fact, I sold my D40 to get my K100D , but these F mount manual lenses are said to be great, I on the other hand have not play with manuals while on D40. So on the need to find out myself basis, I'm going to take a bite. Heard somewhere that F mount lenses can be mounted on K mount camera, with a trick or something like that. So, what's the do's and don'ts here?

04-17-2011, 08:00 AM   #2
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Pre-AI Nikon lenses can be force fit without modification. AI lenses need to be modified to be force fit, or an optically corrected adapter needs to be used. The adapter reduces IQ and causes increased CA wide open. It also acts as a short tele-converter making wide angle lenses mostly useless.

I'm sure RioRico and Lowell Goudge will be along with more advice.
04-17-2011, 08:04 AM   #3
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I have a few lenses here that I've played around with this way and tbh. I was a little disappointed with the whole - you can mount a Nikkor lens on a Pentax outcome

The main issue is that it never actually seats properly on the mount. And so there seemed to be stray light getting into the mirror box. However, the main point is, that it can be done! and that it works(to an extent )

One other issue I'd point out is where Nikon lenses twist-on in reverse in contrast to PK lenses

Whatever the case, if you decide to try it, be careful when messing with other lens mounts.
Some people have chipped away small flakes of metal off their mount of flanges only to find some in their mirror boxes later.

FTR. I converted a NIkkor *ED 180 prime to PK mount(officially). It was an ad-hock job, but it turned-out to be much safer than twisting it onto the mount and using it that way.
04-17-2011, 08:22 AM   #4
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QuoteOriginally posted by boriscleto Quote
Pre-AI Nikon lenses can be force fit without modification. AI lenses need to be modified to be force fit, or an optically corrected adapter needs to be used. The adapter reduces IQ and causes increased CA wide open. It also acts as a short tele-converter making wide angle lenses mostly useless.

I'm sure RioRico and Lowell Goudge will be along with more advice.
This is what I've heard, just can't really picture it myself.
Adapter would be out of the question. Besides IQ drop, it cost quite high. I might as well saving it for the real K's.

QuoteOriginally posted by JohnBee Quote
I have a few lenses here that I've played around with this way and tbh. I was a little disappointed with the whole - you can mount a Nikkor lens on a Pentax outcome

The main issue is that it never actually seats properly on the mount. And so there seemed to be stray light getting into the mirror box. However, the main point is, that it can be done! and that it works(to an extent )


One other issue I'd point out is where Nikon lenses twist-on in reverse in contrast to PK lenses

Whatever the case, if you decide to try it, be careful when messing with other lens mounts.
Some people have chipped away small flakes of metal off their mount of flanges only to find some in their mirror boxes later.

FTR. I converted a NIkkor *ED 180 prime to PK mount(officially). It was an ad-hock job, but it turned-out to be much safer than twisting it onto the mount and using it that way.
Ok, I see a bunch of E series on my friend's collection. I'm assuming that they're AIs mounted? What's my chance of ruining my K100D mount here?

04-17-2011, 08:38 AM   #5
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QuoteOriginally posted by minahasa Quote
Sorry if the title seems a bit provocative, but it's not, really
See, I have a friend that own an arsenal of Nikon stuff. Well, I'm a true Pentaxian, like anyone here as a matter of fact, I sold my D40 to get my K100D , but these F mount manual lenses are said to be great, I on the other hand have not play with manuals while on D40. So on the need to find out myself basis, I'm going to take a bite. Heard somewhere that F mount lenses can be mounted on K mount camera, with a trick or something like that. So, what's the do's and don'ts here?
You might want to take a look here
04-17-2011, 09:21 AM   #6
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Hi
I have modified a few Ai, you use the original mount as a .98mm spacer by
filing or sanding it flat. removing all of the original bayonet mount.
Redrill a Pentax mount using the Nikon one as a guide.
Reinstall all of the Nikon aperture controls ( Less the aperture lever )back on to the flange that is now a spacer.
Using the Nikon screws install the Pentax mount onto the lens.
If the infinity is off, remove the Pentax mount and sand the back of it to make it
a little thinner.
The aperture will work manually like a preset in AV mode.

Remember don,t do any work on the lens and always wash and dry completly
any parts before reinstalling onto the lens !
You don't want ANY dust or metal to get into the lens or camera.
05-26-2011, 04:20 PM   #7
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I have a few left over Nikon lenses and thought about doing the cut-and-grind mod to use them as manual PK lenses but decided against it

I've seen a few different ways to use a Nikon lens close focus only on a pentax body (no infinity focus) using parts from glassless TCs, or joining extension tube parts from both brands.

