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12-08-2015, 10:27 AM   #1
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Question on M-Trick

Can the M-Trick shown here
damage the camera circuit or electronics? I am using K5IIs and Pentax-M 50mm 1.7.
I tried it but not sure if long term use will cause any damage to the camera?

Thanks.

12-08-2015, 10:40 AM   #2
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I don't see what they are doing?

Are they unlocking the lens a bit? If yes, than this is causing no damage, I believe.
12-08-2015, 10:47 AM   #3
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Only after the lens falls off.

The "trick" rotates the lens a little on the mount so the lens aperture lever doesn't meet the camera's aperture control arm. I suppose you could rotate the lens while you did something to make the camera arm move, and break the arm.

The trick doesn't work well when the lens has a focus or aperture ring that's hard to turn.
12-08-2015, 11:20 AM   #4
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Actually, what's the point to make such a thing? Just having the lens stopped down as you move the aperture ring, or am I missing something?

12-08-2015, 11:32 AM   #5
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Well the M-trick does work. Yes I have to be careful about the lens coming off and falling. But with this trick I could convert M lens to behave partly like A lens when camera is set in Av mode.
12-08-2015, 12:31 PM   #6
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QuoteOriginally posted by MVK Quote
Well the M-trick does work. Yes I have to be careful about the lens coming off and falling. But with this trick I could convert M lens to behave partly like A lens when camera is set in Av mode.
Well no, it doesn't behave anything like an A lens, rather it behaves exactly like like an M42 lens mounted on a Pentax DSLR - with an added thrill of playing Russian Roulette with your M lens.
12-08-2015, 12:35 PM   #7
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QuoteOriginally posted by excanonfd Quote
Well no, it doesn't behave anything like an A lens, rather it behaves exactly like like an M42 lens mounted on a Pentax DSLR - with an added thrill of playing Russian Roulette with your M lens.
ANd I love it with M50 1,7 at 1,7-2,8
12-08-2015, 01:32 PM - 1 Like   #8
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QuoteOriginally posted by excanonfd Quote
Well no, it doesn't behave anything like an A lens, rather it behaves exactly like like an M42 lens mounted on a Pentax DSLR - with an added thrill of playing Russian Roulette with your M lens.
Yep, that is the executive summary. In short, the only trick is finding a fool-proof way to keep the lens on the camera short of drilling a second hole in the base. There are no metering advantages and you have the headache of always having to mess with the aperture ring when refocusing. Fully manual aperture sucks for general shooting for most cameras having TTL viewfinders*. There is a reason why auto-aperture actuation was a premium feature when it first became widely available and why almost all SLR lenses since have supported the feature. (Prominent exceptions are (all?) bellows and tilt/shift lenses.)

All that being said, many users state that they like not having to use the green button for every shot. I have never quite figured that out. I shoot quite a bit with K-mount glass lacking the A-contacts (straight K-mount) and almost never touch the green button. I simply use a flow that is essentially similar to that I use with my stop-down meter cameras. It goes like this:

Meter once...shoot freely
  1. Camera in M mode
  2. Aperture ring on desired setting
  3. Determine appropriate shutter speed. This may be done any number of different ways, though stop-down metering using the green button is easiest. Almost as easy and somewhat more accurate with most dSLRs is to use a hand-held meter in either incident or reflected light mode.
  4. Do a test shot, chimp, and fine adjust the exposure settings as needed
  5. Frame
  6. Focus
  7. Expose
  8. Repeat steps 5-7 until your finger gets tired, card fills, battery dies, or the subject/light changes
As long as the light hitting the subject remains the same, there is no need to mess with the settings. Sound too simple? Perhaps, but such has been the practice with stop-down meter cameras since the mid-60s and is the universal fall-back technique regardless of available exposure system for difficult lighting.** Oh, it is also how strobists work (at least one way).


