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specks on new Leica lens normal

barney

Member
I was able to take advantage of the 5% discount from Leica last Friday and bought the R9 with the Summicron-R 90mm ASPH. I wanted the R9 with the black top instead of the other color so I'll be picking that up in about a week when it comes in. In the meantime, I took home the lens and have had a chance to look at it closely.

The back of the lens looks perfect, however the front of the lens has about 7 or 8 tiny "specks" in what seems like air bubbles or something like that inside the front glass. I'm pretty sure it's not air bubbles, however I'm at a loss of words to describe it. I know it's not going to effect the quality of any pictures I take, though I was wondering if anyone else with
Leica lenses can see the same type of "specks".

Just a note, I can only see them when holding it close and at a angle when the light hits it just right. When held out at the distance of my arm, I'm very hard pressed to see them.

I will have the dealer look at it though I was wondering if it's normal.

Thanks!


Barney

PS, when I have a little more time, I'll fill you in on how I had a chance to meet one of the reps.
 

ttam

Active Member
>Barney wrote: >" . . . seems like air bubbles or something >like that inside the front glass . . ." > In the 'olden days' of lens making, the signs of 'air bubbles' in the lens was a 'badge' of a quality lens as the process of making optical quality glass (I guess in contrast to making 'window' glass) in those days more often than not, created air 'pockets' or bubbles in the the optical glass. Modern glassing making techniques, I'm sure, has lessened the occurence of air bubbles dramatically or has reduced it to a point so that it is a non-issue

A noted optical expert in astronomical optics (Harold Richard Suiter or Dick Suiter) analyzed that optical performance is affected if the amount of 'dirt' on the optical surface EXCEEDS 1/1000 of the surface area - or a single obstruction of roughly 1/30 the diameter. Extrapolating his research to 'air bubbles' should mean that YOU NEED HAVE NO CONCERNS with degraded image creation with your new 90mm aspherical Summicron.

The questions is whether Leica is using a special formulation of optical glass for some elements. With current glass making technology, having air bubbles may be unavoidable for this type of glass.

Tsun
 
O

oskar_b

I once saw an old 50mm ‘lux (M) which had a bubble clearly visible in the front element. I was not overly impressed by its presence, but was informed that it was a sign of good quality optical glass and that the image quality would not be affected.

Just a little story that perhaps has little relevance here.

Craig
 
H

hektor

My Godfather bought an new 90mm Summicron in the sixties which had a surprising number of bubbles within the lens elements.

On one of his visits to Germany he took it back to Wetzlar where they checked the lens and reassured him the performance was of the highest order.

For aesthetic reasons, and also in consideration of resale value to those not so understanding, he requested and was given a replacement without bubbles.
 

colin

Well-Known Member
The air bubbles in lenses (Leitz/Leica at least)is a sign of quality and are caused by the VERY slow cooling of the glass. Slow cooling, by definition, takes time and therefore money. Many lesser manufacturers would rather be making lenses than watching glass cool!
Colin
 

cmdr

Active Member
Dear Barney,

It is not uncommon to see small specks of dust in a new Leica lens, as well as any other manufacturers lens for that matter. If you take a flashlight and shine it through the lens with the aperture fully open, you will see some small specks. Even if a lens were to leave the factory absolutely speck free, it would be just a matter of time before a few specks would end up on one of the lens elements. The Leica factory is an ISO 9001 certified manufacturing facility which means that they have to maintain a very high standard in order to maintain this certification. If the specks bother you, you can send it back to Leica and I believe that they will clean the specks for you under your USA passport warranty. Remember that even if your lens is cleaned and there are no longer any specks visible, it won't be long before you do see some specks again. Generally speaking, small specks on the inside elements of a lens do not pose a problem and are usually not visible on your slide or negative.

Regards,
Dale
 
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