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08-26-2012, 04:36 PM   #1
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Modifying lens

What might happen if one cut the aperture leaver off of a 'M' type lens?

08-26-2012, 04:39 PM   #2
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QuoteOriginally posted by Boker Quote
What might happen if one cut the aperture leaver off of a 'M' type lens?
Then it would be like an M42 and would stop down with the ring when mounted. Some people have done that so they can use aperture priority mode and not bother with "green-button" metering.
08-26-2012, 04:56 PM   #3
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The disadvantage is that if you stop down quite a bit (for example for landscape) then you have to focus then change aperture.

I'm finding that the more I get used to manual the less metering (using green button) I am doing. For example once I have the exposure right for a particular scene / area then I don't have to stop down again between shots and if I want to adjust exposure then just tweek shutter or aperture a bit
08-26-2012, 05:01 PM   #4
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Thanks for the answers.Will try a couple older cheaper lens.Seems to me there is no advantage to the lever on M lens but some advantage to taking it off

08-26-2012, 05:11 PM - 1 Like   #5
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The advantage is what kiwi_jono just mentioned. With a m42-type lens (i.e. what you would be creating) there is a lot of aperture ring turning -- opening to focus, stopping down to shoot, etc that can be annoying when you shooting several shots under the same lighting and really just want to use the same stop all the time (but you need to open up to focus properly). Also consider than you've either got to count clicks or take your eye away from the viewfinder and look at the lens to get the stop you want as there is no display telling you. With an M lens as-is, you have to again look at the lens or count clicks at least once but if you just want to shoot on f8, you can just set it to f8 and be done with it, and then you can focus wide-open and meter with the green button without delay. Once you get used to it, green button is probably faster and bit easier, especially if you are shooting multiple shots of the subject and you can just concentrate on focus. For slower and more deliberate shooting I prefer the m42 style -- my favorite old lenses are the presets because I can then open and close the aperture quickly without looking but still get to use Av mode. I've got lots of both style lenses -- I have no desire to go chopping any of them, I just adapt to them -- its not a big deal in the end.

Oh, and the other disadvantage is that you destroy the value of the lens by chopping the lever, should you ever want to sell it...
08-26-2012, 05:21 PM   #6
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Also, due to the non-linear nature of the focusing screen, you will never get accurate metering in Av mode at smaller apertures, so a hacked lens will never be as good as a true A lens.
08-26-2012, 05:26 PM   #7
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Hi Boker, It is easy to do non destructively, putting the parts in a zip lock bag.
I did it to 2 Rikenon P zooms when I removed the Ricoh pin
The problems are, auto focus might not always work when stopped down below f/5.6 or so, also exp linearity in Av mode was a problem (forget now) as has been discussed on the forum.
I ended up converting back and I use M mode almost all the time, with spot metering and exposure lock, sometimes exp bracketing.

(by auto focus i meant focus confirmation)

Last edited by wombat2go; 08-26-2012 at 05:32 PM.
08-26-2012, 07:33 PM   #8
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QuoteOriginally posted by elliott Quote
Also, due to the non-linear nature of the focusing screen, you will never get accurate metering in Av mode at smaller apertures, so a hacked lens will never be as good as a true A lens.
The lens is physically stopped down for metering either way, what's the difference? Neither version is like an A lens -- the body never knows what the aperture is, just reads the light coming in.

08-26-2012, 08:03 PM   #9
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QuoteOriginally posted by vonBaloney Quote
The lens is physically stopped down for metering either way, what's the difference? Neither version is like an A lens -- the body never knows what the aperture is, just reads the light coming in.
Exactly, you deal with the same metering either way, so why cripple your focusing ability just so you can use Av mode instead of hitting the green button occasionally? Most people who consider cutting the aperture tab think that it will meter just like an A lens, it won't, so you're losing more than you're gaining by cutting the aperture tab.

Instead of getting a cheap lens to hack up, get a cheap M42 lens if you want to see how well Av mode works without A contacts and to see how easy focusing at f8 is or manually opening and closing the aperture for each shot. I love using my Super Takumar 50mm f1.4, but my M 50mm f1.4 is so much more convenient to use.
08-26-2012, 09:20 PM   #10
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I picked up else where in this forum that if you are using M42 lens you might as well shoot in Av mode for the following reasons:

1) In M mode my K10D will only use spot or center weighted metering. In Av mode the multi-segment metering is also available.

2) Also, in Av mode I can use the exposure compensation feature to dial in correct exposure for a particular lens/aperture. If I'm in M mode, I need to use a control wheel to adjust the shutter speed +/- after pushing the green button in order to obtain exposure compensation.

