Log in

View Full Version here: : The SWA F/5 Coma Corrector


atalas
27-03-2022, 09:21 PM
Hi Guys

I picked a cheap used GSO 8" F/5 newt on IIS the other day and after setting It up with the Skywatcher F/5 coma corrector and getting It ready for imaging I decided to review my findings on the setup and performance of the Skywatcher F/5 Coma Corrector.

First of all some specs on the unit.

Back focus spacing: 55mm

Best for F/5 scopes...that's It?cool just the way I like It.

Once you've connected the spacers required to get you to the 55mm backfocus your ready to take the next step.....you guys still with me?

The unit is designed to slip into a 2"eyepiece holder on the telescope end(I've seen those adds)and, although, a screw in unit would be preferable for astrophotography, I didn't have too much trouble getting It to sit fairly square in the focuser(I wouldn't of had the focus travel with a screw on anyhow's)

Ok,got past that hurdle so on to the next....hows the star field look? and is my spacing right?

Now for the back story!

Using an old QHY8(which has the early APSc size sony sensor)I had to look up the back focus for It and after googling and finding a dozern people all with differing measurements? I decided to go with the 14.1mm the previouse owner had on a sticker on the camera(lol..didn't see It)got to start somewhare!

Are we there yet? nope....noooot quite, but luckerly I stumbled across this link on CN which saved me chasing my tail.

https://www.astro-physics.info/tech_support/accessories/photo_acc/determining-ring-spacing-change.pdf

Conclusion? is good!

A 7 x 5min test shot of the field(sorry heavy jpeg compression)

xelasnave
28-03-2022, 10:15 AM
???

atalas
28-03-2022, 11:23 AM
Yeah Alex...the Skywatcher F/5 coma corrector works well when good spacing is achieved..... no doubt.

Oh,I forgot to mention in the review that this corrector(to my surprise) does reduce by .9 so, down to F/4.5 which might be wanted for some but, when you don't have much in focus and lots of light pollution maybe not wanted like my case.

Still, the main point is that SW F/5 coma corrector works well and If your paying a few hundred bucks or so that's the result you want :)

Oh by the way guys, If someone wants a raw fits file so they can have a closer clean look at the field just PM me and I'll email one out to you.