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MTO-1000 problem in winter
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PostPosted: Thu Feb 18, 2010 7:07 pm    Post subject: MTO-1000 problem in winter Reply with quote

My MTO-1000 is making blurry image in cold weather (below 0 degrees), even after one hour cooling. Other mirror lens MTO-500 works fine even at -25 degrees below zero.
what do I do? Smile


PostPosted: Thu Feb 18, 2010 7:52 pm    Post subject: Reply with quote

Going to a warmer country ? Razz


PostPosted: Thu Feb 18, 2010 7:56 pm    Post subject: Reply with quote

Hm, but if i like Canada? Confused


PostPosted: Thu Feb 18, 2010 8:22 pm    Post subject: Reply with quote

That's quite common for mirror lenses, especially on telescopes. I can take my refractor telescope out and almost observe instantly, but my mirror scope needs atleast 1 hour prior to observing. That's a Newton scope so it has an open construction at the front and cools quicker than a closer Maksutov design like the MTO.


PostPosted: Thu Feb 18, 2010 8:29 pm    Post subject: Reply with quote

So you think i need to try to cool lens for a longer time?
Maybe when i focusing, and touching the lens one side is warmer than other, and there is some temperature difference?


PostPosted: Fri Feb 19, 2010 5:25 am    Post subject: Never encoutered this problem, myself Reply with quote

Physics suggests that cooling too quickly will cause problems with metal and glass, distorting or permanently damaging. I am sure that you will not stress the lens too much, by taking care?

There may be trapped moisture inside and this will, when cooled, fall as rain within the lens, leaving beads of "condensation" which will each act as a microlens, distorting the image and if fine enough, it will appear as "cloudy".

I suggest drying out the lens by putting in an air tight container with lots of cat litter, aka silicate, or even salt or sugar, in a breathable but restraining container inside the container, to suck in the moisture from the lens. This might take a day or two? Discard or microwave the dessicant and repeat as required.

Let us know how you get on?


PostPosted: Fri Feb 19, 2010 5:49 am    Post subject: Reply with quote

Thanks pat donnelly!!
Yes indeed i have condensate inside!!
I will try to do something!!
Thanks! Smile


PostPosted: Fri Feb 19, 2010 6:18 am    Post subject: Reply with quote

shauttra wrote:
So you think i need to try to cool lens for a longer time?
Maybe when i focusing, and touching the lens one side is warmer than other, and there is some temperature difference?


I doubt that. Maybe it's just not made for low temperatures. You know, glass and metal contracting at different rates thus deforming the primary mirror out of shape. These mirrors are very easy to get deformed, and the 1000mm focal length exaggerates any imperfections in their shape.


PostPosted: Sun Feb 28, 2010 9:33 am    Post subject: Reply with quote

Hi all, I'm new here.

My MTO-11CA needs to cool down for some 3hrs in temperatures below 0°C.

To prevent it from cooling down too suddenly, especially when there is wind, I cover it loosely with a plastic garbage bag.

My lens had what appeared to be condensation on the large mirror. After closer examination it turned out to be a film of tiny oil or grease droplets.

After I cleaned the mirror (very gently using isopropyl alcohol reagent grade) it performed a lot better.

Yvan.