The Beauty Biokor-S 45mm f1.9 Conversion

This is an interesting camera.  I never knew this brand even existed until I got this camera.  Some Googling reveals there are some fanatic followers for some of its rangefinder camera.  The one I have, unfortunately (or fortunately), has damages, and was dead.  I don't have to feel bad gutting it for the lens to transplant it for use on digital.

A Beauty, no?

I originally wanted to preserve the built-in focus mechanism, but the lens has some strange designs that prevents this from happening.  On most rangefinders, there are two focus guides; one on each side of the lens and are small and very close to the helicoid.  On this lens, there is a single focus guide and is placed quite a distance away from the helicoid.  If I were to retain the original focusing, I would have to machine the mount much larger than the diameter of the lens to accommodate the focus guide.  If I were more skilled, I could probably create my own focus guide, but I am not there yet.  In the end, the built-in focus is abandoned, and the Pentax 17-33mm focus helicoid is used.  There are many advantages of using a helicoid with 16mm of focus travel, and one of which is extreme close focus while still retaining infinity focus.  Another advantage is the focus feel.  The Pentax helicoid is smooth as silk and what a pleasure to use.

The skin on the front of the camera need to be removed, which will expose the screws that secure the lens module.  The top plate probably does not need to be removed, but I did it anyway.

Once the screws were removed, the lens module can be pulled out easily.  Note the focus guide circled in red.  

I need to use an M42 mount for the lens, so that it could be screwed on to the Pentax helicoid. This M42 mount came from one of the three sections of a Pentax extension tube.  I have to somehow mount this onto the lens.  The obvious way to do it is to attach it to the inner helicoid.  The only problem is there is less than 3mm of space available between the lens and the focus helicoid.  I machined the inner helicoid tube from its original 25mm to about 1mm thick, and the M42 mount to about 3mm, just thin enough to achieve infinity focus.  I then epoxied the two parts together.  Since the weight of the whole lens is held together by the glue, I am not too comfortable trusting glue to handle this by itself, so I intend to drill/tap and screwed them together for some added assurance.

Remove everything at the rear of the lens, but keep the retention plate.  This plate is used to hold the M42 mount to the lens.  See next picture for the plate. The screw circled is a key that makes sure the plate does not move around.

On the left is the M42 mount I cut from the Pentax extension tube and machined to the required thickness.  In the middle is the retention plate that I machined so that it will fit inside the back of the M42 mount.  These two pieces are glued together with metallic epoxy. 

The retention plate is glued onto the M42 mount. Note the recessed groove; it's just small enough that the retention ring can't go through the hole.  This is where the retention ring on the right will be pressing on while screwed onto the lens.  This secures the mount on the lens.

All the pieces fitted together.  The notches circled in red is where you use the spanner wrench to tighten the retention ring and secure the mount.

Disabling the shutter

This is actually the trickiest part that took more time.  It involves disassembling the front of the lens.

Remove the retention ring with a spanner wrench and remove the diffuser piece. Next unscrew the front element group, and take out 3 pieces under it. Now remove the 3 screws circled in red.

Once the 3 screws are removed, lift this piece out, and the piece below it.  This will expose 4 more screws that need to be removed.  Note the small retention ring in the middle, pointed to by the blue arrow.  This one also needs to come out.

Take out the piece secured by the 4 screws, and now the inner retention can be removed.  Note the locking screws in red.  It needs to be turned so that it's not touching the retention ring.  Using a pointed spanner wrench, remove the retention ring.

Once the retention ring is removed, take it out, as well as the two other pieces under it. This is the end of the disasembly.

This is where you will find the shutter cocking mechanism, circled in red.  Find the part that actually engages/disengages the shutter, and glue/solder it in place.  For this particular lens, I just removed the shutter blades using a long nose plier since I didn't feel like I wanted to go through all the disassembly steps, but I did the steps here to show where you can do it without removing the blades.

Everything together.  Looks nice with the Canonet hood :)

A real beauty, ain't she?

One issue that this lens has, is the very stiff aperture ring.  I think there are two much gunk that gums it up.  But, I am not going to do further disassembly to fix it since I hardly use the aperture :)  I shoot mostly wide open.

Next time, we will look at some pictures taken with this lens, and see if Beauty is only skin deep, or it actually has substance.

