The M42 adapter used on Nikon F can make a huge difference

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Albert Silver Veteran Member • Posts: 3,373
The M42 adapter used on Nikon F can make a huge difference
2

I have a few 55mm lenses and have two plain metal adapters for M42 lenses I bought from different vendors to use on my Nikon D750. So the takeaway is that the actual adapter and how thin it is makes a huge difference.

Using this adapter model (you will find a ton of clones so I won't waste time citing brands) I measured exactly 1m70 from end of lens to object of focus (very small text):

However, using this model (I found produce by Fotodiox and K&F, and probably some others) I get a full 1m91 with tack sharp focus:

As a very small aside, the Mamiya-Sekor 55 f/1.4 is easily the sharpest of my three (remarkably sharp in center already at f/1.7), followed by the Mamiya-Sekor 55 f/1.8, and in third is the Super-Takumar 55 f/1.8. it is quite possible later versions of the Takumar with SMC will do it better justice, but these are my results with what I have.

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Albert

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Ching-Kuang Shene
Ching-Kuang Shene Veteran Member • Posts: 6,330
Re: The M42 adapter used on Nikon F can make a huge difference
1

Frankly speaking, any adapter that is built to the standard does not affect image quality.  If you found an adapter that can affect image quality, it is usually (1) it is not built to the standard (e.g., thickness maybe different from side to side, etc.) , (2) it is too thin or too thick, or (3) you did not focus properly.  Let me reiterate: an adapter is just a tube without optical elements and won't affect image quality if its is built to the standard.

CK

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OP Albert Silver Veteran Member • Posts: 3,373
Re: The M42 adapter used on Nikon F can make a huge difference

Ching-Kuang Shene wrote:

Frankly speaking, any adapter that is built to the standard does not affect image quality. If you found an adapter that can affect image quality, it is usually (1) it is not built to the standard (e.g., thickness maybe different from side to side, etc.) , (2) it is too thin or too thick, or (3) you did not focus properly. Let me reiterate: an adapter is just a tube without optical elements and won't affect image quality if its is built to the standard.

CK

Who said anything about affecting image quality? I merely pointed out the maximum focusing distances.

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petrochemist Veteran Member • Posts: 3,054
Re: The M42 adapter used on Nikon F can make a huge difference
1

It will make a significant difference yes, but I wouldn't call it a huge difference.

Results from these should be miles better than those with most adapters containing 'corrective optics'. The advantage gained from this adapters will be greater when used with shorter focal lengths.

I'm surprised no-ones made an adapter that fits entirely within the bayonet. this is done regularly for PK adapters - isn't it possible on Nikon F? The screw thread certainly seems to fit inside the bayonet.

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Heritage Cameras
Heritage Cameras Senior Member • Posts: 1,846
Re: The M42 adapter used on Nikon F can make a huge difference
1

petrochemist wrote:

Results from these should be miles better than those with most adapters containing 'corrective optics'. The advantage gained from this adapters will be greater when used with shorter focal lengths.

I'm surprised no-ones made an adapter that fits entirely within the bayonet. this is done regularly for PK adapters - isn't it possible on Nikon F? The screw thread certainly seems to fit inside the bayonet.

That's an interesting idea, but an internal adapter still wouldn't achieve infinity focus with most lenses. The flange focal distance for M42 is around 1mm less than Nikon F. Still, it would focus further away than the current external ones, and infinity might just be possible with some longer lenses that focus past infinity.

Locking could be a challenge, as it is for many of the M42-PK adapters.

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Dave, HCL

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E Dinkla Senior Member • Posts: 2,321
Re: The M42 adapter used on Nikon F can make a huge difference
1

petrochemist wrote:

It will make a significant difference yes, but I wouldn't call it a huge difference.

Results from these should be miles better than those with most adapters containing 'corrective optics'. The advantage gained from this adapters will be greater when used with shorter focal lengths.

I'm surprised no-ones made an adapter that fits entirely within the bayonet. this is done regularly for PK adapters - isn't it possible on Nikon F? The screw thread certainly seems to fit inside the bayonet.

