Dust on mirror

Discussion of all digital SLR cameras under the Minolta and Konica Minolta brands
Forum rules
No more than three images or three external links allowed in any post or reply. Please trim quotations and do not include images in quotes unless essential.
classiccameras
Viceroy
Posts: 1044
Joined: Sun Oct 21, 2012 9:33 am

Dust on mirror

Unread post by classiccameras »

Hi

Has any one come across dust on the SLT mirror and: how do you tell, will it affect pictures/exposures and can it be user cleaned. I read one thread on another site recommending that you do not touch it because it can easily be scratched/marked and its not cheap to replace. Whats the best course of action.

Happy New Year

Pete
David Kilpatrick
Site Admin
Posts: 5985
Joined: Sat May 19, 2007 1:14 pm
Location: Kelso, Scotland
Contact:

Re: Dust on mirror

Unread post by David Kilpatrick »

Blower - not brush, just air blast. There's not much alternative really. The SLT mirror will, like all air-substrate surfaces, eventually become hazed by atmospheric deposits. Old lenses lose their new performance even if they are just left in a cupboard for a decade or two. We don't know yet what will happen with the plastic film used in the SLT design, how it attracts particulate deposits. I would certainly advise against keeping an SLT in an environment where there is smoking or open fires, make sure it's in a room with clean air. Visible larger dust hopefully will be removable by air blast, pollution film won't be. I guess that one day, an ultrasonic wet cleaning service wlll be offered for un-replaceable SLT mirrors. Just as you get from optical cleaning firms for old lenses.

David
classiccameras
Viceroy
Posts: 1044
Joined: Sun Oct 21, 2012 9:33 am

Re: Dust on mirror

Unread post by classiccameras »

Thanks David

I seem to remember some body mentioned a Video which shows how to replace the SLT Mirror, and apparently its not hard.
Was it not atmospheric 'hazing' of the lens surface that the German optical industry discovered gave a better optical performance, namely, flare and light transmission through the lens elements which led to the lens coating/multi coating technique.
Perhaps I have got this wrong, but its some thing like that.

Pete
classiccameras
Viceroy
Posts: 1044
Joined: Sun Oct 21, 2012 9:33 am

Re: Dust on mirror

Unread post by classiccameras »

Thanks David

I seem to remember some body mentioned a Video which shows how to replace the SLT Mirror, and apparently its not hard.
Was it not atmospheric 'hazing' of the lens surface that the German optical industry discovered gave a better optical performance, namely, flare and light transmission through the lens elements which led to the lens coating/multi coating technique.
Perhaps I have got this wrong, but its some thing like that.

Pete
David Kilpatrick
Site Admin
Posts: 5985
Joined: Sat May 19, 2007 1:14 pm
Location: Kelso, Scotland
Contact:

Re: Dust on mirror

Unread post by David Kilpatrick »

No - the 'coating' was not from atmospheric deposits, it was from 'blooming' or oxidation of the lens surface. Of course it could be accompanied by smoke hazing at that time, which gave people a dilemma - polish the lens, to remove the smoke haze which was a really serious problem in the 1920s to 50s, and also remove the beneficial oxidation.

For lenses, it's nearly always only the front element which is exposed enough to get filmed by smoke, traffic fumes and other pollution. But all air to glass elements acquired oxidation blooming. Sadly, by the time a lens had got its bloom the balsam cementing the elements had often separated or gone yellow!

I had a Zeiss Novar from 1937 which had a really good 'coating' bloom by the 1960s. I also bought some darkroom gear a couple of years ago from a smoker, and all his enlarging lenses were horribly filmed over. No wonder he decided to sell the equipment, I don't think any he print he made would ever have been properly crisp and clear.

David
User avatar
KevinBarrett
Emperor of a Minor Galaxy
Posts: 2449
Joined: Wed Aug 13, 2008 5:32 pm
Location: Seattle, Washington, USA
Contact:

Re: Dust on mirror

Unread post by KevinBarrett »

David Kilpatrick wrote:I had a Zeiss Novar from 1937 which had a really good 'coating' bloom by the 1960s. I also bought some darkroom gear a couple of years ago from a smoker, and all his enlarging lenses were horribly filmed over. No wonder he decided to sell the equipment, I don't think any he print he made would ever have been properly crisp and clear.

David
You reminded me of when I first opened up my Minolta 70-210/4 , purchased second hand through an online auction, and it smelled like I'd just stepped onto an elevator with a smoker. I still can't ever get the color from that lens matching what I get from the rest of my kit, but I've used it so long now that I'm almost fond of its quirks.
Kevin Barrett
-- Photos --
Post Reply

Who is online

Users browsing this forum: No registered users and 9 guests