Anti CA filters

[jabberwocky]

Simple question, do they work?

And is it worth the 45 to 60 quid getting one for my ST102?

[John]

I used a William Optics VR-1 with the Skywatcher 6" F/8 I had recently. It reduced the visible CA by around 50% I would say. It did impart a slight yellowish tint to the view in return for this though.

An F/5 shows quite a lot of CA compared to an F/8 - a filter is going to reduce it a bit but there will still be plenty showing.

I've only tried one device that virtually eliminated CA in F/8 achromats and that was the Chromacor corrector. Hard to find and pricey but it really works with the right scope

The Chromacor is an optical corrector though, not a filter.

[alan potts]

Why are chomacors not made any longer ?

Alan.

[John]

Why are chomacors not made any longer ?

Alan.

They are working on a Mk III version but the gestation period is long. Also the emergence of the chinese ED doublets dented the market for the Chromacor's given that a Chromacor costs around $500.

[username]

I see you have a LP filter in your signature? If it's a neodynium type then I've read that you can stack it with a fringe killer rather than a 'semi-apo' to turn it into a 'semi-apo' as the semi-apo is just a fringe killer with neodynium coatings. Might save you some pennies......

I couldn't tell you if they work as I haven't used one

[username]

Also if it's just for planets have you tried stopping the frac down a little bit and just trying a cheaper light yellow filter? Cheaper if it's just for temporary looks and the yellow might help a bit on jupiter.

[ronin]

They reduce CA they do not eliminate it.

For the 102 you will still have some remaining after puting the filter in the path and the amount of light will be reduced overall.

[username]

just found this in the equipment reviews section - might be of use

http://stargazerslounge.com/topic/30187-baader-ca-filter-comparison/

[jabberwocky]

Thanks for the link,the semi apo looks like what im after, couldn't cope with the yellow of the others.