ADC- essential for planetary?

[Paz]

It looks like there's a shadow transit of Io tonight followed by the GRS so I'm going to be giving mine a good workout, cloud permitting.

[johninderby]

Cloud permitting. 😁

 

 

 

 

Edited July 18, 2020 by johninderby

[BGazing]

Enjoy! Washout here...

[johninderby]

I couldn’t resist a little mod. 😁

The Altair doesn’t have a bubble level so thought I would add one so bought a rifle scope bubble level with a 40mm bore which fits the ADC perfectly. Just for Alt-Az though as it doesn’t rotate with the ring. The level works from just a few degress elevation so will work fine with the ADC fitted to the Baader prism and is nice and clear. 👍🏻👍🏻👍🏻

Edited July 18, 2020 by johninderby

[JeremyS]

28 minutes ago, johninderby said:

so bought a rifle scope bubble level with a 40mm bore

Do you need a licence for that, John?

🙂

 

[johninderby]

3 minutes ago, JeremyS said:

Do you need a licence for that, John?

🙂

 

Rifle scopes and scope accessories are the same as regular telescopes in the eyes of the law so anyone can buy them.

 

 

[Paz]

I was clouded out, as usual.

However I now have this awesome light-sabre-contraption ready for next time. I just need to find a step ladder to be able to look down into it!

[johninderby]

Wonder what it would look like with a Vixen finder eyepiece 100 instad of the TV? 🤔.       😁😁😁😁

Edited July 18, 2020 by johninderby

[Moonshane]

Funny how we start modding straight away! 😂

Here's my initial set up. 

Using things I had already. Baader 1.25" clicklock, Baader quick release clamp, 1.25" 2x Barlow element, 20mm TV Plossl. I think this will  give about 180x in my 120 Equinox assuming 4x factor on the Barlow.

Have lots of options eyepiece wise.

 

[johninderby]

If anyone is interested this is the bubble level I fitted. The 40mm version.

https://www.nightmaster.co.uk/products/vector-optics-offset-bubble-acd-mount?variant=16731914535023

Edited July 18, 2020 by johninderby

[BGazing]

Uh-huh lads, some long contraptions.

@Paz you may get 2.5 powermate to T2 adapter to significantly shorten that tower. Here https://www.firstlightoptics.com/barlow-eyepieces/tele-vue-125-powermate-t-ring-adapter.html

 

@johninderby there has to be a shorter way to that 😁 Actually you can screw on the bottom bit of the ADC directly to the T2 diagonal, it will be only a bit off horizontally so a bit of rotation of the whole diagonal will bring it level. (tried with ZWO version)

 

[bomberbaz]

Why the bubble level guys, is it to assure the eyepiece setup is vertical ?

I am happy with my understanding of the rest of the set up but not this!

 

[johninderby]

The ADC needs to be level with the horizon so the bubble level just makes it easy to check it is level.

[Moonshane]

Does that mean that you have to readjust throughout the night with an eq mount but not an altaz?

[andrew s]

37 minutes ago, bomberbaz said:

Why the bubble level guys, is it to assure the eyepiece setup is vertical ?

I am happy with my understanding of the rest of the set up but not this!

 

The correction has to counter the atmospheric dispersion which is along the parallactic angle. Near the meridian the parallactic angle is vertical ie at right angles to the horizontal. 

Regards Andrew 

[johninderby]

As I will only be using it with an Alt-Az mount won’t be a problem for me..

Came across this post on Cloudy Nights. by John Boudreau

 

That would work well for a leveled Alt-Az mount, as the horizon reference wouldn't change wherever you pointed the scope--- you'd only have to adjust the prism lever spread to adjust the ADC's dispersion to properly counteract that of the atmosphere. However many use an ADC on an equatorial mount, and as an EQ mount moves across the sky it's horizon reference changes. The rotating ring scale and white screw are intended as a way to update the horizon reference now and then to aid in lever adjustment as the EQ mount tracks across the sky. To allow at least a few hours of adjustment before running out of lever slot travel, the lever slots are quite long and have about 60° of overlap.

>I assumed the white screw was supposed to be lined up with the middle of the overlap of the two slots.

It can be set up that way to allow easily referenced adjustment for tracking a target along a path several hours before through several hours after the meridian--- and that's probably a good way to start to familiarize yourself with how the ADC and scale works. But it doesn't have to be set up that way as long as you can assure that you'll have enough lever travel for adjusting the prisms during your planned observation period. Once you get the hang of adjusting the thing it'll become self explanatory.

Edited July 18, 2020 by johninderby

[Moonshane]

Cheers John. Makes sense 👍

[johninderby]

I will understandd it properly............some day. 😁😁😁

[Matthew]

This is a really good thread,i intend to get one for my C14,when you include that power mate Paz ,it looks like something you could build at Galaxy's Edge 🙂 

[Moonshane]

I reckon it might work well in my 6" f11 1/10 PV newt.  I presume in a newt you get the alignment along the axis of the scope. Might be a lot more experimentation with that scope!

[andrew s]

11 minutes ago, johninderby said:

Came across this post on Cloudy Nights. by John Boudreau

 

That would work well for a leveled Alt-Az mount, as the horizon reference wouldn't change wherever you pointed the scope--- you'd only have to adjust the prism lever spread to adjust the ADC's dispersion to properly counteract that of the atmosphere. However many use an ADC on an equatorial mount, and as an EQ mount moves across the sky it's horizon reference changes. The rotating ring scale and white screw are intended as a way to update the horizon reference now and then to aid in lever adjustment as the EQ mount tracks across the sky. To allow at least a few hours of adjustment before running out of lever slot travel, the lever slots are quite long and have about 60° of overlap.

>I assumed the white screw was supposed to be lined up with the middle of the overlap of the two slots.

It can be set up that way to allow easily referenced adjustment for tracking a target along a path several hours before through several hours after the meridian--- and that's probably a good way to start to familiarize yourself with how the ADC and scale works. But it doesn't have to be set up that way as long as you can assure that you'll have enough lever travel for adjusting the prisms during your planned observation period. Once you get the hang of adjusting the thing it'll become self explanatory.

Yes, however, away from the meridian the two leavers will no longer be symmetrical about the  horizontal reference point to counter the atmospheric dispersion. 

Regards Andrew 

[bomberbaz]

1 hour ago, Moonshane said:

I reckon it might work well in my 6" f11 1/10 PV newt.  I presume in a newt you get the alignment along the axis of the scope. Might be a lot more experimentation with that scope!

Alignment for what Shane. It is an AltAZ scope so the alignment of the ADC is still with the horizon unless you mean something else. 😁

[Moonshane]

I cannot think how it can align with the horizon in a newt as the focuser is perpendicular to it and at a slant. Hence my starting assumption that you align down the axis. The only thing I can think of is having the focuser vertical which would get you closeish.

[johninderby]

[Moonshane]

Me too, I think.......