SMC-M 50mm 1.7 tight fit on K-x

[MattB.Net]

<p>I mentioned this in another thread, but I think it may deserve a thread of it's own.</p>

<p>I got my K-x this week and have been having fun playing with it as I find the time. The other night I dug out my old 50mm 1.7 manual lens I used to use with my ME Super to see how it would do. It smoothly came off the old camera but when I try and mount it on the new one it feels very tight at the point where I would rotate the lens to lock it in place. So tight that I decided not to try and fore it and risk my new camera getting damaged.<br>

Has anyone experienced this? Everything looks to be fine and the orange dots were lined up. I'm not sure what to do. This particular manual lens isn't exactly valuable so I'm not overly concerned about it having compatibility issues, but there are other old lenses I would like to acquire and I worry they might have the same problem with the K-x.<br>

Any ideas? Thanks!<br>

Matt</p>

[texasbiker]

<p>I have used my old manual prime lenses on my newer digitals. The biggest problem was setting things to recognize it.</p>

<p>But the mount fit, and it should fit. My newest camera is a K20, but I think I tried my old lenses on a K100 and my *ist.</p>

[michael_kuhne]

<p>Where did you buy this camera? Do you have a store nearby where you could try this lens on a K20D or K-7?? A repair facility with these cameras that would mount it and check it out for you? Nothing protruding on the rear lens mount that may be bumping up against the SDM contacts?</p>

<p>If it were me, and you are certain there has been no damage to the lens which could account for this, and its rear mount looks perfect, I would go ahead and mount it on. If any problem occurs, let Pentax warranty deal with it. The K-x is advertised as being compatible with all Pentax K-mount lenses. They should live up to this. I use an old "M" 135mm on my K200D and K20D from time to time with no issues.</p>

[MattB.Net]

<p>Thanks. I'll spend a little more time with it and see what I can figure out. I live in a small town in the mountains and we have no local camera shop or repair facility. I do have another old manual lens (a 135mm IIRC) so I'll try that one too and see if it feels the same.<br>

I think the nearest Pentax facility is in Golden which is a 3.5 Hr. drive away which is farther than I would want to go for this!</p>

[laur1]

<p>But how tight does it really feel? Some lenses mount more tightly than others and that's not a bad thing. My M lenses require more force in mounting them than the DA kit lenses. Of course, on the other hand, if you have to strain as for opening a jar, something might be wrong.</p>

[dan_daniel2]

<p>Look at the mounting surafaces of the lens. Sometimes there is a build-up of sludge or grease or something over the years, Wiping down with alcohol or naphtha might clean this away. Get up on the inside of the lower flange areas, also.</p>

<p>There might also be small pits in the metal from oxidation. A little scraping with a metal edge could handle these, but this is heading towards a delicate operation that I wouldn't suggest unless you've done such metal work before.</p>

 

[joe_jackson4]

<p>Matt, just tried my M 50/1.7 on my K-x (again)... It's a little tighter than the kit lens, but not too bad. Easily mounted with index finger and thumb...</p>

[jeremy_corbin]

<p>Matt, I noticed that my Ricoh P 50mm f/2 fit nice on my ZX-M, but when I got my *istDS it fit scary tight as well. Although it concerned me, I did press on and it fit fine. I believe that the tolerances were just smaller than they were on the ZX-M. I went slowly and consistently while turning. I didn't notice that same tight fit with my Vivitar A 28-80 or my Tokina M 80-200. Proceed slowly and I believe it should be fine. YMMV</p>

[MattB.Net]

<p>OK, I tried again last night, first with the 135 f/2.5 which went on pretty smoothly. So I cleaned the surface of the 50 f/1.7 and tried again and it seemed a little better and went on all the way without that "jar opening" force, although still a bit tight.<br>

So thanks for the responses, I think it was maybe just a little gummed up (but not visibly so) or something. I just didn't want to be too forceful with my shiny new camera!<br>

Now, is there a guide to using old manual lenses on our newer bodies around here that someone can point me to? I think I have the basics down, but would love to read up on it a little more if there's something written up.<br>

Thanks again!</p>

[michael_kuhne]

<p>I suppose you already know to enable aperture ring using the custom functions menu, shoot in Manual mode, and use the green button for metering and setting shutter speed. Next, you'll need to get a feel for metering variance as you adjust aperture. I have found metering around f/3.5-5.6 to be quite accurate with the old lenses I use, but stopping down to smaller apertures results in over exposure. So, I set exposure comp accordingly. I don't know about the wider apertures of your faster lenses.</p>

<p>You'll get to "know the ropes" with a little practice.</p>

<p>We would appreciate seeing further posts on how you are liking your new K-x!</p>