Going for the 8 Inch

[TheAstroChannel (Sean)]

Hey everyone, so I'm finally upgrading to the celestron C8 on the CG-5 mount.
Just want to know everyone's pros and cons are about an 8 inch cassegrain and what you can see through it with the eye
Thanks, Sean.

[Camelopardalis (Dunk)]

C8 is a sweet spot IMO...nicely compact and light, rides nicely on the CG5/VX/HEQ5 class mount (which is also light), but also 8" of light grasp

Expect to resolve loads of stars from your favourite globs, swirls of detail from the big bold nebulae. On a good night, she'll show you plenty! Maximum FOV is about 1.4 degrees with a 2" diagonal and 40mm SWA eyepiece. Cool down isn't a major problem with the 8, just take it out as the first piece when you start setting up.

Cue the usual comments about how you'll save $1000+ by getting yourself an 8" Dob instead

[Allan]

That's a great telescope Sean, and you will get years of use out of it without running out of things to see. Plus an 8" is big enough to reveal lots of detail in the objects you observe.

BTW, have you considered an 8" Dob? I reckon you could save at least a $1000.

[Renato1 (Renato)]

Ignore the comments about an 8" dob being cheaper - yes it is, and yes it is good.

But with an 8" SCT you can sit down behind it in a comfortable stool and view for hours, without having to stand up a lot of the time. Though you'll need a dew shield, and I have a 12 volt hair dryer and battery pack handy for when the dew shield fails.

And it's a nice 2000mm lens for your Sony A57 (I've got one of those too).

You'll want a wide angle 20mm eyepiece for it seeing the faint stuff easily (though I've just switched to a 19mm Flat field one). And at least a UHC filter for planetary nebula.

And initially a 32mm 1.25" plossl for low power. Though with a 2" diagonal, a 40mm wide angle, or even a cheap 30mm ultrawide angle makes for interesting viewing.

Have fun.
Renato

[TheAstroChannel (Sean)]

I was considering the 10" orion dob a month or two back, but after some research, i saw that the EQ mount with an 8" would be great to start proper long exposure astrophotography.
Also, thanks heaps for the info Renato That is extremely helpful, and even more helpful than that when someone else is using a Sony

[Camelopardalis (Dunk)]

Regarding photography, you might want to start off with a dovetail adapter for your camera so you can get started with the lenses you already have.

Unless you have an exceptional HEQ5, you're not going to be able to get very long exposures with the C8, without autoguiding anyhow. Or using a reducer. Meade used to make a f/3.3 reducer for photography, but I've not used one.

Having my EQ6 drift aligned at SPSP, my C8 at f/7 was showing star trails at 10s exposures. YMMV.

[raymo]

There must be something wrong with your EQ6 Dunk. My HEQ5 working at f/5, has, up to now, given me between 45 and 115 secs with perfect
stars, depending on how good the P.A. was on the night. I don't drift
align; I just use the P.A. function in the hand controller. I realise that
you were working at f/7, but that would still translate to 26 to 69 secs.
raymo

[Camelopardalis (Dunk)]

You're probably right raymo, I've got a little drift with the mount, I just need to find someone nearby that knows how to tweak one!

[raymo]

Why don't you try the P.A. function; it works well for me; remembering
that the Alt & Az figures it shows after alignment are not the error, they
are the adjustments you need to make. The first few times you do it, it
takes a while, but you soon learn how much to turn the knobs.
raymo

[Steffen]

Originally Posted by raymo

remembering that the Alt & Az figures it shows after alignment are not the error, they are the adjustments you need to make.

Are you sure about that? I believe (from muscle memory more than anything else) that for Az the displayed Maz is actually the error, i.e. a reading of -1 means the mount is pointing a degree too far West, and that the South leg needs to be dragged further eastward.

In Alt (Mel) I'm not so sure, it may well be reversed there, which I'd attribute to a northern vs southern hemisphere software issue. I'm less certain on this one because I don't often have to adjust this.

Cheers
Steffen.

[Renato1 (Renato)]

Originally Posted by TheAstroChannel

I was considering the 10" orion dob a month or two back, but after some research, i saw that the EQ mount with an 8" would be great to start proper long exposure astrophotography.
Also, thanks heaps for the info Renato That is extremely helpful, and even more helpful than that when someone else is using a Sony

Thanks. The Sony A57 is a recent acquisition for me, as my main cameras have been the older Sony A550 and A900. A chap at our club has the super looking Sony A99, and a few have been using the Sony Nex cameras where they have "washed" off the IR filter to get better H alpha response.

If you want to take snaps of the planets and moon, you are probably best off buying a cheap remote control from Ebay (a few dollars) and holding it in front of the camera and pressing the button. For long exposures you'd want the remote with the cord - which always manages to get tangled somewhere. And for 30 or so dollars on Ebay you can get intervalometers which make your camera shoot at intervals and holds the shutter open for time intervals that you set.

Unfortunately, you now have to be careful what you buy, as I read that Sony changed the remote plug as well as the flash hotshoe in the newest cameras. Plenty of people at Dpreview though, keep asserting that the A57 is a much better camera than the newer A58, because Sony merged the A37 and A57 to make the A58, and dropped many features that were in the A57.
Cheers,
Renato

[raymo]

Hi Steffen,I use it every time I set up, and apply the shown figures. If it says Alt +1degree, I raise the alt by that much, and if it saye AZ +1 minute, I increase the Az by that much, in other words, if looking down
at the mount, I rotate it clockwise. If this were wrong it would be immediately apparent, as the error reading would get worse instead of better. I now routinely get down to under an arc minute, which is allowing me to get subs of at least 60secs, and some nights 90 or even more. I have to adjust both axes each time I setup because the surface is not all that level.
raymo

[TheAstroChannel (Sean)]

I already have a remote with a cord attached, and i have been using it for a fair while! It works superbly, and is a lot easier than just using a 10 second timer I will look into those intervalometers, they seem very useful I have managed to get this with my current ALT-AZ GOTO (5" reflector) mount, so i'm keen to see what i can get with my next scope
CARINA
http://s981.photobucket.com/user/the...tml?sort=3&o=2
PLANETARY
http://s981.photobucket.com/user/the...tml?sort=3&o=1

[Renato1 (Renato)]

Originally Posted by TheAstroChannel

I already have a remote with a cord attached, and i have been using it for a fair while! It works superbly, and is a lot easier than just using a 10 second timer I will look into those intervalometers, they seem very useful I have managed to get this with my current ALT-AZ GOTO (5" reflector) mount, so i'm keen to see what i can get with my next scope
CARINA
http://s981.photobucket.com/user/the...tml?sort=3&o=2
PLANETARY
http://s981.photobucket.com/user/the...tml?sort=3&o=1

Nice shots.

The good thing about the Sony A57 is that you don't have to worry about shutter slap or having to have mirror lock-up for a decent shot.
Cheers,
Renato