Digital Special

Using Old Lenses

Folder Lens Modification


Now for the technical stuff, a detailed guide to converting old folder lens for use with a DSLR.

The difference with this group is that they will need some extra bits and a modicum of engineering. I use m42 plastic body caps, there are loads of these about and usually for less than 1. The other thing you will need is a set of extension tubes, again these are readily available at little cost. Try to find the manual types as the kick down pin is not necessary and can get in the way. OK now you have your old camera, an M42 plastic body cap, set of tubes and an adaptor for M42 to your digital SLR.


Open up the back of your old camera with the lens closed. In the middle of the bellows is a big nut, usually with two or four cut out notches. You need a pair of fine nosed pliers to slacken this nut, it should now be finger tight. Open the front of the camera carefully and hold the lens assembly while unscrewing the nut on the inside. Et voila you now have your shutter and lens assembly removed.


Now you need to mount this to the body cap, be careful to ensure that is central. If you have a set of hole cutters it will make the job easier but it's not essential. You can drill a pilot hole and open it out with a round file or similar until you have a snug fit to the shutter housing thread. Note: there is usually a pin on the back of the shutter housing to stop it rotating on the mount, you will have to accommodate this. Again, not essential but to make the controls easier to use, mark the position where the aperture slider is and cut away a relief to make it easier to adjust when in use. You now have your shutter housing mounted on your M42 plate, next you need to hold the shutter fully open. Search through your "bits" box and find a small screw which will fit into the cable release thread, just long enough to hold it open. Set the speed ring to B, or T if you have it, cock the shutter and run the screw down to open the shutter. This will now stay like this until you accidentally move the speed ring so you have to reset to B and re-cock the shutter gently releasing it until it stops with the shutter open.


The next bit is down to trial and error because all of these lens units vary. Using the extension tubes and with the aperture wide open set the focus to infinity and select the extension which works best when the assembly is fitted to the camera. Now bring the focus in to close range and see how far you get. You will need to experiment with this to get the best compromise between having the capability to focus to infinity and close up. If you're really keen you could obtain some spacing washers for fine tuning but there's not much thread to play with. I have found that as little as 1mm can make a difference so it's worth the effort. Another note: the distance scale on the lens ring is now basically useless so don't rely on it. You can now use the spare tubes for ultra close up and macro, you can get very close indeed, go on give it a try.



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