Q:Clean dust inside the lens

Hi,

I wonder if it's worth while to clean the inside of the lens. There'a lot
of tiny dust particles inside my Yashica 50mm 1.4. It's a very nice lens.
I wonder if it is very hard to do.

I have the screwdrivers (small ones) to take the lens apart. Is there
additional tools that I need?

My plan is to just get to the part where the dusts are and use air (the
stuff that comes in a can) to blow off the dust and then reassemble it.

Has anyone did this before? Let me know what you think of my idea.

Thank you for your advice in advance.

 

Don't consider doing it yourself. Getting all the parts back together
in the exact relationships that are required to maintain proper operation is
not something most people can do.

I would generally not bother having it done. Even a good professional
may not return it as good as it was. Those small specks of dust are not
likely to degrade the image in any meaningful way. If there were an extreme
amount of dust in it, then and only then would I consider a professional as
the lens would be subject to enough flare to make it worth while. So unless
you are experiencing flare problems, I suggest you leave it alone.

 

Probably quite a few that won't be obvious to you until you're trying to
get the thing back together.

Don't do it. Take it to the local camera store for a cleaning.

No, I'd rather entrust my lenses to people who know what they are doing
and who do it regularly, have the proper tools, skills and knowledge.

 

I disassembled a Ronkkor 58mm f/1.4 because the iris was jammed. I
considered it more or less junker anyway. I wanted the experience. The
result? I don't think that I got the f/stop settings calibrated quite
right because there is a ring in there that allows one to set the iris
to anything irrespective of the actual setting. So I set the aperture
ring to f/1.4 and adjusted the slip ring to what I thought f/1.4 should
be. You know, the verge of wide open. Best guess. I was able to get
into the iris without removing any glass elements from their mountings.
Aside from the iris deal, the lens seems to function no worse for the
experience. Before I say go for it though, you should know that I had 9
year experience as a machinist and tool maker to help me along. The
other thing that I noticed was that there are some special tools need to
get the glass elements out of and back into the barrel properly. Those
are available but a bit spendy for a one time deal.

For a lens that is worth more than the cost of a clean, lube, and adjust
job, (about $100 to $200) I think that I would allow a a factory
authorized service center to do the work as the cost of the proper tools
to do the job cost about that.

There are special interest groups and websites devoted to the repair of
photographic equipment. I discovered this site with using a basic
Google search. http://www.kyphoto.com/classics/forum/ I am interested
in resurrecting some 60's and 70's range finders gleaned from eBay and
needed some guidance. Check out this site or look for some of your own.
Good luck.

 

Well, that depends on how good you are with small, delicate things and
lateral thinking. In my experience (admittedly somewhat limited) - the ease
of dismantling depends entirely upon the type of lens. A 50mm shouldn't be
too difficult.

Probably not, but I wouldn't rule it out. If you just want to get the front
element off (which should give you access to the rear element as well in a
simple prime lens), then you'll probably only need a very small cross-headed
screwdriver. Of course, it's a lot harder if you need to get actual lens
groupings apart.

In general - a standard prime lens will probably come apart by removing the
infinity stop and then turning the focus ring until the front element comes
off the front. It's not rocket science, but you need to make sure that
everything goes back on exactly as it came off - including marking
orientations of things like the focusing ring, elements, etc. There may be a
group of screws (usually three) which hold the front element into it's
surrounding lens housing. You shouldn't need to remove those.
As I said, lens designs are different so in many cases you may need to
figure out how your particular lens works before you get too carried away
removing screws if you don't know what they do. In general, it's best to
start by removing the rubber grip from the focus ring (although sometimes
there's nothing underneath!).

After saying all that, it's probably only really worth going to the trouble
of cleaning the interior glass of a lens for two reasons:

1. Picture quality is noticably poor
2. You don't mind completely wrecking the lens if you mess it up

Yes, but the only time I did it to clean the interior glass, my actions made
no difference to the performance of the lens whatsoever.
One final note - make sure you have a pot to keep the little screws in and,
if necessary, it could be a good idea to make notes about how the lens comes
apart.


Chris.

 

Scratch some of that. Getting confused late at night with my different
lenses. You'll probably find that all the lens groups move together on a
prime - when you turn the focusing ring, the front group and rear group will
all move as one whole unit. I think this makes things a tad more complex -
looking over the lenses I've taken apart, I just realised that they were all
zooms. I figured taking a prime apart would be easier, sure it looks like
you can get the lense groups out easy enough but somehow they'll be attached
to the aperture ring and then you also have to get the groups apart. Still,
I think it'd be possible but the post by 'columbotrek' probably gives more
accurate advice for primes. I'll have to wait till I get a bad one before I
take one apart

Chris.

 

*Generally* with *most*, NOT AF lenses, primes from 35mm - 200mm you only
need to remove the entire front group to access the diaphragm assembly.
This is usually accomplished by removing the name plate ring, where the
focal length is written, and or the filter ring. You may need to remove the
rear group if the diaphragm assembly is held from the rear. I would never
separate the helicoids to get at the diaphragm, you are asking for trouble.
Generally you will need screw drivers, tweezers, gum rubber stoppers and or
a good spanner wrench.
Take LOTS of notes or photos as you go.

 

Hi Guys,

Thank you for sharing the valuable comments and experiences. I think I can
do it with more information from you guys out there.

I have 3 50mm lens 1.4, 1.7, 2.0. There's like at least 100 little dust
particles inside. It just bugs me. Picture wise, I can't really tell. The
lens is about $55 on ebay (decent), so if I screw up, I will go and get one
from ebay.

I read your postings TWICE so make sure I don't miss out anything.

I managed to get the front part of the lens out (the metal part that the
filter attaches to). I unscrew the "name ring" (whatever you call it).
When I removed it, I saw 3 screws holding the lens unit to the focus ring.
Do I take the screw out. Not wanting to go any further without consulting
you guys first.

http://www3.telus.net/300b/ is my web site. On there, the image 0244 and
0245 shows the screws as well as images to show the lens.

I really appreciate the help so far from everyone here.

Or should I attack from the rear. I just need to get to the aperature blade
part and use compress air to get rid of those dust and then reassemble. I
think it's way beyond me to take the lens piece out.

Thank you!

 

The three screws hold the focusing ring, it looks like, leave them alone.
You should be able to
unscrew the entire front lens unit. What brand is the lens?

 

Hi Mike,

The lens is a Yashica 50mm 1.4 ML.

How can I unscrew the entire front lens unit? Do I have to losen the 3 tiny
screws on the aperature indicator ring and then turn it?

Or do I attack it from the rear? I can see how I can turn the front lens
unit to unscrew it.

This lens is all metal, no plastic or rubber, so no hidden screws. Only the
ones on the front hidden by the naming (filter attachment) ring, 3 on the
aperature indication ring (right below the focus ring), and the rear screws.

I just want to get to the middle part, where the aperature blades are and
shot some air in there to get the dust off (hopefully). There's just way
too many tiny dust particles in there.

Thank you for your help so far.

 

From the photos it looks like the three screws turn down on to the focus
ring tho it's hard to tell from the photos. What you need to do is unscrew
the glass from the lens barrel, the glass is not held in with screws
Email me at
Mike