Rusted

Hi Peter I've searched around the subject of your H-alpha conversions but still don't have enough info to DIY my 7" f/12 R35 iStar. Or even know if it is a suitable donor for conversion. So I've PM'd you in case you'd prefer to keep your exact methods a secret.

Thanks for the honest and realistic review. Everything in life is a compromise. The dealer and wholesaler are expected to make a profit and then there's the freight and VAT. It doesn't leave much for the manufacturer to spend on making the instrument itself after they've paid their wages, taxes and heating bills. Use this thread as an important lesson in OTA length V class of mounting. Bresser are not alone in hiding the great length of their refractors by using a ridiculously long drawtube. Vixen did it on their refractors at both ends even on their 90mm F/11. They hide a ridiculously extended lens cell inside a ridiculously stumpy dewshield. [Add dew, to taste!] And then use a ridiculous length of drawtube to reach focus even with a star diagonal. All, so they can use a much shorter main tube like it's a pretend Apo to the desperately wishful thinking. Bottom line, for me, is to decide whether the objective lens quality of this 'scope really warrants scrapping everything except the nice lens in its cell. It really wants a longer alloy tube, proper rings and dovetail and a decent focuser. Now add in the cost of a much better commercial mounting, tripod or pier. Bresser only offers the illusion of a quality OTA to those expecting quality well above the asking price. Reality is [arguably] several hundred dead squid above the very low retail price. Instead of buying a more expensive refractor I'd suggest using the plastic clam-shell to add a couple of plywood, altitude bearing disks. Then mount the Bresser on a Berry-style, counterbalanced, offset, plywood fork on a simple but solid wooden post pier tall enough to be really useful with a refractor. Years of fun at ridiculously low cost for what sounds like a fairly decent 90mm refractor lens. Add an ATM solar-foil filter for solar fun without the flames. Transits anybody? Add 'proper' rings and a couple of altitude bearing supports for serious support. The cast rings cost absolute peanuts whether new or secondhand! CNC really means massed produced by unskilled, bored and unhappy workers. My generation would have given several kidneys apiece to own a half-decent 90mm achromat. The initial purchase is just the starting point of a lifetime of ATM improvement and free, manual skills training. Then there's the years of enjoyable observation brought to you by Bresser at remarkably low cost. Just think of the savings, spread over a lifetime, compared with chasing the endless, commercial rainbow of over-optimistic expectation and exploitation of those acquisitive desires!

An offset fork, Berry style, plywood, Dobby, altazimuth mounting can be made by anyone who can wield an axe or blowlamp, or both. Teeth or saws optional. When I were a lad... 1980s? 5" f/15. [12" f/5] The second image shows the "raw" refractor on scaffolding tripod.

Hi Many thanks for all the positive comments and the "likes." Most of my collection of astro "bits" was bought secondhand except for the 7" iStar objective. My heavy duty GEM was built almost entirely from scrap metal to cope with the long and heavy load.

Just a selection of my refractors. The piers are self welded and far too massive to lift. For decades I longed for Fullerscopes mounts. I started with a used, driven MkIII and then bought a driven MkIV as well. Vixen 90M f/11 on a MkIII. Celestron CR150HD on MkIV. iStar 180 R35 f/12 with stumpy dewshield very under-mounted on the MkIV. And finally, the same 7" lens "folded" with two 1/20th wave, optical flats in a DIY Porsa framework on my home made GEM with 2" shafts on a temporary test stand.