Baader wedge - suitable scope.

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andyg
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Baader wedge - suitable scope.

Post by andyg »

I've laid my hands on a 2" wedge for visual use (initially) but need a scope to drive it.
I'm looking for something relatively portable and have an SM40 along with a twin mount to ideally give white and Ha views. Budget is an issue and I'm not afraid to wait for something second hand.
I need a 2" focuser but how good does the scope need to get? I was looking at perhaps an ED80, possibly ED100 but is it worth going to 100mm for visual use? Should I get a longer focal length scope or stick with something around f7 or so? Are there any scopes I should actively avoid? Branding is not important to me, good quality and value for money is!

Thanks

AndyG


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Re: Baader wedge - suitable scope.

Post by marktownley »

How much cash do you have to spend?


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Re: Baader wedge - suitable scope.

Post by andyg »

Let's say £500-£600 ish

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Re: Baader wedge - suitable scope.

Post by marktownley »

ED80 or ED100 would both work well.


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Re: Baader wedge - suitable scope.

Post by andyg »

Is it worth going for FPL-53 rather than FPL-51 elements or is the abberation not significantly different?

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Re: Baader wedge - suitable scope.

Post by marktownley »

For monochrome white light views I don't think matters too much. Better to go with a scope with a good focuser.


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Re: Baader wedge - suitable scope.

Post by andyg »

Cheers

AndyG


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Re: Baader wedge - suitable scope.

Post by MjrTom »

I used the Baader wedge with a Skywatcher Equinox 80ED and 100ED and they both work very well.

There was very little in the way of lateral chromatic aberration (LCA)
The 100mm aperture did show quite a bit more resolution than the 80mm however the scope was over double the weight therefore far less portable when you factor in a suitable mount.

I also occasionally use the wedge with the Vixen 102mm achromat.
There is a small amount of LCA but not objectionable.

I would echo Marks comments, the wedge is fairly weighty so a good focuser helps enormously.

If you want something fairly portable an 80-90mm f/7 is what I would suggest.


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Re: Baader wedge - suitable scope.

Post by Valery »

andyg wrote: Budget is an issue and I'm not afraid to wait for something second hand.
AndyG
If the budget is an issue and you can wait for a second hand telescope, then I would suggest you to find a second hand chinese 120mm F/5 achromat (Sky Watcher, Synta, Conus, Bresser etc).
Such a telescope is not that heavy and very portable. 120mm aperture will show you granulation and penumbra details much easier than 100mm not say about 80mm.
The only two requirements when you test the scope - it must be free of coma (lenses decentering) and show no significant spherical aberration in a green-yeallow light.

The test of such a scope is very easy:

1. Install a barlow 2x lens in a scope
2. Take 6mm or 8mm eyepiece
3. Install a green or green-yellow or deeeep yellow color filter in front of eyepiece.
4. In a sunny day point the telescope at a reflection of the sun on distant (100m or farther) electricity insulator
5. Focus your telescope and see if the reflection looks like a star - Airy disk surrounded by one faint diffraction ring. The picture must be fully symmetrical, no any coma.
6. You can repeat the same test (5) at night using a moderately bright star (2-3 magnitude)
7. Test for spherical aberration. Defocus the star in and out fo focus to see 3-4 rings and see how they are identical. If the pictures in and out of focus are identical, then the telescope is
free of spherical aberration. There must be some difference (very seldom telescopes have no SA), but it must be slight. See if the outer rings are of the same or very similar brightness.
Bif difference of the brightness and definition between outer rings in and out of focus is the be is.

A 120mm telescope with very small SA is very powerful tool for solar observing. And a selection of such a telescope is well worth of efforts.
A second choice for portable solar telescope is Meade or ES 127mm F/6.7.

Of course if a 100mm aperture is your limit, then a lot of achromats and apochromats are for your choice. Again - betetr to test a scope before you put your money. Well worth to do.
I spent a fair amount of time searching for 150mm F/5 telescope with no coma and no SA. Finally I found one and now this telescope works extremely well.


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Re: Baader wedge - suitable scope.

Post by grimble_cornet »

I have a 2" Baader Wedge and have used it with a range of refractors:
Equinox 80 2014 0724 1245 ut.jpg
Equinox 80
Lunt 60 2014 0724 1301 ut.jpg
Lunt 60mm - came as part of CaK outfit
DSSR_20140724103019 P1 X1 103019 sx.jpg
Tal 100RS - just purchased for use with CaK120 unit

These are just quick captures with basic processing but give an idea of what each scope gives.

For a better idea:
Equinox 120 plus Baader Wedge - 10th August 2012 - 2000px.jpg
This is an extensive test of the Baader wedge on an Equinox 120
Equinox 80 - Baader Wedge - August 28th 2012.jpg
And a similar one with the Equinox 80

Conclusions?
Equinox 120 wins with best resolution and decent focuser (important for high mag imaging)
Equinox 80 is closer than I would have expected..... and much easier to use for a quick imaging session or in the field.
Lunt 60mm left me speechless. It is a 'basic' 60mm scope costing about 290 GB pounds (?) which works very well with the CaK unit (I bought them as a 'complete CaK scope') BUT..... it is incredibly well build with a good 2 speed focuser and works surprisingly well with the Baader wedge. Most of the time I use it for CaK and whitelight to avoid having to drag several scopes outside.
The Tal 100RS is my latest 'toy' which I got for high res CaK imaging. I tried it with the wedge just for fun....but it works. Optically it is very good and excellent value BUT it only has a basic - although quite good - single speed focusser.
If I could only use one scope for solar imaging it would be the Lunt 60. It will produce a full disc in two panels with my DMK41 or ZWOASI120mm cameras plus quite good detail when combined with a x2 Barlow. It also produces excellent results at the same scale with the Lunt CaK unit.
If only doing whitelight imaging then I would go for the Equinox 80 as the detail is slightly better while giving the same kind of scale.

Hope some of this helps :?
Hope this helps


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