3D printed Minolta MD to EOS mount conversion

There are different ways to convert a Minolta SR mount to Canon EOS mount. In this case I went for a conversion that is less destructive on the original mount. It has been done before but I have not seen a successful 3D printed version of this method.

When I saw a Minolta MD III 50mm 1.7 at 5 Euro a purchase could not be resisted. The actual bayonet cams of its mount (stamped steel part) can be removed, so I asked a friend (with a lathe) to alter a Chinese EOS reverse adapter that it no longer had the flange but just the bayonet part. A 3D printed part to fill in the gap between the two bayonets and secure it on top with the same screws as used on the stamped steel cam part fixed it. Added some glue between the 3D part and the Chinese EOS bayonet cylinder. Position marks for an EMF chip to glue etc added in the 3D design. With a Dremel I added the EOS lock hole in the MD original flange, it is on the edge so not ideal and a bit ugly. To overcome that I added a 3D printed ring that fits around the flange edge and creates more of the locking hole.

As the register distance of the Minolta SR mount is 43.5mm and the EOS mount has a register distance of 44mm there is still a difference, the lens will be 0.5mm too far from the sensor. However that is not much and can be compensated in the infinity calibration of the lens. Where to find that varies per Minolta SR lens. On the Minolta MD III 135mm 3.5 it is as easy as removing the rubber grip, take the black tape off, adjusting the infinity stop with the lens set at infinity ( I use a my hand made collimator) and adding tape + grip again. More often some screws have to be freed a bit and a similar calibration done.

Not all the Minolta SR mounts have the bayonet cams part stamped out of steel sheet. I thought it would be possible to 3D print both a female Minolta SR bayonet + a male Canon EOS bayonet with no flange added. A kind of sleeve that is turned on the SR mount. Similar 3D designs I downloaded were rudimentary, reversed 3D printed and by that not accurate, etc. As I intended to buy a Minolta MD III 35-70mm 3.5 Macro anyway I bought one together with a body + a Vivitar SMS Close Focusing 28mm 2.8 (Komine). Nat as nice as the 2.0 but quite good already at 4.0.

Paid 40 Euro in total which is a good deal. Both in excellent condition, helicoids turn well, glass superb.

Long story, now the images:


Finished MD to EOS bayonet sleeve. Small hole added for the screw that fixes it on the SR bayonet lock slit/indention on one cam. That creates the Minolta SR to EOS register so aperture/focus marks are on top.


Ring to cover the half lock hole on the flange, also makes it easier to mount the lens as it will be more straight when inserted.


Bayonet sleeve on the Minolta zoom. Small screw fixes the sleeve in the MD bayonet although it is already very difficult to turn the sleeve off again.. Beauty ring also added with an epoxy glue to the edge of the MD flange.. The parts are printed with black PETG filament. It would be perfect when it is made with polyamide on a better 3D printer than I have. Probably outsourcing that is the way to go.


Vivitar mounted as it is more cute than the Minolta zoom




35mm setting




70mm setting




at the 1:4 macro setting




near the 1:4 macro setting






more near the 70mm setting




35mm setting




70mm setting




Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Another one done, the conversion of a Minolta MD I 50mm 1.4 went fast this way. This weekend I will make a drill mold of an old EOS metal camera mount to get the lock hole fast and precise.

Now at 4 adaptions/conversions of Minolta MD to EOS mount with a 3D printed dual bayonet I am looking at other mounts that have a near 44mm register distance where the mount flange will be used, as it is, to engage to the EOS camera mount flange. Register distance difference solved by adjusting the infinity setting of the lenses themselves.

There is more to consider than the register distance and (free) mount throat opening, like for example the flange diameter, but this is a short list of potential candidates:


Actual free opening of the Canon EOS is 51.2 mm.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

E Dinkla said:

Another one done, the conversion of a Minolta MD I 50mm 1.4 went fast this way. This weekend I will make a drill mold of an old EOS metal camera mount to get the lock hole fast and precise.