I find the real time exposure metering in Av mode with a m42 lens more convenient than using M mode with a K or M series lens, but that convenience disappears when you are shooting with a smaller apertures because the view finder gets too dark to focus. You are then forced to open up the aperture to focus and close it back down to shoot-Yuk!

Last edited by wiseman; 08-26-2012 at 09:22 PM. Reason: to clarify
08-26-2012, 09:21 PM   #11
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I do use several m42 lens and like the way they function better than the M lens.Most any daylight shot I don't use the green button anyway,just guess the exposure.Can usually focus down to about f8 in daylight especially if focus conformation is working.Focusing is harder when using macro as the depth of field is so short by the time the lens is stopped down to get good focus then stopped back down focus is lost.Don't plan on bothering my macro lens or any other that is worth more than 30 bucks or so.Have one 28mm that the lever is so flimsy it can just be bent out of the way,will do it first.This may not work out to my liking it but will give it a try.
08-26-2012, 10:16 PM   #12
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QuoteOriginally posted by wiseman Quote
I picked up else where in this forum that if you are using M42 lens you might as well shoot in Av mode for the following reasons:

1) In M mode my K10D will only use spot or center weighted metering. In Av mode the multi-segment metering is also available.
You do not get multi-segment metering with any non-A lens (anything with no contacts), even in Av mode. Not without some mods to trick the camera into thinking it is an A lens (which has its own drawbacks for M lenses because the lever works differently).

QuoteQuote:
2) Also, in Av mode I can use the exposure compensation feature to dial in correct exposure for a particular lens/aperture. If I'm in M mode, I need to use a control wheel to adjust the shutter speed +/- after pushing the green button in order to obtain exposure compensation.
On the K10D, I think that is true, but on newer models like K-5, you can use Ev comp to adjust what the meter will give you when you hit green button in M mode, so that makes it much nicer.


QuoteQuote:
I find the real time exposure metering in Av mode with a m42 lens more convenient than using M mode with a K or M series lens, but that convenience disappears when you are shooting with a smaller apertures because the view finder gets too dark to focus. You are then forced to open up the aperture to focus and close it back down to shoot-Yuk!
Yep, although normally I like to focus wide open no matter what (even if it isn't too dark, it is just easier to focus on a spot with the most limited DOF). But sometimes it is nice to see the "full-time" optical preview so you can see the DOF shift as you focus. I do like being in Av mode more than M mode though. But they've each got their advantages -- it just depends on what you're shooting.

In any case, the "S-type" focusing screen is a big help for these old MF lenses.
08-27-2012, 05:13 AM   #13
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i shoot a mix of M42 and K mount manual focus lenses. SInce I have built a kit of each, i don't interchange them when out and about, i am either one or the other. there is no real pain in using green button for exposure occasionally. and not making adjustments in between, as long as the light does not change, therefore, having open aperture focusing is a very nice thing to have. removing the lever will take this away.

Most people get confused about the convenience of M42 and metering, but in reality, there is no need to meter every shot, when shooting in identical conditions. meter once, shoot check, and keep going until conditions change. Open aperture focusing is a real nice thing to have, especially in night shots or low light.

you say you can focus down to F8, that is really only the difference between wide open in bright sunlight and a cloudy day. You might want to rethink that a little
08-27-2012, 08:23 AM   #14
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No one has mentioned the curse. Cutting the lever invokes powerful demons who cause you to only see unscrupulous sellers on eBay, magnify local gravity to make you drop your DSLR, and other terrible effects.

If you don't mount a lens fully, the lever doesn't engage and you can test the lens without permanent modifications. Set the aperture ring to its largest f number and watch the blades as you mount the lens. When they start to move, turn the lens back a bit. Now you can see how exposure, focus and different modes work with your model.
08-27-2012, 09:57 AM   #15
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QuoteOriginally posted by Just1MoreDave Quote
No one has mentioned the curse. Cutting the lever invokes powerful demons who cause you to only see unscrupulous sellers on eBay, magnify local gravity to make you drop your DSLR, and other terrible effects.

If you don't mount a lens fully, the lever doesn't engage and you can test the lens without permanent modifications. Set the aperture ring to its largest f number and watch the blades as you mount the lens. When they start to move, turn the lens back a bit. Now you can see how exposure, focus and different modes work with your model.
This had been suggested earlier,think it is good advise but a little more complicated as to use a lens used this way would have to have another stop cut into it.Will try this on a lens,CPC 28mm macro which I used a lot until a Sigma 24mm af came into my lens assortment.I like this because it leaves the information on the lens on the left side where it is easier to see than in the center.We definitely don't want to cause daemons to come out and affect gravity or buy from unscrupulous sellers on eBay as I have run into some of these.
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