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It is not just a matter of dropping these long and heavy tubes gently into the open rings. It means stepladders and hoists and struggling to reach the upper tube ring, clamping thumbscrews. You can't just leave the telescopes resting in the open rings if the balance is not already perfect. The mounting will want to rotate and the tube to slide downwards. Dropping them would be an expensive disaster!
I'm not complaining. Merely warning those with potentially foolish ambitions. Adding an inch to a classical refractor's aperture is 10lbs minimum extra weight and at least a foot greater length. Most affordable mountings can't cope with refractors of this size because the length. Length means moment. Mass x distance from the pivot. Sadly, your big and heavy lens is on the very end of a long tube.
A 5" is about the limit for most affordable mountings and even then the OTA oscillates every time you touch it. Like focusing for example. Even an "electric" focuser won't help if you touch the telescope with your face or nose while trying to squint though it in the pitch dark. Remember that tall and solid pier just to use the thing visually. Or suffer long seconds of shaking images.
Forget all about imaging unless you have really serious funds available. Like £10k-£15 for the bigger AP mountings alone. Or the skill and stamina to build something seriously big and heavy yourself.
Older mountings, intended for much larger reflectors [like 15-16"] with a minimum of 2" shafts can be updated and restored to take a 7" classical refractor. Think 3" shafts for an 8" or larger. Have you ever tried lifting long, steel bars of that diameter unaided? How big a wormwheel do you need to control literally hundreds of pounds?
The sheer weight and
height of these mountings, for comfortable viewing, soon becomes a major
hurdle to set up for regular enjoyment. Don't bother unless you have something
permanently set up under a decent, weatherproof cover. Lifting and fitting an 8" refractor OTA is strictly weight lifter [on steroids] territory. 60lbs minimum and 10' long.Are you feeling lucky? Go and lift a good length of 10" PVC sewer pipe in a builder's merchants if you can find one who stocks pipes of that huge size. Scottish caber tossers might be handy mates to have around if they are sober and live near enough.
The Berry, offset and counterbalanced fork, with Dobsonian bearings, will give you a cheap visual [altazimuth] support. Though only if you make it strong enough. Then you can just drop the OTA into the cradle and start viewing. You'd still need a serious cover and a very tall and very solid pier. Nor will it track Mars as you hoped when you imagined yourself another Percival Lowell but without all of his money.
Tripods are an absolute nuisance with refractors. Because the legs get in the way of the very long OTA when looking high up. The legs would need to have really serious timber cross sections and a really serious head and leg design to work at all. I used hefty scaffolding tube for a tripod in my youth and it was hopelessly flexible for my home made 5" f/15 on a Berry mounting. Even though it still wasn't nearly tall enough for looking high overhead. There was a bright comet high up at the time but I really struggled to see it.
The reason there are so few large classical refractors sold these days not just the supposed false colour. It is the handling of the huge instrument unless properly housed. Take a look at a classical instrument from the past. If you are not immediately awed by the massive iron and bronze castings then you really aren't paying attention.
I would smile when people complained on the forums about their stumpy 6" f/8 refactors being a problem. Until I obtained a secondhand one and struggled to mount it on the sturdy, Fullerscopes MkIII. So it needed a MkIV with its massive alloy castings and 1.25" shafts. A Fullerscopes MkIV is a large and hefty mounting by modern Dinky, Chinese standards. The MkIV is still dwarfed by the massive pier I welded together just to support it.
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