Now at 4 adaptions/conversions of Minolta MD to EOS mount with a 3D printed dual bayonet I am looking at other mounts that have a near 44mm register distance where the mount flange will be used, as it is, to engage to the EOS camera mount flange. Register distance difference solved by adjusting the infinity setting of the lenses themselves.

There is more to consider than the register distance and (free) mount throat opening, like for example the flange diameter, but this is a short list of potential candidates:


Actual free opening of the Canon EOS is 51.2 mm.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Click to expand...

Congratulations Ernst, on your conversions. I've been interested in building my own adapters with a 3D printer for a long time, but I always shy away because I fear the time it takes to learn how to design the adapter. I'd have quite a few lenses that I'd use much more, were they adapted properly.
Did you learn it by yourself, just because of the lens adaption or do you have some work related practise as well?
What does it take to build an adapter (aside from owning a printer - I might have free access to one)?
Regards, Rolf

The shop I own (sole employee) does not do 3D printing for commercial activities but I use 3D printed parts for the commercial 2D printing workflows though, repair parts etc. The learning process of (simple) CAD design is interesting in itself. I always designed and tinkered stuff, not so strange while being raised in a family of engineers and educated as an industrial designer. I recall that I made miniature chairs of paper at kindergarten and did some chair designs as a 25 years old employee of a furniture company. Looks like I never made career switches

For the adapters it is often a trial and error thing to get a product that is optimal. You can measure a lot and add the shrinking percentage learned by experience but 3 or 4 prototypes are often needed for the more complex items. For example the dual bayonet here has some play on the Canon made mounts (on the throat diameter) where it will not fit the Sigma MC-11 diameter without some knife scraping on the rim of the 3D print, then it will snap in. I guess it means Sigma gives its EF lenses a slightly narrower mount as well. If you hit that size in between it can not be a bad product ;-)


Minolta MD I 50mm 1.4 at the right, hole at the front.

The fun starts with buying lenses at a good price and the fun + satisfaction does not end while examining an excellent print on the wall.

Made the Canon mount lock hole drill mold yesterday afternoon + evening. Weekend started early. Works perfectly.

Edit; the lens itself is not at the level I expected. My Olympus OM 50mm 1.4 is better edge to edge at 4/5.6 than this Minolta that needs 8.0 to be somewhat similar. Flare is not better prevented either, something I was actually going for as the OM is neither good at that aspect but this one is worse. In general not at the level of the Minolta MD III 135mm 3.5 or MD I 200mm 4.0 either.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

E Dinkla said:

The shop I own (sole employee) does not do 3D printing for commercial activities but I use 3D printed parts for the commercial 2D printing workflows though, repair parts etc. The learning process of (simple) CAD design is interesting in itself. I always designed and tinkered stuff, not so strange while being raised in a family of engineers and educated as an industrial designer. I recall that I made miniature chairs of paper at kindergarten and did some chair designs as a 25 years old employee of a furniture company. Looks like I never made career switches

For the adapters it is often a trial and error thing to get a product that is optimal. You can measure a lot and add the shrinking percentage learned by experience but 3 or 4 prototypes are often needed for the more complex items. For example the dual bayonet here has some play on the Canon made mounts (on the throat diameter) where it will not fit the Sigma MC-11 diameter without some knife scraping on the rim of the 3D print, then it will snap in. I guess it means Sigma gives its EF lenses a slightly narrower mount as well. If you hit that size in between it can not be a bad product ;-)


Minolta MD I 50mm 1.4 at the right, hole at the front.

The fun starts with buying lenses at a good price and the fun + satisfaction does not end while examining an excellent print on the wall.

Made the Canon mount lock hole drill mold yesterday afternoon + evening. Weekend started early. Works perfectly.

Edit; the lens itself is not at the level I expected. My Olympus OM 50mm 1.4 is better edge to edge at 4/5.6 than this Minolta that needs 8.0 to be somewhat similar. Flare is not better prevented either, something I was actually going for as the OM is neither good at that aspect but this one is worse. In general not at the level of the Minolta MD III 135mm 3.5 or MD I 200mm 4.0 either.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Click to expand...

E, it is not clear to me what are the mounts, and I really tried to read it all. I get the CAD designs, but what is the mount part? I find it amazing you can design your own 3D printed adapters.

