Cleaning a diagonal

[Rob]

Hints & tips please... got a new one, but boy its dusty!. Badly boxed I have blown 30% off but the rest seems a little stubborn

Rob

[Brass n glass]

Prism or mirror?

[Rob]

Sorry 2" mirror diagonal

[Brass n glass]

Oh dear, what make?

[Rob]

Antares

[Brass n glass]

I would ask them. I don't know whether they take kindly to direct consumer inquiries, but their website gives fax numbers: 1-800-648-4188 or 604-270-2330

The coatings on diagonals can sometimes be damaged by careful cleaning action that would do no harm on, say, a Newtonian primary. The reflective area is so small that even a tiny mark or scratch can degrade the image. Sky Instruments say their mirror diagonal surfaces have "overcoating protection" so something like a lenspen might be all right. But I would certainly check with them or maybe one of their dealers in Canada - Hugh

[barkis]

I would use a bath of 50% Isopropyl Alcohol 50% distilled water. You could use a clean glass to hold the liquid and the diagonal. Leave it immersed for half an hour, and then remove and rinse with more distilled water. Resist all impulses to dab it with anything. Try to support it along it's minor axis edge, and if necessary, pick off any persistent droplets from the surface with a corner of a Soft Tissue. If it is surface dirt, then it will be removed by this method, if the coating has been penetrated by whatever is on it's surface, then a recoat will be required I am afraid.

Ron.

[Rob]

Thanks guys. I was thinking of running some distilled water over the mirror to wash away the box dust (thats all it is really).... its not a major damage issue, just irritating

[Rob]

Sorted it. I've unscrewed the for 4 screws, dropped the base and using a photographic bobble blower removed the dust thats improved it by 70%... so I'm happy with that