p.9 #1 · lens repair, modification and disassembly guide thread
Nice!
I have my Minolta/M/G28 sitting on the ready for that new a7R. The only thing I added is a modified click stop aperture ring that has more even aperture steps.
For now, I chose the ZM 50 Planar versus building a G45 Planar "FrankenZeiss". And that m-a-x converted Oly/G45 sold for $1000US! Wow.
p.9 #2 · lens repair, modification and disassembly guide thread
dkerins wrote:
Thanks to triplelatte for the aluminum adapter rings and sebboh for the guidance, I have brought a new FrankenZeiss to life. I used a ribbon of tin from a coke can to make the aperture control on the lens body connect to the aperture ring. Seems to work well.
excellent!
dkerins wrote:
I found if the back aluminum adapter ring is tightened too much against the aperture ring that the aperture ring binds. Anyone else experience that? If they are lightly tight then is it fine.
that indicates that the rear alunimu ring is making contact with the aperture ring and that the exterior portion is too deep (ring on the left): http://farm9.staticflickr.com/8536/8748600956_f7936ed861_o.jpg
you could file that down a little (just put that side down on some sandpaper and rub it in a figure 8. it shouldn't actually be pressing against the aperture ring but simply containing it from moving up and down too much.
dkerins wrote:
I am keen to do my G45 now but need to get the one (or is it two) aluminum rings from somewhere (someone). Anyone have a lead for me to get them?
i order my aluminum stock and any raw materials from mcmaster carr. i've been meaning to beautify my g45 conversion, should measure it when i do so...
p.9 #4 · lens repair, modification and disassembly guide thread
dkerins wrote:
It is a good idea, doing a light sanding on the rear adapter. I will try it.
Sebboh, sounds like you have your own lathe, very nice for this kind of custom work.
yeah, i have a crappy mill and lathe at work which are very helpful, but a bit lacking for anything that requires a high level of accuracy. i can use better tools if necessary, but i have to pay for time on them.
p.9 #5 · lens repair, modification and disassembly guide thread
If you are looking at making adapters for your G45 conversion and want to user the better lathe, I would be interested in getting a set of adapters and would certainly split the cost. And if we can find any other interested parties that might help spread the cost. Otherwise off-shore CNC small job might be a way to go...
p.9 #6 · lens repair, modification and disassembly guide thread
If the measurements end up being the same as the G28 conversion, or similar enough where maybe a spacer ring might make them work, I still have a set of the rings available.
Otherwise I can give you the contact info for the company that made the rings for me.
p.9 #7 · lens repair, modification and disassembly guide thread
Thanks Christopher. At this point I am not sure if the adapters for the G28 will work for the G45 but if they would, I will like to buy them from you.
Yes, I would like the company info if I have to follow a similar route as you and get a set of adapters made off-shore.
triplelatte wrote:
If the measurements end up being the same as the G28 conversion, or similar enough where maybe a spacer ring might make them work, I still have a set of the rings available.
Otherwise I can give you the contact info for the company that made the rings for me.
p.9 #8 · lens repair, modification and disassembly guide thread
triplelatte wrote:
If the measurements end up being the same as the G28 conversion, or similar enough where maybe a spacer ring might make them work, I still have a set of the rings available.
Otherwise I can give you the contact info for the company that made the rings for me.
the front ring for the g45 requires a larger opening than the g28 and the screw holes to attach the optical block are further apart as well. the rear ring for the g45 is identical in design, but needs to be thicker by a few millimeters (haven't measured yet).
p.9 #9 · lens repair, modification and disassembly guide thread
After a bit of tweaking, my Frankenziess seems to be working fine. I sanded the rear adapter and the now the aperture ring is no longer binding. I lens attaches firmly to the adapter after I spread the adapter couplings.
But the distance scale seems to be really off. In this photo, I focused on an object 2 feet away. (Focus peaking was glowing and it looked sharp in the EVF), however the distance scale is showing about 10 feet.
p.9 #10 · lens repair, modification and disassembly guide thread
dkerins wrote:
But the distance scale seems to be really off. In this photo, I focused on an object 2 feet away. (Focus peaking was glowing and it looked sharp in the EVF), however the distance scale is showing about 10 feet.