Has anyone ever tried to design an iris that is 3D printed? I could VERY much love to replace blades or iris mechanisms of old lenses for new, even funky shaped ones, like triangular apertures and such. Surely may need a metal printer, and I am not sure how much this would be good. But, it would be amazing and maybe not so extremely hard.

Or even rehouse some lenses that have blocks (maybe 2 blocks) and have a manual Iris (something you can slide in then cover to block light) for things like inserting a filter at the iris position, for example. For example, funky apodising filters, that make ultra smooth bokeh, or maybe very rare shapes.

Of course, this is a bit delirium on my side. I wish so much things where more "tinkerable" like a lego bricks.

Minolta SR/MC/MD to Canon EF/EOS in the pictures shown.

All the DIY 3D printed aperture mechanisms I have seen have too thick blades and parts to be used as replacements. Professional 3D metal printing using metal powders might be a solution.

For blade replacements I think laser or etch cutting of thin metal is the way to go. The reason I stocked SLR shutter blades as a base material. On the other hand where the pin has to be reconstructed too the electroforming process might be more appropriate. Philips used that process to make the nickel electric razor blades in the past.


Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Great work!

I wish I could buy commercially available replacement bayonets for converting Minota SR lenses to EOS.

This would allow ditching Minolta to Sony E adapters, which tend to be the heaviest, and stacking at least some Minolta lenses on top of more universal EOS speedboosters.

aidaho said:

Great work!

I wish I could buy commercially available replacement bayonets for converting Minota SR lenses to EOS.

This would allow ditching Minolta to Sony E adapters, which tend to be the heaviest, and stacking at least some Minolta lenses on top of more universal EOS speedboosters.

Click to expand...

I am waiting for some Pixco EMF chips to add to the conversions. After that step I will evaluate what can be done. Probably add the 3D design to Thingiverse. There still remains some tinkering to be done on the lenses to fit Canon cameras and the MC-11 + the calibration to infinity.


Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Received the EMF chips some days ago. A new version it seems. The contact spots are smaller but more accurately positioned, identical to the contacts on recent Canon EF mount lenses. What improved as well is that when programmed the max aperture setting is now also recognized by the MC-11 adapter next to the set focal length. That has been alright for Canon EOS cameras with the older versions too but not on the MC-11. Functionality on the MC-11 + A7RII is not changing much that way but at least it gives extra indicators which lens is used in ExifTool to add more information.


New version chip on top. Top lens is the Minolta MD 35-70 3.5 Macro, chip focal length set on 48mm as that focal length is roughly half way the scene areas covered by 35 and 70mm. Programmed chip 49mm focal length was already taken by a 50mm lens. One may argue that IBIS would be better with an even shorter focal length but this is also a Macro lens that extends a lot on that setting. Anyway it will always be a compromise with a manual zoom lens. Bottom lens is the Mamiya Sekor CS 135mm 2.8


Made a better mold to glue them on 3D printed bayonet sleeves. Old EOS camera mount fitted to 4mm thick white polystyreen sheet. Drilled the lock hole through to the other side, added thread. Added a tapered screw from this side to fix the lens. Transparent sheet has two sided tape to bond the chip in the process and fix the sheet between the tabs during curing of the epoxy glue. Position of the chip contacts is indicated with engraved lines on both sides of the transparent sheet. Height is correct with the 4mm polystyreen sheet in between. Very neat glue bond with little excessive glue as a result. I sand the chips a bit where the glue will be applied to get a better bond.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Hi!

I was wondering where can i get the 3D files of these peaces, Im about to get a Minolta MD III 50mm 1.4 and this is the only way that i can transform this lense... The other methots are so complicated to me.

Thank you so much!

Regards from Spain

domitakes said:

Hi!

I was wondering where can i get the 3D files of these peaces, Im about to get a Minolta MD III 50mm 1.4 and this is the only way that i can transform this lense... The other methots are so complicated to me.

Thank you so much!

Regards from Spain

Click to expand...

