OM-1 general questions

I have an old manual camera that doesn't work in cold weather (anything

colder than 10c) -- the mirror sticks in the up position, so I am considering

acquiring another body that I can use my m42 (pentax screw mount) lenses

with in cold weather. As it happens, my brother has an OM-1 that he no

longer uses...

 

I see KEH is selling T-mounts for OM -- is that the same thing as an M-42

adaptor? If not, is there an m-42 adaptor for OM?

 

I've read that the batteries (mercury?) the OM-1 originally used are no longer

made, but there is a substitute battery that will work, what is it?

 

What are the odds that an OM-1 of 'unknown provenance' will require

servicing (e.g. CLA, mirror foam replacement), or can I reasonably expect to

just start using it 'as is' ?

 

Sorry if these basic questions have already been asked, and answered a

zillion times already here. I did a search, but it didn't turn up the answers.

 

Thanks!

Well, chances are pretty likely that it will need new light seals and possibly new mirror foam. But these are trivial repairs that can easily be done one's self, with materials that cost little. There's an ebay seller named "interslice" who sells foam kits with excellent instructions at very reasonable prices ($6-10 depending on which kit you get, including shipping) to allow you to do these seal and mirror foam replacements yourself.

 

There are a few major issues that you might run into. The light meter could be shot, and the shutter could be slow from lack of use, or the curtain could be separating or torn. I'd put the odds of any random 25-30 year old OM-1 having any of these problems at around 10% each, perhaps a bit higher for a dead meter.

 

The other major issue will be batteries. The OM-1 uses 625EXP Mercury batteries, and it does NOT work well with 625A Alkaline replacements. There are several work arounds, but the one I most strongly recommend is to use 675 size Zinc-Air hearing-aid batteries. These batteries will put out the right voltage, but they wear out fast after they are exposed to air - not too much of a problem, because they are very cheap and sold in packs of 4, 8, 16 or 24 batteries at reasonable prices at either Radio Shack or any drug store. The other issue with these batteries is that they are smaller than the OM-1 battery chamber. To remedy that problem, I use a rubber washer known as a #9 O-ring, which fits snuggly in the OM-1 chamber and makes it the correct size for a 675 battery. These rubber washers cost around 29 cents at Home Depot or other plumbing supply stores. If you need to get your OM-1 CLA'd and repaired, there are two highly reputable sources who used to do the warranty repair work for Olympus. They are:

 

Camtech, in Huntington, NY www.zuiko.com

 

and

 

Photosphere, in Dallas, TX www.olyfix.com

 

I can recommend either of these places without hesitation.

 

As for your other question, A T-mount for OM is for T-mount lenses to be used on your Olympus. I don't know if there's an adapter that would allow Pentax M-42 lenses to be used on an Olympus, but I can tell you that if there is, you will NOT have automatic diaphragm operation with those lenses, so you will not get the full functionality of the OM camera. I recommend that you use Olympus OM mount lenses on the OM camera.

Hi! According to this <a href="http://www.a1.nl/phomepag/markerink/mounts.htm"><b>list</b></a>, you will <i>never</i> be able to get your focus to infinity. M42 screw (M42x1 thread) is 45.46mm, Olympus OM bayonet is 46.00mm. What this means is that your adapter would have to be sunk into the camera so that the lens can be about 0.5mm <i>closer</i> to the film plane than a normal Olympus lens. As this is probably close to impossible, and also because all adapters have a <i>positive</i> thickness (ie. they project the lens <i>away</i> from the film plane), your set up would work only for macro, but not for normal photography!

Along with the information already supplied you should know that some early OMs need expert attention to remove old decaying foam under the top plate to prevent damage to the pentaprism mirrors.

 

Camtech (www.zuiko.com) and others should be able to handle a full CLA to keep an OM-1/N running for years to come.

 

John Hermanson (and possibly others) offer a circuit modification that enables the use of commonly available silver oxide batteries with the same accuracy as the original mercury cells. Or you can use 675 zinc air hearing aid batteries and get awfully close to the output and discharge curve of the mercury cells.

 

The threads on T-mount adapters and Pentax screw mounts are not the same. T-mount adapters enable the use of a generically designed lens on almost any SLR. I have three such lenses that I've used between my Canon FD, Olympus OM and Nikon AI SLRs.

 

These T-mount lenses are invariably either of the preset aperture types or of a fixed aperture. I have two preset types, a 135/3.5 Lentar and a 300/5.6 Vivitar, and one fixed aperture type, a 100/4 Spiratone Portragon which has no adjustable diaphragm or iris.

 

T-mount adapters allow you access to a large number of affordable and sometimes interesting alternatives to the excellent Zuikos.<div></div>

The M42/OM mount question is interesting. The Olympus FTL was an M42 thread mount SLR which I think was introduced shortly before the OM-1. They don't seem to be very common though. Olympus must have made at least a few Zuikos for it in M42 thread mount.

B&H seems to carry one. See <a href="http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=97560&is=REG">here</a>. Just wonder what camera sticks? Are these non-mechanic shutter causing problem in cold temperture.

Also T-mount and m42 mount are not compatible and have different thread size. As I notice M42 mount has smaller diameter than most bayonet mounts such that the m42 lens can move a little bit under bayonet mount using an adapter. So check with your OM1 mirror lock to see if the mirror can move freely after the lens, particular an wide angle lens, mounted using an adapter. I have use S.M.C Takumar 35/3.5 lens on my eos630 camera using a M42-to-EOS adapter. Unfortunately, the mirror hit part of the middle metal which surrounding the rear lens element and left some scratch on the protecting metal and the mirror itself if the focusing distance is more than 10M.

Thanks for the answers, I hope they will be helpful to someone. I managed to

snag a near-mint spotmatic for a very good price. Needless to say, no

screwmount adaptor issues there ;-) The battery stuff may be relevant

though...

I couldn't have found this thread at a better time. I have just bought my 1st OM-1 (thank you Ebay...) and was a little concerned about the battery issue.

 

Thank you :)