I take the center out of a T-mount to PK adapter (ebay $3 to $5) and just put the adapter over the Nikon Bayonet and hold it in place with the 3 adapter set screws. Just make sure the set screws catch the bayonet lugs. You can do this to an old lens or clamp the adapter to a Nikon extension tube, converting it to a N to PK extension tube to keep from damaging a good lens.
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05-26-2011, 07:45 PM   #8
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Yes, I've modded a few N/Ai lenses. As mentioned, pre-AI lenses don't need modification, will just press-fit, but not very securely. Modded or not, I wouldn't recommend trying to use any longer heavier lenses. I sometimes mount a 200mm pre-AI but I must be very careful using it. And the one AF lens I tried just didn't grasp the PK mount. So the only lenses I attempt are manual-focus N/AI's.

My first mod was a Nikkor 85/2 that cost me US$9, and it scared me silly. I worked fretfully for a couple days. Now I can do a mod in five minutes, ten if the phone rings. I work on a railing on my back porch in good weather, or on a 1x8in plank over my bathroom sink in bad weather. Yeah, it's a real state-of-the-art workshop, eh?

Needed: A Dremel tool, with a metal-cutting disc and maybe a sanding disc; a dust blower. The aperture ring has two protrusions, what I call the "nub and arc". Use the Dremel to cut those off, so the bottom of the aperture ring is flat. Use the sanding disc to smooth the lower surface of the ring. Blow all the metal dust away. Mount the lens on a PK mount, and you're ready to go! NOTE: Some N/AI's have a long flag extending down that might foul the Pentax mirror. I use wire cutters to clip it off.

That is still only a press-fit. For more security, you need a slot for the PK lens locking pin to engage. I suggest using the metal-cutting disc until it's worn down to about 12mm diameter, so you won't cut away too much lens base metal. Find the appropriate place on the lens base and cut a slot about 1.5mm wide and deep, and 6mm long. Now position the lens so the locking pin bites in. You're set!

It takes me longer to write about it than to do it. For your first attempt, try a cheap disposable lens, for practice. Only mod lenses that you KNOW you will never want to sell, because this is irreversible. A modded lens will safely short the PK mount contact pins, so you can use Catch-In-Focus. I have modded several lenses now and am very satisfied with the results.

09-06-2013, 08:50 PM   #9
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QuoteOriginally posted by RioRico Quote
...Needed: A Dremel tool, with a metal-cutting disc and maybe a sanding disc; a dust blower. The aperture ring has two protrusions, what I call the "nub and arc". Use the Dremel to cut those off, so the bottom of the aperture ring is flat. Use the sanding disc to smooth the lower surface of the ring. Blow all the metal dust away. Mount the lens on a PK mount, and you're ready to go! NOTE: Some N/AI's have a long flag extending down that might foul the Pentax mirror. I use wire cutters to clip it off.
....
Would you be having some pics of the conversion process?

Thanks
09-07-2013, 05:28 AM   #10
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I too have modified Nikon lenses, one using a Pentax M42 flanged adaptor (they only cost about$5' the other using an M42 mount from a donor lens.

If the lenses are cheap, or free, I think it would be better to pick up a Nikon body that supports manual metering(there are a few) and use it.
05-30-2014, 07:13 AM   #11
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QuoteOriginally posted by boriscleto Quote
Pre-AI Nikon lenses can be force fit without modification. AI lenses need to be modified to be force fit, or an optically corrected adapter needs to be used. The adapter reduces IQ and causes increased CA wide open. It also acts as a short tele-converter making wide angle lenses mostly useless.

I'm sure RioRico and Lowell Goudge will be along with more advice.
I don't agree with you. Look at the picture on the website so that you will learn how to mount a Nikon lens onto a Pentax DSLR body.

http://www.mitbbs.com/article_t/PhotoGear/35129953.html

AI-type Nikon F-mount lenses are just ok on a Pentax k-mount body. You even don't need to modify the lens's mount. You just need to turn the lens a little bit to left or right (depends on which side you are looking at the camera and the lens. After it is mounted and when you hold the camera to take a picture, the aperture center mark should be tilted to left) and try to find a best position to connect them. The connection is tight enough for most prime lenses as long as the weight is moderate, so that you are free to change aperture and focus. I am not sure whether the connection is secure or not if a lens is too weight.

With my experience, Both Non-AI and AI Nikon lenses can work on a Pentax body directly without an adapter. The focusing distance is exactly as the distance marks on the AI lenses, and a little bit change on the non-AI lenses but focusing on infinite is still ok.

However, you must be very careful when you try to mount a Nikon lens onto a Pentax body. "Tightened enough" is enough. It should not be over tightened, otherwise it may hurt your camera body's mount.

Last edited by PTCLG; 06-06-2014 at 09:09 AM. Reason: Added a link and correct some incorrect statement for non-AI lenses.
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