To Lathe or Not to Lathe

As many of you know, I have been doing pretty much all of my lens conversions, modifications with glue, tape, and filter rings and a Dremel.  It's getting to the point where I am not happy about this BAND-AID solution any more.  I really want to use the right tools, such as a lathe, and a milling machine, but I have zero experience with either, so I started reading more about these tools, especially the mini-lathes.

To start with, what I want is really simple.  A tool that allows me to create a tube/ring that can be securely mounted on a lens, like an enlarging lens, and then mate to a helicoid or a lens mount, with precision, and if it looks nicer, that would be a bonus.  I probably don't even need to do threading initially, but I would love to be able to create threads like M39 or M42 that can easily work with other standard parts, but cutting threads is probably not easy with a mini-lathe.

The world of the lathe is full of confusion for beginners like me.  The dazzling variety of them is already headache inducing, but it's the accessories/tools needed to make the lathe work, that really screw my head and sometimes I feel I am slipping into a coma out of helplessness. One resource I highly recommend, is Frank Hoose, whose site www.mini-lathe.com is an excellent source of information.  However, I am more of a visual person, and Frank's Youtube videos are detailed, easy to understand, and well presented.  If you are thinking of getting a mini-lathe, be sure to check out his site/videos.  I learned a lot from him.  But, reading and watching video can only help so much.  There is no substitution for learning by doing, so I have decided to jump in with both feet :)

Buying a lathe is not like buying a camera or a lens, that you can hide from your significant other, so it's probably a good idea to clear that first with him/her.  I talked to my wife, with my oiled tongue, extolled the virtue of a machine that can do amazing things, like making useful household gadgets for the home.  Unbelievably, she went with it, and even encouraged, as long as I can cough up the money myself, which means I have to sell some of my toys, er, tools first :)

The tough part, of course, is deciding what to get.  I have a small house and space is limited.  Noise is a factor too as I share walls with neighbours. I don't want something so small that it's uses are severely limited, but on the other hand, not something very big and noisy.

At first, I thought about the micro lathe/mill combo that you can put together like Lego blocks. These usually have a small 30-60 Watt motor, which really is not suitable for working with metal.  But, they are very small, and relatively cheap at around $350.  Great for teaching kids or learning, but probably not able to do what I want.

My next target is the Taig Micro Lathe II.  This is an extremely popular lathe for home hobbyists and is available in Toronto through Lee Valley Tools.  It's very compact, well made and crafted in the USA.  The basic kit is reasonably priced and there are immensely vast number of accessories/tools available to make it into a full blown CNC lathe/mill machine.  But, in its basic form, it does not have power feed, thread cutting, etc.  Adding these features costs a lot of money and for beginners like me, might be a challenge to setup.

The last group of machines I consider is either a 7x12 or 7x14 mini lathe.  7x12 or 7x14 describes the size of material you can work with, which is 7 inch high by 12 or 14 inch long.  In practice, the length is 2 to 3 inches shorter, as you will need to account for the chuck and the centre that support the stock/work piece.  Usually, these machines have power feed and thread cutting with a variable speed DC motor.  On the Taig Micro Lathe II, speed is set by using different sized v-bells on an AC motor, although one can make a DC motor option for the Micro Lathe II.

What makes finding the right mini lathe so frustrating is the lack of availability of low end models in Toronto, unlike in the USA, our lucky southern neighbours, or our friends in China whom I envy for having such affordable and variety of lathes.  There used to be more variety of models and cost a lot less, when I looked at them few years ago, but now very few machine/tool shops stock low end metal lathes.  The lowest price ones I found is the Taig Micro Lathe II, costs around $380 without the $150 motor, and the King Canada 7x12 (probably made by Sieg of Shanghai, China) for a cool $1000 CAD. When the Micro Lathe II is configured to have the features of the 7x12 lathe, the price is probably more, or close to $1000.

I am leaning towards the 7x12 mini-lathe.  If I am not able to find a reasonably priced used one, this is probably the one I will get, but it will probably be a couple of months before I get one, and it would take even longer for me to get familiar with it to make it useful.  But, I am excited and look forward to the new tool.  There are so many possibilities!

True Love Cafe - Nikkor-H 48mm f2 rangefinder lens from Nikkorex 35 on Sony A7 at f2.