M42 Adapter Question

Fruit1985

Hello all,

I'm a bit slow and require a bit of hand-holding here. (There are guides on the internet but I don't really understand them.)

I have a canon 6D, loads of old pentax lenses and an M42 adapter. I don't care about the camera having the correct metadata attached to the photo so no need to worry about that part. I only care if the image is properly exposed or not. Is the process for taking a picture as follows:

--- Scenario ---
Imagine I want to take a photo of an apple and an orange. The orange is behind the apple on the able. I wish to focus on the apple and blur out the orange. (Assume I have a lens with an aperture capability to do this and proper focal length.)

1. I attach the lens to the camera using the adapter.
2. I switch the camera to AV mode.

What do I do next? Can someone correct these steps if possible

3. I open up the aperture on the lens to it's widest e.g. f 2.0
4. I half press the shutter to expose the image - the camera sets the relevant shutter speed
5. I "step down" the lens to f 4.2 to ensure the image is properly exposed?
6. I then take the shot

Very confused after step 3 on how to take a picture so appreciate anyone explaining it to me in a "for dummies" type way.

Pete67

Your 6D will default to 'Stop Down Metering' mode when there is no lens attached, or when an old manual focus lens is attached. The old lens has no electronics to communicate with the camera about aperture settings, or no actuator to close down the aperture automatically. So you have to do it all manually. The good news is that the camera will meter perfectly fine in Av, P or M modes. (If you use M remember you have to manually set the shutter speed to the match what the meter recommends)

So your step 3 onwards would be something like this:

3) Open the aperture fully to assist focusing (brighter viewfinder combined with minimum depth of field)
4) Focus as required.
5) Stop down the lens as necessary to get the depth of field you want.
6) Half press the shutter button to enable metering
7) Check that metered shutter speed is acceptable (vary aperture and/or ISO to suit conditions if not)
8) Take the shot.

Check in advance that when you turn the aperture ring on the lens the diaphragm actually closes and opens, some older M42 lens need an adapter that presses a pin on the lens mount to close the aperture. If the lens has a Manual / Auto switch then just leave it in Manual and it will be fine with any adapter.

It would be worth doing a few test shots to see how accurate the meter is with each lens.

Good information here