When Lens Conversion Goes Wrong, or Why Lenses with Auto Aperture Control Suck

I was somewhat encouraged by the semi-successful conversion of the Vivitar 40mm f1.7 from the Vivitar 35ES, so I ventured on to start another rangefinder that did not have aperture control: the Minolta Electro Shot.  This camera has a 40mm f1.8 lens but much larger than the Vivitar 40mm f1.7. Well, things didn't turn out as well as the Vivitar conversion.  The Electro Shot does not have separate shutter and aperture blades, like pretty much all other rangefinders from that era, but it employed a single shutter/aperture system. I didn't know this until the very end.

Lens Conversion Gone Bad

As I assumed the shutter and aperture blades were separate, and from experience that I gained, the shutter mechanism is usually accessible from the front. But when I disassembled the whole front, there was nothing.  All the controls are from the rear of the lens.  Long story short, in the process of trying to find the mechanism for aperture control, I mistakenly loosened three screws on top of the lens from the rear, and this caused the aperture/shutter blades to fall out of the lens :(  The timing and shutter/aperture control system is very complicated and I decided to just give up on aperture control. After some more thought, I further decided that I should make another Borg lens, with a Steampunk look.  Incidentally, my first Borg lens was also a Minolta.

From now on, I will stay away from rangefinders that have no manual aperture control on the lens. It's just not worth the trouble, unless the camera is dirt cheap or is unusual.  Of course, this could change if I gain enough skill to make more complex parts to enable the aperture in the lens.

Wilted Rose - Minolta Rokkor-QF 40mm f1.8 & Sony A7

Minolta Chyoko 4.5cm f3.5 Rangefinder Lens Conversion Part II

This little lens is a pure joy to use.  The lens barrel is made of brass, so it's very dense and focuses like silk, after I re-lubed the helicoid.  This is one of the things you can not get from modern lenses, aside from Leica and few other exotic and expensive lenses that come out of Germany.  It does not contribute to the quality of images, but it sure makes creating images more pleasurable.

Obviously, a lens with an f3.5 maximum aperture is not a great low light shooter, but it has other desirable attributes that shine over the short comings of the slow-ish maximum aperture.  Bokeh is one of its strong suits, and I adore it.  It has not the smoothest bokeh in all situations, but it's distinctively enjoyable. With highlights, you can see a strong outline on the rings, which to some, is not a good attribute of smooth bokeh, but I like it.  Reminds of the same kind of effects from a Trioplan/Triplet lens.  It's visually bold, as compared to bokeh from a Planar or Sonnar. Your mileage may vary, of course.  You may hate it, or like me, you may like it a lot.

Most very old lenses aren't great when it comes to sharp corners at wide apertures, and this is one of these lenses.  It's by no means very bad, but stopped down to around f11-f16, it's quite respectable.  It won't win any sharpness contests, but definitely usable, especially with a bit of sharpening applied.

The 5-blade aperture gives a more star-like shape when stopping down than other lenses with vanilla 5-blade apertures; the blades are shaped differently, giving the shape a bit more pleasant appeal visually , to me at least.

So, if you overlook the slow maximum aperture, this is actually quite an enjoyable lens to use, and it makes images with nice bokeh.

All images below were taken with the Minolta Chyoko 4.5cm f3.5 & Sony A7:

Minolta Chyoko 4.5cm f3.5 Rangefinder Lens Conversion Part I

I know a lot of people just could not understand why anyone would even bother with a standard lens having an f3.5 maximum aperture.  Today's modern 50mm lens of f1.8 is considered slow.  So yes, why bother?

All I can say is that each lens has its place, and justification for its existence.  f3.5 is slow for low light photography, but there are many places where it can still make wonderful photographs, and you often find the photos they render is not reproducible by modern lenses.  The Minolta Chyoko 4.5cm f3.5 is one slow lens that I really, really like.

Minolta "A" in its original form.  Note the round design.  Very hard to hold and use.

This lens came from the Minolta "A" rangefinder, introduced in 1955 as an entry level rangefinder.  I have never held a more un-ergonomical camera than this one.  I think the design is terrible.  The camera feels like a melon in my hands, but we are only interested in the lens, so it's ergonomics is inconsequential. The lens came out quite easily from the camera with just a few screws from the front of the camera.

Lens is very easy to remove.  in fact, the lens can be removed without touching much of the camera body.

Lens as it came out of the camera.  Note the shutter mechanism at the rear of the lens.  Since we don't need it, it can be easily removed, and the best part of this, is that you don't have to worry about keeping the shutter open like most rangefinders with shutter assembly built into the lens.

The focus mechanism of this lens had very little damping so I decided to disassemble the lens to clean it and re-lube it. To do that, the front group of elements need to be unscrewed, but do be careful when removing it; this lens group is used to secure the aperture mechanism.  I made a mistake of tilting the lens while removing the lens group and the aperture assembly came out of its place.  Took me a long time to put the blades back.

