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I am thinking on grinding my own lightweight mirror (first f4 16", later f4 24"). The lightest and cheapest option is to get a thin blank and slump it in a decent kiln.
Anyone has longer term experiene with slumped mirrors? Overall doesn't seem to be more work than a normal (not pregenerated) blank.
Do I have to grind the backside as in case of normal flat back mirrors to avoid astigmatism? How do people support a convex back while grinding? Does it make sense to grind a hole in the middle for additional support? I am remotely considering a convertible Newtonian/Cassegrain system anyway...
I'm tempted to go down the route of getting myself a brand new reflector... My friend's old Meade 114/900 is a good telescope, but I want something of my own and with a bit more light gathering power. To this end, I've been looking at a couple of different models and manufactures.
I must admit, the Skywatcher Explorer 130M floats my boat, as it's motorised with a speed controller.
Any thoughts or observations?🤔
By Kevin Francis
Purchased the Orion Astroview 6 three years ago. Found out later that I could not attach my Canon EOS XTi and obtain focus. Everything I saw online required sawing and drilling the OTA. That makes the scope a single purpose telescope. After reviewing the primary mirror holder I created a holder that moved the mirror 25 mm. This way I can keep the scope ready for visual observing and sell later if I desire. If you're interested in saving a few dollars in this hobby check out the link below.
How I Moved Prime Focus: Link to the detail.
Photo from this telescope
So I picked up a classic... a 1970's - 80's edmund optics f6 150mm newtonian...
... like this one but mine has a different mount. It was cheap. Very good condition. The focuser is pants. The mechanics of the secondary holder is (IMHO) brilliant and apparently the primary is 1/10th wave.
But its f6 and I trhink I'd rather swap it out for a faster synta f5 mirror. . The thing is its a one shot job bc to make the f5 mirror work I will have to saw off a good few cm from the barrel of the scope.
So the question is: Is a high quality f6 mirror better than a faster synta f5 mirror for wide deep space astrophotograhy?
All comments gratefully received. 😉