Suitable focal reducer for saxon 8" mak./cass.

[lookus]

i have a saxon 8" mak/cass (f/l = 2500mm) does anybody know which focal reducer might work with my scope. I would really like to try to reduce the focal length but i understand that not all are suitable for every scope.

any help here would be greatly appreciated.

[rider]

Hi Lookus
I've got the same scope and found that the focal reducer option is not as good a view as a Williams Optic 40mm Eye piece FOV 70 degrees. If you hunt around the e-shops, you'll get one for about the same price as a good quality reducer. It brings the magnification down to X62.5 which is about as low as you would want to try on a scope with such a high F value.
This EP seems to suit the scope so well that I use it over 50% of the viewing time.

Rider

[lookus]

thanks for your reply rider.

i am after a focal reducer for astrophotography mainly. have you tried a focal reducer that did give you a wider field of view? what was it?

i have a 2" meade 4000 qx 36mm fov 68mm for viewing. i just need something to help with imaging. how do you find your scope. what mount do you have? do you do any imaging?

[rider]

Hi Lookus

Mrs Rider and I are purely visual observers, no photographic work at all. I'm not knocking it for others, but I cant get the idea of missing out on the best viewing conditions to produce photos that Hubble does better. For us, its about "being there".

We have 3 scopes: the 8inch Saxon Mak (mine) SW 8inch Newtonian (hers) and a SW 10inch Newt (ours).

The Saxon is my travel scope, (it's built about twice as strongly as any other Mak that I've come across and doesn't mind a long ride in a car.) Great optics, it's easy to collimate and has better contrast than most of the name brand Maks. At the price, it's the best kept secret in the industry.

When I first got it I had one complaint: The thread on the back of my model is not standard and wouldnt take standard aftermarket fittings like an upgraded diagonal until I bought acelestron back-plate skylight filter and re-cut the scope side thread to match the scope. Now I use a WO Diagonal and that has improved the scope enormously.

It rides on either a EQ5 with Argo Navis for trawling , or a HEQ5 go-to mount if I'm after a lazy night.

I've tried a Vixen Focal Reducer, but settled for a GSO cheapie, cos I couldnt detect a difference in performance. - both had slight vignetting. I dont tend to use it, I get better wide field views out of the two Newtonians. The Saxon is a High Magnification specialist for DSO's and planets.

Sorry I cant help you with the photography side of things.

Rider

[gbeal]

While the first thought is to try a Meade or Celestron, you will find they are made for SCT's, and you will introduce coma with them.
You need something that is designed either for a refractor, or a Mak.
In my case I use an AP67CCD, but Optec make a refractor model as well.
Gary

[Wavytone]

Hi lookus,

I have a 7" f/15 Mak too... even longer f.l. than yours ...

Basically your Mak is a long focus scope which is optimal for high-power views of the Moon and planets, it can give some gorgeous medium power views but it can't do low power wide fields.

Even if there was a suitable focal reducer you'd run into another problem - the field of view is limited by the size of the hole through the primary and coming out through the back of the scope and the focusser.

My scope can fill the FOV of a 2" barrel and I'd guess yours can too. The best views your scope can give would best be achieved with a low-power eyepiece around the 40-60mm focal length that have a field stop somewhere round the 45-47mm diameter - just look inside the eyepiece from the telescope end - you should see an awful lot of glass, seemingly straight through, with little or no field stop. Examples include the the various Plossl's around the 50-55mm mark, or if you want to go a little more upmarket, the Vixen LV 50mm (50 degree AFoV), the Vixen LVW42mm (65 degree AFoV), and the TMB 40mm Paragon (69 degree AFoV). I've just bagged a Paragon and it should have a 47mm field stop giving a true field of view of 1 degree in my scope.

Lastly, inserting a focal reducer followed by a medium focal length eyepiece will be distinctly inferior to using a good eyepiece with a really wide truefield of view (the field stop). It doesn't have to be an expensive widefield one, a 60mm Unitron Kellner from the 1980's will give an amazing view in your scope.