Mirrors rescue

[FrenchyArnaud]

Hi all, 

I received a second hand (tbh honest, probably a 37th hand) meade 4504. First surprise, it's a 2" focuser ??? 

Anyway, the plan was to modify it for astrophoto (moving the primary upwards). So I dismantled it to the last screw in order to clean it thoroughly and have the tube naked. Bad news, both mirrors are clearly whitened, it looks like the silver coating has somehow oxidized.  Difficult to explain, and I was unable to take a proper picture of the phenomenon, but it is really evident with the naked eye. It's a bit like there is a deposit of calcium underneath the coating, or as if the metal had just got dull rather than shiny over the years.

Of course I could just discard it, (we are speaking a £17 investment.... I'll survive) or send it back to the seller, but I thought, maybe there is someone here with a genius idea ? 

[ChrisLX200]

Not much to be done other than get the mirrors re-aluminised, but that is going to cost you much more than £17. It's probably an uneconomic repair to be honest.

ChrisH

[Putaendo Patrick]

Recoating the primary mirror will cost about 50 pounds, maybe less depending where. Here is some information from Orion Optics UK: http://www.orionoptics.co.uk/OPTICS/mirrorrecoating.html

It seems one of these with mount secondhand might be worth about 100-150 pounds, so whether the trouble is worth it to you is your decision. However these telescopes were/are well considered for their size.

Older models will almost certainly have focusers for smaller size 0.965 inch eyepieces which are now quite difficult to find - if this is the case, although there are probably adaptors or new focuser units available for 1.25 inch EPs, again this is an addition to the cost.

[Putaendo Patrick]

Sorry - I'm being stupid today. Ignore what I said about 0.965 EPs, sounds like someone has already done an interesting upgrade!

[Dave In Vermont]

If it cost me £17, and I had no sentimental attachment to it, and considering it's diminutive size (4¼" F/8), and the mirror was essentially deceased unless I was wishing to spend a pile of £££'s on - I'd return it if possible. Or play 'Taps' on my bugle and bury it in my yard. But that's just me.

There are good bargains out there on occasion. I just wouldn't call this one of them. For AP, the aperture is all fine & well - if it had a good mount. But F/8 would need a VERY good mount. Depending on what sort of AP you're looking at. It would be fine for Video-AP, especially for live-capture (or close to live). But again we slam into the mirror problem. Perhaps it could be good for Comedic-AP: The Bargain With FANGS!

I'll go away now...

 

Dave

[FrenchyArnaud]

Well, thanks for your answers, I think the case is judged without appeal. 

I have found a SPC900. On both my celestron 114lcm and the 150-750 it can't get exactly in focus even with a barlow2x and I am not ready to modify those. The idea was to modify this tube (moving the focal point outwards) to do mainly planetary video/stacking and maybe try with the dslr for big easy DSOs (M31 and so on) - that, was the plan. As for mounts, it the LCM and the EQ3 (modified for more stability).

I guess I will have to search another cheap OTA "spares or repair"