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11-12-2010, 01:21 PM   #1
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Pentax-M 1.4 50mm focus ring smoothness?

Alright I just got this lens in the mail of some guy on ebay, optically it is beautiful, clear, no scratches, no fungus, nothing. The body is pretty well kept also. I just was wondering for those with the same lens, is the focus ring a bit slow or not as smooth as other 50mm manual lenses, I ask because I have a Minolta and Nikon 50mm from back in the day and they both focus quicker.

Example:

Nikon = No pull resistance
Minolta = medium resistance
This Pentax = About twice the resistance of the minolta

Just wondering is all.

11-12-2010, 01:25 PM   #2
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From experience MF Nikkors have rather light and quick focus rings. Pentax MF lenses are rather heavy in comparison. Also, M lenses must be at least 20 years old now and beg for relube.
11-12-2010, 01:28 PM   #3
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Maybe it is something I need to get used to and normal then? There is not bumps or harder parts when focusing, I am gonna assume its normal...though I have no other pentax lens to compare it to which is a bummer.

Last edited by Abstract; 11-12-2010 at 01:36 PM.
11-12-2010, 01:39 PM   #4
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my own opinion, which is limited to owning only 3 M lenses is that the M lenses are not as consistent as other pentax lenses in the action of the focusing ring and the drag on the ring.

both my M50/F2 and my M50/F1.7 have a "bump" in the middle of the focusing range, and each has a different level of drag. My M100/F4 macro is the most consistent of the bunch, and I can remember not getting an M100/F2.8, opting for the K105/F2.8 because the M lens just felt cheap, (I know that is not a good way to judge things but it just did not feel right)

My K50/F1.4 is perfectly smooth and consistent in the action of the focusing ring, and a little lighter than the 2 M series 50's I own.

note however, my K50/F1.4 has been mine for more than 20 years, the two M series cost me about $30 total in a second hand bin. They may not have had the same level of care, but the observation still holds, my experience with M lenses (except my macro) is that the focusing action is just not as consistent.

11-12-2010, 01:44 PM   #5
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The bump you have experienced with M lenses is probably caused by the 2 brass guiding plates inside the lens not perfectly aligned as the tolerance is very tight (unlike Limited lenses). Usually they can be readjusted for smoothness with the rear removed.
11-12-2010, 01:45 PM   #6
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Ahh I see, this one is consistent throughout the focus ring I must say, it looks like it was very well maintained besides the cap being half broken(stays on alright). I just felt it had more resistant then my other 50mm lenses, I will not know how I feel about that until I actually use it on a camera though(Waiting to get a K-5). Hopefully I feel good about it, I always felt my Nikon was a bit hard to focus cause it was to "slippery" I guess you could say. The Minolta was always at the sweet spot though.
11-12-2010, 01:48 PM   #7
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QuoteOriginally posted by wlachan Quote
The bump you have experienced with M lenses is probably caused by the 2 brass guiding plates inside the lens not perfectly aligned as the tolerance is very tight (unlike Limited lenses). Usually they can be readjusted for smoothness with the rear removed.
except that my K50/1.4 is silky smooth. as I said the M series lenses just feel a little cheaper
QuoteOriginally posted by Abstract Quote
Ahh I see, this one is consistent throughout the focus ring I must say, it looks like it was very well maintained besides the cap being half broken(stays on alright). I just felt it had more resistant then my other 50mm lenses, I will not know how I feel about that until I actually use it on a camera though(Waiting to get a K-5). Hopefully I feel good about it, I always felt my Nikon was a bit hard to focus cause it was to "slippery" I guess you could say. The Minolta was always at the sweet spot though.
my K50 is a lighter focusing coller also. but the two M50's have not just stiffer focusing but different. again, I attribute this to my own impression that the M series lenses may not be quite as good as the K's they replaced.

edit note, my K50/1.4 and my Super Tak 50/1.4 are very similar in the focusing action.

please do not ask why I have 4 different 50's

Last edited by Lowell Goudge; 11-12-2010 at 02:11 PM.
11-12-2010, 01:51 PM   #8
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I do not have the f/1.4 but my f/1.7 from some years back had a similar stiff focus. It's not really surprising considering the age of these lenses.

The stiffness could simply be due to lack of use or to dust/dirt in the focus helicoid. I have a favourite treatment for such problems but you have to be careful. These lenses had a viscous damping which can become hard with age or use in the cold. My treatment consists of gently warming the lens up to about 40 deg. C. - don't cook it for obvious reasons. Once the lens is warm try gently rotating the focus ring back and forth until it runs smoothly. Thereafter, it should remain smooth. This treatment is also useful if you have a 'sticky' zoom lens.

