help please - second hand scope

[smoothound54]

hi folks

i just bought a second hand SW 200p on an EQ5 - it was a basement price but needs some work - i am reasonably technically competent

two main concerns are....

1 the primary mirror is really dirty - imagine it has been left out in the rain for a few days - have seen other posts saying not to wipe with a cloth - do I just accept it as it is? or is there a way of safely cleaning it - for all I know the secondary is dirty too! (I tipped the tube upside down and a load of white dust fell out)

and.......

2 the kit came with a laser colimator - and a quick check put the red dot about 3 inches adrift of centre on the primary mirror - I checked youtube and the process to colimate seems straight forward - but the centre philips locking screw seems to be stuck - and I guess that this needs to be loosened to allow the allen keys to be adjusted? I tried as much force as I dared - but the mirror posts are very flimsy - wont move even if i hold the assembly to brace it - cant see any grub screw - any ideas please?

thanks in advance

cheers

alan

[neil phillips]

Hi clean the mirrors first. ( go online how to safely clean mirrors ) and check the state of them. but if it has been out in the rain, acid may have tarnished the coatrings. if so a recoat will be needed. As for the secondary centre bolt, first lossen the 3 tilt screws. when that is done the centre bolt will loosen. It sounds very poorly stored, untill the mirrors are cleaned theres no way of knowing the condition, but ill guess from what you say it might need recoating. Thats not a bad thing if needed. the mirrors will be as new when done. Hilux from Orion optics might be the best coatings. But also the most expensive. Standard coatings will be fine on a budget.

[smoothound54]

Hi clean the mirrors first. ( go online how to safely clean mirrors ) and check the state of them. but if it has been out in the rain, acid may have tarnished the coatrings. if so a recoat will be needed. As for the secondary centre bolt, first lossen the 3 tilt screws. when that is done the centre bolt will loosen. It sounds very poorly stored, untill the mirrors are cleaned theres no way of knowing the condition, but ill guess from what you say it might need recoating. Thats not a bad thing if needed. the mirrors will be as new when done. Hilux from Orion optics might be the best coatings. But also the most expensive. Standard coatings will be fine on a budget.

great advice thanks neil - I removed the secondary to check it out - actually it was perfectly clean - and after the screw loosened - reassembled and colimation took 5 mins - got it totally spot on thanks - it was a mile out

I don't think it has been left in the rain long term (if at all) - the mirror itself looks bright and sharp behind the dust - its just totally spattered maybe like dew has adhered the dust - will check how to clean properly and have a go and see what it looks like - as you suggest

cant wait for a clear night!!!!! :grin:

many thanks

alan

[brantuk]

Get "bobs knobs" for the secondary - makes it a darned sight easier to collimate and obviates the likleyhood of dropping an allen key down the tube and onto the primary