Home

Please support mflenses.com if you need any graphic related work order it from us, click on above banner to order!
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

bubbles...
Post new topic   Reply to topic
Home   Manual Focus Lenses
View previous topic :: View next topic  


PostPosted: Sun Apr 06, 2008 10:55 am    Post subject: bubbles... Reply with quote
In an old manual for dealers of a photo-shop I read something about tiny bubbles in lenses. They state, that this bubbles would have no effect on the image quality. But avoiding them with better production techniques would rise the price enormously, and they would be only a matter of taste. I am ready to believe that. On the other side this is a statement of the prejudiced producer ("VEB = volkseigener Betrieb"). So what do you think?

Brauer, Egon. 1983. Foto Optik. Eine Warenkunde für den Fachverkäufer und den Fotoamateur. Leipzig: VEB Fachbuchverlag. Seite 29, "2.3.6. Luftblasen im Objektiv":
Quote:
"... Luftbläschen im Objektiv bringen keine Funktionsstörung mit sich. Die Bläschen sind kleine Schönheitsfehler, die man im Interesse eines erschwinglichen Objektivpreises in Kauf nehmen muß...".


PostPosted: Sun Apr 06, 2008 11:32 am    Post subject: Reply with quote
I think it depends on what you want to have...

...a perfect lens in collector's quality? The bubbles are bad! Wink
...a perfect lens for professional shootings? The bubbles are perhaps problematic.
...a nice user-lens for "our" normal standards? Don't worry about the odd bubble. Very Happy


PostPosted: Sun Apr 06, 2008 12:24 pm    Post subject: Reply with quote
How to see those bubbles? do you need a microscope


PostPosted: Sun Apr 06, 2008 1:37 pm    Post subject: Reply with quote
@poilu:
Quote:
How to see those bubbles? do you need a microscope

I saw such bubbles (in a black biotar) a few month ago with my eyes and didn´t buy that lens because I estimated them as bad quality. I didn´t have the information I got recently from the mentioned book.

@LucisPictor:
Quote:
...a perfect lens in collector's quality? The bubbles are bad!

I fully agree.

Quote:
...a perfect lens for professional shootings? The bubbles are perhaps problematic.

That´s what the author of my book is denying. Far from this he states, that "...Besonders hochwertige optische Gläser weisen meist kleine Luftblasen auf, die während des Herstellungsprozesses entstehen...Technisch gesehen, haben die kleinen Luftblasen keinerlei nachhaltige Folgen. Sie sind, auch in ihrer Gesamtheit, viel zu klein, um einen sichtbaren Licht- oder Schärfeverlust zu bewirken...".

Freely translated and abbreviated for our "non-Krauts": "...this bubbles appear especially with the production of high quality lenses and have no negative effects whatever..."


PostPosted: Sun Apr 06, 2008 3:05 pm    Post subject: Reply with quote
In practice, you won't see these bubbles on the end result, any more than you would see a speck of dust or even a scratch.

About the only things that will compromise a lens' optical performance are fungus that's not removed and a LOT of scratches.

I have an Orestor 135 with one bubble in the centre of one of the elements of the triplet - mount the lens on the camera and look through the viewfinder and one can no longer see the bubble....


PostPosted: Sun Apr 06, 2008 3:30 pm    Post subject: Reply with quote
I have some bubbles on the edges of one of my zuilko 24's (it has 3 scratches as well. The other zuiko 24 I have is mint with no bubbles. The image quality is exactly the same provided I use a hood against the scratches. Minolta has an M mount 28mm rokkor that is famous for it's perfectly patterned white spots visible behind the front element. Those white spots are little micro bubbles. These lenses function perfectly and still bring a fat dollar. It would seem that if there was a really foul bubble that was in the center of an element it would have gross negative effect . Otherwise minor one should be undetectable in photographs.


