FED 50mm f2.8, 61 CLA Tutorial

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Fungus Removal

and Helicoid
Relubrication

FEBRUARY 8 2022

Hubregt Photography
Hubregt J. Visser

FED 2,8/52
Industar-61

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© 2022, Hubregt J. Visser All Rights Reserved

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Contents

1. Introduction 4

2. The Lens 6

3. The Optics 7

4. The Fungus 8

5. Disassembly 9

6. Removing Fungus 25

7. Helicoid Cleaning and Lubrication 30

8. Reassembling the Lens 34

9. Potential Pitfalls and Solutions 42

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1. Introduction

And warning

In this document I describe how I have removed fungus from the inside of a FED
Industar-61 2,8/53 lens and how I relubricated the helicoid of a FED industar-61 2,8/52
lens.

I have had no training as a camera repair technician. Most probably, some - or all - of
my techniques and procedures will be frowned upon by a proper repair technician.
Notwithstanding that, the many pictures I have taken during the disassembly and
reassembly of the lens may be useful to a wide community.

Having said that, let’s begin.

Recently I purchased, through ebay, a FED Industar-61 2,8/53 (M39 LTM) lens. The
photographs in the listing showed a tiny spot on the glass, but since the price was very
low, I accepted this. On arrival though, the tiny spot appeared to be a serious case of
fungus and it was on the inside of the lens. This became best visible when
photographing with a macro lens having the right light shining on the back of the
Industar-61.

A spot of fungus (left) and photographed with a macro lens using grazing light (right).

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Obviously, I had to open the lens and see if I could cure this fungus problem. Besides
this fungus problem, the focus ring was not running very smooth. The grease, most
probably, had hardened and needed to be removed after which the helicoid should be
regreased.

So, I searched the web for instructions and since disassembly did not seem that hard, I
started servicing the lens. The disassembly wasn’t hard indeed. The reassembly
however appeared not to be the simple reverse of the disassembly as mentioned in the
resources I did find on the web. I made some mistakes in reassembly, but these were
not that hard to fix. It is very difficult to do something seriously wrong or even damage

the lens. That’s one of the things I like about Former Soviet Union (FSU) photography

gear. Although I made a lot of pictures during the process with the idea to write a
manual, the mistakes I made would not make for a good manual.
Luckily, for this situation, I had another Industar-61 (a 2,8/52) with a stiff focus ring. I
repeated the procedure, but now taking care of the lessons learned in servicing the first
Industar-61.

In this document I describe how to disassemble this Industar-61 lens, how to clean of
the old, gummed-up grease and how to relubricate the helicoid. I then describe how to
clean the lens from fungus, using the photographs taken in the process of cleaning the
first Industar-61. Then, I describe the reassembly of the Industar-61, using again the
pictures taken in the processing of the second lens. Finally, I dwell a bit on the mistakes
I have made in processing the first lens and how these mistakes can be fixed.

In both Industar-61 lenses the aperture blades were oil-free and the aperture setting
operating smoothly.

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2. The Lens

The Industar-61 is a Tessar based lens produced by the FED factory in the Ukraine from
1958 till after the fall of the iron curtain. Over the years several versions have been
released, having slight differences in appearance but all having the same optical

formula. Here we deal with a Industar-61 2,8/53 и-61л/д , which I believe stems from
the 1980s, and a so-called Zebra Industar-61 2,8/52 и-61 from 1972. The first one

comes with a 6-blade aperture, the latter with a 10-blade aperture. For both lenses, the
focus ranges from below 1 m to infinity and the aperture click-stop settings range from

2.8 to 16.

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3. The Optics

The lens consists of four elements, organized in three groups, as shown in the drawing
underneath. This configuration is known as ‘Tessar’, derived from the Greek word for
‘four’. The design was conceived by Paul Rudolph in 1902 while working for the German
Zeiss optical company. It was originally known as ‘Zeiss Tessar’, since the design was
patented by Zeiss and the patent was hold for two decades.
The front of the lens - facing the world - is on the left. The back of the lens - facing the
camera - is on the right.

The Industar-61 consists of four elements in three groups (Tessar design).

The red dot shown in the figure indicates the position where we will find the fungus.

The aperture is placed between the second and third group, counting from the left.

