Home

Please support mflenses.com if you need any graphic related work order it from us, click on above banner to order!

SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

need help with RF Rokkor 80cm f8
View previous topic :: View next topic  


PostPosted: Mon Sep 06, 2021 3:32 pm    Post subject: need help with RF Rokkor 80cm f8 Reply with quote

RF Rokkor 80cm f8? Anyone has experience with it? Would be my first catadioptric, whats the proper way of checking these lenses for fungus or issues? Thanks


PostPosted: Mon Sep 06, 2021 7:31 pm    Post subject: Re: need help with RF Rokkor 80cm f8 Reply with quote

kiddo wrote:
RF Rokkor 80cm f8? Anyone has experience with it? Would be my first catadioptric, whats the proper way of checking these lenses for fungus or issues? Thanks


My 500mm Tokina has fungus in it. I have it stored away and can't get to it now. I think you can just look into it like other types of lenses. On mine it stands out like a sore thumb. I found this image:



If you have not purchased it yet, you might want to wait for confirmation. I've never tried to open it up, only used it in the 80's. Then my old rat shack I call home ate it. Still worked, but I didn't like the results on my APS-C.


PostPosted: Mon Sep 06, 2021 7:42 pm    Post subject: Re: need help with RF Rokkor 80cm f8 Reply with quote

Knudsen wrote:
kiddo wrote:
RF Rokkor 80cm f8? Anyone has experience with it? Would be my first catadioptric, whats the proper way of checking these lenses for fungus or issues? Thanks


My 500mm Tokina has fungus in it. I have it stored away and can't get to it now. I think you can just look into it like other types of lenses. On mine it stands out like a sore thumb. I found this image:



If you have not purchased it yet, you might want to wait for confirmation. I've never tried to open it up, only used it in the 80's. Then my old rat shack I call home ate it. Still worked, but I didn't like the results on my APS-C.


Thanks, ive read before about some weird way on checking these lenses, different of the normal ones - thanks anyway


PostPosted: Mon Sep 06, 2021 8:26 pm    Post subject: Reply with quote

Simple visual inspection should easily reveal fungus and/or mirror degradation. Checking collimation is not s difficult either if you have the lens.


PostPosted: Mon Sep 06, 2021 8:40 pm    Post subject: Reply with quote

visualopsins wrote:
Simple visual inspection should easily reveal fungus and/or mirror degradation. Checking collimation is not s difficult either if you have the lens.

Checking collimation is not difficult? Never had a catadioptric before


PostPosted: Mon Sep 06, 2021 10:05 pm    Post subject: Reply with quote

kiddo wrote:
visualopsins wrote:
Simple visual inspection should easily reveal fungus and/or mirror degradation. Checking collimation is not s difficult either if you have the lens.

Checking collimation is not difficult? Never had a catadioptric before


http://forum.mflenses.com/how-to-collimate-your-lens-diy-method-t16145.html

There are other great threads here on search.


PostPosted: Thu Sep 09, 2021 9:40 pm    Post subject: Reply with quote

visualopsins wrote:
Checking collimation is not s difficult either if you have the lens.


All RF lenses I own go quite a bit beyond infinity (they intentionally were constructed correspondingly).
Checking collimation thus is not required.

S


PostPosted: Thu Sep 09, 2021 10:03 pm    Post subject: Reply with quote

stevemark wrote:
visualopsins wrote:
Checking collimation is not s difficult either if you have the lens.


All RF lenses I own go quite a bit beyond infinity (they intentionally were constructed correspondingly).
Checking collimation thus is not required.

S


I do not understand what you mean to write here...proper collimation would increase sharpness across the frame. Tilted elements and or mirrors cause decollimation...


PostPosted: Tue Sep 14, 2021 4:30 am    Post subject: Reply with quote

I've only understood the term collimate to refer to aligning the mirrors and am not familiar with the term being used to set infinity. I think calibrate is a better term for setting infinity or other measurements.


PostPosted: Tue Sep 14, 2021 1:35 pm    Post subject: Reply with quote

I can't comment on minolta, but I've had both sigma and tamron mirrors apart to clean fungus. These are usually mechanically relatively simple lenses, to get into them just figure out the focus stop and separate the helicoid (nb note separation point). Fungus or other issues affecting the correcting lens group rather than the mirror or objective however is more problematical. Overall I can say that tamrons are reliably consistent quality, sigmas less so. And those itty bitty little fungus growths in that tokina won't even notice.
I had a sigma with deteriorated slivering, but in fact the effect on iq was only marginal. I think this peripheral ring of deterioration is something to look out for with sigma 600mm f8's, I've seen more than one. It's unusual because these, like the tamrons, are back silvered ie the silvering is not on the front of the glass but the rear side, under protective paint etc.