They are not yet available on the web. The conversion is to EOS mount and you still have to calibrate infinity in the lens itself. I actually do not know whether used on a Canon FF camera the mirror will not touch the rear of the lens. I use it on the MC-11 or Metabones IV adapter to a Sony camera.

So at this moment enough reasons not to bring the design to the web.


Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Just saw this post. Nicely done. With MC-11, it expands the fun factor of the adapted lens world. I just don't know when I have the time to work on similar things.

vivaldibow said:

• vivaldibow wrote:

Just saw this post. Nicely done. With MC-11, it expands the fun factor of the adapted lens world. I just don't know when I have the time to work on similar things.

Click to expand...

Semi retired man, that makes the difference to other people. Yes, I prefer the in between EF mount for these adaptations for more reasons.

Designed an EF bayonet sleeve for the Mamiya Sekor CS/E mount last week (1 dollar 50mm 2.0 E lens as an excuse) but that is no solution. Very little material left between the two bayonets. It fitted but reversing the mounting action already cracked the 3D printed part. The flanges do not get more than 1 mm circumference contact so not ideal either. Then there is the small aperture ring Just in front of the wide EF female mount flange, ergonomically a disaster. All in all a bad Idea. Used parts of the 3D design to make a straight adapter to FE mount. Now I am going for a lens internal conversion that gives the 'electronic' M-S E lens a manual aperture control.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Oh! Thank you for the answer

Yeah I have a aps-c DSRL so I need to set my lense to infinity when I get the adapter.

Actually I found a super thin and SUPER expensive adapter for Minolta MD to EOS EF on ebay, including the gap for the lock system. Here is the link:


It looks good quality and thin, so It will be easier to adjust to infinity (and you can make sure that you can do It in any minolta MD lens) ¿Am I wrong?

I'm still looking for information

Thank you so much!

domitakes said:

Oh! Thank you for the answer

Yeah I have a aps-c DSRL so I need to set my lense to infinity when I get the adapter.

Actually I found a super thin and SUPER expensive adapter for Minolta MD to EOS EF on ebay, including the gap for the lock system. Here is the link:

https://www.ebay.es/itm/Thin-Minolt...a-Adapter-without-glasses-MD-EOS/111751120312

It looks good quality and thin, so It will be easier to adjust to infinity (and you can make sure that you can do It in any minolta MD lens) ¿Am I wrong?

I'm still looking for information

Thank you so much!

Click to expand...

Based on the same idea that I had but with a twist.I have not seen it before. Nicely made in metal I have to say, price accordingly. I think the thin blade that will be between the EOS camera mount flange and the MD lens flange must be 0.75mm thick at least to lock the lens safely in the EOS mount. So about 1,25mm has to be taken out on the infinity calibration. Might be too much for some lenses. The text mentions that the adapter aims at 250mm lenses and infinity is lost with shorter lenses, no mention of infinity calibration there. My solution requires not more than 0,5mm infinity calibration but a small hole has to be drilled in the MD mount for the EOS lock. I still think that drilling a hole, the infinity calibration needed and even further conversions on zoom and floating element lenses to keep the register distance correct makes both conversion solutions awkward for 90% of the MD lens users. I wonder whether AF confirm chips can be glued on the metal adapter like I do with my solution.


Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

E Dinkla said:

E Dinkla wrote

Designed an EF bayonet sleeve for the Mamiya Sekor CS/E mount last week (1 dollar 50mm 2.0 E lens as an excuse) but that is no solution. Very little material left between the two bayonets. It fitted but reversing the mounting action already cracked the 3D printed part. The flanges do not get more than 1 mm circumference contact so not ideal either. Then there is the small aperture ring Just in front of the wide EF female mount flange, ergonomically a disaster. All in all a bad Idea. Used parts of the 3D design to make a straight adapter to FE mount. Now I am going for a lens internal conversion that gives the 'electronic' M-S E lens a manual aperture control.

Click to expand...

