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Help needed please Minolta mc 85mm f1.7
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PostPosted: Tue Jan 03, 2017 9:04 pm    Post subject: Help needed please Minolta mc 85mm f1.7 Reply with quote
Some time ago I won the auction of 2 Minolta MC lenses the 85 f1.7 and 35mm f1.8, for the price of one:).
Before arrival I decided to resell the 35mm and keep the other. However, when I tried them, changed my mind to the other way around. My 85mm copy is soft and less contrasty than I expected. Also I have the jupiter f2 in the same focal length.
Many
Back to the title, the aperture of the 85mm is stuck with some oil on the blades, it closes down when I move the pin on the back, and works temporarily when I put some drop of lighter fluid and sticks again when it dries out.

My experience with DIY is limited to a successful clean of a flecktogon 35mm f 2.4 and a failed repair of 2 zooms.

Has anyone tried cleaning this minolta before, I searched for a guide but no luck.

My copy is similar to the first one in the rokkor files link:
http://www.rokkorfiles.com/85mm%20Page%201.htm

Do you know a reasonably priced service in the UK or is it better to sell it as a spares/repair, I would rather repair it to see if there's any change in IQ, the glass seems to be clean though.

Thanks for looking and your help is muchly appreciated

Badr


PostPosted: Wed Jan 04, 2017 1:33 pm    Post subject: Reply with quote
I have both the MC 58/1.2 and 85/1.7, IMO, they are 2 of the most sensitive lenses to oil moving from the helicoid to the aperture mechanism and gumming it up.
I've done the 58 3 times, and the 85 2 times, I last cleaned them 3 months ago, and the 58 needs it again, though I only flushed the aperture rather than fully disassemble it, an oversight on my part, I've had no issues using the same grease on other lenses.
It's not that hard to do, it just takes more care and attention then others because the front element is so close to the retaining rings.

I'll see about doing a guide in the next few days.


PostPosted: Wed Jan 04, 2017 8:59 pm    Post subject: Reply with quote
Thanks a lot James,indeed that will be very helpful to me and hopefully many others, as like I said there isn't any.
I will be waiting Smile
No pressure though, It doesn't matter how long it takes

Badr


PostPosted: Fri Jan 06, 2017 6:56 am    Post subject: Reply with quote
The front: Use extra caution, you will be very close to the front element, Ive seen a few lenses damaged from lack of caution.
there are 3 rings at the front, each has 2 slots for spanners, the inner holds the element into the cell, you don't need to touch this unless you need to clean inside the front cell.
the outer ring is a jam ring to keep the front cell secure, removing this is strait forward, I advise to loosen it with your spanner, then switch to a plastic/wood pick to spin the ring because they will be less likely to scratch the lens element.
Now you use the spanner to loosen the cell which looks like another outer ring, this will expose the aperture.
around the perimeter you will see 4 screws, remove them and the optics will be freed from the helicoid and mount

If the helicoid and aperture ring work fine, there is no need to go further into the mount.
The rear/mount: Remove the 3 screws(edit, not rings... doh) at the rear, they hold the silver trim ring that hides the 4 screws that hold the mount on. take care when you remove this part, the aperture ring can easily come off and the detent ball can spring/fall away.

the rear cell is now easily unscrewed from the aperture section, which will leave you with the guts of the aperture, I advise you to clean by flooding the whole unit with lighter fluid(outdoors away from sparks and flames), a dental syringe works great for this, submerge the unit in a small bowl and use the syringe to force fluid into the nooks and crannies, and operate the aperture mechanism to be sure all oil is washed away, now blow away the excess with compressed air, or soak it up with a lint free cloth.

Now you can put it back together.

If you need to access the blades, 3 small grub/set screws hold the retaining ring above the aperture, getting it out is easy, but getting it back together is not.

Good luck.


PostPosted: Wed Jan 18, 2017 11:34 pm    Post subject: Reply with quote
I've got a broken MC85/1.7 (heavy damage to the front element) lying around here. It has the same oil problem as yours (less severe though, the aperture blades move slowly but turning the aperture ring is enough to get them moving)
but if you need any spare parts for your repair (in case you damage something or lose a part), I can send it to you (no charge except shipping costs).


PostPosted: Sun Jan 22, 2017 4:57 pm    Post subject: Reply with quote
Lightshow wrote:
The front: Use extra caution, you will be very close to the front element, Ive seen a few lenses damaged from lack of caution.
there are 3 rings at the front, each has 2 slots for spanners, the inner holds the element into the cell, you don't need to touch this unless you need to clean inside the front cell.
the outer ring is a jam ring to keep the front cell secure, removing this is strait forward, I advise to loosen it with your spanner, then switch to a plastic/wood pick to spin the ring because they will be less likely to scratch the lens element.
Now you use the spanner to loosen the cell which looks like another outer ring, this will expose the aperture.
around the perimeter you will see 4 screws, remove them and the optics will be freed from the helicoid and mount

If the helicoid and aperture ring work fine, there is no need to go further into the mount.
The rear/mount: Remove the 3 screws(edit, not rings... doh) at the rear, they hold the silver trim ring that hides the 4 screws that hold the mount on. take care when you remove this part, the aperture ring can easily come off and the detent ball can spring/fall away.

the rear cell is now easily unscrewed from the aperture section, which will leave you with the guts of the aperture, I advise you to clean by flooding the whole unit with lighter fluid(outdoors away from sparks and flames), a dental syringe works great for this, submerge the unit in a small bowl and use the syringe to force fluid into the nooks and crannies, and operate the aperture mechanism to be sure all oil is washed away, now blow away the excess with compressed air, or soak it up with a lint free cloth.

