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Forum: Pentax Lens Articles
01-03-2016, 03:27 PM
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@fotograffiti
To your 6 points:
1. It is, but there are 2 exceptions from this rule.
1a) If you own a lot of M42 lenses and do often switch lenses, the screw mount is unconvenient. There is a reason all main camera brands changed to bayonets in the sixties and seventies. But leaving one adapter on every lens does not make sense with the OEM adapter. This one fixes the lens on the body by pressing the adapter FROM THE INSIDE against the body mount. So this adapter always stays on the body when you remove the lens. If you remove the spring from an 3rd party adapter (and smooth sharp edges a bit), these adapters can do the trick. You may have to use a thin shim between lens and adapter if the adapter never comes off together with the lens. If the shim is too thick, the lens will be to loose; and the diameter of the shim should not be bigger than of the adapter, otherwise you may loose infinity.
1b) If you don't want to do surgery on M42 lenses with auto diaphragm - but no auto/man switch - you have to use a specially flanged adapter. This will set an auto M42 lens to manual. The Kipon brand is best known.
2. That's correct. Green button measurement uses the aperture actuator for closing the aperture to the set value. But with M42 lenses, there is no lever which it could move.
3. Yes.
4. No comment. My Pentaxes don't offer TAV (and if, I doubt whether I would use it).
5. With consistent light, in many cases you would need the Green Button only for the first shot. In M mode, the set value will not change for all the next shots.
6. AV is the way to go with M42 lenses. TAV includes AV, is a Pentax special, and was introduced only with the K20D. And about Green Button with M42 lenses: no, see point #2.
---------- Post added 03-01-16 at 23:37 ----------
@Not a Number
Isn't this true only for pre A 3rd party lenses with an anodized mount ?
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Forum: Pentax Lens Articles
08-14-2015, 09:13 AM
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@semaca
Can you explain what you mean?
If you do not screw the lens fully into the adapter, there is a different behaviour of original Pentax and 3rd party ones.
Without a lens attached, (only) the original one will stay loose. Screwing in a lens in (fully!) will force the adapter to press against the mount from the inside of the body. Otherwise you may adjust distance with LV, but shooting can put the lens to a slightly different position, and focus will be lost.
EDIT:
This behaviour of the original adapter is also the reason why you can't use these for staying permanently attached (and fixed) to each of your M42 lenses. Putting it on the body, the combination would stay loose.
You can do it with 3rd party adapters; but remove the screw prior to attaching it, otherwise you could be in serious trouble when trying to remove the lens. And test it carefully before making it a permanent solution, because of bad meeting of tolerances the set may still not come off, even with the screw removed.
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