Which focuser do I buy

[Mike73]

The thing with the Baader is it appears from pictures as though it sits on to feet rather than a plate wrapped against the tube. With the weight of a powermate and a 2" EP I am worried this may be more prone to flexing on the OTA.

Steve

I tried the older Baader steel track on my 12" SW Flex and returned because it also had the feet the same as the new Baader Diamond. It does mean that with the focuser fitted you can still see the hole going through the OTA.

It really doesn't make any sense to me? You try and maximise contrast with quality EP's, flocking and dew shields but then you have a great big hole where light may get in just where you don't need it!

I went for the Moonlite in the end and was very happy with it.

[ChrisLX200]

I'm with Olly - I hate Crayfords! All of them. They have no place on an imaging rig IMHO. The initial design was for a cheap yet accurate method of creating a focuser for visual application (where not much weight is involved compared to camera + filterwheel) without the requirement to machine a helical rack and pinion gear which DIY scope builders would find very difficult. Yet manufacturers have taken on the design and 'beefed up' their Crayfords over the years in an attempt to overcome the inherant basic deficiency of poor traction. Why? Big companies can afford the tooling to make excellent helical racks and gears which are necessary to avoid 'cogging'. Anyway, Crayfords  are now just as expensive to buy as a decent R&P yet still don't perform as well under heavy load. The latest Baader design is a micro-rack and pinion they hope will avoid these issues but mere fact that the 'teeth' are so tiny would make me wonder how long that traction would last - and if it should ever slip under load those teeth will quickly disappear! The Revelation modified R&P are excellent traditional focusers, not expensive, and they don't slip! Sadly, I'm not sure they are still in production as Telescope House have very little stock of the many different models. I have an SCT version which I'm currently machining an adapter for so it will also fit my Altair 8" RC, I would buy another but they just aren't available.

ChrisH

[bomberbaz]

I tried the older Baader steel track on my 12" SW Flex and returned because it also had the feet the same as the new Baader Diamond. It does mean that with the focuser fitted you can still see the hole going through the OTA.

It really doesn't make any sense to me? You try and maximise contrast with quality EP's, flocking and dew shields but then you have a great big hole where light may get in just where you don't need it!

I went for the Moonlite in the end and was very happy with it.

Based upon this which was one of my concerns I think a moonlite is likely the choice, just waiting a call from flo first begore i press the pay button

[CraigT82]

Have you had a look at the Revelation super focus R&P units?  I've fitted one to my mounted 200p and I'm dead pleased with it.  It's lovely and smooth and has a real quality feel.   Bargain at £118.

It's very low profile with only 22mm of focus travel but it has a built in 50mm extension tube.  Result of that is that I have enough in focus for DSLR use and enough out focus for my EPs without needing a separate extension tube.  the built in tube is really solid and doesn't flex at all at full extent, though admittedly i don't have any EPs as heavy as that Nikon!

Downsides are that it isn't collimatable (as far as i can tell, there were no instructions in the box), and also it's footprint isn't that big  so it barely covered the hole in the tube from the previous focuser, though admittedly it was a big hole (95mm diameter).  Also the 2" - 1.25" adaptor it ships with is a bit weird but works ok.

I've got no experience of moonlights or steel tracks so can't compare it to those.

Craig

[bomberbaz]

Moonlite has arrived but no allen keys for grub screws! Is this normal any other moonliter's 

Steve

[CodnorPaul]

Yes got one myself yesterday. It's lovely though and collimation was spot on

[ollypenrice]

If it's American it will doubtless have obsolete imperial allen screws. If you live in the UK you'll be fine but, oh boy, try asking for these in France. Even at my local builders' merchant (where they know I'm an astronomer) they slap their sides and sing, 'Mars lander, Newton metres, pounds feet,' and, well, they do have a point!

Olly

[bomberbaz]

off to the hardware store it is then

[John]

The ones that hold the focuser to the spacers are 5/32 inch Steve. Mine didn't come with the hex keys either.

I found that I needed both the .5" and the 1.0" spacers to cover the range of travel my eyepieces need but your needs may will be different.

[Peter Drew]

I solve all my focuser slippage issues with a couple of anti gravity rubber bands. Cheapest effective upgrade available. 

[bomberbaz]

The ones that hold the focuser to the spacers are 5/32 inch Steve. Mine didn't come with the hex keys either.

I found that I needed both the .5" and the 1.0" spacers to cover the range of travel my eyepieces need but your needs may will be different.

Thanks John. Although having placed it to the side of the existing SW crayford and also there is a need for a little more inward travel (The Nikon focuses just short when fitted with a filter and the 14EIC), I appears as though the 1" will suffice although it was only a rudimentary comparison. 

I will do some rough land horizon tests with all my EP's before I do the actual fitting.

My intention is then to take the scope apart once that is sorted, clean the primary then do a full collimation from scratch. I had been getting a slight slur top left if you get what I mean, so makes sense to do it all at the same time.

Steve