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04-14-2015, 04:15 PM   #1
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Please help; Adapting Pentax lens to Canon 70D, lens cleaning.

Hello everyone! I am new to this forum and mostly new to vintage lenses. I have recently bought a almost mint Pentax SMC-M 50mm 1.7 that came on a k1000 pentax camera for 20 dollars. I have also, with great luck, aquired an Auto Chinon 55mm MCM 1.7 MACRO, which is a rather rare m42 mount lens that i scored for 40 US dollars. The aperture blades work perfectly and it is in rather good shape, except it has some optical issues. Like I said, I am rather new to this fun part of photography and here is where I can hopefully find some help from some of you experts of people who have experienced similar issues.

I had no problems mounting the m42 adapter on the Auto Chinon 55mm, and at first, it was a little tight being put on the canon 70D front mount, but after a couple of lens swaps, I feel pretty comfortable with it. However, the next day I received my k-mount to eos adapter for my pentax SMC-M 50mm 1.7, and I had a quite different experience. I figured out how to put the adapter on the lens rather quickly, and I feel it fit just perfectly. There was no wiggle, but at the same time I was able to remove it when holding down the pin with ease.

However, when I tried to mount the lens on my 70D body, I could not get it to go in. I was having a hard time lining it up and putting it in there, and once I had it somewhat in there, I could not rotate it to the pin for the life of me. I did not want to try too hard as to not damage my Camera body mount. Thinking to myself that it could be the lens, since I read sometimes certain lenses need certain parts "filed off", I removed the adapter from the lens and tried to fit in the adapter by itself, but to no avail. Once again, it was too right, and the ridged of the adapter and my mount felt too sharp against each other. I went back on amazon, checked the reviews (which were good) and almost no one else had this problem except one person. Most people had problem with "too much wiggle" with their connection to the lens, not the camera body.

Sorry with the long preface, but here is where I need help. I decided to return the k-mount adapter and now I am not sure if it was just a matter of quality control and I should order another one, or try another brand? Does anyone have any experience using a certain adapter with canon 70D, as well as pentax smc-m 50mm 1.7 lenses? I realize all camera body mounts are supposed to be the same, but I just cant be sure at this point Also, even tho I do not believe it was a problem, is there usually any shaving or filing that needs to be done with that lens for the canon 70D? I really like the lens and want to use it, as the one picture I got to take with it barely mounted was really amazing.

Second thing I need help with is lens cleaning. Now I know the Auto Chinon isn't a Pentax lens, but I figured the cleaning and repair with most lenses would be very similar, so I hope it is okay. The lens focuses and works great, but is just has a certain haze to it, and it seems to diffract light quite a bit. I did the flashlight test, which was my first time, and I could see lots of little white dots as well as what looked like just foggyness on one part of the lens. Is there any certain way of being able to know if its fungus or something else? from what I could tell, it seemed to be mostly on the front lens element. I wasn't sure whether it was from the inside or outside, and so I carefully cleaned the outside of the front element with acetone, and it helped a little, but most of it was still left on there, so I assume its from the inside. I really like this lens, as it is not truly macro but has a short focusing distance, great bokeh, and very nice focus ring that is a joy to use for video.

I live in Lincoln, Nebraska, and there doesn't seem to be that much help around. I would really like to make this lens as nice as I can. Can anyone give me any input as in how to go about it, if this lens is easy to disassemble, how to go about cleaning it? If there was a service or person someone could recommend, I would be willing to spend a little extra money on this lens as I have only 40 dollars invested, without the camera it came with, and I think it really has potential. I know I'm throwing a lot out there and I am not very concise, but any help or input in either matter would be SO greatly appreciated! I look forward to getting more immersed into this wonderful world of vintage lenses. I will also be picking up a second 50mm 1.7, so if someone goes overboard in helping me, I might feel inclined to reward them with it Thank you all in advance.

04-14-2015, 05:48 PM   #2
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I am not sure how much help anyone here can be regarding the adapter. This is after all a Pentax forum and the adapter seems to fit the lens fine so while we might have been some help with lens to adapter that does not seem to be an issue. Perhaps someone else might be able to help but I honestly do not see how since you do not even link to the adapter you purchased. Have you contacted the adapter seller or manufacturer?

Second, as you might imagine "filing off" or otherwise damaging a perfectly good Pentax lens to mount it on another brand camera is somewhat frowned upon here. May I ask why you did not just buy a manual Canon lens?

As to the Chinon lens, without complete details, meaning the exact model and description again it will be hard to help. You might get better answers if you provide that information as there are a lot of M42 experts on this forum. But particularly with older lenses you must be precise as over 30 or 40 years Chinon might have made several models that are similar but not the same.

Without pictures it is impossible to tell if you have haze, fungus or element separation. Haze might be cleaned by opening the front of the lens and cleaning the element that is affected. Fungus would need to be cleaned, usually with alcohol or other cleaner, from all affected surfaces, however if it has been there a long time it is possible it has etched the lens coatings or even the glass rendering the lens useless. If it is element separation the individual lens elements will need to be completely separated, cleaned and then glued back together. As you might think this is extremely expensive and if this is the case it is usually not considered cost effective except for very rare or expensive lenses. Either post some well lit images of the issue or take the lens to a local camera shop for a quote on repair. I would guess, and that is all it would be, that for haze or fungus a cleaning would be maybe $75 to $100. If it is element separation, I doubt it would be possible to repair at anything you would wish to pay.

Hope that helps.
04-14-2015, 06:05 PM   #3
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I believe the cutting down of lenses is for full-frame mirrors to clear the lens.
04-14-2015, 08:04 PM   #4
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I am very experienced with PK to EOS adapting, both apc-c and Full frame. While more information is needed to make a specific diagnosis, the most common cause of the symptoms you are describing are due to the lever and/or shield beside the lever contacting the shielding inside the camera immediately behind the ring. Are the lever or shield on and back of the lens bent in any way at all?

There is a lot of variation in the quality of the PK-EOS adapters out there. Please attempt to mount the adapter all by itself (without the lens) on the camera. If it goes smoothly, the next thing to check is if the lever and/or lever shield are out of spec. I you share a good photo of the lens we may be able to better help diagnose.

QuoteOriginally posted by SpecialK Quote
I believe the cutting down of lenses is for full-frame mirrors to clear the lens.
I will confirm this. I have mounted over 100 genuine Pentax lenses with no clearance problems on any model in the Canon 10D-70D aps-c family. Very few folks know this, but is also possible to mount an unaltered Pentax lens on the full-frame EOS family with no mirror collision if a specific mounting orientation is used. I'm working up an article on this and plan to post before too long.

04-14-2015, 11:10 PM   #5
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Welcome to the forum, it does sound like perhaps a quality issue with the adaptor itself as others have already suggested.
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