Summicron APO 50 in low temperatures.

[David North]

Advertisement (gone after registration)

I am currently in north east China where the weather at this time of the year is decidedly “fresh”.  Clear blue skies with and due to stiff winds, daytime temperatures “feeling like” anywhere between minus 10º C and 0º C.  I am sure that some Forum members would regard these daytime temperatures as positively tropical.

Walking essentially daily and where my camera is always worn outside my jacket.  The strap around my neck, then across my body, with the camera resting on my left side.  No half cases and no bags, with one Summicron on the camera body and another Summicron, in my jacket pocket.

Recently noticed that after a full day out, one of the lenses (Summicron APO 50) develops a stiff focusing action and also during focusing, the lens makes a very slight and hardly discernible, resistance type of noise.  I know this lens very well and something is amiss here.  The body and the lens otherwise, work perfectly.

When back to a centrally heated home and within hours, the lens returns to providing a silky smooth focusing action, without any noise.

I am not really bothered about the core of what I have described here, as the efficacy of the body and the lens is otherwise faultless.  What slightly concerns me however and hence this post, is that if I choose to ignore these weather related symptoms and carry on regardless, could there be permanent damage?  Attempting to have a lens repaired, refurbished or whatever from mainland China, would be an absolute nightmare.

Any comments would be greatly appreciated.

Regards and best wishes,

David

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[frame-it]

Focus helicoid Grease affected by cold weather ?

[AndreasG]

vor 10 Minuten schrieb frame-it:

Focus helicoid Grease affected by cold weather ?

Most probably, viscosity of grease changes with the temperature - turns stiff at lower temperature. 

[frame-it]

i thought that happens with really old lenses..interesting

[David North]

Dear AndreasG and frame-it,

Many thanks for your responses and with the reminder that the viscosity of any “grease” is temperature related or associated.

Any thoughts about the potential long term effect of this and without appearing too theatrical, “cooling down and heating up” scenario ?  

This is my prime concern.

Regards and best wishes,

David
 

 

[Ecar]

A bit more friction caused by a slightly more viscous lubricant should have no ill effects.

[farnz]

Advertisement (gone after registration)

Actually it's more likely to be the different relative thermal contractions of the various metals and other materials inside the lens body.  

For example, polymer materials have a coefficient of thermal expansion (and therefore contraction) about 8 - 10 times greater than most metals and will therefore contract 8 to 10 times  more.  The amounts of the materials in the lens are relatively small so the overall contraction is small and therefore the risk of long term damage should be low.  

The additional stiffness you've encountered will be owing to binding of the moving elements caused by their relative changes of size at low temperatures.  The design and manufacturing tolerances are enough to prevent damage and small tolerances are likely to produce the stiffness in focussing that you've mentioned.  As you might expect, you shouldn't force the focus ring or damage might occur.

I would be surprised if modern greases would stiffen at the temperatures you mention because their function is to lubricate the surfaces across the anticipated temperature range.  Older greases were prone to this but modern technology typically eliminates this.  This is why your lens doesn't drip grease in hot weather.

Pete.

 

[Ecar]

Thanks, Pete. Interesting insight.

One question comes to mind: wouldn't lens designers try to prevent this kind of behaviour by making at least key friction components in the same material?

[farnz]

1 hour ago, Ecar said:

Thanks, Pete. Interesting insight.

One question comes to mind: wouldn't lens designers try to prevent this kind of behaviour by making at least key friction components in the same material?

Ideally yes although there might be other properties in the adjacent materials that become of greater importance, such as service life, weight, durability, workability, availability etc, and therefore different, dissimilar materials might be selected.  The presence of the grease is intended to reduce the risk of frictional and thermal binding but the design and manufacturing tolerances will have the final say I think.

Pete

[a.noctilux]

I don't have the 50mm Apo but the Apo-Summicron 75mm .

With time and use in different temperatures situation, my conclusion is the floating lens mechanism that the two lenses types share.

At higher temperature, the 75mm focus ring can be loose/jerky and not smooth turning when colder.

Normal smoothness when used at regular "room temperature".

[lct]

5 hours ago, a.noctilux said:

my conclusion is the floating lens mechanism that the two lenses types share

+1

[David North]

Again, many thanks for all the comments, observations and suggestions, which are greatly appreciated.  In particular, a thankyou to Pete for the advice provided in his post no. 7.

Regards and best wishes,

David

[steamboat]

Back in the good old days (film, flashbulbs and fixer) if you were going on a real cold weather trip you'd have your camera and lenses 'winterized' or whatever they called it. The equipment would be CLAed but the grease or oil would be replaced by a much thinner consistency product that wouldn't bind up as easily in the cold. Ofcourse when you returned to warmer climate you had to have the cold-weather product replaced with "normal" temperature lubricants. This was mostly something professionals did since there was cost and inconvenience involved.