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4. The Fungus

I don't know the specifics of the fungi I found in this lens. I only know that spores are
omnipresent. You cannot avoid spores entering the inside of a lens, where they may
feed on the coating of lens elements. It is only possible storing lenses in conditions that
are not encouraging the growth of fungi. That means that you must store your lenses in
a dry, not too hot environment. It helps to have the lens regularly subject to light. Using
packets of silica gel will not hurt either.
The lens I have at hand has obviously been stored under less-than-ideal circumstances,
like a dark humid and warm environment. The fungus is at the inside of the lens and
thus the lens needs to be disassembled

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5. Disassembly

We are dealing with a FED Industar-61 2,8/52, i.e., having a maximum aperture of f/2.8
and a focal distance of 52 mm. The lens mount is 39 mm (M39) Leica Thread Mount
(LTM).

FED Industar-61 2,8/52, 39 mm LTM.

The order in disassembly is not that important. Some parts can only be disassembled if
other parts have been disassembled first. For the remaining parts, the order is not
important and different sources use different orders.
Although most Clean, Lubricate and Adjust (CLA) instructions claim that assembly is
simply the reverse of disassembly, this is only true – as I have found - if you know
exactly what the positions of the different elements were at disassembly. Therefore, I
will pay as much attention to assembly as I do to disassembly.

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Let’s start with the procedure I have followed:

Put the lens with the front element on the table. Inside you will see a light baffle (a
metal ring), wedged to the inside, see the red arrow.

Light baffle at the inside of the lens at the mounting side.

This light baffle can be taken out simply by using your fingers.

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Taking out the wedged light baffle using your index finger.

Store the light baffle in a safe place. I like to use plastic compartment boxes. They offer
an easy way to store screws and parts sorted for every step in the disassembly process.

Using a storage box makes it easy to store screws and parts at every disassembly step.

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Later on, we will remove the notched retaining ring visible on the inside, see the red
arrow.

Notched retaining ring, securing the optical block.

This ring secures the optical block. The other notched retaining ring, visible deeper
inside, holds a lens group in the optical block. I will deal with that one later in discussing
the cleaning of the fungus-infested part.

First, we will remove the focus adjustment ring grip. This ring is secured with three set
screws. We will only need to loosen them. It is not necessary to completely remove
them. It is important though to use the right size screwdrivers. Wrong size screwdrivers
can damage your screw heads. In the long run it pays off to spend some time finding
the correct size screwdriver. For these set screws, I have used a 1.2 mm screwdriver.

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Loosen the three set screws of the focus adjustment ring grip (1.2 mm).

The focus adjustment ring gripwill be removed via the frontside of the lens.

Removal of the focus adjustment ring grip via the front of the lens assembly.

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Next, we will loosen the ring with the depth-of-field iscsale. This ring is secured with
two set screws, on both sides of the depth-of-field markings (see red arrows) and one
screw on the opposite site of the markings that connects the ring to the helicoid inside
the lens assembly (blue arrow).

Set screws (red arrows) and ‘through screw’ (blue arrow) securing the ring.

The set screws need to be loosened only, the long (‘through’) screw needs to be
removed (and properly stored). For this, we use a 1.2 mm screwdriver again.

Removing and storing the long (‘through’) screw.

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We will leave the loosened ring for now and turn to the optical block. The optical block
is secured on the inside by a notched retaining ring that we have shown previously. For
loosening this ring, we will use a lens spanner.

Using a lens spanner to loosen the notched retaining ring that secures the optical block.

With the spanner the ring can be extracted, but I prefer to use the spanner to loosen it
only and then use my fingers to extract the ring and store it in a secure place.

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Screwing out the notched retaining ring, using the index finger, and storing it.

The optical block can now be taken off from the front of the lens.

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Taking the optical block out of the lens assembly from the front.

At this point I would have expected the ring with the depth-of-field scale to come off,
but for a reason unknown to me it did not. So, I left it for the moment and directed my
attention to the lens mounting.

With a small screwdriver, we clear the green lacquer from the three screw heads and
we remove the screws then using a 2 mm screwdriver.

Freeing the screws in the mounting ring, taking them out and storing them.

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We can now remove the ring.

Taking off the mounting ring.

We can now also lift off the conically shaped ring underneath.

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Lifting off the conically shaped ring underneath the mounting ring.

We now return to the removal of the ring containing the depth of field scale.
First, we will remove the focus adjustment stop indicated by the red arrow.

Removal of one of the focus adjustment stops.

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This is not necessary for the ring removal, but in my search for reasons for the sticking
ring I thought at the moment that it was a good idea to remove this stop.

The ring is supposed to come off (easily) at the front side of the lens, but it seems to be
stuck.

Depth-of-field scale ring.