Finished the conversion of the electronic to manual aperture of that M-S E lens. As the auto aperture lever normally only commanded by the M-S Z cameras travels half the distance of the electronic only aperture ring, I used a "pulley and rope" like construction with a nylon wire connected at one end to the ring and on the other end to the lens body. The auto aperture lever in the loop between them is pulled half the distance then. Using wire there is only a small slit needed in the barrel. Can not show a picture how it is done as it is a kind of ship in a bottle process and the bottle not transparent here.

That Mamiya-Sekor E 50mm 2.0 has potential if I go by the image samples shown here:


Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Hello,

this is actually geat solution.

Are there CAD files free for share? I would like to convert mine Minolta lenses to EF as well.

Thank you for your reply.

VintageLenses said:

Hello,
this is actually geat solution.
Are there CAD files free for share? I would like to convert mine Minolta lenses to EF as well.
Thank you for your reply.

Click to expand...

No, I did not put them on the web. As I have written before the infinity calibration in the lens itself has to be adjusted as with the 3D bayonet sleeve added the lens is 0.5mm too far forward when mounted on an EF camera or adapter. With lenses that have only one optical block moving while focusing, it is usually not so difficult for the better tinkerers. Although a collimator in the shop would be nice as there are always small changes in the created register distance possible with conversions like that + an intermediate adapter EF<>FE that may be a bit off as well. With floating element lenses / zooms it may be impossible to do it correctly or there has to be a 0.5mm thick ring inside the lens near the mount that is part of the infinity calibration and can be removed. Like there was in my Minolta MD III 35-70mm macro zoom.

Also a lock hole for the EF mount lens locking has to be drilled in the MD flange. Not everyone's favorite hobby.

I am not sure whether all MD/MC lenses would fit a FF Canon EF camera either without obstructing its mirror movement.

Then there are Minolta lens aficionados that will not like their beloved lenses converted and reappear on the market in whatever visible or non visible altered condition.

I expect that there are more commercially minded people with less ethical concerns that will bring something similar on the market. I had some experience that way.


Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

E Dinkla said:

E Dinkla said:

E Dinkla wrote

Designed an EF bayonet sleeve for the Mamiya Sekor CS/E mount last week (1 dollar 50mm 2.0 E lens as an excuse) but that is no solution. Very little material left between the two bayonets. It fitted but reversing the mounting action already cracked the 3D printed part. The flanges do not get more than 1 mm circumference contact so not ideal either. Then there is the small aperture ring Just in front of the wide EF female mount flange, ergonomically a disaster. All in all a bad Idea. Used parts of the 3D design to make a straight adapter to FE mount. Now I am going for a lens internal conversion that gives the 'electronic' M-S E lens a manual aperture control.

Click to expand...

Finished the conversion of the electronic to manual aperture of that M-S E lens. As the auto aperture lever normally only commanded by the M-S Z cameras travels half the distance of the electronic only aperture ring, I used a "pulley and rope" like construction with a nylon wire connected at one end to the ring and on the other end to the lens body. The auto aperture lever in the loop between them is pulled half the distance then. Using wire there is only a small slit needed in the barrel. Can not show a picture how it is done as it is a kind of ship in a bottle process and the bottle not transparent here.

That Mamiya-Sekor E 50mm 2.0 has potential if I go by the image samples shown here:

https://www.flickr.com/photos/59224964@N05/albums/72157668479224577

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Click to expand...

BTW, the Mamiya-Sekor CS/E/EF mounts 43,5mm register distance mentioned in some lists of register distances should be 45,5 mm as mentioned in the Wikipedia list. I started on the wrong foot. This opens up a better adaptation to Canon EF mount when using 3D printed conversions.


Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Ed I am wondering what is your aim converting these lenses to EOS. When mirrorless was not available that made sense since the EOS mount has one of the shortest registration for DSLR.

Not saying this is bad but if I was to use an MD lens on DSLR I would felt compelled to use live view x10 magnification so no viewfinder here which negates the DSLR.

I did notice that infinitesimal changes in focus turned a supposedly so so optic into a marvel.

So how do you plan to focus with these lenses?

As a sidenote try the MDIII 50 1,4. You may like it. For edge to edge sharpness 50 1,7 and MDIII 2,0 might be better choices. Good copies of course.

I admire your skills and I'm somewhat jealous .