[Balog]

So I recently spent a day walking around trying out my new (to me) Vivitar 135 f2.8 m42. Great lens, I really enjoy it so far. However, I'm wondering if my experimental technique is off. Here's what I'd do.

I normally shoot a fast 50 wide open indoors at night, so I was happy to get the chance to try out some of the smaller apertures a little more. But when I'd put it down to f11 or smaller, the lack of light coming in made focussing really difficult. So I'd throw the aperture to 2.8 then compose and focus, rotate the aperture down to whatever stop I wanted, then do the green button for a shutter speed and take the shot. I found that my body with this lens tends to go one stop too slow and over expose, so I'd usually then adjust the shutter speed one stop faster and take a second picture.

In any case, when using screw mount lenses is using the widest aperture to compose and focus, then turning down to a higher f-stop for metering and taking the picture a bad thing? It seemed to work pretty well for me, but I don't want to develop bad habits.

[boriscleto]

You're not doing anything wrong.

[ismaelg]

That's how older pre-set lenses used to work. Your technique is good, but sorry, you can not file for patent.
On those lenses (I have 2 of them) the aperture has 2 rings. One to set the desired aperture and another one that opens the lens fully for focusing and composition. When you are ready you close this second ring and it stops at the aperture set by the first ring.
Glad to see older lenses been enjoyed as intended!

Thanks,

[Lowell Goudge]

You are not doing anything wrong, but you can be more efficient.

You do not say what body you are using so there could be "translation errors" in terms of commands

first, You should be using EV compensation, if the lens is always giving over/under exposure. This is much easier than clicking up/down by a stop after picking exposure

To my knowledge, only the K10D does not provide EV compensation in manual, the *istD and K7D do for sure.

Second, Av mode is much more convenient, than manual for M42 lenses because it continually sets the shutter speed as you half press the shutter release. Unless you really want a specific exposure (aperture and shutter speed) this is the way to use M42 lenses.

Lastly, and others have mentioned this, the auto manual switch on most M42 lenses switches from opened to stopped down, so focus in Auto, and shoot in manual this will always stop down to the desired aperture. Preset lenses are even easier, since you can preset the aperture and turn the ring to stop down to the preset.

K mounts are different because you can;t use Av mode (except wide open) so you are stuck with the green button.

BTW, if you don;t want to change the setting but see the exposure, use the DOF preview as it activates the metering in the viewfinder at the same time