AT YOUR OWN RISK, OF COURSE.

11-12-2010, 01:58 PM   #9
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QuoteOriginally posted by Lowell Goudge Quote
except that my K50/1.4 is silky smooth. as I said the M series lenses just feel a little cheaper
my K50 is a lighter focusing coller also. but the two M50's have not just stiffer focusing but different. again, I attribute this to my own impression that the M series lenses may not be quite as good as the K's they replaced.
Hmm really, I heard this lens was brilliant.

QuoteOriginally posted by fotaki Quote
I do not have the f/1.4 but my f/1.7 from some years back had a similar stiff focus. It's not really surprising considering the age of these lenses.

The stiffness could simply be due to lack of use or to dust/dirt in the focus helicoid. I have a favourite treatment for such problems but you have to be careful. These lenses had a viscous damping which can become hard with age or use in the cold. My treatment consists of gently warming the lens up to about 40 deg. C. - don't cook it for obvious reasons. Once the lens is warm try gently rotating the focus ring back and forth until it runs smoothly. Thereafter, it should remain smooth. This treatment is also useful if you have a 'sticky' zoom lens.

AT YOUR OWN RISK, OF COURSE.
Well I will use it for a while, maybe it will loosen up? Warming it hmm...wondering how I would even go about that haha.
11-12-2010, 02:14 PM   #10
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QuoteOriginally posted by Abstract Quote
Hmm really, I heard this lens was brilliant.
Optically there is not a lot of difference between any of the 50mmF1.4 lenses, with the exception of my super tak, that is the 8 element version. All other pentax 50/1.4 lenses have the same optical formula, perhaps slightly different coatings over time.

it does not mean the lens is bad, it is just the feel, is a little different than my K series or takumars.
11-12-2010, 02:17 PM   #11
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QuoteOriginally posted by Abstract Quote
Well I will use it for a while, maybe it will loosen up? Warming it hmm...wondering how I would even go about that haha.
Not too difficult really. I use our domestic oven heated to 40 deg. C (as stated) using a thermometer. Allow the oven to stabilize at this temp. for a few minutes and then place the lens (wrapped in tissue or soft cloth) for about 5 mins. I usually keep the oven door ajar during the warming time.
11-12-2010, 02:30 PM   #12
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QuoteOriginally posted by Lowell Goudge Quote
Optically there is not a lot of difference between any of the 50mmF1.4 lenses, with the exception of my super tak, that is the 8 element version. All other pentax 50/1.4 lenses have the same optical formula, perhaps slightly different coatings over time.

it does not mean the lens is bad, it is just the feel, is a little different than my K series or takumars.
Ah alright because on ebay the A version seemed to go for about twice as much.

The only difference is I can't put it on aperture priority correct? I usually go full manual anyways.

QuoteOriginally posted by fotaki Quote
Not too difficult really. I use our domestic oven heated to 40 deg. C (as stated) using a thermometer. Allow the oven to stabilize at this temp. for a few minutes and then place the lens (wrapped in tissue or soft cloth) for about 5 mins. I usually keep the oven door ajar during the warming time.
Hmm not sure I would be comfortable with that...but maybe if it does bother me...thanks.
11-12-2010, 02:33 PM   #13
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QuoteOriginally posted by Abstract Quote
Ah alright because on ebay the A version seemed to go for about twice as much.

The only difference is I can't put it on aperture priority correct? I usually go full manual anyways.



Hmm not sure I would be comfortable with that...but maybe if it does bother me...thanks.
the A series lens has aperture contacts, aside from aperture priority amd in fact all auto modes, not just Av mode, the big advantages are matrix metering as opposed to only spot and center weighted, and P-TTL flash capability.

An A series lens can command a lot more just because the metering and P-TTL flash work.

That bothers me a little, and I rreally wish pentax came out with a body that still supported TTL as well as P-TTL, because presently if I want good flash with mymanual lenses I am using my *istD which is a little long in the tooth
11-12-2010, 03:22 PM   #14
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Oh damn, I knew about the other stuff, was not aware about matrix metering issues...well that should not be so much a problem being that I wont use to for landscapes, only street shooting I suppose. Does the same go for M42?
11-12-2010, 03:31 PM   #15
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QuoteOriginally posted by Abstract Quote
Oh damn, I knew about the other stuff, was not aware about matrix metering issues...well that should not be so much a problem being that I wont use to for landscapes, only street shooting I suppose. Does the same go for M42?
Yes

with either K or M42 lenses, the camera has only spot and center weighted.

Matrix metering is better for scenes with high contrast or bright spots because the camera has a better chance of deciding to ignore one or the other.

You can still work using spot metering, which is probably the best in tough to meter situations any way
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