PostPosted: Tue Sep 14, 2021 2:50 pm    Post subject: Reply with quote

Thank you all for the replies, finally It looks like vgc ,a very small fungus , but i would need a special adapter for tripod, as It seems to be thicker than normal ones
Tested it already and the dof seems to be very thin even on large distance


PostPosted: Tue Sep 14, 2021 3:04 pm    Post subject: Reply with quote

marcusBMG wrote:
I can't comment on minolta, but I've had both sigma and tamron mirrors apart to clean fungus. These are usually mechanically relatively simple lenses, to get into them just figure out the focus stop and separate the helicoid (nb note separation point). Fungus or other issues affecting the correcting lens group rather than the mirror or objective however is more problematical. Overall I can say that tamrons are reliably consistent quality, sigmas less so. And those itty bitty little fungus growths in that tokina won't even notice.
I had a sigma with deteriorated slivering, but in fact the effect on iq was only marginal. I think this peripheral ring of deterioration is something to look out for with sigma 600mm f8's, I've seen more than one. It's unusual because these, like the tamrons, are back silvered ie the silvering is not on the front of the glass but the rear side, under protective paint etc.



You are correct that Tamron quality is much more consistent than Sigma. That outer ring of mirror deterioration is actually quite common with the Sigma mirrors, both 600mm and 400mm. While Tamron holds up much better, the SP 350 all too often suffers from rear element coating or balsam separation.


PostPosted: Tue Sep 14, 2021 8:13 pm    Post subject: Reply with quote

sir,

I concur with the above advice to just have a look at it. Mine is the Leicaflex mount version, Both this and the Minolta verrsion have the excellently smooth focussing handle which is far easier to use without cfreating vibrations than usual helix focus devices.

The only issue which a buyer should insist on is to get the original rear filters. Minolta specified a particular type of glass,, ordinary glass filters will presumably not do.

p.


PostPosted: Tue Sep 14, 2021 10:22 pm    Post subject: Reply with quote

I'm not sure if they are originals , but about 5-6 filters have been included even though ,I'm not sure if ill get to use em on digital . The original leather case needs the bottom side to get it fixed, but no big deal.


PostPosted: Tue Sep 14, 2021 10:27 pm    Post subject: Reply with quote

I still don't get it what would be the best way to use this lens on my normal mount plate tripod , the hole is way too large
Handheld, the hills about 10 miles away straight jpeg


PostPosted: Tue Sep 14, 2021 11:10 pm    Post subject: Reply with quote

Sounds like you need a step-up adapter for the tripod mount.


PostPosted: Tue Sep 14, 2021 11:24 pm    Post subject: Reply with quote

Thought about it, wonder if that would be reliable ,or is it anyway to remove the silver tripod mount and replace it with a normal one?


PostPosted: Wed Sep 15, 2021 12:08 am    Post subject: Reply with quote

kiddo wrote:
Thought about it, wonder if that would be reliable ,or is it anyway to remove the silver tripod mount and replace it with a normal one?


Click here to see on Ebay


PostPosted: Wed Sep 15, 2021 12:33 am    Post subject: Reply with quote

visualopsins wrote:
kiddo wrote:
Thought about it, wonder if that would be reliable ,or is it anyway to remove the silver tripod mount and replace it with a normal one?


Click here to see on Ebay


Yup, that's it.


PostPosted: Wed Sep 15, 2021 6:38 am    Post subject: Reply with quote

sounds like an old standard mount thread, there are sturdy adapters. Ad filters, the filters have o be in place, use the clear one. Also, judging from the picture, unsharpness is not just due to heandholding, The atmospheric conditions are crucial , as is a very long sunshade.

p.


PostPosted: Wed Sep 15, 2021 9:14 am    Post subject: Reply with quote

I've made it to remove the aluminum mount ring, and now there is the normal mount for the tripod. I still have to figure if there is any way to turn de mount ring around the lens, as is doesn't sit right on the tripod (camera is upside down )


PostPosted: Wed Sep 15, 2021 2:15 pm    Post subject: Reply with quote

kiddo wrote:
I've made it to remove the aluminum mount ring, and now there is the normal mount for the tripod. I still have to figure if there is any way to turn de mount ring around the lens, as is doesn't sit right on the tripod (camera is upside down )


Is the adapter to the camera adjustable by screws on the side? It sounds like the adapter just needs rotating of the internal section. Many M42 adapters are like that.


PostPosted: Wed Sep 15, 2021 3:36 pm    Post subject: Reply with quote

I am familiar with other lenses that have rotating mount, but this one is different ...


PostPosted: Wed Sep 15, 2021 3:41 pm    Post subject: Reply with quote

my leica-R version has a lever near the filter-drawer knob which allows the mount to rotate 90 degrees. The native Minolta mount has a much shorter distance to the film plane, hence Leitz must have specified major surgery on the mount , so no idea on whether the Minolta version rotates. Adapted on a camera with a suitable connector,however, the connector might be modified.

p.


PostPosted: Fri Sep 17, 2021 7:47 pm    Post subject: Reply with quote

Finally, piece of cake . Removing the whole rear group through the 4 rear screw on the big round ring, that are screwed to the body, will allow changing position of the mount and acces the rear group optics to clean it . This one is pretty clean all around , and I would doubt that this lens have gotten any use, because the mount was totally awkwardly shifted .