Baader Planetarium Semi-APO Telescope Filter

Comments about Baader Planetarium Semi-APO Telescope Filter:

Dramatic reduction in chromatic aberration in my achro refractor. Yielded crisp well defined images, and increased contrast of the Moon and Jupiter with little or no discernible color tint. Only a very thin color (purple) halo on Lunar limbs.

Service and delivery comments:

The service was excellent; the delivery was prompt - just a couple of days as promised.

Comments about Baader Planetarium Semi-APO Telescope Filter:

I was thoroughly impressed with this filter. I've come to expect a degree of "padding" of the capabilities of items by the marketing crews over the course of my 40 years, and while I expected this filter would be a good performer, I did expect some of that padding. I have to say for once I was surprised to find a product that lives up to it's marketing claims though. This filter actually does an excellent job of killing fringe.

I have a Celestron C6-RGT achromatic refractor and did see distinct (but moderate) violet fringe on bright objects, such as Jupiter, the moon or even bright stars such as Sirius. I attached the 2" Baader semi apo filter to my diagonal, and it cut the fringe almost completely. In fact it cut it to the point I cant see it at all unless I spend time specifically focusing on the edge of bright objects specifically looking for fringe, and then it is barely perceptible. It cuts it so well you forget you are using an achromat and "fringe" leaves your vocabulary!

In addition to the filter working incredibly for killing violet fringe, it has zero color corruption. Jupiter with the filter on was clearly orange, brown and white, not tinged pink by the filter as I expected, and the moon displayed sharp white, gray and black contrast with no tinting at all. Image clarity is crystal clear as well and objects actually looked sharper with the filter on than without it. I now leave the filter attached to my diagonal all of the time and use it for all viewing. It works that well.

This is one of the pricier fringe killer filters out there, and I wouldn't complain if they dropped the price. With as well as this filter works though, it's worth the money!

Comments about Baader Planetarium Semi-APO Telescope Filter:

This is great filter and does just what it says it gonna do. I'll add on a moon and sky glow or a minus violet and its even better. Considering what an APO costs, having a few inexpensive filters that can make the viewing almost as good is well worth it. I wound highly recommend this filter to anyone with an Achromat or even a reflector.

Comments about Baader Planetarium Semi-APO Telescope Filter:

This is a great addition for anybody with a Refractor. What a difference it makes when using high power on bright subjects. I've mixed it with a moon filter and good results on a very bright venus and an almost full moon. I would highly recommend getting this filter and using it every chance you get.

Comments about Baader Planetarium Semi-APO Telescope Filter:

This filter reaaly pulls its weight!

I use it on my 6" Celestron achromatic refractor. With an objective that size, chromatic aberration can be an issue. Now, the CR150HD (and its heir, the C6) have very little CA already, despite that beefy objective.

But the Baader semi-APO filter removes all traces of CA (at least to my eye). And it introduces only the faintest trace of color. Really, if you didn't know there was a filter in place, you just wouldn't notice. Except, of course, you might notice that there's *no chromatic fringing*!

I keep this filter screwed into my diagonal full-time, except for those really faint DSOs where I need every photon. (And with a 6" refractor, galaxy hunting is on the menu!)

If you have an achromatic refractor, you won't be sorry about getting a Baader semi-APO filter for it.