PostPosted: Sun Apr 06, 2008 4:20 pm    Post subject: Reply with quote
Almost every Carl Zeiss Jena Biotar 75mm f1.5 has bubbles! One of the best quality lens what I ever seen. With bubbles can be laser sharp at f1.5 ! They not impact picture quality at all in Biotar 75mm.


PostPosted: Sun Apr 06, 2008 5:12 pm    Post subject: Reply with quote
The bubbles are not a concern for collectors, as they exist in some of the most collectible lenses.... they were unavoidable in some of the glasses used in the "exotic" high performance lenses of the 1930s and 40s and were something of a badge of rank. They become less common after WWII, but my 50/1.4 LTM Nikkor, 50/1.5 Zeiss Opton Sonnar and 85/2.0 LTM Jupiter-9, all from the early 1950s, still have them.

The presence of a bubble in the glass can never be an optical benefit, but in small numbers and being the size of a particle of dust, their presence was more than outweighed by the benefits of the glass that caused them to appear.


PostPosted: Sun Apr 06, 2008 7:48 pm    Post subject: Reply with quote
rick_oleson wrote:
their presence was more than outweighed by the benefits of the glass that caused them to appear.


Thats a nice summary.


PostPosted: Sun Apr 06, 2008 9:04 pm    Post subject: Reply with quote
Perfectly put Rick!

Cheers,


PostPosted: Thu Apr 10, 2008 3:33 pm    Post subject: Reply with quote
After a day of hard working I rewarded myself with this lens (black biotar 58/2), now knowing, that the bubbles are not a sign of bad quality:



First impressions: This lens is so sharp, that one needs a gun licence for it.

Poilu wanted to know, if one can see the bubbles with the mere eye. Yes. Here is a picture:



PostPosted: Thu Apr 10, 2008 4:30 pm    Post subject: Reply with quote
Retro - what a great piece of glass! I love this lens and I'm dreaming about its bigger brother (Biotar 7.5cm). My copy of black Biotar (SN 3332409) also has some small bubbles - despite this fact it produces very sharp images Smile I noticed some air bubbles in old Sonnars 18cm and Biotars.
The conclusion is: don't search microscopic bubbles - enjoy your lens!


PostPosted: Thu Apr 10, 2008 8:13 pm    Post subject: Reply with quote
Here you get two pictures with this very nice lens from this evening:




Picture two was made under very low artificial light.
It is very harp, has very decent colors and a wonderful bokeh.
There was only few post processing needed, that means good output-contrast. Very Happy

As you can see: forget the bubbles... Cool


PostPosted: Thu Apr 10, 2008 10:54 pm    Post subject: Reply with quote
About 10 years back when travelling in Hungary I bought a Fed 1 in a little antique shop somewhere behind Vaci Utca towards Doheny Utca. Nice shop but when I got the camera back to Oz (Australia) and examined it closely it was only then that I noticed that the lens looked like it was made of fizzy lemonade. I had examined the camera body itself carefully for function and appearance but being in a rush had not thought to examine the lens. I never got around to using it.
The point is that there is benefit in checking carefully.


PostPosted: Thu Apr 10, 2008 10:59 pm    Post subject: Reply with quote
peterm1 wrote:
About 10 years back when travelling in Hungary I bought a Fed 1 in a little antique shop somewhere behind Vaci Utca towards Doheny Utca. Nice shop but when I got the camera back to Oz (Australia) and examined it closely it was only then that I noticed that the lens looked like it was made of fizzy lemonade. I had examined the camera body itself carefully for function and appearance but being in a rush had not thought to examine the lens. I never got around to using it.
The point is that there is benefit in checking carefully.


Probably a Lite edition Smile


PostPosted: Thu Apr 10, 2008 11:16 pm    Post subject: Reply with quote
Dohany utca is jew district you will not find any trustworthy seller there Smile Sorry about your disappointments.

http://www.jewishbudapest.hu/
Post new topic   Reply to topic
Home   Manual Focus Lenses
Page 1 of 1