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10-03-2012, 02:19 PM   #1
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Pentax K5 + Asahi 35/f2.3 lens locking issue

Hi everyone,

So I finally got my SRB Griturn adapter ring to mount my 35mm f.23 Asahi lens. The problem is this: the asahi lens' focusing ring is quite stiff, so when I mount it to the camera, focusing the lens inevitably turns the lens off of the camera.

I assume the problem is the mount is not locking into the body properly. What I do is as follows. Maybe I'm doing things out of order?

1. Thread the adapter on to the lens.
2. Insert the lens into the body and turn until movement stops.

The lens red dot is a couple of degrees off from the centre where it should line up, but I physically cannot turn the lens any further without feeling like I'm going to break the lens or the body.

Am I not turning hard enough? It feels like I'm applying too much pressure, and the adapter always comes off with the lens. I haven't removed the spring-steel lock, so I'm not sure why it won't stay on.

Thanks for your help!

10-03-2012, 06:53 PM   #2
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The adapter should lock onto the camera mount if you have not removed the spring lock. However, there is nothing to prevent the lens from unscrewing from the adapter which i assume is what is happening.
That's just how M42 works.
The solution is to loosen the focusing ring on the lens. It is most likely just old grease. Sometimes turning the ring back and forth many times will loosen it enough other times it needs to be opened the old grease removed and new applied.
It could also be physical damage to the focusing ring but i would assume the grease is the problem first.
10-04-2012, 07:47 AM   #3
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QuoteOriginally posted by jatrax Quote
The adapter should lock onto the camera mount if you have not removed the spring lock. However, there is nothing to prevent the lens from unscrewing from the adapter which i assume is what is happening.
That's just how M42 works.
The solution is to loosen the focusing ring on the lens. It is most likely just old grease. Sometimes turning the ring back and forth many times will loosen it enough other times it needs to be opened the old grease removed and new applied.
It could also be physical damage to the focusing ring but i would assume the grease is the problem first.

Nope. What is happening is that the adapter ring is not locking on to the body. I don't feel like I can push the adapter ring around any further without damaging. Since SRB doesn't provide and instructions (but it operates essentially the same as the Pentax branded model) i thought I would try the forum first since many people have the SRB Griturn adapter.

Should I have to use a substantial amount of force to get the adapter ring to lock into place, or should it gently slide and click?
10-04-2012, 11:53 AM   #4
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QuoteOriginally posted by GnipGnop Quote
since many people have the SRB Griturn adapter
Hiya GnipGnop, I don't have the above mentioned adapter. The official instructions with the Pentax adapter are attach adapter to camera body, then screw the lens in. This does make a difference with some of my lenses. It doesn't take much force with the OEM adapter, easy to install or remove without tools.

10-04-2012, 12:31 PM   #5
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Fair enough! I'll e-mail SRB and see what's up.

thanks very much!
10-04-2012, 08:17 PM   #6
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QuoteOriginally posted by riff Quote
The official instructions with the Pentax adapter are attach adapter to camera body, then screw the lens in.
That is the way I usually do it as well. At least with Pentax OEM adapter. I have a couple of generic ones permanently attached to my 300mm and 400mm lenses because it is too hard to screw those into the camera.

But the adapter should just turn a quarter turn or so just like any k-mount lens and then lock into the camera. Try that without a lens attached to the adapter and maybe you can see why it does not lock. I looked at the image on the SRB website and that looks like the generic ebay style adapters. If so those have a wide range of quality control. Some are nearly as good as the Pentax one, others are poorly made with rough edges and things that do not quite line up. It is possible the lock spring is just a bit miss-aligned on yours.
10-04-2012, 09:29 PM   #7
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QuoteOriginally posted by riff Quote
The official instructions with the Pentax adapter are attach adapter to camera body, then screw the lens in.
Unless, of course, you have one where the instructions say to attach the adapter to the lens first (I have one of each) or a camera manual that suggests adapting the lens rather than the camera (my KX film camera manual, page 28). I ALWAYS put the adapter on the lens first and snug it with a K-mount back cap. It is so much easier to mount to the camera that way.

