Focuser upgrade, aperture envy and associated questions

[Probablynot]

I've decided to sell on my 3-month-old SW Exp 150p OTA, and buy a new 200p DS OTA. If FLO has got one in stock, that is.

This is mainly so that I get an OTA with a 2-speed focuser ready-fitted, instead of buying a 2-speed focuser and fitting it myself on to the 150 tube. The net cost will be roughly the same, and I get the added bonus of a 2-inch aperture upgrade.

However...

When I sell on the old (Old? Three months? Huh!) OTA, I suppose I ought to sell it with all the bits that came with it. So I'll lose my 10mm and 25mm ep, but gain a 28mm one. Fair enough - I've been buying some Plossl EPs anyway.

Most people seem to regard the 25mm ep as OK, and the 10mm one as pants. I haven't yet seen any comments on the 28mm ep that comes with the 200p. Would anyone care to comment?

I'll miss the barlow though. If I now buy a decent one, will it come with a thread to accept my DLSR camera t-ring, like the one that came with the 150p did?

Steve (at FLO) reckons my CG-5 GoTo ought to be able to cope with the extra weight of the 200p. I confess I'm a little worried about this, though, and I would welcome any advice that other CG-5 owners can provide.

[LukeSuppalot]

Hi Brian.

Is the only real problem you have with the 150p the focusing? If so, have you thought about an auto focuser? FLO have a SW one at £45. Got to be cheaper than upgrading your scope.

As for the CG5-GT, it should easily cope with a 200p. FLO supply the 200p on an EQ5 which has a maximum payload of 9kg. The CG5-GT has a maximum payload of 12.5kg.

If you're looking to buy a new Barlow then I can recommend a Tal 2x. It's threaded for filters and is a fair improvement on the SW barlow.

Afraid I can't comment on the 28mm Ep as I don't have one but I'm sure someone will be along who can.

Hope this helps.

Luke

[Caldwell 14]

I could be wrong about this but don't you have to buy a coma corrector to use 150/200PDS scopes visually?

[LukeSuppalot]

I could be wrong about this but don't you have to buy a coma corrector to use 150/200PDS scopes visually?

I don't think so. I believe the only difference between the 150p and the 150pds is that the focuser has been moved down the scope a little towards the primary mirror to allow a little more back travel on the focuser when using a DSLR. The primary and secondary mirrors are the same on both scopes. A coma corrector would certainly sharpen up the edges of a widefield view tho.

Luke

[Caldwell 14]

Check this out: visual use can be achieved when used in combination with Sky-Watcher's Newtonian coma corrector (Prod.Code 20233) £99

SkyWatcher Explorer 150PDS Newtonian Reflector OTA

[Tribal-Wolf]

There are also these to upgrade your focuser if it's a single speed crayford.

[LukeSuppalot]

Check this out: visual use can be achieved when used in combination with Sky-Watcher's Newtonian coma corrector (Prod.Code 20233)

I think they mean better performance for visual as well as astrophotography can be achieved with a coma corrector.

All Newtonians with parabolic mirrors suffer from coma, a tendancy to blur stars towards the edge of the field of view making them sort of comet shaped with the tails pointing away from the centre of the field of view.The faster the scope is the more pronounced the effect is. A coma corrector reduces this effect giving sharper images to the edge of the eyepiece or photographic field.

A coma corrector is a nice addition to a Newt but not a neccessity.

Luke