Flattener/CCD distance?

siriusdoggy

Hey guys. I just picked up a second-hand Explore Scientific ED127mm scope and it came with the ES 0.7x focal reducer/flattener. I've been doing some research online regarding the flattener and can't find any info about this specific flattener but I did run across a couple other brands and they all mention there should be a space of 55mm between the flattener and the CCD. Is that the magic number for all flatteners? If so, my ZWO1600mm has a back-focus of 6.5mm and the mini EFW is 20mm thick so does that mean I need a spacer that is 28.5mm? And if so, suggestions on where to get one?

einari

Well my first google search tells me that the distance is 55mm (if it's the 3" ES 0.7X reducer/flattener).

The distance is not same for all reducers and can vary depending of the focal length of scope.

So you need T2 spacer rings.

Nearly all astro stores carry them. Don't know where you are located but here's one US store:

http://www.highpointscientific.com/telescope-accessories/astro-photography/extension-tubes

siriusdoggy

einari wrote:
Well my first google search tells me that the distance is 55mm (if it's the 3" ES 0.7X reducer/flattener).

The distance is not same for all reducers and can vary depending of the focal length of scope.

So you need T2 spacer rings.

Nearly all astro stores carry them. Don't know where you are located but here's one US store:

http://www.highpointscientific.com/telescope-accessories/astro-photography/extension-tubes

Thanks for the info. I've Googled it as well and never found anything specific about this flattener. And you are correct, it is the 3" ES 0.7x that I've purchased.