Meade LX90, Focal Reducer / Field Flattener and Zero Image-Shift Micro-focuser

[smersh (Michael)]

I'm having a frustrating time setting up my Canon 40D, LX90 with a Meade Series 4000 Focal Reducer / Field Flattener and Meade Zero Image-Shift Micro-focuser.

The problem is that I have serious coma and I am unable to collimate;
After collimating using a defocused star in the center of the field, it appears uncollimated (i.e. The donut and whole are not concentric any more) as soon as it is moved out of center of field.

I have 3,6 and 20mm spacers also.

I understand that this is all to do with the spacing of the FR/FF to the secondary, and FR/FF to the camera focal plane.

Can someone please tell me the correct configuration for these items.

e.g. Should the FR/FF be between the Focuser and Scope or the other way around?

Are the spacers actually required if the Focuser is used?


thanks for any help
Michael

[Bassnut (Fred)]

Mike

I just found this.This was a user review on the listing for this device on the OPT web site http://www.optcorp.com/product.aspx?pid=778&tb=8 (scroll down). Is your LX90 an ACF or R ?.

Great for the Money But Needs to be used on a Old Style SCT and not ACF or HD Telescopes.
First of all this accessory is not desgined to be used on a ACF or EdgeHD Telescope. These scopes already have either a field flattener installed in the baffle tude or have a other type of field flattener incorporated into the optical train. Now if this accessory did not have the Flattener then it will work on these types of scopes. Again its not fair to judge it on the basis of being used on a ACF or EdgeHD scope since they already have field flatteners in them this device over corrects and causes optical defects.

[smersh (Michael)]

Thanks Fred - it's Old Skool / pre ACF.

[Bassnut (Fred)]

Sell it.

[tlgerdes (Trevor)]

In case anyone is confused about Mikes question, should it be:

Scope - FR/FF - Focuser - Camera
or
Scope - Focuser - FR/FF - Camera

[Bassnut (Fred)]

Im kidding ;-). It seems the reducer must be screwed into the primary cell before everything else, although this is interesting, seems to be mounted after the focuser. Perhaps his reducer is different to the 4000 series Meade. I had good results on my LX90 (non R) with the Meade 6.3f reducer screwed into the primary and then a DSLR (no focuser), but it wasnt the 4000 one, Im sure someone else must be able to give actual experience.