Front lens group removed.  Note the aperture blades are just sitting there without anything else to second it in place.  The lens group is the only thing keeps it secured.  Don't tilt the lens while removing the lens group, otherwise prepare to spend a lot of time trying to put them back.

All the parts of the lens disassembled.  It's quite easy and simple.  Just remove all screws, but don't lose any screws and remember the sequence.

The disassembly of the lens is quite easy by removing the screws.  Be sure to note where the specific screws go and don't lose any.  The only tricky part, is putting the helicoid back.  You DO need to put the parts back at the specific location or the distance scale will not line up.  I usually mark where the parts separate, and this will help later.  Otherwise, you will have a lot of trial and errors and this is not a fun thing to do, believe me.

After the helicoid is taken apart, I used Ronsonol lighter fluid on a Q-Tip to clean off the old grease, and re-apply a light grease.  In a future post, I will talk about the different greases I tried and why I ended up with what I am using, which is Slickoleum Light Grease, that I also use for my bicycles chain and other parts.  This grease is light and provides the right amount of damping than the others I have tried.

Once the lens is cleaned and reassembled, the next part is the machine a spacer between the lens and the Pentax focus helicoid, which will act as part of the spacer between the lens and the Sony E-Mount.  With a lathe, this was very easy to do, especially when I decided to just glue the parts together, instead of drilling and tapping screw holds and use screws to hold them.

Simple parts required: on the left is a mount from an M42 2x teleconverter which I cut out.  Middle is the spacer I machined from aluminium.  The M42 mount will be glued to the top of this part. What's not shown is the rough marks I make on the surface to make the glue adhere better.  On the right, of course is the lens.

The other side of the parts. Note the screw holes on the lens.  If I wanted to, I can drill and tap the spacer and screw them together, but I find glue is strong enough.  I am still having trouble getting perfect alignment for screw holes.  I need a drill press, which I don't have, to do this properly. 

This lens has a rather long flange distance.  At first I thought it could be used on my Nikon D810, but no dice; it's still shorter than the very long F-Mount flange.  However, the distance allows the Pentax focus helicoid to be used as part of the space between the lens and the E-Mount, but just barely.

Minolta Chyoko 4.5cm f3.5 mounted on the Pentax Focus Helicoid and then on the Sony A7.  The lens itself has a focus mechanism, and can be used for medium to infinity focus.  For close up, I use the focus helicoid, or a combination of the two, for extremely close up.

In part II, we will take a look at what the lens can do.  You already had a peek from the picture in the last post, showing it's interesting bokeh.  We will explore more next time.

Adapting Manual Focus Lenses to Your Digital Camera - Part I

Another reader, Mathew, has asked me to do a guide to adapting manual focus lens to digital cameras.  I actually have had this idea for a while, but unfortunately, even though I use a lot of manual focus lenses, I am not an expert on this topic.  But, I think I will put out something for what I know, as I am sure there are quite a few people out there who are confused by all the different adapters and lens mounts.  I will only be discussing adapters for Canon EF (EOS), Micro 4/3 and Sony E-Mount, as these are the only cameras I have more experience with.

So, how do you use your grandfather's old manual focus lenses from the 1950s on your brand new 2012 digital interchangeable lens camera?

There are at least two ways to do this.  One is to modify the old lenses to have the new mount of your camera.   This is usually done when adapter is not available, or the even possible.  The other, more common way, is through the use of lens mount adapters.

A small sample of my adapter collection

We won't be talking about the drastic lens modification option, since this is usually non-reversible and are expensive, not to mention finding the right person to do the job.  Common lens mounts that get modified is Canon FD to the new Canon EF (EOS) mount, or Minolta MD to EOS, since these two mounts generally are not adaptable unless you use an adapter with glass elements.  Lens mount modification is actually the best way to use old lenses on new cameras, because the converted lenses will behave like native lens on your DSLR, minus the auto focus/aperture function, unless you go the very best conversion with Contax N lenses for Canon EOS from the great Canadian company Conurus.  The conversion itself will cost hundreds of dollars, so unless you have some really nice Contax N lenses, this is probably not worth it.  Even the new mount that allows aperture settings on EF lenses for the Sony E-Mount costs hundreds of dollars, and it won't auto focus.

So, we will then be concentrating on the non-destructive adapters, but we won't be talking about the ones with glass elements, as these adapters basically act like a teleconverters which increases the focal length of the lens, as well as decreasing the maximum aperture, and at the same time degrade the optical quality of the lens.

Enough mumble jumble.  Let's get on with it.

How do I know which lens will work with my camera?

We will discuss this in Part II.