I have a "Kalcor" bellows w/M42 mounts and a "Honeywell Pentax slide copier" that I have linked together with some left-over lamp parts (kitchen ceiling lamp)
The lens I am using is my SMC Takumar 50mm 1:1.4. I have had to make some adjustments

to this set-up and I'm getting closer to being able to copy my slides as "same size". Would same-size be referred to as 1:4, 1/4, or 1.4 (there's an awful lot of 1-4s out there

)
My main question here is; Is my Tak 50 an optimal lens to use for slide copying with this, or any other bellows/copier setup? If not, what would be the best or most okay lens I could use? I've been looking at f:4 Macro Tak 50s but I'm not sure if I would get too much magnification or if it would just focus better?
Any and All feedback/advice/help/etc. is greatly appreciated!