Do I need to shim the lens body so it sits more forward on the front aluminum ring? Or is this expected?
It certainly has been an education for me to bring the Frankenzeiss to life. Thanks for any replies.
David.
the distance scale is for a 55mm lens, it won't be accurate for a 28mm lens. i would tune the infinity stop so it really hits infinity accurately and then test what the actual focus distance is at the other markings and either remember them or mark over them with tape.
there is possibility that the focus ring from the MC 55/1.7 can be replaced by one from the MC 28/3.5 but i doubt it (i've only seen pictures, need to get a copy of the lens).
p.9 #11 · lens repair, modification and disassembly guide thread
dkerins wrote:
If you are looking at making adapters for your G45 conversion and want to user the better lathe, I would be interested in getting a set of adapters and would certainly split the cost. And if we can find any other interested parties that might help spread the cost. Otherwise off-shore CNC small job might be a way to go...
You can count me in for this cost splitting venture.
PM me if we go ahead.
p.9 #12 · lens repair, modification and disassembly guide thread
sebboh wrote:
the distance scale is for a 55mm lens, it won't be accurate for a 28mm lens. i would tune the infinity stop so it really hits infinity accurately and then test what the actual focus distance is at the other markings and either remember them or mark over them with tape.
Thanks for the response. That makes sense. I don't use the distance scale marking normally but they were brought to my attention when the measurements were not not at all in the ballpark.
p.9 #14 · lens repair, modification and disassembly guide thread
dkerins wrote:
If you are looking at making adapters for your G45 conversion and want to user the better lathe, I would be interested in getting a set of adapters and would certainly split the cost. And if we can find any other interested parties that might help spread the cost. Otherwise off-shore CNC small job might be a way to go...
i'll try to take my g45 apart sometime this week and can send measurements if anyone else wants make another 3d printer/cnc machine friendly file from them.
p.9 #16 · lens repair, modification and disassembly guide thread
sebboh wrote:
i'll try to take my g45 apart sometime this week and can send measurements if anyone else wants make another 3d printer/cnc machine friendly file from them.
p.9 #18 · lens repair, modification and disassembly guide thread
ok, i did the measurements and put them in to the old lens diagrams made for the g28. i made the values that are different bolder in print so they're easier to spot. on the front ring the screws holding the optical block on cannot be on the same axis as the screws attaching the ring to the helicoid, so i offset them by ~10 degrees. i was to lazy to calculate the trig on that so i just rotated the measurements 10 degrees. i assume measurements will need to be recalculated for the same axis to make instructions for a cnc machine. the only change on the rear ring is the thickness.
please look these over and let me know if you have any questions, i did them in a hurry.
this design is a little bit different than what i did for my conversion because my original g45 didn't have it's own filter ring (i filed down for an earlier conversion). this one will look just like the g28 conversion.
edit: oh, and regarding cost splitting – i'd be interested in getting a set of these rings too.
p.9 #19 · lens repair, modification and disassembly guide thread
sebboh wrote:
i assume measurements will need to be recalculated for the same axis to make instructions for a cnc machine. the only change on the rear ring is the thickness.
please look these over and let me know if you have any questions, i did them in a hurry.
edit: oh, and regarding cost splitting – i'd be interested in getting a set of these rings too.
Thanks for doing this Sebboh. I am not well versed in these type of drawings/specifications so I am not sure if I can offer much in the way of feedback.
I was given a link to the CNC firm used by triplelatte for his batch of g28 adapter rings. I bought a set from him and can confirm they worked well so that may be a vote of confidence to the firm that manufactured them.
I can take the lead in contacting this firm and working with them on getting a small batch (5 sets) created.
I will start with sending them these specification files. You mentioned that the measurements may need to be recalculated before they would be acceptable to a CNC machinist firm. If that is the case, I may need some extra help.
