which focal reducer?

[bloodhound31]

I am thinking of getting either the f/6.3 focal reducer/field flattener from meade for my celestron nexstar 11 gps and piggybacking a ed80 for a guidescope with illuminated reticule eyepiece. It is on the bintel website. For a little bit more there is a f/3.3 ccd focal reducer.

I am using an unmodded canon eos 400d.

Which is the better item, and why?

Baz.

[[1ponders]]

G'day Barry. For a DSLR you will want no more than the 6.3. The 3.3 is meant for small chipped CCDs like the DSI and similar. If you use the 3.3 with a DSLR you will get a very unflat field around the edges. If you really want to get more focal reduction with a DSLR then you might need to consider a Nexgen 0.5x reducer.

http://www.optcorp.com/product.aspx?pid=3531

But even this won't fully cover a DSLR chip.

[[1ponders]]

If you want to fully cover the DSLR chip then you might need to consider somthing like Lumicon Easy Guider with FR http://www.astrocruise.com/geg.htm

Or just the focal reducer
http://www.bhphotovideo.com/c/product/457518-REG/Lumicon_LR1015_Giant_Focal_Reducer_ for.html

[tempestwizz]

I would suggest not getting either, and imaging through the ed80 and using the Celestron as the guide-scope. I do this with my 8" Meade LX90 and ED80 and it seems to work well. With a well-balanced and aligned equatorial set-up, I can get up to about 5 minutes unguided. For guided, I use a DSI Pro in the meade as the guiding source and a Canon 20Da on the ED80. Guiding can then be manual via cross hairs on a laptop screen, or auto via Envisage (for Meade)
It's worth spending time on the piggy-back mounting arrangement to get the ED80 as close to the main OTA as possible so that 3d balancing is achievable. Many of my earlier problems arose from poor balance.

[bloodhound31]

Thanks guys. Yes, I do intend on using the C11 as a guide scope and imaging thru the soon-to-be-purchased ED80. Until then, I want to put the C11 to the test and try to see what I can get out of it.

I do not think it justice that a ten thousand dollar scope should be wasted as a guidescope alone while an ED80 worth 600 dollars beats it in image quality.

I'm just trying to get the most out of my existing scope as well.

So far, I am not terribly impressed with the images coming from it.:doh:

Baz.

[Gama]

This is OK for certain objects, but when you need resolving power and a little more image size, then you cant help but use the main scope.

Plus your able to go fainter to gather the harder to see objects.

Theo