Pulling on the ring loosened a retainer ring. The opening in this retainer ring (see next
picture) allows the long screw to protrude through the helicoid cylinder. The retainer
ring is stored.

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Removing the retainer ring from the dept-of-field scale ring.

The removal of the retainer ring did not ease the removal of the cylinder with the depth
of field scale. A closer inspection revealed that it was nowhere stuck (see the red circle,
showing an even spacing); it is simply a matter of a tight fit. FSU photographic
equipment is often blamed for wide tolerances and I guess this is an encounter of a
nearly too tight tolerance.
I didn’t want to wedge the cylinder with a metal screwdriver, so I put some more force
on my fingers and that finally did the trick.

Loosening and taking off the depth-of-field scale ring.

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Snapping the ring on and off a few times confirmed that it is only a tight fit and that
nothing has been deformed or broken.

Before removing the focus adjustment ring, we need to take a good look at its position
on the helicoid. The helicoid is not a single thread, but consists of five – interwoven –
threads, each with its own beginning and end. That means that the focus adjustment
ring can be positioned in five different ways and only one is correct. It is often
suggested to make scratch marks on the focus adjustment ring and the helicoid tube,
but I prefer to note the position relative to the infinity and close-focus stops.
Note in the figure that for focusing to infinity, i.e., the helicoid is maximally subtracted
(lens length is minimal), the stop is positioned about two thirds from the rim of the
focus adjustment ring (red arrow in the left picture) and this rim is nearly touching the
end of the helicoid cylinder (red circle in the left picture).
For the closest focusing position, i.e., the helicoid is maximally extracted (lens length is
maximal), the center of the stop is positioned at the rim of the focus adjustment ring
(red arrow in the right picture).

Position of the focus adjustment ring relative to the focus stops.

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These pictures are very important in reassembling the lens later on. If you forget to
take these pictures or make notes, the correct position can be found through trial and
error in less than five steps. The two focusing stops only allow for a limited number of
positions (of which still one is correct). However, for every trial and error step a lens
disassembly and reassembly is required. So, better take notes or pictures.

Now we will remove the last stop using a 2 mm screwdriver (notice that this stop is
longer than the stop at the top) and take the focusing adjustment ring apart from the
helicoid. To remove the ring, we have to turn it clockwise.

Removal of the second aperture stop and the focus adjustment ring.

Now, we have taken apart the Industar-61 to the level that we can clean and
relubricate it.

Before we do so, we will first pay attention to the optical block.
For that we will show the results of the Industar-61 2,8/53 (that’s the all black Industar-

61), that had a fungus problem. The optical block is identical for both lenses.

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Industar-61 disassembled and ready for cleaning and relubrication.

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6. Removing Fungus

In our first Industar-61 (the all black one) we still have to deal with fungus in the optical
block.

The Industar-61 optical block.

Since the fungus is not present on either one of the outsides, the next step is taking out
the lens block that is accessible from the back side. This lens block is secured with a
notched retainer ring. This ring appeared to be fairly loose and could be unscrewed
using a screwdriver instead of a lens spanner.

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Taking out the lens block that is secured by a notched retainer ring, being part of that

lens block.

We don’t have to note the position of this lens block, since only one end has this
notched retainer ring. That ring is an integral part of the lens block.

The fungus appeared to be on the inside of this lens block, but luckily on the outer
surface. Only the glass was affected. No fungus was observed on the housing parts.

We remove the fungus by first swabbing the glass surface with a q-tip soaked in 3%
hydrogen peroxide (H2O2). The hydrogen peroxide is for killing the fungus, but it serves
equally well in wiping off the fungus. To be sure that all fungus is killed, we also swab
the lens block housing with hydrogen peroxide.

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Swabbing the lens surfaces and the lens housing with hydrogen peroxide to remove the

fungus present and kill eventually remaining spores.

Luckily, the fungus has not etched the glass surface. Finally, we clean the lens block and
optical block, swabbing them by using q-tips soaked in 96% ethanol and we finally wipe
the glass surfaces with a carbon-tipped lens pen. This will remove any grease residue
left on the lens surface.

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Cleaning the lens surfaces using ethanol and wiping with a carbon-tipped lens pen.

The optical block elements are now freed of fungus and have been cleaned. We now
reinsert the lens block into the optical block and secure it, this time using a lens
spanner.

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Reassembling the lens block, securing it with a lens spanner.

We check the optical block for cleanliness and carefully put the block aside while we
will clean and relubricate the rest of the lens assembly.

