[Cerebum]

Wasn't sure which thread to put this in, sorry if its the wrong one

OK. When I have a k mount lens on, pressing the green button in manual gets me good exposure. This is supposed to work with M42 but it doesn't! I get a shutter speed of 1/250 irrespective of where I am metering! Any ideas? It isn't a problem because I can always meter in Av, it would just be nice if I had the option

[pepperberry farm]

does the M42 lens have an A/M switch?

[kypfer]

Wasn't sure which thread to put this in, sorry if its the wrong one

OK. When I have a k mount lens on, pressing the green button in manual gets me good exposure. This is supposed to work with M42 but it doesn't! I get a shutter speed of 1/250 irrespective of where I am metering! Any ideas? It isn't a problem because I can always meter in Av, it would just be nice if I had the option

It will work with M42 lenses, but you have to stop the lens down to the taking aperture before metering. If you have an automatic aperture lens with an A/M switch on your lens(es) you need to have this set to "M", then rotate the aperture ring to the taking aperture before metering ... the viewfinder image will go darker.


If your lens is a pre-set, again, the aperture needs to be closed down for metering. Exactly how this is done can vary slightly depending on which lens you have.


If your lens is auto-aperture only then you can either use it fully open all the time, or modify it to act like a pre-set lens. Again, this modification can vary slightly depending on which lens you have.


All this assumes you're using one of the original M42-PK adaptors or a clone thereof, which allows infinity focus. If you've got one of the "flanged" M42-PK adaptors which doesn't allow infinity focus, the auto-aperture pin is possibly permanently activated and the lens acts very much like it has an A/M switch (the viewfinder gets darker as you turn the aperture ring).


Using these older lenses on a more modern camera can be a very satisfying pursuit. It can help you relax, step back from it all and concentrate a little more on "making" a photograph, as they used to say


Do remember, if you do not have your eye to the viewfinder when taking the meter reading (pressing the Green Button), stray light may get in through the eyepiece and affect the exposure ... that little black viewfinder blind that may have been supplied with your camera actually does have a use!


Good luck and enjoy

[Cerebum]

does the M42 lens have an A/M switch?

They are a mixture. Some do, others have a dial to open the aperture

---------- Post added 07-23-19 at 02:49 PM ----------

I just tried it, manual mode, aperture shut down it gave me 1/250 both when pointing at a dark wall and pointing directly at a light bulb. I checked in the menu and the green button is set to p line in Manual! Could something be set wrongly?

[kypfer]

They are a mixture. Some do, others have a dial to open the aperture

---------- Post added 07-23-19 at 02:49 PM ----------

I just tried it, manual mode, aperture shut down it gave me 1/250 both when pointing at a dark wall and pointing directly at a light bulb. I checked in the menu and the green button is set to p line in Manual! Could something be set wrongly?

I know this may sound obvious, but one's got to ask, when you say "manual mode" you do mean the "M" setting on the dial on the top of the camera, not the autofocus/manual-focus switch?


Could almost be as if the Green Button isn't working ... is it possible to allocate a different function to it on your camera?


I'm just a little bit baffled as I use "Green Button" mode with a lot of old lenses on several of my bodies with no problem

[Cerebum]

I know this may sound obvious, but one's got to ask, when you say "manual mode" you do mean the "M" setting on the dial on the top of the camera, not the autofocus/manual-focus switch?


Could almost be as if the Green Button isn't working ... is it possible to allocate a different function to it on your camera?


I'm just a little bit baffled as I use "Green Button" mode with a lot of old lenses on several of my bodies with no problem

Yeah, manual mode on the dial. The green button works with K mount and in aperture priority it switches to auto iso so I know it works, just not with M42 in camera manual. It has had the aperture block fixed, I don't know if that could affect it somehow. Maybe I will just have to put it down to being a pentaxian mystery lol. I can still shoot in Av so it isn't a major problem, I just wondered if I needed to switch something on or off