For infinity it would still require the M42 lens flange to fall 1mm deeper than where the Nikon camera flange sits. If Markerink's register distances and mount diameter for Nikon F are correct.  BTW, mount diameter 44mm could have been measured on the bayonet wings instead of the really open diameter and then there is no 1mm wall thickness available for the adapter. For the Canon EF mount the lists's diameter number is not correct in my experience, 51 instead of the quoted 54mm if the real mount hole is measured. The Nikon camera mount contacts might be in the way too, quite different on a Nikon than on other mounts.

On a Tokina PK lens mount I measure about 44,5mm for it minimum diameter so the actual camera mount hole will be between 45 and 46mm which allows more than 1,5mm wall thickness for the M42 sunken adapter.

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Ching-Kuang Shene
Ching-Kuang Shene Veteran Member • Posts: 6,330
Re: The M42 adapter used on Nikon F can make a huge difference
2

Albert Silver wrote:

Ching-Kuang Shene wrote:

Frankly speaking, any adapter that is built to the standard does not affect image quality. If you found an adapter that can affect image quality, it is usually (1) it is not built to the standard (e.g., thickness maybe different from side to side, etc.) , (2) it is too thin or too thick, or (3) you did not focus properly. Let me reiterate: an adapter is just a tube without optical elements and won't affect image quality if its is built to the standard.

CK

Who said anything about affecting image quality? I merely pointed out the maximum focusing distances.

Reading your post from the very beginning to its very end, I did not see you were referring to MAXIMUM FOCUS DISTANCES.  I only saw you talked about lens A is the sharpest, etc.  BTW, isn't the MAXIMUM FOCUS DISTANCE  infinity for any lens?  If the MAXIMUM FOCUS DISTANCES are not infinity, isn't that your adapter has an infinity focusing issue?

CK

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Heritage Cameras
Heritage Cameras Senior Member • Posts: 1,846
Re: The M42 adapter used on Nikon F can make a huge difference

Heritage Cameras wrote:

petrochemist wrote:

Results from these should be miles better than those with most adapters containing 'corrective optics'. The advantage gained from this adapters will be greater when used with shorter focal lengths.

I'm surprised no-ones made an adapter that fits entirely within the bayonet. this is done regularly for PK adapters - isn't it possible on Nikon F? The screw thread certainly seems to fit inside the bayonet.

That's an interesting idea, but an internal adapter still wouldn't achieve infinity focus with most lenses. The flange focal distance for M42 is around 1mm less than Nikon F. Still, it would focus further away than the current external ones, and infinity might just be possible with some longer lenses that focus past infinity.

Locking could be a challenge, as it is for many of the M42-PK adapters.

You can check what the maximum focus distance would be with such an internal adapter by holding the M42 lens directly against the camera's bayonet mount.

There are some potential collision points inside the camera's mount such as the electrical contacts and/or auto diaphragm lever, so caution is advised...

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Dave, HCL

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Sittatunga Senior Member • Posts: 3,151
Re: The M42 adapter used on Nikon F can make a huge difference
1

E Dinkla wrote:

petrochemist wrote:

It will make a significant difference yes, but I wouldn't call it a huge difference.

Results from these should be miles better than those with most adapters containing 'corrective optics'. The advantage gained from this adapters will be greater when used with shorter focal lengths.

I'm surprised no-ones made an adapter that fits entirely within the bayonet. this is done regularly for PK adapters - isn't it possible on Nikon F? The screw thread certainly seems to fit inside the bayonet.

For infinity it would still require the M42 lens flange to fall 1mm deeper than where the Nikon camera flange sits. If Markerink's register distances and mount diameter for Nikon F are correct. BTW, mount diameter 44mm could have been measured on the bayonet wings instead of the really open diameter and then there is no 1mm wall thickness available for the adapter. For the Canon EF mount the lists's diameter number is not correct in my experience, 51 instead of the quoted 54mm if the real mount hole is measured. The Nikon camera mount contacts might be in the way too, quite different on a Nikon than on other mounts.

On a Tokina PK lens mount I measure about 44,5mm for it minimum diameter so the actual camera mount hole will be between 45 and 46mm which allows more than 1,5mm wall thickness for the M42 sunken adapter.

