ZWO ADC

[bosun21]

Has anyone used one of these for visual astronomy? I was thinking about whether this would be any good for planetary observing. It states that it can be used for both AP as well as visual. Thoughts anyone.

[Peter Drew]

We have one that we use visually on a 16" SCT.  It is very effective whilst the planets are low in declination, the AD can be completely dialled out.  Not so sure as to its value on small apertures.     🙂   

[bosun21]

3 hours ago, Peter Drew said:

We have one that we use visually on a 16" SCT.  It is very effective whilst the planets are low in declination, the AD can be completely dialled out.  Not so sure as to its value on small apertures.     🙂   

Thanks. I was thinking about using it on my 12” dobsonian on an EQ platform. Thoughts?

[johnturley]

2 minutes ago, bosun21 said:

Thanks. I was thinking about using it on my 12” dobsonian on an EQ platform. Thoughts?

It was quite effective on Jupiter and Saturn through my 14 in Newtonian when they were quite low down, but did not make so much difference through my Esprit 150.

Now Jupiter and Saturn are moving higher up it will make less of a difference, I don't think many people bother using them for AP as you can correct any false colour due to atmospheric dispersion in the processing software.

John 

 

[Louis D]

10 minutes ago, bosun21 said:

Thanks. I was thinking about using it on my 12” dobsonian on an EQ platform. Thoughts?

You might not have enough back-focus to insert the ADC in the focuser.  If you have one of those Synta focusers with the high-hat 1.25" adapter, you could probably substitute it with the ADC with the proper low profile adapters to hold it in the bare focuser opening.

I only have 25mm of back-focus on my Dobs due to undersized secondaries and low profile focusers, so an ADC is not an option for me.

[bosun21]

1 minute ago, Louis D said:

You might not have enough back-focus to insert the ADC in the focuser.  If you have one of those Synta focusers with the high-hat 1.25" adapter, you could probably substitute it with the ADC with the proper low profile adapters to hold it in the bare focuser opening.

I only have 25mm of back-focus on my Dobs due to undersized secondaries and low profile focusers, so an ADC is not an option for me.

Good point. I have a Stella Lyra dobsonian and I’ll need to calculate how much spare focus travel i have to see if it will accommodate the ADC. I presume that the addition of a barlow would sort it.

[Louis D]

13 minutes ago, johnturley said:

Now Jupiter and Saturn are moving higher up it will make less of a difference, I don't think many people bother using them for AP as you can correct any false colour due to atmospheric dispersion in the processing software.

Not completely true.  You can shift the individual RGB channels relative to each other in post, not the frequencies within each color band.  Blurring within each band cannot be corrected in post.

Here's an image from a rather thorough article about ADCs showing the improvement an ADC can make over doing the shifting in post:

Edited June 7 by Louis D

[Zermelo]

Have you seen this thread?

 

[johnturley]

19 minutes ago, Zermelo said:

Have you seen this thread?

 

When you get to my age, its easy to forget what you posted 3 years ago.

John 

[Zermelo]

1 hour ago, johnturley said:

When you get to my age, its easy to forget what you posted 3 years ago.

John 

I'm worse - I didn't notice you in the other thread! 🤣

[Paz]

I've used an adc visually for quite a few years now.  I find it to be a trade off in that it reduces atmospheric abberations but it adds scatter. I've found it works best for me on Jupiter amd Mars,  and quite well on Saturn. It's not so useful on Venus as the added scatter is not worth it, and on the outer planets they are dim enough that atmospheric scatter doesn't matter for me.

Here's a picture of mine on action. It's in front of the diagonal to reduce how far off axis the eyepiece mass is.

[bosun21]

19 minutes ago, Paz said:

I've used an adc visually for quite a few years now.  I find it to be a trade off in that it reduces atmospheric abberations but it adds scatter. I've found it works best for me on Jupiter amd Mars,  and quite well on Saturn. It's not so useful on Venus as the added scatter is not worth it, and on the outer planets they are dim enough that atmospheric scatter doesn't matter for me.

Here's a picture of mine on action. It's in front of the diagonal to reduce how far off axis the eyepiece mass is.

That’s an interesting placement for the ADC. They recommended that it’s immediately before the eyepiece or camera. Have you tried it in both positions?

[Paz]

4 minutes ago, bosun21 said:

That’s an interesting placement for the ADC. They recommended that it’s immediately before the eyepiece or camera. Have you tried it in both positions?

Yes, if I remember rightly it's effect is stronger when it's further away from the eyepiece but you can dial in the right strength with the adjusters. The reason I have it there is to make balancing easier and by the way it is simpler to orientate there in that if you rotate they eyepiece to the side like in the photo you don't have so many complications reorientating the adc. In this set up it's a short path diagonal plus t2 connectors so is not too much further ahead of the eyepiece.