Wow, looks like a lathe is needed for this type of conversion. For the ones who have done conversions, do you own these lathes? they are pretty expensive, aren't they? and you have to be skilled too.
I tried to do the same thing with a grinder and oh boy did I make a mess with my 28 f/2.
No Paul, aluminium and even bronze adapter itself is quite soft to screw in and make thread - just make a drill hole a bit less then original screw itself.
Dim.ka_ wrote:
No Paul, aluminium and even bronze adapter itself is quite soft to screw in and make thread - just make a drill hole a bit less then original screw itself.
debuggerus wrote:
Wow, looks like a lathe is needed for this type of conversion. For the ones who have done conversions, do you own these lathes? they are pretty expensive, aren't they? and you have to be skilled too.
I tried to do the same thing with a grinder and oh boy did I make a mess with my 28 f/2.
debuggerus wrote:
Wow, looks like a lathe is needed for this type of conversion. For the ones who have done conversions, do you own these lathes? they are pretty expensive, aren't they? and you have to be skilled too.
I tried to do the same thing with a grinder and oh boy did I make a mess with my 28 f/2.
Yeah, this is "high-end" conversion, for sure. Not really DIY like the 58/1.2, unless you have some good tools and skills.
If the new EOS flange is attached to the lens base from the underside with the 4 original screws, then how did you get that clear anodized ring with the 3 radial screws in the side, over the new EOS flange? The EOS flange has a larger diameter than the clear ring, if I remember correctly.
Once you have the old bayonet mount off what do you actually have to lathe?
From your photo it looks like you have removed material from the outer ring of the M42 adapter so it will center in that ring around the rear lens element. Are you making the M42 adapter thinner for infinity focus? Is this where the lathe comes into play?
Thanks for all the advice and photos by the way...
Here is a photo of the old mount and the M42 adapter. It seems like the diameter of the opening on the M42 adapter is ever so slightly wider than the Minolta mount. Is it possible to mount the four screws through the factory holes on the back of the aperture ring and have enough material for the new screw holes on the hole opening edge of the M42 ring?
JimBuchanan - this is just cutted inner part from the whole m42 adapter.
Like here on the right side of the photo you need cut it till the end and you will get this inner part which we will screw in to the original minolta base
I know a lathe would make removing all that material much cleaner, but I wonder if using a Dremel grinder tool with the M42 secured in a vise would work?
Sorry for all the questions but I want to be clear what I have to do here...
Photos help:
The top pic shows the old Minolta mount on the back of the main aperture ring. Four screws go from the underside of the aperture ring into the stainless steel Minolta mount.
The second pic shows the slight ridge that centers the Minolta mount. A section of this ridge has been circled. The third pic shows the new M42 mount resting on the aperture ring.
Would it work If I shaved off this thin ridge or even shaved off some of the entire area I have made green? I think this would allow me to sink new screw holes a little further way from the center hole which would make anchoring he M42 better. I would not need to cut the edges of the M42 adapter this way. That little ridge does stick out a bit and I think it pushes the M42 away from the aperture ring which messes up the focus.
This could be one of those "don't raise the bridge just lower the river" exercises...
Another question: is the thickness of the M42 an issue?
Dim.ka_ wrote:
JimBuchanan - this is just cutted inner part from the whole m42 adapter.
Like here on the right side of the photo you need cut it till the end and you will get this inner part which we will screw in to the original minolta base
I'd like to try and help you out, but I'm not quite sure where to jump in... I have a procedure, that differs a bit from Dim.ka_.
The basis of my procedure is based on this thread by rgallie: https://www.fredmiranda.com/forum/topic/689201/0#6187652
I drill and tap holes for setscrews to secure the new EOS flange to the Minolta flange stub that I turn down to a cylinder. I take advantage of the inherent strength of the original flange stalk.
Wow, that seems like a lot of precision work! I think I would need more detail on how you connect the Minolta mount to the M42 adapter. The one guy talks about cutting out the shape of the Minolta mount so it will slide in the M42 mount(which also needs careful milling.) Each Minolta lens looks different so following photos takes some imagination.
There aren't many people who want to just throw all their cards on the table like that.
On the other hand, the people here are sure making an effort to help. I think it is just because most of us reach a certain threshold of how far we can go on one of these DIY projects. I am constantly pushing my limit further, but I've had my share of "oops" moments along the way.
This conversion is anything but "easy".
In the end, you have to simply consider how much the lens cost you and whether you think there is a risk of loss/damage.