The SRB adapter is highly regarded and supposed to be first rate. I am surprised that it is giving the OP grief. As for the index mark on the lens not lining up vertical to the body...welcome to the world of M42 lenses. I have a ton of them (Pentax, Mamiya/Sekor, Rikenon, Vivitar, and FSU) and there is wide variability involving both bodies and lenses. My later-version Pentax SV lines up perfectly with my early Super-Tak 55/1.8, but put my other (newer) Super-Tak 55/1.8 on the same camera and it snugs up several degrees earlier. Ditto for the newer lens on my Pentax SPII. Nothing lines up on the Mamiya/Sekor 1000 DTL or the Ricoh Singlex. The Pentax Spotmatic lines up perfect with the Vivitar 28/2.8, but not with any of the Taks. Of my two genuine Pentax M42 adapters, neither lines up with any of the Taks, but all of my Vivitars line up perfectly, but only with one of my two adapters. Go figure...


Steve

Last edited by stevebrot; 10-04-2012 at 09:38 PM.
10-04-2012, 09:35 PM   #8
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QuoteOriginally posted by jatrax Quote
I looked at the image on the SRB website and that looks like the generic ebay style adapters.
They aren't the generic adapters. They machine their own (or at least they did when I was researching quality alternatives to the Pentax product) and can make custom adapters to suit if you provide the specification. If I lived on the other side of the Atlantic, the SRB would be my first choice.


Steve

10-05-2012, 07:11 AM   #9
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Thanks for the detailed response Steve. It really is appreciated.

Here's the update on the lens adapter. I emailed SRB Griturn stating the issue. Their website says to expect a reply within 2-3 days, but I got a reply by the next morning. The email was from a technician (not a customer service rep) and he first and foremost apologized for the issues I was having. He then went on to give a bit more instruction (as the product comes without any. Since this was my first foray into m42 adapters (and the OEM Pentax models run over $90 in Canada from the camera stealers) I am a bit new with how things "should" work. I did research for quite some time and this is why I settled on the SRG Griturn in the first place.

The technician did a great job explaining it to me, and I sort of arrived at the conclusion he stated almost at the same time. The spring mechanism that is supposed to lock the adapter on to the body wasn't latching all the way. The technician has offered to replace the ring, but I think it will be fine if I don't. I just have to help the spring latch a bit more by giving it a bit of a nudge. That's in.

Since these rings have such tight tolerances (and I was a bit scared after reading the horror stories about the cheap chinese rings getting stuck on bodies) I wanted to make sure my ring wasn't a lemon.

If I bend the spring upwards a bit it should lock into place from now on, but I'm not overly concerned. The adapter is working as it should. It really wouldn't be an issue if the lens I'm using wasn't so hard to turn to focus.

All in all, I'm satisfied with how SRB handled the issue. The ring slides nicely, but isn't removable by hand. It can be a bit tricky to get off, but with the tool and bit of practice it should become easier.

I wonder if lubing the ring with a tiny tiny amount of graphite would help this?
10-05-2012, 10:21 AM   #10
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QuoteOriginally posted by GnipGnop Quote
I wonder if lubing the ring with a tiny tiny amount of graphite would help this?
I would think that would be a bad idea, as the graphite could potentially get into the camera body and onto the sensor.
QuoteOriginally posted by stevebrot Quote
They aren't the generic adapters. They machine their own
Thanks for the correction, I was just going by the image on the website. As the price is a good bit higher than the ebay ones I would expect better quality but these days you are never sure if price is a reflection of quality or not.
10-05-2012, 12:24 PM   #11
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QuoteOriginally posted by stevebrot Quote
I ALWAYS put the adapter on the lens first and snug it with a K-mount back cap. It is so much easier to mount to the camera that way.
I agree. It shouldn't make a difference but I do have a lens or two that will not lock if I put the adapter on the lens first.
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