383L + Mono Spacers

[sazam91]

Hey Everyone!

I just purchased the Atik 383 L + mono package from OPT and I also currently possess a Astrotech 2" Field flattener. I use a WO Megrez 80 APO triplet F/6 refractor and currently experience curvature around the edges when imaging with DSLR. I have already ordered a set of Orion T-Thread Spacer Ring Kit. I wanted to know what distance I need to achieve a flat field with the Atik camera, filter wheel with 1.25" LRGB filters, and the field flattener.

Orion Spacer ring set: http://www.telescope.com/catalog/search.cmd?form_state=searchForm&keyword=Orion+T-Thread+Spacer+Ring+Kit

Field Flattener: https://www.astronomics.com/astro-tech-2-inch-field-flattener-astro-tech-tmb-refractors_p17393.aspx

Thanks for the help!
-Sal

[MikeM]

Hi Sal, well according to the Astrotech website it states that 57mm (+/-4mm) is needed to the plane of the camera from the rear glass of the flattener.
Keep in mind though that flatteners are usually designed for specific scopes and may or may not necessarily work well with the Megrez. Lots of times
a bit of experimenting needs to be done to find what distance and or flattener will work for a specific scope if it doesn't have a specified flattener.
Maybe someone here will have a similar setup and can give you their experience.

[joelshort]

As Mike says the back focus spacing can be tricky and you will need to experiment.  But start by trying to put the flattener at 57mm distance from the CCD chip (focal plane).  The 383L has 17.5mm, the EFW2 has 22mm, total = 39.5mm.  So that means you nee to add 17.5mm between the filter wheel and the flattener. 
joel

[sazam91]

Thanks guys,

That's exactly what I have for required spacers. I've ordered a set of spacers and will test them out.