bern

Dead right Ant, and if you use a 2x Barlow for imaging the real amplification ratio is more likely to be 2.3x or thereabouts because the CCD is set back further than the focal point of an eyepiece.

bern

Just to (try to) make things clear, reducers can be called .5x, .6x, .6598x or whatever BUT the value will only be true with a specific distance between the chip and reducer which hardly ever applies!

The AE .6x reducer is probably about the same as the Atik .5x reducer, because of the laws of physics, it's really just what they choose to call it for marketing purposes.

The whole art of using reducers, especially with Newtonians, comes down to a balance of the initial F ratio, size of CCD and focuser in-travel available. Experience helps here but experimentation is often called for too.

bern

I've already ordered a 0.6x focal reducer, so i'll se where i get with that, hopefully it will work.

Out of curiosity, which reducer did you order in the end?

bern

As KK says it can be done and it depends a lot on how big the chip is as to what's feasible.

It's easy to do with small CCD's (1/2" or less) but you have to be realistic .6x/.66x is probably the bottom line.

Here's an online calculator:

http://timosastro.1g.fi/tools/focalreducer.html

bern

PS I often use reducers with Newtonians especially for Video Astronomy and imaging with cameras like the Atik 16IC.