Steve

* Manual aperture comes with the package on view cameras and adding the feature would only marginally improve work flow...not worth the effort.
** This is the dirty little secret of many birds-in-flight, sports, stage, and event photographers.


Last edited by stevebrot; 12-08-2015 at 01:53 PM.
12-08-2015, 01:49 PM   #9
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QuoteOriginally posted by Just1MoreDave Quote
I suppose you could rotate the lens while you did something to make the camera arm move, and break the arm.
Or have the camera's actuator mechanism accidentally wack the lens actuator arm as opposed to flicking it under tension. Such would likely not be too good for either the lens or the body.


Steve
12-08-2015, 06:20 PM   #10
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just cut the lever on the lens off. were not talking rare or expensive lenses here.
12-08-2015, 06:56 PM   #11
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QuoteOriginally posted by jkomp316 Quote
just cut the lever on the lens off. were not talking rare or expensive lenses here.
Resale value will then approach zero. The M series lenses are inexpensive, but not free. What's more, they are not depreciating. Intentionally neutering a lens with automatic aperture actuation is, shall we say, less than intelligent and even less so if you have a camera that supports the feature.* People don't even do that with cheap Soviet glass.

As for availability, a good-to-excellent M 50/1.7 may not be as easy to come by as you might think. KEH currently has four K/M series lenses, but no fast 50s. I did a walk through eBay and found three M 50/1.7 for under $75. The cheapest, I would grade as "good" for $51.50. The next least expensive was $61.50 in "v. good" condition. Above that was one advertised as "mint" (could not confirm from photo) at $67.50 or make offer. Shipping was included for all at those prices.


Steve

* See comment above for how to shoot fast and easy with such a lens
12-08-2015, 07:37 PM   #12
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its interesting; many people prefer A series for aperture control or m42 for lack of lever. yet i always get pushback when i suggest modifying an M series to operate in the same manner as an m42. the new china 85mm K lenses don't even have levers.
12-08-2015, 09:02 PM   #13
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so an M lens will automatically open/close the aperture like an A lens based on what you set the aperture to but it just won't automatically adjust aperture to compensate for exposure or meter i guess is the terminology? like an A lens? i never knew that. if thats not what this "trick" is bypassing I'm missing something.

---------- Post added 12-08-15 at 11:12 PM ----------

QuoteOriginally posted by stevebrot Quote
As for availability, a good-to-excellent M 50/1.7 may not be as easy to come by as you might think. KEH currently has four K/M series lenses, but no fast 50s. I did a walk through eBay and found three M 50/1.7 for under $75. The cheapest, I would grade as "good" for $51.50. The next least expensive was $61.50 in "v. good" condition. Above that was one advertised as "mint" (could not confirm from photo) at $67.50 or make offer. Shipping was included for all at those prices.
timing may be bad for your searches purposes because I've come across a bunch of m 50 1.7's usually they go for around 20-30$ at most id say on eBay. the a 50 1.7's usually go for like 30-40$. i bought and sold an A 50 1.7 in great shape (wife's stepdad happened to have one too that he gave me) for about 30$ in both cases. The M and A f2's go for even less, like 10-20$ usually. the ones that you are talking about are not that high are based on condition alone. they are usually people hoping someone will be stupid enough to spend that much on one due to either no other availability or naivety or they're from somewhere overseas like japan. japanese vendors always seem to have rando prices for their goods that varies from a little cheaper than everyone else to like thousands of dollars more than appropriate. (i always wonder how customs dues works with the cheaper options if it winds up being worth it) its pretty funny sometimes. the sources like KEH or such have a higher price because you are assuming it is a more reputable source.
12-08-2015, 10:03 PM   #14
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Thanks folks. So I am now convinced that M-Trick as thrilling as it may sound is not the way to go. I will surely not risk my lens falling off. I will stick to a fully engaged lens and use green button for automatic stop down and measurements in M mode like I have been doing all this time.

