Over the last few weeks I have been making another refractor. I purchased the lens from Istar, it is a 5 inch f12 R30 doublet achromat lens in cell. http://www.istar-optical.com/istar_019.htm
If anyone is interested in building a scope like this with thin ply then I encourage you to go ahead and give it a try. It is a step by step methodical process and lot's of fun. Please ask questions and I will do my best to help.
I haven't completed the mount yet but have cobbled together a means of using the scope. I only managed a brief first light last night and will follow up with more as I get to use it more. I am happy with the lens for now.
Malcolm I will try and bring the scope out to Jarrahdale some time in the next couple of months, maybe July or August DSO night. You can check it out yourself. I would like to hear your thoughts.
A couple of years ago I built an 12 inch F/5 plywood tube using two sheets of ply.
It saved me 5 kg in weight over the steel tube. Would do that again if needed
Ken
Molly, the cost is aout $550 AUD for the lens including postage, the GSO focuser is about $150, the finderscope and diagonal (GSO) about another $150, a sheet of top quality 4mm marine ply is around $120, various bits like screw, glue and paint maybe another $50-60.
You can make it cheaper but when you are investing a lot of time into a project like this it will be more satisfying in the end if you use quality materials.
Regards
Andy
Last edited by anj026; 13-06-2011 at 08:25 PM.
Reason: spelling
Performance is very good. High contrast sharp images with very low amounts of false colour. The above link to the Cloudy Nights build thread has an observing report at the end that describes a comparison with a 6" f15 achromat stopped down to 5" f18.3. The observing conditions at the time were not ideal. I am away from home now for a few weeks but will try more observing tests and comparisons when time permits.
I have been away from home (and my scopes) anyway Malcolm, but will be back again next week. Looking forward to finishing off the mounting and doing some more observing, weather permitting.