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01-21-2009, 05:23 AM   #31
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well, exposure/IQ degradation was expected with the correction lens.
too bad for the 1.5 teleconverter effect.

01-21-2009, 09:56 AM   #32
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QuoteQuote:
QuoteQuote:
While many nikon F's will fit directly on a pentax camera the fit is sometimes not too secure.

It is often pretty easy to remove the Nikon's bayonet & replace it with a pentax bayonet. A pentax bayonet plate can be scavanged from a scrap lens or use a flange-type m42-Pentax K adapter that can be purchased from ebay - drill holes in it to align with the screw holes in the nikon lens.
This sounds fascinating, but I thought there was something about distance from the sensor? Have you, personally, done this with a Nikon to Pentax mount? If so, which lenses and what are your feelings? Was it worth it is what I am getting at here? Thanks.


Here's a link to how to do the conversion. UPDATE - First Conversion to K Mount Success!: Pentax SLR Talk Forum: Digital Photography Review

I have not done it but plan to. I will do an easier conversion resulting in a non-auto aperture.

There is a small flange distance problem (the nikon expects to be 46.5mm from the sensor and the K's mating surface is 45.46mm from the sensor.) To insure focus at infinity a 1mm or thicker shim is used to increase the length of the nikon lens.

Dave
01-21-2009, 11:15 AM   #33
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The test shots HGM posted are very helpful. You'll need to compensate for the crop factor and seemingly darker rendering of the scene (most notably the word "Shack" on the door almost cannot be read).

I don't think there's anything to be lost in trying. Takumar fans are some pretty die-hard folk, trust me I know this, and they have great glass to back up that attitude. Every brand has it's "Damn!" lenses. I'm not too well versed in Nikon, but Canon has it's L series for example, Pentax the Limited range and DA* tele-primes, etc. Trying to cobble together the strengths of multiple brands is worth a shot, you just have to know there will likely be obstacles inherent in making two things work together that were obviously never intended to. If there is sufficient IQ loss, for example, then the benefit of that Nikon glass becomes nil, or even a detriment, compared to Pentax lenses.

It's all dependent on that lens in the adapter. This is why I've never used a teleconverter and use most of my lenses "naked" (no filters), because the quality of the glass is almost always going to be better in the lens than on the auxiliary bits, and then you're limiting yourself to what the filter/converter can do, and not the lens.

Let us know how this pans out.
01-21-2009, 05:22 PM   #34
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Drew, that's a good summation. there aren't too many 'bad' Pre-Ai, AI & AIS Nikkors, some are rated higher (legendary! eg. 105/2.5, 180/2.8) than others, but so far I can't find a good reason to buy a Nikkor with the intention of using it on a P/K mount camera. It's not like there are no 'native' equivalents, unless you're talking about some exotic item (maybe a PC lens... do Pentax do them?).

In some of the other experiments I've done I can see the Nikkors (and a Tokina ATX 80-200/2.8 that I bolted on) can potentially be better than my Pentax lenses (DA16-45 & DA50-200) but the focusing (and I have a split image focusing screen... the viewfinder is just so much smaller and dimer than my Nikon 35mm cameras) and stopping down (after focusing) is just too much of a pain to by worth it. Maybe usable if using a tripod.

I'll try to perform some 'quality' based tests soon.

Nige.

01-21-2009, 05:28 PM   #35
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QuoteOriginally posted by newarts Quote
Here's a link to how to do the conversion. UPDATE - First Conversion to K Mount Success!: Pentax SLR Talk Forum: Digital Photography Review

I have not done it but plan to. I will do an easier conversion resulting in a non-auto aperture.

There is a small flange distance problem (the nikon expects to be 46.5mm from the sensor and the K's mating surface is 45.46mm from the sensor.) To insure focus at infinity a 1mm or thicker shim is used to increase the length of the nikon lens.

Dave
what I find interesting is the use of a flanged mount, as any conversions I have considered always come down to where to get a mount.


HGMonaro

As far as focusing and metering is concerned, having now bought a couple of M42 lenses, I actually find the stopping down issue not an issue at all. and I don't see where some complain about dark viewfinders. I would only consider converting a fast lens that I don't already have an equivelent of in K mount. with faster than F2.8 it is not a question of a dark finder, but a bright one
01-21-2009, 06:08 PM   #36
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Lowell,

No doubt practice makes perfect!

I just can't see myself persisting with these (the Nikkors via adaptor) unless the results are worth it (initial experiments would say no... combined with the lack of viewfinder clarity, multipler factor & light loss). Would depend on the type of photography you're doing too, no good for chasing kids around the yard!

Manual focusing with my FM2n & FE Nikons is a breeze, even in low light. The split image and surrounding micro-prism is very easy to see. I only have a 'cheapy chinese' screen in the Pentax but it's nowhere near as easy to see (most of my mucking around has been with a 50/1.8 lens)

Cheers, Nige
01-21-2009, 09:55 PM   #37
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QuoteOriginally posted by Lowell Goudge Quote
what I find interesting is the use of a flanged mount, as any conversions I have considered always come down to where to get a mount.

...
I used a flanged m42 adapter as a replacement for an Olympus OM flange on a 200/2.8 Soligor lens and it worked well. Just remove the OM flange and replace it with the m42/K adapter.

Dave
01-22-2009, 01:18 AM   #38
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I e-mailed JinFinance (EBay seller of Nikon Adapter) asking how much light is lost through the adapter. His answer is "1/4 of a stop." I think it would a mistake to use the adapter, but the advice found in DPR forum on how to bayonet F-Mount Nikon lenses directly onto Pentax bodies might be a good option. A couple of F-Mount lenses will actually bayonet right onto K-Mount Pentax and lock! Other lenses do not lock, but apparently turn into the mount enough to be usable. Here are 2 shots Carpenter posted which are the product of the Nikon Nikkor 55mm f/3.5 on a Pentax body--both are wide open. You can read the entire thread here thanks to Troyz:

Using Nikon F Lenses On Pentax K Bodies (LBA Post): Pentax SLR Talk Forum: Digital Photography Review


Last edited by Jewelltrail; 09-25-2009 at 08:59 AM.
01-22-2009, 11:19 PM   #39
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Thank you, to everyone, for all of your contributions in this thread--I appreciate the help.
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