Lightbridge

[Anubis]

Hi,

I'm currently using a Meade ETX80 for casual observing, and have just started trying my luck at astrophotography. I've been looking into buying a Meade 16" Lightbridge, since it is portable (I'm a member of an observing group and we meet up 20 or so miles outside the city)

Would this be any good for astrophotography?

Thanks,

Bryan

[MikeP]

Bryan,

The Lightbridge will give you fantastic views of the night sky, particularly from a dark site.

Unfortunately, for astrophotography, even with the light grasp of a 16", you need to expose for a long enough time for the rotation of the earth to affect the image. Most imagers use motor driven (usually equatorially mounted) scopes that counteract this motion. I believe you can buy driven platforms for dobsonians, but they are beyond my expertise.

Also, imaging is trickier than you'd imagine and I think short focal length scopes are the place to start, say in the 400mm to 700mm range (I'm guessing the Lighbridge is around 2000mm).

I solved the problem by buying two scopes - one for visual and one for imaging (a SkyWatcher ED80) but invested in a good equatorial mount as well.

You have a tough decision to make.

Mike

[Beyond_Vision]

You will also find that there may not be enough inward travel on the focuser to bring a DSLR to focus. You can use the Lightbridge for imaging the planets and the Moon but you will probably need to fit a low profile focuser.

Regards

Kevin

[Anubis]

I solved the problem by buying two scopes - one for visual and one for imaging.

I like your thinking

Joking aside though, its obviously not going to be any good for astrophotography. I think I'll continue to put money by for it and by the time I have enough saved I will have a better idea of which direction I want to go in.

[MikeP]

A wise decision.

Mike

[Eddie]

In theory it would be possible, but you would need to modify it with a set of argo navis DSC, a servo cat drive system and a field derotator like the pyxis one. I have seen images taken with Obsession telescopes and they look pretty good!

Eddie

[narrowbandpaul]

if u want to get into imaging, then spend most you cash on a mount. You will need to exposure for at least 5 minutes to get a useful signal

The mount is the most important thing.

Next is cameras, DSLR (modded or unmodded), small CCD

I would think it exceptionally difficult to image with an non Equatorial Mounted dob

If u get a set of tube rings, and a light shroud, and an GEM you might get away with it, but 16" F5 is a long focal length to begin with

A small refractor (80mm) would be a good starting place...theyre easy to image with, and place less importance of accurate tracking on your mount

[Sam]

if u want to get into imaging, then spend most you cash on a mount. You will need to exposure for at least 5 minutes to get a useful signal

The mount is the most important thing.

Next is cameras, DSLR (modded or unmodded), small CCD

I would think it exceptionally difficult to image with an non Equatorial Mounted dob

If u get a set of tube rings, and a light shroud, and an GEM you might get away with it, but 16" F5 is a long focal length to begin with

A small refractor (80mm) would be a good starting place...theyre easy to image with, and place less importance of accurate tracking on your mount

Agree about the mount - but there are plenty of great images on this forum done with exposures under 120 secs - 5 minutes is a good thing to aim for but you'll probably need to be autoguiding for that. Roy's M27 is a recent example of an awesome image with 60 secs exposures.

I have an HEQ5 and a 8" reflector I use for imaging - I'm working on the autoguiding bit but at the moment I can get unguided exposures of up to 90 secs. Like Mike says it might be good to have an imaging scope and a viewing scope (mine's a 16" Lightbridge for that).

Sam

[narrowbandpaul]

with an unmodded DSLR, I have found that 2minute exposures at F/5 very low in signal, due to response. I was imaging NGC7000, and the canon has poor red response.

If u image a planetary which are blue, due to the hot central star, then your exposures can be short because the canons peak response is around the O[iII] line at 500nm

Paul