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Lost dioptre....again


Jennifer

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As my ancient eyes aren't what they used to be I use a +1.0 VF dioptre on both my M's. Unfortunately and very irritatingly, I've found that these have a habit of unscrewing themselves and falling off. As a result I have now lost two. At £110 a pop this is an expensive business. It has been suggested by a non photographer that I should use a low strength Loctite on the screw thread but I'm loathed to do so without more informed advice. Any thoughts?

Edited by Jennifer
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Get a fitting Flexiclamp from Microtools and tighten it just a little bit more.

 

 

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Similar problem with the finger loop screw. Develop a "tighten screws" habit whenever picking the camera up.

 

Talking of screws, how does one engineer a screw which locks when it's fully on? I'm thinking of the hood on the Summilux-M 1:1.4/35 ASPH. This has to stop in the right orientation so it's not possible to screw till tight, but it does seem to lock in the right place.

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+1 is mild long sightedness, a problem for reading. I thought people (eg my wife) who wear reading glasses have to take them off if they want to focus on distant objects, ~ 20cm or beyond. I presume the correction is to allow RF focusing, but doesn't this interfere with composition if the scene isn't in focus? 

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Similar problem with the finger loop screw. Develop a "tighten screws" habit whenever picking the camera up.

 

Talking of screws, how does one engineer a screw which locks when it's fully on? I'm thinking of the hood on the Summilux-M 1:1.4/35 ASPH. This has to stop in the right orientation so it's not possible to screw till tight, but it does seem to lock in the right place.

By using a self-locking thread

http://www.threadcheck.com/self-locking-thread/

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I use a +1 in addition to my glasses.  The rangefinder and LED's are set at IIRC 1.5m, and my distance Rx is too strong for that.  If I didn't add the diopter I would need to use a mid-position on my progressive lenses, which is a PITA.  I have never had the diopters come unscrewed.  The native eyepiece is rubber-coated as is diopter eyepiece, and when it is attached with a firm twist, there is apparently enough friction between the rubber surfaces to keep it from slipping (kind of like the clutch plates on a car).  I have a set of flexiclamps but I found wearing a rubber glove when attaching the diopter offered more than enough grip to get the job done. 

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I've used Leica dioptres for over 40 years. They do unscrew. I lost one in China, and had to tape on a Nikon -4, until I returned home, and could attach the spare. Leica stopped with -4 in the 70's, and finding them again is super difficult.

A tiny, tiny, dot of mild cement would work. Or a tiny dot of Loctite mild formula.    ......Tiny is the key.

Checking for tightness is a better method.

I often use a Leica 1.25 magnifier, which means I need to unscrew the diopter and screw it on top of the magnifier. Adding to losing one doing this screwing and unscrewing.

Another alternative is using one of these;

http://www.japanexposures.com/shop/accessories/ms-mag-x1.15-magnifier-for-leica-m.html

it has a variable focus adjustment so no diopter needed.

I use one and its works fine. Research if it would work for you.

If you think to buy one you need to say you need it for a spotting scope etc.  some kind of patent restriction to selling it for Leica cameras .... google the work around.

good luck

ralph

 

* The above are only  suggestions. You decide what is best .... what you feel most comfortable with ......

Edited by rafael_macia
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Do you mean Teflon? Too slippery.

 

Could be the case, but it does let you tighten further and if the threads are inherently loose it eliminates the gaps. Presumably air is slippery than teflon. Seen it used on head studs for racing engines and they don't back out when wrapped properly.  But like I said, no clue in this instance... just a thought and something cheap, easy and wont leave a trace if it doesn't work.  

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Do you mean Teflon? Too slippery.

 

 

I think he means plumbing sealing tape. That could work but I loathe to think how fiddly that could get given how small the thread is. 

 

Jennifer the diopters seem to pop up on eBay on a regular basis for under 50 quid. I keep a spare myself if ever I lose one of mine. Touch wood, hasn't happened so far but I'll keep checking them going forward. 

Edited by BBHewee
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Another suggestion is to apply a small amount of clear silicon sealant (and I mean small) to an equally small angular arc of the thread. It won't come off in a hurry, that's for sure. 

 

In passing, and in relation to plumbing and PTFE tape, for chrome compression fittings, PTFE tape spoils the clean look, so plumbers often use clear silicon sealant instead. No leaks.

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+1 is mild long sightedness, a problem for reading. I thought people (eg my wife) who wear reading glasses have to take them off if they want to focus on distant objects, ~ 20cm or beyond. I presume the correction is to allow RF focusing, but doesn't this interfere with composition if the scene isn't in focus? 

 

Steve, you're mixing up a couple of issues here. You're right that +1 can be for mild longsightedness, but it sounds like your wife is using her glasses to correct her presbyopia which is another issue. 

As we get older, the lens in the eye gets stiffer and is less able to change shape to focus light on the retina. Someone may need +1 all their life in order to relax their eyes for viewing the far distance but simply focus their eyes negating the need for glasses. However, approaching their 50s, the stiffened lens in the eye means they need a correction of +1 to sharpen the distance. They will need a stronger prescription to focus up near.

It sounds as though your wife is perfect for distance, but needs her +1 to focus close print. As she doesn't need glasses for distance, when she puts on her readers the distance is blurred.

Someone who is +1 longsighted will benefit from the viewfinder  dioptre and will see the distance and rangefinder patch clearly. Someone who is mearly presbyopic by +1, such as your wife, will find her distance vision is blurred viewing through the viewfinder diopter.

Maybe Rick can explain it as he's an ophthalmologist I think.

Pete

Edited by Stealth3kpl
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Stealth3kpl, yes my wife is short sighted but has no interest in photography, other than the finished product hanging on the wall. I only quoted her in the sense of someone who uses reading glasses. On the other hand I have a prescription of -1 and wear glasses out of choice as I'm legally entitled to drive without, Consequently I'm comfortable using the RF focusing with or without glasses, but often wear them for added acuity.

 

Anyway, this is miles away from the OPs thread about loosing the diopter correction device. I think she already has plenty of answers to help prevent another £100 down the swanny.

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I thought to add that a small piece ¼" or so,   of masking tape, on the threads would bind up and tighten things, .... maybe a loop of waxed dental tape/ floss?

anyway,

Jennifer most likely has more than enough suggestions ...

Edited by rafael_macia
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