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Forum: Troubleshooting and Beginner Help
09-07-2021, 07:42 AM
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A Pentax A series lens has its A contact retracted when the aperture ring is not in the A position. When you move the ring into the A position, the contact sticks up slightly above the level of the mount. There's a spring within the contact so it can be pushed back down level with the mount. When the lens is mounted with the aperture ring in A position, the contact gets pushed in and level with the mount, until the lens is fully rotated. Then the A pin springs back out and makes contact with the camera's A contact, which is slightly recessed.
I think the A contact on your Samyang lens isn't springy enough. The contact is probably getting stuck on the hole for the autofocus screw drive when the aperture ring is in A position. It does extend and retract like it's supposed to when you move the ring. It's just not temporarily spring in and out when the lens is mounted. I haven't seen an actual Samyang lens so I'm guessing. You might be able to free up the spring action, or just work around it.
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Forum: Troubleshooting and Beginner Help
09-07-2021, 12:39 PM
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Well, that is strange. My Samyang 14/2.8's contact is marginally more prominent than my other lenses, but has no problem catching on screw holes and such*. Too bad you waited so long before giving it a try, otherwise you could simply return to the seller. It might be worth a try, though.
Steve
* The design is such that the mount contacts are clockwise of the AF drive well during rotation into the mount.
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Forum: Troubleshooting and Beginner Help
09-07-2021, 02:12 PM
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If a warranty solution is available I'd grab it … living with the problem might suit you now, but if/when you come to sell it (and it's out of warranty) a niggly fault like this is bound to affect the resale price.
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Forum: Pentax Medium Format
01-16-2020, 05:11 AM
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The 645 120, in both A and FA are fantastic lenses. I perhaps, favor the 120 A for my style of work. That said, although it does produce beautiful images on the K mount, it is quite cumbersome to use due to the lack of an automatic diaphragm. It’s just too dark to view and focus when stopped down. Both lenses do still function and produce outstanding images on all iterations of the 645’s.
I too have a number of macros, 35, 50, 100, 180 and find them much easier to use on a K mount. Since purchasing the 645z, however, I find that I am very comfortable using the Z with the 120 A for nearly all my macro work.
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Forum: Pentax Medium Format
01-15-2020, 02:11 PM
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I finally found the 645 to K adapter.
Here are some quick shots, nothing scientific, utilizing the Pentax 645 *600mm lens on a K-5 with a 645 1.4X, 2X and a Sigma 35mm APO 1.4X extender. Image exposures varied due to dynamic changes in outdoor lighting. But hopefully, you will get the jist of the images.
First images is of a box face using the lens without a converter.
Second images is the Sigma APO 1.4X converter. (Looks quite nice in my opinion)
Third is with the 645 1.4X. Different lighting and subject top possible focus issue
Fourth is with the 645 2X. Subject to the same conditions as the 1.4X.
All shots on K-5 at iso 1600 at f8, mounted on a Gitzo GT5540LS and Wimberley Gimbal.
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Forum: Pentax Medium Format
01-12-2020, 10:02 AM
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I have used the 645 1.4 and 2x adapter with my 645 *600. The 1.4 is very good on the small sensor K5. The 2x is not too bad either. It was not quite up to the image quality of the A*1200 I had, but it did the job when I needed the extra focal length. I have yet to put it on my K1ii. Perhaps i will give both a shot today and report back to you. That is if I can find the 645 to K adapter I have misplaced 😂.
Sorry, I don’t have the current K 1.4 so I can’t help you there.
Stephen
---------- Post added 01-12-2020 at 10:04 AM ----------
I’ll second your comments. Very accurately stated.
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Forum: Pentax SLR Lens Discussion
01-07-2020, 05:31 AM
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I've had a look at the lens diagram, the front elements aren't cemented
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Forum: Pentax SLR Lens Discussion
01-05-2020, 09:29 AM
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I would also recommend returning the lens for a full refund.
Another thought is that if you were to sell the lens in the future, you may find it difficult to recover your cost -- many potential buyers would shy away from a cracked element.
- Craig
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Forum: Pentax SLR Lens Discussion
01-05-2020, 09:21 AM
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I have the A* 400/2.8 and I picked it up for $2700 in the middle of last year. It had some scuffs on the lens barrel but only minor and looks to be from normal use not abuse. So given yours has a crack in a lens element I would be running from it.
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Forum: Pentax SLR Lens Discussion
01-05-2020, 06:42 AM
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That seems a lot of money for a lens which has a major fault.
It may not notice now but in the future who knows.
And how did it get cracked? Strange it should be the second element which is not immediately accessible from the outside
I would get my money back.... unless the seller is prepared to accept a fee which is reasonable.
Having said that there was a 560 which had been dropped down a mountain that fetched big money a couple of years ago on the bay of e.
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Forum: Pentax SLR Lens Discussion
01-05-2020, 06:35 AM
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If you're doing rocketry photography I'm fairly certain that you'll always be at hyperfocal distance. Why not use an A/A* lens? I don't know if its the same for all the long MF pentax lenses, but my 645 A* 600 has a movable detent lock for setting a desired locking focus point/limit as well. At that distance, you probably don't need AF.
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Forum: Sold Items
12-15-2019, 10:03 PM
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the potential sale has not worked out
so the items are still for sale under the original conditions:
I want to sell as a bundle but ????
stand alone price for the K-01 and Carry Speed LCD ViewFinder - $190.00
stand alone price for SMC Pentax-DA 40mm F2.8 XS - $140.00
bundled price for Pentax K 01, Carry Speed LCD Viewfinder, Battery Charger and SMC Pentax-DA 40mm F2.8 XS - $290
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Forum: Sold Items
09-01-2019, 06:54 AM
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I may have the original rom if the buyer wanted to replace the failed sdm. It would require that they reprogram the lens which would disable screw drive. Then the buyer would have the sdm motor replaced.
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Forum: Pentax Lens Articles
01-31-2012, 01:58 AM
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I was that request:D!!
Thanks for taking the time to post such a detailed guide to dissasembly of this lens. The sliding hood on my otherwise perfect copy was quite loose, so I wanted to replace the felt slider inside it. There is no way I would have figured out how it came off, but now I know.
Many thanks for providing such a useful article, and in under 24 hours of my post to you! Guys like you make Pentaxforums the great resource it is!
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