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Betlog
Tinkerer
Username: Betlog
Post Number: 6
Registered: 09-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 07, 2012 - 12:02 am: | 
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Wanted: people experienced with, owners of similar ZM lenses (ZM-5A, ZM-6A), or lens diagrams. To help me determine if my lens is performing and assembled correctly.
I have a (3M)ZM-6A 500mm/6.3 catadioptric lens that takes photos that seem to have absolutely no focus.
Not just very slim DOF, but virtually NO part of the field that is actually focused.
I have heard that some ZM lenses rear element groups have been incorrectly assembled, so perhaps the issue is as simple as that.
I have attempted trial-and-error to go through each of the combinations represented by two elements and one spacer in the relatively few combinations of orientation...but unless I missed something (possible) what I have right now is as good as it gets. However I cannot believe it could actually be this bad.
Can anyone advise?
Here is todays quick-comparison shots, note the absence of an apparent focal plane and that even where *some* focus should be seen the ZM clarity sucks, even compared to the damaged-mirror Sigma.
http://oh-hi.info/tech/Compare_Tamron-500mmf8-55BB_ZM-6A-500mmf6.3_Sigma-600mmf8 -2048px.jpg |
Betlog
Tinkerer
Username: Betlog
Post Number: 7
Registered: 09-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, April 22, 2012 - 05:51 pm: |
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Answered my own question:
http://www.flickr.com/groups/10494981@N00/discuss/72157629758572451/ |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1205
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 24, 2012 - 09:24 pm: |
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Nice job, and great information! I'll be interested to hear whatever additional detail you get around to adding to your account. |
John_shriver
Tinkerer
Username: John_shriver
Post Number: 75
Registered: 12-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 04, 2012 - 08:17 pm: |
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I'd say that rear ring should have the smooth side against the mirror glass, not the three nubbins. The nubbins would definitely deform it! |