Regarding recent prices on ebay, just purchased a good condition(keeping fingers crossed as I am yet to receive the parcel) Pentax-A 50mm F1.4 for USD 91 from ebay including shipping. Also got Pentax-A SMC 28mm f2.8 plus tiffen filter for 80 bucks. I know I paid a little more but wanted to give my daughter these two lenses and her first Pentax DSLR(my old K10D) before her study abroad trip to Europe. She has never used a DSLR before, so in her Xmas break I am going to give her a crash course in DSLR photography with manual focusing. A next generation of Pentaxian in making. , I hope.

I know Pentax lenses used to be cheaper but lately these Pentax glasses have become expensive. Earlier I didn't see many Japanese sellers on ebay. Now they list their lenses at ridiculously high prices and so everyone else has ended up raising their prices. My hypothesis.

On a funny side,...
I came across a garage sale where a young lad wanted to sell me his Pentax-A 50mm f2.0 for 200 dollars. When I said that lens is worth 20 bucks, he showed me a print out from ebay for Pentax-A 50mm f1.2 listed at USD 580 and said its a rare lens and he is selling at half what's listed on ebay. I couldn't stop laughing. Explained to him the difference showed him real price on internet for f2. He was very reluctant and didn't believe me. So I walked by next day with my camera gear, took out my Pentax-A 50mm 2.0 (same as his and better condition) told him if he wanted to buy mine for 100 bucks(half what he was offering). He was speechless and started laughing. Surely he didn't know anything about lenses. Finally with tons of disappointment he realized that there is a difference between f 2.0 and f 1.2.

Anyways so no M-Trick for me, no mutilation of my lenses either. Thanks again.
12-09-2015, 09:33 AM   #15
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QuoteOriginally posted by stevebrot Quote
Yep, that is the executive summary. In short, the only trick is finding a fool-proof way to keep the lens on the camera short of drilling a second hole in the base. There are no metering advantages and you have the headache of always having to mess with the aperture ring when refocusing. Fully manual aperture sucks for general shooting for most cameras having TTL viewfinders*. There is a reason why auto-aperture actuation was a premium feature when it first became widely available and why almost all SLR lenses since have supported the feature. (Prominent exceptions are (all?) bellows and tilt/shift lenses.)

All that being said, many users state that they like not having to use the green button for every shot. I have never quite figured that out. I shoot quite a bit with K-mount glass lacking the A-contacts (straight K-mount) and almost never touch the green button. I simply use a flow that is essentially similar to that I use with my stop-down meter cameras. It goes like this:

Meter once...shoot freely
  1. Camera in M mode
  2. Aperture ring on desired setting
  3. Determine appropriate shutter speed. This may be done any number of different ways, though stop-down metering using the green button is easiest. Almost as easy and somewhat more accurate with most dSLRs is to use a hand-held meter in either incident or reflected light mode.
  4. Do a test shot, chimp, and fine adjust the exposure settings as needed
  5. Frame
  6. Focus
  7. Expose
  8. Repeat steps 5-7 until your finger gets tired, card fills, battery dies, or the subject/light changes
As long as the light hitting the subject remains the same, there is no need to mess with the settings. Sound too simple? Perhaps, but such has been the practice with stop-down meter cameras since the mid-60s and is the universal fall-back technique regardless of available exposure system for difficult lighting.** Oh, it is also how strobists work (at least one way).


Steve

* Manual aperture comes with the package on view cameras and adding the feature would only marginally improve work flow...not worth the effort.
** This is the dirty little secret of many birds-in-flight, sports, stage, and event photographers.
I did exactly what you mention, drill a second hole in the mount so it locks in two positions on an old 50/2. it works as advertised like a M42 and doesn't really damage the lens. you can always fill the hole or just need to "double click" during install if you ever want to use it as an M series. In the end I didn't do it to any of my other M lenses, but it seems less drastic than cutting off the lever arm.
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