6200 + FLT132 + EFW -> how much vignetting?

OzScott

Heya,

I have the 6200 connected with the EFW to a William Optics FLT132 (with 0.72 flattener/reducer) and I don’t know how much vignetting I should expect. Below is an example of what I see through each filter. Does that look right?

Everything is connected as per the ZWO diagram on this website. It has the 48mm 16.5 tube between the flattener and the EFW…would replacing this with a 54mm tube reduce the vignette significantly?

thanks.

enaiman

48 mm is not enough with a full frame camera - replace everything in the optical path with 54mm
Filters need to be 2' as well.

OzScott

If only ZWO made a 54mm tube for the connection…

enaiman

OzScott Why are you so fixated on ZWO? There are plenty of manyfacturers for extension tubes - leterally, google "54 mm extension tubes" and buy from the first result.

OzScott

enaiman I have been looking. To replace the current tubes I would need an 18.5mm M54 tube with M54m on each end? I can see nothing like this online. I can soak up a bit of a different length tube by adjusting the flattener (I think). I see lots of 2” tubes but not 54mm tubes.

EDITED: just had a closer look at the setup and I see that it’s M54m on each end.

enaiman

OzScott I don't know where you live but in Australia Testar is selling them. Just bought a bunch of them myself recently.

w7ay

OzScott I see lots of 2” tubes but not 54mm tubes.

You can always get them custom made by PreciseParts.com.

They can even fabricate an extension that has a "bolted" flange to match the screw holes of a couple of the ZWO EFW models. Be sure to test the backfocus first since the custom parts are not cheap. Don't just depend on numbers, test the backfocus at the corners of the frames (especially with the sensor size of a 6200 camera) with a real star field. The lead time is also rather long -- last time I ordered, it was between three and four weeks.

Chen

OzScott

enaiman I’ll have a look at the Testar site. I used to be in Oz but I am in the US now. Thanks.

Tech@ZWO

@OzScott#61232 What EFW did you use? is a 2" version?
Please also check the thread size of you telescope.

OzScott

Tech@ZWO
Yep, 7x2”(unmounted) EFW. I also purchased the optional 54mm adapter of the WO flattener that replaces the 48mm part.

OzScott

w7ay
I have been looking at these. It’s definitely an option. With some clever planning it looks like I could have a single piece that connects from the main body of the flattener to the EFW. As you say, not cheap! Better than a bunch of images through a keyhole though.