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View Poll Results: K and M series only - Leverectomy Usability and favored mode.
No Leverectomy - I prefer full manual, no automation. 1229.27%
No Leverectomy - I prefer Manual mode with green button metering. 2356.10%
With Leverectomy - I prefer full manual, no automation. 12.44%
With Leverectomy - I prefer Manual mode with green button metering. 12.44%
With Leverectomy - I prefer AV Mode metering. 49.76%
Voters: 41. You may not vote on this poll

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04-20-2015, 04:37 PM   #1
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POLL: K and M series only - Leverectomy Usability and favored mode.

Definition: Leverectomy - the removal of part or all of the lever and/or lever shield at the rear of the lens so that the aperture functions as a preset lens. The diaphragm of the lens will match the setting on the aperture ring at all times. Although stop down metering is disabled, some other metering modes become usable without using green button.

Only the following is in scope: USABILITY. How do you prefer using the Pentax K series and Pentax-M series. (and 3rd party functional equivalents.)

Out of scope for this poll: How leverectomy affects lens value and aesthetics. The 'morality' of altering original condition lenses. Any non K or M series lens


Last edited by jbondo; 04-20-2015 at 09:36 PM.
04-20-2015, 04:53 PM   #2
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With m42s or K/M lenses that have had a leverectomy, Av is the only choice other than full (M)anual, right? (i.e. all other modes act the same as Av, so there is no TAv, Tv, or Sv -- it obviously can't set the aperture on such a lens, so those modes don't work as usual, but the same as Av)

I have only given a leverectomy to a couple of lenses with not-worth-repairing/unrepairable sticky apertures just so I could use them, and also to one lens where it is easily reversible, but I do generally prefer using Av mode rather than green button. I find myself buying m42s over M-style lenses among old lenses for this reason...
04-20-2015, 05:01 PM   #3
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On my K50, those additional modes seem to work fine. Exposure does adjust continuously on the fly.

---------- Post added 04-20-15 at 07:11 PM ----------

ok, did some more tests. based on your comment. Both K-50 and K-01 are overriding what is selected on the dial and using AV regardless of what is set in other modes. That invalidates some of our poll questions. Let me see if I can update the poll to reflect this.

Last edited by jbondo; 04-20-2015 at 06:44 PM.
04-20-2015, 05:13 PM - 1 Like   #4
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Ummm...this is silly.
  1. Av metering is less reliable than green button. They use different algorithms. So, if you want the meter linearity of the K10D, go ahead and use Av
  2. The automatic aperture* (what you have with the lever intact) is a good thing because it allows you to focus and frame wide open with stop-down for exposure only. Back in the old days, it was a heavily promoted feature and is still a huge usability consideration when buying M42 vs. K-mount lenses. For perspective, I suggest shooting an M42 body with the lens in both the M and A positions. Ten minutes will make a believer out of you. Translation? Usability with a fully manual aperture sucks. Just 45+ years of experience speaking here.
  3. Ruins the resale unless your intended market is the MILC crowd and even then they more experienced users are springing for a coupled adapter. I know this is out of scope, but should still be a consideration. Really folk, they are not making this stuff anymore.
Part of the confusion comes from the notion that there is sometime special or desirable about "continuous" metering. To be honest, it is often enough not your friend, though is usually pretty benign due to the nature of a center-weighted averaging meter. Below is a short primer on stop-down metering, yes the kind you are using with a non-A contact lens.
  • Meter the subject. This may be done a number of different ways depending on what your aim is. If is a face meter for the face.** Sometimes this means taking your reading up close and backing away. Sometimes it is enough to simply measure the incident light (gray card or equivalent).*** Use the camera's meter or a hand-held unit. Both work equally well. If none of this makes sense there are books on exposure. All metering failing, you can simply shoot/chimp/adjust and go from there.
  • Once you determine your exposure, shoot at will until either the light or your subject changes. Surprise! You don't have to re-meter in between exposures.


Steve

* Not the same as automated aperture control where aperture is controlled by the body and not the ring on the lens.

** For Caucasians this means taking the meter's numbers and adding two stops more light. For darker skin, let experience be your guide.

*** Incident measurements work incredibly well. Unless you are wanting to place the exposure to a particular value in the subject (spot metering), measuring reflected light (what your camera normally does) is sort of a mess.


Last edited by stevebrot; 04-20-2015 at 05:28 PM.
04-20-2015, 05:22 PM   #5
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QuoteOriginally posted by jbondo Quote
Both K-50 and K-01 are overriding what is selected on the dial and using AV regardless of what is set in other modes.
Yes, that is how it works with all Pentax dSLRs. If no A contacts are detected, the camera will default to Av except when in M, X, or B modes. There may be some variation regarding the green button and conductive bases, but that is a different question.


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04-20-2015, 05:26 PM   #6
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QuoteOriginally posted by jbondo Quote
so that the aperture functions as a preset lens.
No, a preset lens allows you to toggle from full-open to stopped down by flipping a switch, lever, or ring. An M42 lens with A/M switch operates very similar to a lens with a preset aperture mechanism. A leverectomized lens has a fully manual aperture. As noted above, fully manual apertures are only really useful on cameras where you do not focus or compose through the lens. Pre-set lenses rock for tilt-shift and bellows work...oh, and on a darkroom enlarger.


