Camera Lens - Glasses Quality / Build / Durability

redrede

Recently look back those talks about the different of optical lenses and plastic lenses, there is much evidence of what are those lenses made of, only talks and rumours. But there is certain fact is that the plastic lenses don't last.
Do any Ching know more about its history and background? I don't have the resource to get all the lenses and open them up for inspection.....interesting to know

http://en.wikipedia.org/wiki/Low-dispersion_glass
http://en.wikipedia.org/wiki/Fluorophosphate_glass
http://www.stsite.com/camera/cam02.php
http://www.humansinvent.com/#!/8 ... fting-a-leica-lens/
http://www.designlife-cycle.com/camera-lenses/
http://www.sony-mea.com/microsit ... 3ADSLR%3AThumbnails
http://www.zeiss.com/corporate/e ... -camera-lenses_2015

wolfmkc

Redrede CHing,

There are books in the public library about lens development.  They are really good and can give you a clearer picture of the lens design progress since the dawn of "chemical photography", which pushed the development of photographic lenses.

A History of the Photographic Lens   R. Kingslake
The photographic Lens                    S. F. Ray

vincecharus

Does anyone know whether Leica uses any plastic in its M lenses?

頭文字L

It was said that ALL asph are of a very special kind of GLASS raw material .... Technique was co-developed by Hoya + Leitz + Pentax

redrede

Can we finalize which lenses is purely made of optical glass or cheap advanced glass?

bubu

Embrace the change or not, each to its own.

I was brought up with the notion that quality lenses are made of nothing but genuine glass (not to mention lanthanum and alike).

Time changes. To cope with digital sensor's great ability,
either the lens would be very expensive being wholly made of high end glass,
or, one has to accept the trend of non-glass lenses.
After all, non-glass doesn't necessarily mean inferior.
For example, technical fabrics for sports wear is way better than traditional cotton/linen make.

But I am an old timer. I still want whole glass.

redrede

bubu 發表於 2015-5-21 23:14
Embrace the change or not, each to its own.

I was brought up with the notion that quality lenses ar ...

Bubu兄，I don't think it is whether an old timer wants to use purely high end glass material, if we are just debate on image quality instead.

If you remember I got the vm 21 f4 from you, I have been using it for sometimes now, this is a great performancer on sunny occasions. However I'm finding it quality change especially on a cloudy day, both sides of the photo is awful and I'm thinking an upgrade would be worth it. That's why I'm doing the research why and what would be the reason behind it. From my limited experience, I have only found this problem on wide angle lenses, and of course I would like to keep a lens for a life time.

redrede

Please kindly see the photo, I have converted from RAW file to JPG file. You can see the colour have changed on both sides of the photo and clear in the centre. This is normal but this wouldn't happen when I took a photo on a sunny day with f4 wide open.

Apart from the reason I might have a shaking hands, otherwise the colour shift should not be so obvious

M3fans

I guess part of the problem for the above picture was caused by the sensor. The rear end of the VM 21/4 goes deep into the camera and getting very close to the sensor. The sensor corners receive the light at a steep angle magnifing a problem exists in most wide lenses. I think this lens also is not designed for digital sensors.

wolfmkc

Suggest take a few test shots on tripod, see if that make a difference.  

edwardyung

VM21/4 後鏡片太貼近sensor... 冇乜其它digital相机会Like呢類鏡,
就算Leica都冇法完全遷就晒佢.....
在M9上我覺得少少紅移外, f/4 sharpness一点問題都沒有.
附图的变形是改過的... 現實沒那麼直.