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03-19-2008, 09:23 PM   #1
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Need Lens Help.. Vivitar on Pentax

Hey Alll,
New to the forum, I just got a heck of a deal on Ebay and have heard different things about compatibility of Vivitar lenses on a Pentax DSLR K100D Will auto focus work? Just need to know what to watch out for. I know the pic on Ebay is not good but it's all the seller had. Hope the price wasn't too good to be true.

Pentax K100D digital SLR - Pentax K1000 + Lot of EXTRAS - eBay (item 200208485557 end time Mar-17-08 09:56:46 PDT)

Barry

03-19-2008, 09:46 PM   #2
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Not too bad, but not great either on the price. I dont think you will have a problem with the lenses seeing as I own a couple of them my self.
03-20-2008, 07:15 AM   #3
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Depends on the mount as to whether you'll have trouble. If the Vivitar lenses are K or K/A mount, they'll be fine. If they are K/AR mount (Pentax/Ricoh) you need to be careful, because there is a pin the protrudes from the lens mount that can stick on the mounting plate on the camera.
03-20-2008, 07:23 AM   #4
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QuoteOriginally posted by afs760bf Quote
Depends on the mount as to whether you'll have trouble. If the Vivitar lenses are K or K/A mount, they'll be fine. If they are K/AR mount (Pentax/Ricoh) you need to be careful, because there is a pin the protrudes from the lens mount that can stick on the mounting plate on the camera.
Not quite right.

there are two separate issues with third party K mount lenses on pentax DSLRs.

1) on many lenses, specifically Vivitar Series 1 K mount lenses, there is a protective shield for the apature activation lever that is too large and interferes with the mounting of the lens on the cameras. there is a simple modification for this.

2) on KA/R lenses, which were for Ricoh cameras, there is a small pin that interferes with the autofocus coupling and can cause the lens to get locked onto the body. This pin should be removed before using these lenses

Both issues are well documented in the forum.

As an Aside, and I am not sure who can do this, we should look at getting a good set of links for these issues, and any other generic third party lens issues added to the new database.

Adam?

03-20-2008, 08:50 AM   #5
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QuoteOriginally posted by Lowell Goudge Quote
Not quite right.

1) on many lenses, specifically Vivitar Series 1 K mount lenses, there is a protective shield for the apature activation lever that is too large and interferes with the mounting of the lens on the cameras. there is a simple modification for this.
Hmmm, first I've heard of a problem mounting Vivitar Series 1 lenses. I had one and it mounted just fine, and the auto aperture (almost) worked. It reported f/2.8 as a constant even though it varied from 2.8 to 4.0 when zooming.

Just wanted the OP to know that not all Vivitar Series 1 lenses will cause him trouble mounting.
03-20-2008, 10:44 AM   #6
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QuoteOriginally posted by rfortson Quote
Hmmm, first I've heard of a problem mounting Vivitar Series 1 lenses. I had one and it mounted just fine, and the auto aperture (almost) worked. It reported f/2.8 as a constant even though it varied from 2.8 to 4.0 when zooming.

Just wanted the OP to know that not all Vivitar Series 1 lenses will cause him trouble mounting.
Note your series 1 with auto apature is KA mount not K mount, and they may have changed the design by that time, Also, I believe that it actually is more related to the individual subcontractors who built the vivitar lenses, but it needs to be pointed out that it MAY be an issue.

the issue about constant apature is different.

Early KA mount lenses had no real intelligence in them, and they gave the maximum apature all the time, based on either insulators or no insulators to mate to the camera mount. the only "pin" was the AE pin, that was retracted when you took the lens out of AE mode.

Later lenses and specifically zooms had rudimentary logic implemented, that changed the data on pins to represent better the true apature (within +/- 1/4 stop) as you zoomed in and out. I had an example of how this was incoded on a sigma zoom from the early 1990's that I bought for parts, but have since lost the part that did this function. it was a segmented 5 bit binary switch where the slide was keyed into the zoom collar.
03-20-2008, 09:10 PM   #7
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QuoteOriginally posted by Lowell Goudge Quote
Note your series 1 with auto apature is KA mount not K mount, and they may have changed the design by that time, Also, I believe that it actually is more related to the individual subcontractors who built the vivitar lenses, but it needs to be pointed out that it MAY be an issue.
Thanks Lowell! I'm guilty of lumping all the variations of K mount into one generic "K mount". I also occasionally read about the "crippled" KA mount on the current cameras and I'm not really sure what that means. I just know I've never had a problem with any K mount (in the generic sense), but the first M42 screw mount I tried nearly got stuck. I figured there were some many K-mount lenses out there I'd just stick to them. Of course, the vast majority of people have no problems with screw mounts.
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