Now you can put it back together.

If you need to access the blades, 3 small grub/set screws hold the retaining ring above the aperture, getting it out is easy, but getting it back together is not.

Good luck.


Thank you James for taking the time and the detailed info. You made it look easy. I will need to buy the right spanner then mine is poor quality and has already damaged a lens for me. is it the same as the 58mm?


PostPosted: Sun Jan 22, 2017 5:19 pm    Post subject: Reply with quote
Boris_Akunin wrote:
I've got a broken MC85/1.7 (heavy damage to the front element) lying around here. It has the same oil problem as yours (less severe though, the aperture blades move slowly but turning the aperture ring is enough to get them moving)
but if you need any spare parts for your repair (in case you damage something or lose a part), I can send it to you (no charge except shipping costs).

Thanks Boris for the kind offer, sure it will encourage a lot having a spare one just in case. please pm with your Paypal email and i will send you the address. Alternatively I have a very clean vivtar series 1 35-85 f2.8 variable focus with a sn 22****** but focus ring is stuck, in Minolta MD , together with Sears 50mm f2 pk mount. Let me know please if that would be useful to you I can post them both.
Badr


PostPosted: Mon Jan 23, 2017 1:50 am    Post subject: Reply with quote
Badr12 wrote:
Lightshow wrote:
The front: Use extra caution, you will be very close to the front element, Ive seen a few lenses damaged from lack of caution.
there are 3 rings at the front, each has 2 slots for spanners, the inner holds the element into the cell, you don't need to touch this unless you need to clean inside the front cell.
the outer ring is a jam ring to keep the front cell secure, removing this is strait forward, I advise to loosen it with your spanner, then switch to a plastic/wood pick to spin the ring because they will be less likely to scratch the lens element.
Now you use the spanner to loosen the cell which looks like another outer ring, this will expose the aperture.
around the perimeter you will see 4 screws, remove them and the optics will be freed from the helicoid and mount

If the helicoid and aperture ring work fine, there is no need to go further into the mount.
The rear/mount: Remove the 3 screws(edit, not rings... doh) at the rear, they hold the silver trim ring that hides the 4 screws that hold the mount on. take care when you remove this part, the aperture ring can easily come off and the detent ball can spring/fall away.

the rear cell is now easily unscrewed from the aperture section, which will leave you with the guts of the aperture, I advise you to clean by flooding the whole unit with lighter fluid(outdoors away from sparks and flames), a dental syringe works great for this, submerge the unit in a small bowl and use the syringe to force fluid into the nooks and crannies, and operate the aperture mechanism to be sure all oil is washed away, now blow away the excess with compressed air, or soak it up with a lint free cloth.

Now you can put it back together.

If you need to access the blades, 3 small grub/set screws hold the retaining ring above the aperture, getting it out is easy, but getting it back together is not.

Good luck.


Thank you James for taking the time and the detailed info. You made it look easy. I will need to buy the right spanner then mine is poor quality and has already damaged a lens for me. is it the same as the 58mm?

The procedure is a bit different for the 58/1.2


PostPosted: Mon Jan 23, 2017 8:05 pm    Post subject: Reply with quote
OK I thought so


PostPosted: Mon Jan 23, 2017 9:06 pm    Post subject: Reply with quote
From memory... The front cell comes out the same way, but the aperture section stays, the 4 screws around the perimeter are for infinity adjustment and removal of the focus ring.
The rear cell comes out the back, to remove the mount, there are 8 screws, 4 long and 4 short, leave the short ones screwed in.

To dive in further, I'd need to take mine apart to be sure on the procedure, shoot me a PM if you or anyone needs help with either of them, or any lens for that matter, I'm willing to help as much as I can.


PostPosted: Tue Jan 24, 2017 8:12 am    Post subject: Reply with quote
I wish I have that one Smile waiting for a good deal , my friend has it though and trying to clean it. I will send this to him thanks.


PostPosted: Sat Feb 25, 2017 5:13 pm    Post subject: Reply with quote
Happy to help


PostPosted: Sat Mar 11, 2017 11:35 pm    Post subject: Reply with quote
I recently picked up the Rokkor 35mm f1.8 and it's a keeper to be sure. Wonderful lens and great build.

JT


PostPosted: Sun Mar 12, 2017 6:52 am    Post subject: Reply with quote
Jtrcy wrote:
I recently picked up the Rokkor 35mm f1.8 and it's a keeper to be sure. Wonderful lens and great build.

JT


Good for you - but what does it have to do with a thread about the repair of a 85mm Minolta lens??


PostPosted: Tue Mar 14, 2017 4:28 pm    Post subject: Reply with quote
The Op's original post mentioned he purchased the 85mm PLUS the 35mm f1.8 initially thinking he'd sell the 35, then decided to keep the 35 - presumably because he found it to be a great lens... Hence, my comment.
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