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I've just checked my Nikon SLR in an idle moment. The 44mm measurement is the clear diameter inside the bayonet lugs; the internal diameter of the mating surface is 47mm. The bayonet lugs are about 1.2mm behind the mating plane, so about 160 microns further from the film plane than the Pentax register distance.  That means that, even without an adapter at all and with an M42 lens less than 47mm outside diameter, you're not going to get infinity focus with a short focal length lens.

The mating surface of my Helios 44M is about 51.7mm external diameter and it's only ⅒mm proud of the body of the lens, so it definitely can't rest on the bayonet lugs. Holding the lens tight against the camera (there's no point for me in an M42-F adapter as my digital cameras are Canons) I can focus to a maximum of about 3m.

The mating surface of my older Jupiter 9 is about 48mm external diameter and it's only ⅒mm proud of the body of the lens, so it can't rest on the bayonet lugs either. Holding the lens tight against the camera I can focus to a maximum of about 6m.

petrochemist Veteran Member • Posts: 3,054
Re: The M42 adapter used on Nikon F can make a huge difference

E Dinkla wrote:

petrochemist wrote:

It will make a significant difference yes, but I wouldn't call it a huge difference.

Results from these should be miles better than those with most adapters containing 'corrective optics'. The advantage gained from this adapters will be greater when used with shorter focal lengths.

I'm surprised no-ones made an adapter that fits entirely within the bayonet. this is done regularly for PK adapters - isn't it possible on Nikon F? The screw thread certainly seems to fit inside the bayonet.

For infinity it would still require the M42 lens flange to fall 1mm deeper than where the Nikon camera flange sits. If Markerink's register distances and mount diameter for Nikon F are correct. BTW, mount diameter 44mm could have been measured on the bayonet wings instead of the really open diameter and then there is no 1mm wall thickness available for the adapter. For the Canon EF mount the lists's diameter number is not correct in my experience, 51 instead of the quoted 54mm if the real mount hole is measured. The Nikon camera mount contacts might be in the way too, quite different on a Nikon than on other mounts.

On a Tokina PK lens mount I measure about 44,5mm for it minimum diameter so the actual camera mount hole will be between 45 and 46mm which allows more than 1,5mm wall thickness for the M42 sunken adapter.

Met vriendelijke groet, Ernst
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Yes I've also found a single diameter measurement is not very helpful for bayonet mounts, which effectively have a clear diameter (without the bayonet lugs) & an outer diameter (including the lugs). I've started collecting my own measurements for every mount I have available trying to include lengths of lugs etc. which shows internet data like the table you've supplied isn't very accurate.

My PK mounts are 44.5mm for clear diameter & about 47.4mm across the lugs as well. My measurements for OM mount make the outer diameter around 46.8mm with the clear diameter significantly smaller at 44mm, so it seems the measurements used in the table are not even consistent.

My measurements on F mount lenses suggest a clear diameter of 43mm & a greater diameter of 45.5mm which will be enough to allow a 42mm (outside diameter) thread to fit. A bit tight certainly  but this is required for the existing adapters with <1mm added registration.

I guess with the added depth from the Nikon mount there's no pressing need for reducing adapter depth as focus will typically be too limited anyway.

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ProfHankD
ProfHankD Veteran Member • Posts: 7,852
Re: The M42 adapter used on Nikon F can make a huge difference
2

Ching-Kuang Shene wrote:

Albert Silver wrote:

Ching-Kuang Shene wrote:

Frankly speaking, any adapter that is built to the standard does not affect image quality. If you found an adapter that can affect image quality, it is usually (1) it is not built to the standard (e.g., thickness maybe different from side to side, etc.) , (2) it is too thin or too thick, or (3) you did not focus properly. Let me reiterate: an adapter is just a tube without optical elements and won't affect image quality if its is built to the standard.

CK

Who said anything about affecting image quality? I merely pointed out the maximum focusing distances.