Steve

Last edited by stevebrot; 04-20-2015 at 05:35 PM.
04-20-2015, 05:29 PM   #7
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QuoteOriginally posted by stevebrot Quote
Av metering is less reliable than green button. They use different algorithms. So, if you want the meter linearity of the K10D, go ahead and use Av
This would be correct and relevant if we were using a lever-intact lens that had the trick done to enable AV mode implemented. That would absolutely be true. However, in this case we are not. There is no lever, so lever action linearity is irrelevant.

QuoteOriginally posted by stevebrot Quote
Back in the old days, it was a heavily promoted feature and is still a huge usability consideration when buying M42 vs. K-mount lenses. For perspective, I suggest shooting an M42 body with the lens in both the M and A positions. Ten minutes will make a believer out of you.
On cameras without live view zoom capability, I 100% agree with you. On late model cameras, however I much prefer not having to hit the green button, and to give more of my attention to critical focus using live view. I very much like that it makes stop-down focus shift an non-issue. Seems like a matter of preference to me. -- hence this poll.

QuoteOriginally posted by stevebrot Quote
...until either the light or your subject changes. Surprise! You don't have to re-meter in between exposures.
Preference I do this when circumstances allow. Many of my shoots do not. Everyone has a difference preference and style.


I don't want to get pedantic with technicalities here. I own plenty of presets that have no A/M toggle. I would rather the discussion be an enlightenment of what people like and prefer. It's a matter of discovery in tastes.

04-20-2015, 05:42 PM   #8
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QuoteOriginally posted by jbondo Quote
There is no lever, so lever action linearity is irrelevant.
Lever linearity is not the issue. The meter exposure readings are non-linear when doing stop-down metering. The problem is less severe with green button in M mode due to a modified metering algorithm that has been in place since the K-7. Stop-down metering with the K10D and K20D was/is simply terrible and highly unpredictable at most apertures.

The issue with stop-down metering is common to most (all?) current model dSLRs across brands due to the nature of their focus screens. For wide-open metering the camera's exposure system compensates for the screen.

Steve
04-20-2015, 05:45 PM   #9
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QuoteOriginally posted by jbondo Quote
I very much like that it makes stop-down focus shift an non-issue.
It is a non-issue to start with. Again, 45+ years of experience.

I would suggest that most users have hard enough time nailing focus at all, much less worrying about a 2mm shift at 1.5m distance.


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04-20-2015, 05:50 PM   #10
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QuoteOriginally posted by jbondo Quote
I don't want to get pedantic with technicalities here. I own plenty of presets that have no A/M toggle. I would rather the discussion be an enlightenment of what people like and prefer.
You got my preference and a rational for practicality.

I have half-a-dozen meterless cameras on my shelf and six more bodies that are stop-down meter only. I have shot documentary, street, and sports with those setups and have a small notion of what works.


Steve
04-20-2015, 05:55 PM   #11
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QuoteOriginally posted by stevebrot Quote
The meter exposure readings are non-linear when doing stop-down metering.
Are you implying that a lens which has no lever is capable of being stopped down when the camera attempts to actuate the lever?
That is, after all, what the green button does on a normal lens. It stops the lens down, using the lever, and then it meters with the diaphragm stopped down.
When an altered lens has no lever to start with, the lens is already in the stopped down configuration before there is any involvement with the green button.
04-20-2015, 06:12 PM   #12
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QuoteOriginally posted by jbondo Quote
Are you implying that a lens which has no lever is capable of being stopped down when the camera attempts to actuate the lever?
No, I am saying that the base meter response is non-linear and gives different numbers when not allowing the body to set the aperture. A good example would be my Sigma macro lens on the K-3.
  • Subject: Open sky outside my window just now
  • Av mode with lens wide open, body set to f/2.8 and aperture ring on A position ==> 1/6400s
  • Same setup with lens wide open, but with aperture ring on f/2.8 (top LCD shows F--) ==> 1/3200s
  • M mode with aperture ring on f/2.8 using green button ==> 1/6400s
The numbers should be identical for all three cases since the exact same amount of light is reaching the sensor, but that is not the case.


Steve

Last edited by stevebrot; 04-20-2015 at 06:29 PM.
04-20-2015, 06:18 PM   #13
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QuoteOriginally posted by stevebrot Quote
No, I am saying that the base meter response is non-linear and gives different numbers when not allowing the body to set the aperture. A good example would be my Sigma macro lens on the K-3.
  • Subject: Open sky outside my window just now
  • Av mode with lens wide open, body set to f/2.8 and aperture ring on A position ==> 1/6400s
  • Same setup with lens wide open, but with aperture ring on f/2.8 (top LCD shows F--) ==> 1/3200s
The numbers should be identical since the exact same amount of light is reaching the sensor, but that is not the case.
You must remember to turn off the matrix metering in the first case for them to be equivalent...
04-20-2015, 06:20 PM   #14
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QuoteOriginally posted by stevebrot Quote
The numbers should be identical since the exact same amount of light is reaching the sensor, but that is not the case.
The discussion of this behavior is extremely tangential to your intent for the thread and is discussed in depth on some older posts on this site. So I will leave it be.


Steve

Last edited by stevebrot; 04-20-2015 at 06:28 PM.
04-20-2015, 06:27 PM   #15
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I couldn't imagine any circumstances where I'd de-lever a lens. Green buttoning is much MUCH quicker and more reliable then screwing with dials and knobs on the fly trying to get my exposures right. (says the guy who just de-levered an old teleconverter yesterday because he couldn't green button with the thing).
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