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alps-art.ch
15-Sep-2011, 15:32
Hi, I recently purchased a used Sinaron SE 300mm/5.6 in Copal #3. After a closer look under a lamp, it become obvious that there is enough dust between lens elements in the frontal half of the lens (have no idea how they got there, it must be that one of the previous owners disassembled the lens for a somewhat reason).
Should I try to disassemble and clean it, or better send to a service? What are the risks to DIY? As I live in Switzerland, should I try contact Sinar (although the lens was manufactured by Rodenstock, of course), or anybody can suggest a better service?

Thanks a lot for your answers,
Dmitri.

Wayne Crider
17-Sep-2011, 09:01
DIY cleaning of dust, (outside of simple unscrewing of front or back groups from the shutter and cleaning, blowing or brushing dust off), is considered a job for a service according to what I have read in the past. The problem comes from the ability to keep a dust free environment and the tools clean. In my own cleaning I notice that the tools (cloths, brushes and whatever else) must be kept in pristine condition other wise you just exacerbate the problem. On top of it there is an alignment issue with the elements which require a system of marks. (There is actually a process to do this but I cannot think of the term for anything. Maybe someone else will know it.)

Daniel Stone
17-Sep-2011, 16:21
contact focal point and see if they can help you out. Otherwise, I'd go to Rodenstock directly

http://www.focalpointlens.com/

-Dan

GPS
18-Sep-2011, 03:36
If you take pictures with the lens as-is you'll not notice any degradation of contrast on them. Not using a proper lens shade has much much more detrimental effect on contrast than the dust in your lens. Inversely, using a good lens shade has more positive effect on the picture than cleaning the lens.

domaz
18-Sep-2011, 11:57
If it's really between the elements and not just on the rear surface of the front element it is an expensive repair and probably not worth it. Just use it as-is and don't worry.

alps-art.ch
18-Sep-2011, 20:02
Thanks for all your answers!

Domaz, I also thought the dust was on the rear surface and taken out the front half from the shutter to clean it. No, it is inside... :(

Wayne, what you said is same as my own reflections. I guess factories like Rodenstock use dust-free boxes with attached gloves, like bio-hazard labs.

GPS, good to know. I guess, combination of both dust and letting strong light passing through lens only aggravates the problem?

Finally, I contacted Rodenstock, and they passed my request to www.qioptiq.com (looks like R outsources technical customer service to it). Unfortunately, the representative have not given me any estimates on the price, just proposed send it to them. In the form (http://www.rodenstock-photo.com/mediabase/original/Service_Form_EN_New_Address_8776.pdf) they proposed to specify my request out of: check, revision, quotation, conversion, repair. Will try to find out what does each mean exactly...

Thanks you all guys, again.
Dmitri

Don Dudenbostel
18-Sep-2011, 20:37
unless the dust is very heavy you'll never know its there. Dust just works its way into the lens. Lenses aren't air tight and heating and cooling under normal conditions causes very slight amounts of air to be drawn in and expelled from the lens plus if I remember correctly these are assembled in a room with a relatively clean atmosphere but not in a totally filtered environment. I don't believe they are assembled in a glove box. I have done quite a lot of photography in sterile surgical environments and even then dust gets into those environments through doors opening and closing and is carried in on shoe covers and scrubs.

Some of my lenses have dust in them and I've owned them since new and they've never been opened. Don't fret over it just make photos and enjoy it.

GPS
18-Sep-2011, 23:06
Thanks for all your answers!
...
GPS, good to know. I guess, combination of both dust and letting strong light passing through lens only aggravates the problem?
...
Dmitri

Week or strong, the effect on contrast is the same. If you take a picture before and after cleaning you'll not see a difference - then you can ask yourself why you paid for the lesson...:)

alps-art.ch
20-Sep-2011, 03:07
You convinced me stop worrying and start taking pictures :)

Thanks again for your answers!
Dmitri.