Home made wedge

[jACK101]

I demolished my home designed observatory a few years ago due to increasing health problems. My granddaughter has now become interested  and I have bought her a telescope. She would like to get into astrophotography, but I am not too keen to spend £4-500 on a wedge. I still have my original telescope mounting with 1/2 tonne of concrete. Would it be practical to make a fixed wedge using steel plate and triangular sides cut for my specific latitude? I could make these myself and get them welded by a local engineer? Could this be accurate enough to allow tracking?

Thanks

Jack

 

 

 

 

 

[Earl]

8 minutes ago, jACK101 said:

I demolished my home designed observatory a few years ago due to increasing health problems. My granddaughter has now become interested  and I have bought her a telescope. She would like to get into astrophotography, but I am not too keen to spend £4-500 on a wedge. I still have my original telescope mounting with 1/2 tonne of concrete. Would it be practical to make a fixed wedge using steel plate and triangular sides cut for my specific latitude? I could make these myself and get them welded by a local engineer? Could this be accurate enough to allow tracking?

Thanks

Jack

 

 

 

 

 

It would be a starting point, then how acurate you want the tracking makes it need to be more precise.

[happy-kat]

The shorter the focal length used for imaging with would be more forgiving. If you have a 3d printer there is a wedge you can print at home Cuiv reviewed it on YT.

[Cosmic Geoff]

No reason why you can't make a wedge, but why is it necessary?  It is implied here that the mount that came with the telescope is alt-azimuth (otherwise it would not need a wedge).  Many alt-azimuth mounts are not suitable for astrophotography even when placed on a wedge, so it would appear a better plan to buy an equatorial mount that is suited to astrophotography.

What are the telescope and mount in question?

[Elp]

I'm guessing it's an SCT due to the cost of the wedge, but we'll see.

[michael8554]

Yes it would help to know which mount you have.

My AE MegaWedge is made from 15mm steel.

"Could this be accurate enough to allow tracking?"

If you only want to track, you don't need a wedge, the Alt/Az mount will do that already.

If you want to guide, then Polar Mode on a wedge is best.

You will need a method of adjusting the Alt and Az of the wedge, even if it's made to sub-millimeter tolerances.

To get a PA error of no worse than 5 arcmins.

Michael

[ollypenrice]

Hardly anybody uses wedge-mounted alt az mounts, not because there is anything wrong with them in principle, but because the ones on the market are really not up to the task. In most cases we are talking about the American SCTs. The mounts are lacking in stiffness, precision and backlash control and this is particularly problematic because the focal lengths are long, giving high resolution image scales which are extremely intolerant of tracking error.

I struggled for a while with a wedge-mounted Meade SCT and gave up on it, switching to a German Equatorial.

Olly

[jACK101]

Hi,

 

Thanks for your replies. The telescope is a Nexstar 6se by Celestron. 

[Elp]

If you're already familiar with the following I apologise in advance.

There are in simplified terms two areas of AP, solar system/planetary and deep sky. Neither is particularly straightforward but I'd say DSO probably requires more investment.

If you're planning on using the default mount that comes with the C6 I've read it's not particularly suited to DSO. Planetary you can get away with using it in alt az mode (its default setup) due to this form of AP requiring very quick image capture (milliseconds to microseconds per image) then stacking thousands of images and choosing the best small percentage where the seeing was fairly still to get the best result. For DSO, even with a wedge I think you'll struggle. It really needs a proper equatorial mount.

This is more so because the C6 is a relatively long focal length scope (1500mm) which provides a narrow field of view. Even framing a large planet like Jupiter can be a bit of a task if the camera sensor is small. For DSO it will definitely need autoguiding, even with the F6.3 reducer bringing the focal length down to just over 1000mm, it's a demanding focal length to be doing long exposure imaging, and you need to be doing it for hours to get a decent result.

I'd start trying imaging the moon first in its default configuration either with a DSLR or astro camera and software, then move onto targets like Jupiter and Saturn though they may currently be fairly low in the sky (so imaging through more atmosphere which can be problematic).

Edited April 6 by Elp

[michael8554]

I won't say my imaging expectations are up to Olly's standards.

But many do DSO's with wedge-mounted SCT's, including myself.

The older Meade and Celestron wedges are flimsy, which is why I went for the AE MegaWedge.

The main problem is the time taken to setup if you don't have a permanent rig.

I would expect that the challenges are similar on a EQ mount at 1500mm FL.

Michael

 

Edited April 7 by michael8554