Cleaned lens block.

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7. Helicoid Cleaning and Lubrication

Now that we have disassembled the lens, we can clean the parts and re-assemble. We
will clean the parts before being used in the re-assembly. We start with the helicoid.
We see that the grease has hardened in certain places. This is also true for the focus
adjustment ring. This explains why the focusing was not smooth and rather ‘wobbly’
over the focusing range.

Gummed-up grease in the helicoid and focus adjustment ring.

The best way to get rid of this old grease is to run a wooden cocktail stick or toothpick
through the threads. I object against using a small screwdriver, as is sometimes advised,
since that may lead to scratches and possibly damaging the threads.

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Using a wooden cocktail stick to remove old grease from the helicoid.

In cleaning the helicoid, it becomes clear that this helicoid does not consist of a single
thread but actually consists of five interwoven ones. The next picture shows the
helicoid after running a cocktail stick through one, two and three of these threads.

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Most of the old grease removed from one, two and three of the five interwoven threads.

It will take some time to get rid of all the old, gummed-up grease in the threads. Then,
we employ 96% ethanol to further degrease the helicoid. For that, we use q-tips and
lint-free cloth. Since the helicoid is literally a bit rough on the edges, make sure to
remove any q-tip fluff after cleaning.

Fully degreased helicoid.

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Next, we clean the focus adjustment ring in the same way.

Cleaning the focus adjustment ring.

Then, we will apply helicoid grease to the threads. A small pig hair paint brush is ideal
for this job. The grease (which I obtained from Micro-Tools Europe) needs to be applied
sparingly. If you overdo it, you can simply wipe off excess grease after re-attaching the
focus adjustment ring. The focus adjustment rings does not need to be greased.

Relubricating the helicoid.

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8. Reassembling the Lens

The easy way out at this point would be to say that reassembly is simply the reverse
process of disassembly and leave it at that. But since I encountered most or actually all
‘problems’ in the CLA of this lens at reassembly, it is only fair to go through all the
reassembly steps in detail.

We start with reattaching the focus adjustment ring. As said, five possibilities do exist
and – based on the pictures or notes taken with respect to the position relative to the
focus stops – the right position has to be found through trial and error.
In the picture underneath, we see that the first attempt is wrong. The focus adjustment
ring runs into the helicoid rim before reaching the infinity stop (see red arrow). The
second attempt seems to be right, which is confirmed by checking the position with
respect to the closest-focusing stop.

Finding the correct position of the focus adjustment ring on the helicoid.

In the last picture, the long focusing stop screw has already been put into place. We can
screw in the other one as well. It is best to this now, before we attach the ring with the
depth-of-field scale. The presence of this ring will make it very difficult, although not
completely impossible, to attach the stops.

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The focus stops attached. Note that the shiny one on the right is longer.

Next, we attach that ring, using some force. Note the screw hole in the helicoid cylinder
rim where the ring will be attached to the helicoid cylinder.

Screw hole in the helicoid cylinder for attaching the ring with depth-of-field scale.

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The opening in the retainer ring, that we will position next, needs to be on the opposite
side of this hole.

This retainer ring we simply press into position using our fingers only.

Positioning the retainer ring with the opening at the screw hole position.

Before securing this ring, we will fist attach the lens mounting rings. There is no special
reason to do this first other than that this has been the order of disassembly (since I
was struggling with detaching the depth-of-field scale ring).
Before attaching the mounting rings, we will first clean them. We will start with the
conically shaped ring. In attaching (no screws), note that the clearance will fit over the
focusing stop (red circle).

Cleaning and placing the conically shaped ring.

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Then, we will add the closing ring, cleaning it first and making sure that all loose lacquer
is removed.

Positioning the cleaned closing ring.

Next, we finally secure the ring to the helicoid ring. Therefore, we first position the hole
that is on the opposite side of the depth of field scale over the hole in the helicoid ring
(see circles and red arrow). The position of that hole is found in the clearance of the
retainer ring.

Positioning the depth-of-field scale ring and securing it to the helicoid cylinder.

We screw in the long screw that we had detached before and then secure the two
remaining set screws that we had loosened (or removed) before.

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Securing the ‘through’ screw and the two set screws.

Now, we can reinstall the optical block. This block should simply shift into the front of
the lens assembly. It didn’t however and in trying to find the obstruction it appeared
that I had screwed in the long ‘through’ screw too far (see red arrow).

The securing screw of the depth-of-field scale ring has been screwed in too far.

