Information on Hershell Wedge

[pluton]

Hello,
I just purchased an ED80 refractor, model Skywatcher with zipper focus, old, second hand at a good price, and I would like to use it for solar observation in white light, (personal level and for groups of children (safety first ..) and I was wondering what Hershell Wedge would be best for this, a 1.25 "or 2", Lunt or Baader ..?
I've heard that some of them require a large backfocus, 115mm or so?
Which filters work best? Solar continuum, Polarizer ..?
Thanks Paul

[John]

I think the Lunt 1.25" wedge would work fine with the ED80. I use one with my F/6.5 102mm ED Vixen. It needs a little more outwards focus than the 2" diagonal that I use for nighttime viewing does but not as much as 115mm - more like 40-50mm ?

With the Lunt, you have a built in 3.0 neutral density filter at the bottom of the eyepiece tube and I also use a single polarising filter on the eyepiece which gives final control over image brightness. Solar Continum filters have a good reputation for showing a little more detail but they do put a green tint on the image which might confuse inexperienced viewers perhaps ?

I've used my Lunt wedge for outreach sessions and it's gone down rather well with the punters

[johninderby]

You should also be looking at the Lacerta wedges. Great value for money and performance that rivals the Baader.

http://www.365astronomy.com/Herschel-Prisms-and-Solar-Filters/

         John

[Ibbo!]

I cannot get my ED80 to focus with the Lacerta 2" version.

I have used a polarising filter and a visual O3 so far with mine to good effect.

[Piero]

Well, John summarised pretty much all!  

I have both the 1.25" Lunt and the 2" Baader. Unless you want to 1) observe with 2" eyepieces, 2) use the wedge with other scopes >100mm (2" model for the best heat dissipation), 3) avoid swapping filters between eyepieces, the 1.25" Lunt will serve you well with your 80ED. 

I prefer the 2" Baader optically too, but you need to be a bit fussy to spot differences between the two wedges. 

[kirkster501]

The Baader wedge works great with my SW ED80.

EDIT: I'd always try to go 2" if you can.  It gives you more options moving forward.

[spaceboy]

In reply to your PM Paul...... I'm far from an expert so I wouldn't want to give bad advice and figured it best to post here so others can add comment if I overlooked something.

"I would like to know which models can work best, that is, if with an acromatic refractor, or with an ED or APO, and also with what aperture I could observe well the sunspots with their different shades and shadows, pores, plages, and solar granulation ..
In this case, is the focal length of the telescope important?
An achromatic refractor with short focal length can give sharp and sharp images, or will it give "colored" images?"

I have found that an ED refractor offers the best results in WL but as you are observing in a specific wavelength and often using either a continuum filter (makes the image green until your eyes adapt) or polarizing filter (to dim the image so it is more visually bearable), an achromatic refractor can do just as good a job as false colour is not a significant issue. Where the ED / APO shows improvement is the overall sharpness good quality optics bring not so much the CA control. As for focal length a longer FL refractor is always going to be better corrected towards the edge but a short tube refractor is more manageable and easier to drag in and out between cloud. As for what you will see, pretty much everything you would want to. As with anything astronomy the bigger you go the more you will see. But as with anything astronomy in the UK what you see is also governed by the pee poor seeing we so often suffer.

As you say you no longer have the ED80 your next option is either an ED120 (hugely expensive beyond this aperture) or various achromatic refractors up to 120mm with the 1.25" wedge or 150mm with the 2".

HTH
 

 

[Highburymark]

I bought the 1.25" Lacerta wedge a few weeks ago - haven't had an opportunity to use it yet - afraid lack of activity in the photosphere means meagre pickings for white light observers over the next year or two - though there were some nice sunspots a couple of months ago