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OK, I figured that since I just explained how I make a front cell focus lens into a soft focus lens , I should probably give some broad information on it’s use. First off, this is not going to advise on purchasing a readily made adapter such as one to mount an M42 screw mount lens on a Canon EOS camera. That is a simple one step deal – buy it and use it. Below is in regards to lenses stripped usually from a folder or box camera.

This could run into a long dissertation or assemble quickly. Let me see how I do at short as possible with a minimum of techno-speak.

The whole premiss of making a front cell focusing lens into a soft focus lens is to (1) take a lens from an old camera, (2) modify it by de-coupling the front cell from the rest of the internal lenses, (3) set it up to mount on a different camera (film or digital) via a focusing mechanism, (4) playing with it. Simple so far. Now I will take these four steps one at a time.

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(1) On most cameras the lens will have a notation on it giving the focal length in mm, inches, feet, etc. (A quick note here. The popular phrase ’35mm camera’ is a misnomer for our use. These cameras use 135mm wide film. That is the correct term, it has NO direct bearing to the focal length of the lens OR the registration distance.) Let us use this lens as an example . It is marked as an (f)3.5 75mm lens. This means the lens is designed to be placed with the base of the lens 75mm from the surface of the film or the surface of the sensor depending on your camera.

This is important since it will save you purchasing a lens or camera for the lens that is unusable for normal close-up to infinity shooting. An example here is useful. The Canon EOS system uses a registration distance (the distance from the lens mount on the camera to the film/sensor; the definition of these terms is VITALLY IMPORTANT) unique registration distance of 44.0mm. Camera makers have been using their own registration distances for quite a while. This was a very useful way of preventing people from using a manufacturer A lens on a manufacturer C’s camera. This ensuring a lucrative market for their own lenses. In addition, most manufacturers also made their own lens/camera coupling methods unique. I try to make all intervening couplers to use the M42 screw standard. Macro rings/tubes, bellows, focusing helicoids, etc are all available in M42 thread. This way you can move lenses from one camera to another. Further, since M42 is a very popular standard, usually the components are cheaper.

Onward, taking this 44mm distance and subtracting it from 75mm gives a result of 31mm (~1 5/16 “). This is the distance you have to design a way to mount the lens AND afford a way to focus the lens. This is not a good distance to be using in general. It will mean either designing and manufacturing an adapter of your own; finding a way of cobbling one up; giving up; or looking for a different lens or camera that allows a greater distance. Most easily purchased methods of focusing are much larger than 31mm.

In the previous blog entry I show how I got around this problem by using a different camera – a Samsung NX10 with a registration distance of 25.5 – ignore the 19.25 in the above links values, it is wrong. By using a different camera I was allowed 49.5mm (just shy of 2″). This gave me enough room to be able to get this particular lens to work on a particular camera.

This is the bottom line – just about every lens will cause you to re-think and fiddle around with parts and pieces. This is not an easy part of the photography hobby.

Most of the above was written to give a broad piece of advice. Start with a lens of approximately 105mm. These are quite easily found on auction sites on cameras meant to be used with 120 film. Further, it gets you used to the two terms- registration distance and focal length.

(2) Covered in the previous blog entry

(3) Covered in the previous blog entry

(4) Ah! here we are. You now know the basic terminology needed to play.

Assuming you now have a front cell focusing lens mounted by some means to focus the lens with the cell in the median position on a camera that allows you to see the focusing as you change adjustments, I will tell you how I do this. Your own results and means may vary.

Set the camera and lens on a tripod. This is important, since we are going for soft focus, getting the best soft focus can take some time. Hand holding is for later once you get your methodology figured out. First I will show you some results using the lens mentioned in my prior blog entry.

I have a confession to make, and I say it here to allow only those people who have waded through the above drivel and those smart enough to go directly to the end of ANY presentation, if you have followed me through the mounting of the lens, you may be saying “why did I have to figure out a mount that includes focusing? After all, the front cell will focus by itself.” Because I have been withholding a vital piece of information – namely – the AMOUNT of softness is variable by moving the front cell. THEN you adjust for the actual best focus for that softness. Neat huh? Don’t tell anyone else, let them flounder, it’s fun to watch ;>

Another question may be “where is the glow?” Usually there is a fair amount of glow/glare with soft focus lenses. Simply, in this case, the days I took the pictures there were high, solid clouds. Figured it out? Correct, the more Sun, the more glow.

In the above three images, I focused on the upper windows. If you look closely, you will see a difference in softness in the three images. I set front cell for the middle one at the mid range of usefulness, the one on the left has the most softness, the rightmost has the least – I believe I have that correct – I am getting tired and it may be reversed. The method is simply – move the front cell to adjust the softness you want and then adjust the lens focus for the best focus. Have fun! I’m off for some eye drops and a nap.