Reading your post from the very beginning to its very end, I did not see you were referring to MAXIMUM FOCUS DISTANCES. I only saw you talked about lens A is the sharpest, etc. BTW, isn't the MAXIMUM FOCUS DISTANCE infinity for any lens? If the MAXIMUM FOCUS DISTANCES are not infinity, isn't that your adapter has an infinity focusing issue?

CK,

Without glass, no M42->F adapter will come close to infinity for most lenses.

That said, bragging about 1.9m vs. 1.7m sounds like a guy who really needs to get a mirrorless and go "to infinity" (if not beyond ).

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E Dinkla Senior Member • Posts: 2,321
Re: The M42 adapter used on Nikon F can make a huge difference
2

petrochemist wrote

I guess with the added depth from the Nikon mount there's no pressing need for reducing adapter depth as focus will typically be too limited anyway.

My thoughts too. The only way to use a Mamiya M42 lens on a Nikon F for infinity would be a conversion to F mount on the lens itself. 1mm gain is not impossible with SLR lenses. FD mount conversion to EF takjes out 2mm.

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F8AD
F8AD Junior Member • Posts: 40
Re: The M42 adapter used on Nikon F can make a huge difference

It's interesting noting the mount adapters you show in an image. I have both. One is on a Helios 44-2, the other (silvery looking plating) is on a helicoid and tubes I use with a Meyer Optik 80mm Diaplan . My personal feeling from use is that the silvery plated one is better.
Why ? Because the mechanical fit is somehow better ,and it engages better on my F mount- regardless of the manufacturing tolerances, it performs and connects better.
Although it is true " any adapter that is built to the standard does not affect image quality" I have noted that the non-standard tolerances can be of benefit when adapting to some lens /register distance combinations.. There are many commercial lenses in which the maximum focus distance is not infinity ,and the stop will go past infinity. Common knowledge I thought.
The register distances listed ( thanks !) are correct in as much as the M43 and Nikon F ; I don't know about the rest because I don't use them. The problem with Nikon F and adapters is accurate flange distance ,chiefly being that while the electrical contacts mate up well, the fitment of the (black image) Photodiox -K&F adapter bayonet doesn't always lock onto the Nikon body recess well. The silvery looking adapter does. The other problem that stems from M43 adapting to Nikon F is getting infinity focus ; my Helios has the element set moved 1mm in the blocks with a tiny bit of thickness milling on the adapter flange resulting in the 46.5 register distance. It works fine - good, because those adapters with a lens built in aren't very good..
That's the maximum without mirror strike issues, and likely why an adapter that fits inside the bayonet isn't feasible.
Nikon F DSLR is not a good mount for adapting for these reasons.Sadly I see no way to adapt a Pentax or Minolta to Nikon F without some focus issues. I like the Nikon brand but would choose a different brand ( Fuji or Sony perhaps) with a shorter register so adapter electability wasn't problematic over a wide brand of lenses.

OP Albert Silver Veteran Member • Posts: 3,373
Re: The M42 adapter used on Nikon F can make a huge difference

The register distances listed ( thanks !) are correct in as much as the M43 and Nikon F ; I 
Nikon F DSLR is not a good mount for adapting for these reasons.Sadly I see no way to adapt a Pentax or Minolta to Nikon F without some focus issues. I like the Nikon brand but would choose a different brand ( Fuji or Sony perhaps) with a shorter register so adapter electability wasn't problematic over a wide brand of lenses.

Bear in mind, this was my second DSLR, and first full-frame, which I bought very soon after it came out in late 2014. So adapted lenses were not even a thought when that went down. Nikon is fine for this, and I am certainly going to go mirrorless in my next upgrade. Z6 or Z7, at which point I will get infinity focus like other mirrorless users. I see Z6s going for roughly $1100 on ebay, so that will be my most likely route.

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D Cox Forum Pro • Posts: 28,941
Re: The M42 adapter used on Nikon F can make a huge difference
1

I can think of one practical use for these adapters, which is attaching an M42 lens to a Nikon bellows (or extension tubes) for macro work. The Nikon PB-4 is a superb piece of kit and it makes sense to adapt one to any camera and any lens.