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So, after loosening the screw a bit, the optical block slid in as expected.

Now, before we tighten this screw again, we first make sure that the aperture indicator
is positioned correctly. The easiest way is too select the largest opening and position
the indicator (line, triangle and dot) opposite 2.8 on the aperture ring. We may also
select the smallest opening and position the indicator opposite 16, as shown in the
picture here (see the red oval). Holding the ring in this position, we tighten the screw.
Then the depth-of-field scale (or actually the aperture indicator) is lined up correctly.

Depth-of-field scale and aperture indicator lined up correctly.

To further tighten this ring or to tighten the ring if it cannot be secured with the
‘through-screw’, as I have experienced in different copies of the Industar-61, we next
bring in the notched retaining ring. In securing it, using a lens spanner, we have to hold
the depth of field scale ring in the correct position.

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Attaching and securing the notched retaining ring, fixating the depth-of-field scale ring.

Then, we clean and slip on the focus adjustment grip over the front of the lens. We turn
the focus adjustment ring to give the lens its minimum length. This focuses the lens at
infinity. Then, we position the grip such that the indicator on the depth-of-field scale is
pointing to infinity (see red oval) and tension the three set screws in the grip.

Attaching the cleaned focus adjustment ring grip into the correct position.

Finally, we insert the light baffle at the back of the lens and push it into position with
our fingers.

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Inserting the light baffle.

After a final wipe and throwing away the leftovers of the cleaning process, we are ready
to shoot.

Finalizing the lens CLA.

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9. Potential Pitfalls and Solutions

As I have mentioned, the hardest part is the reassembly of the lens, i.e., the part that is
described in most instructions as ‘just the reverse of the disassembly.’ In the first
reassembly attempt of my first Industar-61 that I gave a CLA, I ended up with this.

First Industar-61 I gave a CLA after the first reassembly attempt.

We see that the focus indicator (on the depth-of-field scale) is not pointing at an
aperture value (red circles and line). I had not realized that the depth-of-field scale
needs to be positioned correctly before securing it (with the ‘through’ screw and/or the
notched retaining ring in the helicoid cylinder).

We also see that the lens being extended to its maximum length leaves a gap between
the focus adjustment ring grip and the depth-of-field scale ring (red arrow). Obviously,

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the focus adjustment ring is not correctly positioned with respect to the long focus stop
(that is the one at the side of the front lens).

The correct way to cure these problems, of course, is to disassemble the lens again and
reassemble in the correct way. However, we can apply some short-cuts.

For the proper positioning of the aperture-indicator, we remove the mounting ring and
conical ring underneath. Then we loosen the notched retainer ring in the helicoid
cylinder. Next, we loosen the two set screws and the one ‘through’ screw on the depth­of-field scale ring. Then, we position the depth-of-field scale ring so that the aperture
indicator points to the correct value. We make sure that the hole for the ‘through’
screw is positioned correct with respect to the helicoid cylinder and once these
conditions are met, we tighten the screws. Then, still keeping the ring in position, we
place and tighten the notched retainer ring, using a lens spanner.

Then, to correct the focus adjustment ring position, we first remove the focus stop at
the mounting side of the lens and take off the adjustment ring. Then, we have to take
out the other focus stop. This will be tricky, since it will be positioned halfway
underneath the depth-of-field scale ring, as is shown in the picture below, taken while
disassembling the second Industar-61 lens.

With a small screw driver, applied under an angle, it may be possible to accomplish this.
If too much force is needed, forget about it and simply disassemble the whole lens. If
the stop can be taken out, the correct position of the focus adjustment ring must be
found and the stop must be reattached, again using a small screwdriver, applied under
an angle. Then, the other stop must be screwed in and the conical ring and mounting
ring be reattached.

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Focus stop, halfway underneath the depth-of-field scale ring.

Having gone through this procedure, it is a good idea to test if the focusing of the lens is
correct.

For that, we mount the lens on a rangefinder camera (here I have used a FED 3), cock
the shutter and change the shutter speed to ‘B’. By taping a piece of tracing paper over
the focal plane, we create a ground glass to check for focus. Then we open the shutter
and keep it open. A mechanical cable release with a lock comes in handy for this
operation.
We check the focus at infinity and – eventually – the focus at the minimum focus
distance (below 1 m). For our lens the check revealed that we finally succeeded in
correctly placing the focus adjustment ring.

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Industar-61 mounted on a FED 3 and a ground glass created by taping tracing paper

over the focal plane.