Minolta MC 58mm f1.4 Service Manuals

LENS REPAIR GUIDE BY MEL PARKER JONES

Minolta MC ROKKOR 58mm f1.4

A step by step guide to repairing the mighty Minolta Rokkor 58mm f1.4

This guide can also be used for many other short focal length MC series lenses such as the

55mm f1.7. Most short focal length Rokkors share a very similar construction and while

there may be minor differences the essentials will be almost identical.

This is NOT true of long focal length and zoom Rokkor lenses which will be very different in

design and construction.

The guide covers the MCII series but MCI series will be identical.

This guide will NOT be appropriate for MCX Series, MD Series or the earlier Auto Rokkor

models which all employ very different construction.

Copyright 2020 Astro-Baby ,

Free to use, copy and distribute so long as no charge is made for use,

distribution or access and authorship is freely acknowledged.

NOTES BEFORE YOU START

Start by putting a rear lens cap on while
you work on the front part of the lens.

The quality of any repair is down to your
skills, your tools, patience and most of
all mindfulness.

Good servicing is taking your time, there
are no prizes for the fastest lens strip
down and rebuild.

STEP 1

Remove the lens beauty ring. This can
be done with a lens spanner but a
rubber cup is a better solution. A lens
spanner can easily mar the finish on the
beauty ring.

The Minolta Rokkor 58mm f1.4 is a relatively easy lens to work on but please bear in mind
that this is a guide, you may well face challenges inside the lens that you will need to work
out. These can include stripped screws, deformed parts etc.

When working on one side of the lens (eg the front) always be mindful about what’s
happening at the other side (eg the back). I always keep caps on as much as possible to
prevent any accidents. The classic mistake is for people to press on the lens while it is on a
workbench and break things on the downside of the lens like the aperture lever.

There is no such thing as luck in repairing optical equipment, if you do it right, using skill and
patience you will be rewarded with a perfectly operating lens. A rushed or bodged job will
result in the lens being devalued, unpleasant to use and possibly unusable so…..take your
time, get the right tools and materials, don’t take shortcuts or advice from people who
know less than you.

There are no prizes for fastest or almost working in the world of lens repair so read the
guide from end to end before starting to familiarise yourself with the process.

With the beauty ring removed all of the
essential screws and fittings for the
front part of the lens are exposed.

STEP 2

Start by removing the front optical
element group. You will see there are
two sets of lens spanner cut outs. You
need only the outer pair.

Apply the lens spanner and gently but
firmly turn the lens while keeping
downward pressure on the spanner.

The front optical group after being
unscrewed can be simply lifted out of
the lens body.

Store this somewhere safely. I usually
store lens groups in a Tupperware box
lined with lint free cloth pending
cleaning and reassembly.

You are advised not to disassemble this
group but cleaning will be discussed
later.

With the front optical group removed
the aperture mechanism is now
exposed…….

Its safest at this point to open the
aperture to its widest. This will
minimise risk of damage to the very
fragile aperture blades as you move
forward in the disassembly.

STEP 3

Using a JIS screwdriver remove the three
screws that retain the filter ring…..

…and simply lift the filter ring away.

Make sure the screws are stored safely
and not mixed up with other screws. I
normally allocate small dishes for the
various screws and fastenings to avoid
confusion later.

STEP 4

You now need to remove the diaphragm
assembly. This is retained by 4 screws
around its edge.

One of them is highlighted in the
picture….

Using a JIS screwdriver remove the four
screws around the aperture
mechanism…..

….and remove the diaphragm assembly
carefully. The rear optical group is still
attached to this so extract this with
great care so that the rear optics are not
damaged.

Here is the diaphragm assembly rear
view after removal. You can see that
the rear optical group is still attached. It
is far easier usually to remove this group
with the diaphragm removed.

Take great care of the diaphragm
assembly, it is fragile and easily
damaged by rough handling.

Take note of the fact that the assembly
has a flat edge on one side. You will see
why later.

STEP 5

With care unscrew the rear optical
group. Be careful here as the diaphragm
assembly has a number of small parts at
the rear and the pins and springs can be
easily damaged.

Remember to stay mindful, keep
focused, and THINK before you act.

Store the optical groups somewhere
safe while you move forward with
disassembly.

Here are the two optical groups from
this lens being stored in a small
Tupperware box line with lint free cloth.

STEP 6

Check the diaphragm assembly for
correct function and see whether there
is oil contamination.

If the oil contamination is light I usually
spray the diaphragm out with a Freon
free cleaning solvent and then let it bath
in Isoprop Alcohol for around an hour
before leaving it to dry thoroughly at
room temperature.

If the unit is heavily contaminated it will
require stripping down completely.

Diaphragm strip down and rebuild is not
usually required and this guide will not
cover this aspect.