Baader filter for achromatic

[SAW]

Hi,

I've just picked up a used Vixen A62SS that I am going to use on my Vixen AP SM mount. Now I've read it's not the best scope in image quality with quite a bit of CA but I'm not expecting miracles from it. It's just going to be used for a little lunar observing but as I don't own any eyepieces yet I can't see how bad the image or CA is ! I am thinking of picking up the StellaLyra 9mm LER but I was also going to order a baader filter, would I be best going for the Semi APO filter for this set up ?

Thanks.

[alan potts]

Moved this for you in an effort to get you some feed-back,

Alan

[CraigT82]

The A62ss a 62mm f/8.4 achro which on the face of it might not show much CA, but it is actually a 4 element design with a shorter FL doublet up front and another doublet at the rear acting like a barlow lens, so this means that the CA is likely to be quite bad due to the short FL doublet up front producing the CA and the barlowing pair at the back simply magnifying it. 

Might be worth going with one of the stronger filters if you find CA objectionable?

Here is a pdf with some test shots through the Baader filters, might be useful if you haven't already seen it.

 

 

testreview_baader_anti_fringing_filters_astronomy_technology_today.pdf

[Clarkey]

The report CraigT82 has included is a very thorough examination of each filter. FWIW I recently went for the contrast booster for my achro. It certainly removes the blue fringing but at the expense of slightly reduced brightness and everything has a yellow colour to it. I am only using it for visual and to be honest, unless looking at very bright objects I go without. If you are thinking of imaging it is probably the best option as the yellow tint can be removed in processing.

[CraigT82]

I also went for the contrast booster for my 102mm  f/11 achro when I had it, that frac didn't give much CA anyway but I wanted to eliminate it completely (being a reflector man I cant stand CA!). The contrast booster does indeed dim the image quite a bit as you can see from the test shots in that pdf, but if you're just going to use it on the moon that's probably the one I'd go for personally.

Just for info here are a couple of phone shots I made with the 102mm f/11 I had, first is unfiltered and second is with the contrast booster. 

 

[Jiggy 67]

9 hours ago, CraigT82 said:

I also went for the contrast booster for my 102mm  f/11 achro when I had it, that frac didn't give much CA anyway but I wanted to eliminate it completely (being a reflector man I cant stand CA!). The contrast booster does indeed dim the image quite a bit as you can see from the test shots in that pdf, but if you're just going to use it on the moon that's probably the one I'd go for personally.

Just for info here are a couple of phone shots I made with the 102mm f/11 I had, first is unfiltered and second is with the contrast booster. 

 

That is a good example of the filter in action. It shows the filter doing exactly what it’s designed to do, boost contrast. It certainly increases my confidence in the filter which I have used a number of times on planets where it excels I think