Trying to adapt a lens to a DSLR for shooting at normal distances is in my opinion pointless. Keep your lenses until you have a mirrorless camera.

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Diacyclops81 Regular Member • Posts: 443
Re: The M42 adapter used on Nikon F can make a huge difference

Going mirrorless is the best idea for using adapted lenses. Getting inexpensive adapters shouldn’t be an issue going forward, except for little used mounts, like Topcor. Nailing focus with an old manual focus lens on a DSLR requires live view to be most accurate. At which point a mirrorless body might well have focusing aids that are better than on that DSLR.

On a side note…it is a very deep rabbit hole to venture into if comparing vintage 50 and 55mm lenses, whether 1.4 or 1.8/2.0. The Mamiya Sekor 55 1.4 is a good one.

OP Albert Silver Veteran Member • Posts: 3,373
Re: The M42 adapter used on Nikon F can make a huge difference

Diacyclops81 wrote:

Going mirrorless is the best idea for using adapted lenses. Getting inexpensive adapters shouldn’t be an issue going forward, except for little used mounts, like Topcor. Nailing focus with an old manual focus lens on a DSLR requires live view to be most accurate. At which point a mirrorless body might well have focusing aids that are better than on that DSLR.

In spite of using glasses, I don't find it that hard, plus if it becomes an issue you can cheat. I.e. Get with range of the focusing, then while deliberately underfocusing and then shooting past it, fire away so that at least one of them is bound to be the 'right' one. It is easier with a shallow DOF as you can see quite clearly what is in focus or not.

On a side note…it is a very deep rabbit hole to venture into if comparing vintage 50 and 55mm lenses, whether 1.4 or 1.8/2.0. The Mamiya Sekor 55 1.4 is a good one.

Yes, I have a couple more on their way, including a Helios 44M-7 (the sharpest of the Helios 58/2s) I picked up for a decent price ($50 with free shipping).

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ProfHankD
ProfHankD Veteran Member • Posts: 7,852
Trap/catch in-focus

Albert Silver wrote:

Diacyclops81 wrote:

Going mirrorless is the best idea for using adapted lenses. Getting inexpensive adapters shouldn’t be an issue going forward, except for little used mounts, like Topcor. Nailing focus with an old manual focus lens on a DSLR requires live view to be most accurate. At which point a mirrorless body might well have focusing aids that are better than on that DSLR.

In spite of using glasses, I don't find it that hard, plus if it becomes an issue you can cheat. I.e. Get with range of the focusing, then while deliberately underfocusing and then shooting past it, fire away so that at least one of them is bound to be the 'right' one. It is easier with a shallow DOF as you can see quite clearly what is in focus or not.

The best cheat is called trap/catch in-focus.

It's a  mode on some cameras, classically intended for wedding photography to capture the bride walking down the aisle, in which you manually focus at a spot and the camera delays firing the shutter until something becomes in focus there. To use this for manual focus, you simply set this mode, press the shutter, and turn the focus until the camera detects something in-focus and fires.

Pentax has had the most obvious implementations of this as a clearly-labeled mode, but setting focus priority, etc., can implement this on various cameras.

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D Cox Forum Pro • Posts: 28,941
Re: The M42 adapter used on Nikon F can make a huge difference

Diacyclops81 wrote:

Going mirrorless is the best idea for using adapted lenses. Getting inexpensive adapters shouldn’t be an issue going forward, except for little used mounts, like Topcor. Nailing focus with an old manual focus lens on a DSLR requires live view to be most accurate. At which point a mirrorless body might well have focusing aids that are better than on that DSLR.

On a side note…it is a very deep rabbit hole to venture into if comparing vintage 50 and 55mm lenses, whether 1.4 or 1.8/2.0. The Mamiya Sekor 55 1.4 is a good one.

I had no problem finding an Exakta/Topcon adapter but the other Topcon mount is difficult.

Don Cox

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Sigma fp
Diacyclops81 Regular Member • Posts: 443
Re: The M42 adapter used on Nikon F can make a huge difference

You are right. I was being lazy, not checking the Bay for all the adapters available for the Z mount. Opens my eyes on perhaps going with a Nikon FF mirrorless.

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