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Minolta MC Rokkor-PF 58mm 1:1.4

This lens was bought from E-bay (one of many unsuccessful purchases on E-Bay). I found the following problems with the lens:

  • Oily blades: the aperture blades were stuck wide open. They couldn't be released manually.
  • Dust and sand inside: seems the previous owner took this camera to the beach. Focus and aperture were smooth, but traces of sand and dust were visible.

Here are some pictures and notes of the CLA performed to the lens. For disassembly and assembly, I used the Factory Service Manual for the Minolta SRT-101. This can be found here <Minolta SRT-101 Factory Service Manual>. I also used Thomas Tomosy's book on Camera Repair and Maintenance for tips on cleaning, adjusting and repair. Here are the results (click on the pictures to enlarge):

 

1) Oil in blades. Make marks on the aperture block and the inner barrel before disassembly to avoid future calibration. 2) Oil was spreaded everywhere. This lens required a total disassembly.
3) Disassembling the lens. Keep your workspace clean and ordered. There are many small parts. 4) Disassembly of the aperture block. Be careful with the blades, they are very thin !!
5) Take note of the order of rings. This ring holds the aperture block in its place. It will be needed for calibration. 6) There are a few springs, difficult to take apart and to assemble.
6) Make marks on the barrels if you are dismounting them. 7) Make a mark in the helicoid, the outer barrel, inner barrel and focus barrel for future assembly.
8) Take pictures and notes of springs and mechanism. 9) Bayonet ring.
10) Aperture ring. Take note of springs. Do not disassemble the calibration levers. Make marks on barrels for future assembly. 11) Be careful with those small bearing balls!
12) Take notes of springs and mechanism. 13) Focus mechanism. It should be cleaned thoroughly with lighter fluid or camp fuel. Then oiled with heavy bearing grease.
14) All elements disassembled. Keep them ordered and safe. 15) Focus ring. It is difficult to calibrate without marks in the barrels.
16) Lens number ring. This one is metal and difficult to take appart. Be careful not to scratch the surface. 17) Front lens group. There is no need of further disassembly unless there is fungus inside.
18) Rear element group. No need of further disassembly. Don't store them on hard surfaces. I use soft felt to handle all optics.
19) Try not to touch the glass with your hands, during disassembly and assembly.
20) Keep all small items separated and labeled.
21) Be careful with the aperture blades. Any damage will render the lens useless.
22) Cleaning the metal rings with warm water and mild soap. I use camp fuel only to dissolve grease and oil from metal parts.
23) I used Kleenex and Windex to clean the optics (Tomosy). See footnote 1.
24) Mounting the lens. I used graphite powder to lubricate big rotating surfaces.
25) I also used graphite to lubricate the cam and lever. Vacuum the remains of graphite (you don't want it to end up in the lens)
26) Move the rotating ring and observe the operation on the cam lever. This will be important for calibration.
27) Clean aperture blades. I used camp fuel to clean them
28) Assembly of the aperture block.
29) Aperture block assembled. Check the operation. Should be smooth. See footnote 2.
30) Aperture block mounted on the inner barrel. Mount the support ring before turning upside down.
31) Final assembly. Check smoothness of operation.
32) Calibrate the minimum aperture before further assembly (see how to calibrate aperture).
33) Mounting the clean back element group.
... to be continued ...
 
 
 
 
 
 
 
 
 
 
 

 

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Footnotes:

  1. Instead of using tweezers, I used my fingers. I have a better control on the pressure. (Return)
  2. There are still some stains in the blades but they are not from oil and it doesn't affect operation. (Return)