Atmospherc dispersion corrector's advice please

[gonzostar]

Hello

I'm intendending to use my C8 SCT with a ZWO 385MC camera to image Saturn and later Jupiter. I use sharpcap. Can you correct for ADC using sharpcap or registax?

If not FLO do two types of ADC, Stellalyra (£85.50) and a ZWO (£127) version. Why a big difference in price for the two? and is it worth it.  If anyone has opions i would like to know

 

Thankyou

Dean

[Veloman]

Can't help with the question re. SharpCap/Registax. But is the ZWO's  built in little level worth the extra £41.50?

Rob

[gonzostar]

I've got a spirit level int shed 😁

[Vroobel]

The ZWO one works, I used it with the SharpCap which has a dedicated feature for it. 

 

[Louis D]

There's a CN posting about ADC vs Aligning RGB channnels:

[gonzostar]

Wow a huge difference thanks, thats convinced me to get one. How essential is the usage of the spirit level? Or is it the quality of the glass in prism that makes the ZWO ADC more expensive

[Cosmic Geoff]

Louis D's post nails it.  I use the ZWO ADC and find it works well, better than aligning colours in software. 

[Elp]

I believe the whole point of the spirit level is so that the ADC is aligned with the horizon, so any prism adjustment works as per light diffraction per altitude to the horizon or something like that.

[Paz]

I have a ZWO ADC, the spirit level is to keep it level with the horizon but it is not essential and in the dark it's not easy to see.

I orientate mine by eye through the eyepiece (I'm visual only), I tune it to cause a bit of dispersion then rotate it around to see at what orientation it counters or adds to atmospheric dispersion. Then set at the right orientation then tune to the right amount of adjustment.

[CraigT82]

An ADC needs to be aligned in the  focuser so that the levers at the null point (zero correction) are parallel with the horizon as seen through the scope.

In a frac/mak/SCT and without a diagonal, the horizon as seen through the scope is level with the actual horizon and so in that case the bubble level is useful. Introduce a diagonal and you’d need to make sure the diagonal is level in the focuser (I.e. the base of the diagonal is pointing to the floor) then the bubble is still useful.

With a newt though the view of the horizon through the focuser will not usually be parallel with the true horizon so the bubble is useless. 
 

As for the two ADCs mentioned I can’t see much difference beaten them except the SL unit has 2.5 degree prisms and the ZWO has 2 degree prisms. The SL unit should therefore be capable of stronger correction assuming the maximum travel of the levers is the same. 
 

I have the ZWO unit and it works well, I’m sure the SL unit will work well too though I’ve never used one. 
 

here is a vid I made about setting the ADC horizon on my newt….

 

Edited July 8 by CraigT82

[gonzostar]

Thankyou for your youtube clip. The  explanation is clear and useful. May actually go for the ZWO version.  Me faffing with a spirit level in front of the SCT, all sorts could go wrong! 😁

Cheers

Dean

[WatcherOfTheNightSkies]

I've now had 2 nights with the SunObserver eADC. Previous software errors have been fixed. First time I've seen diffraction patterns on a star at 17 deg altitude, and the awful colour fringes on Saturn simply disappear while the rings' shadow on the disk is a nice contrasty black line. I'm a visual observer at 53N.  I really appreciate the plug n play, set it and forget, wheel the scope around the sky on an equatorial doing double stars at various altitudes, it self-adjusts. Simply need a USB port to power it, no computer required, but according to documents it can be remotely controlled (I haven't tried that).  It just might turn me into a planetary observer. No more "ack, the object is only 15 degrees up, why bother?" A game-changer for me. 

[CraigT82]

5 hours ago, WatcherOfTheNightSkies said:

I've now had 2 nights with the SunObserver eADC. Previous software errors have been fixed. First time I've seen diffraction patterns on a star at 17 deg altitude, and the awful colour fringes on Saturn simply disappear while the rings' shadow on the disk is a nice contrasty black line. I'm a visual observer at 53N.  I really appreciate the plug n play, set it and forget, wheel the scope around the sky on an equatorial doing double stars at various altitudes, it self-adjusts. Simply need a USB port to power it, no computer required, but according to documents it can be remotely controlled (I haven't tried that).  It just might turn me into a planetary observer. No more "ack, the object is only 15 degrees up, why bother?" A game-changer for me. 

That interesting, never heard of this one… going to go and have a look

[CraigT82]

Looks like a nice bit of kit. Does it need to be set manually at the beginning of each session, and then it changes the prism settings automatically as the scope moves around the sky? Does the image shift when the prisms adjust? 
 

I have read the operation manual but it wasn’t quite clear. 

[WatcherOfTheNightSkies]

Apologies for the late reply.... I've been observing! The eADC is literally is set once. Not once per session, once for life. Every time you swing the scope or remove it to compare to no eADC, you can hear it quietly buzz. There is image shift if you swing and look in under 5 seconds, but it settles in 10 seconds. When I make the scope goto up the meridian say 10 degrees, the target is often within the FOV at 440x (been doing double stars recently), and there is only the slightest buzz and shift as the scope finishes slewing. If I cross 90 degrees of sky, I usually switch back to low power to center the target, and by then it has already settled down.  In practice, if you didn't know it was there, you'd never notice except how good the images are at lower Alt. 

What the eADC has triggered in me is wanting adaptive optics. Living so close to the Rocky Mountains, and under mid-latitude jet streams, I often get 3 arcsec seeing, at which point the eADC changes a coloured mush into a colour-free mush. 10 nights ago I was going to show it off to other keen observers, but the seeing was so awful it was pointless. 

Edited September 16 by WatcherOfTheNightSkies
Clarification

[globular]

@WatcherOfTheNightSkies Do you know if it works on a AZ mount? I've read the description of how it self adjusts to changes in altitude including rotating to allow for EQ rotation. But if you use an AZ mount then you want the altitude adjustments without rotation. I've not seen that mentioned anywhere. I guess they must have allowed for this - can you confirm?

Edited September 16 by globular

[WatcherOfTheNightSkies]

Although I have not tried the eADC on an AltAz mount, I can't imagine a problem since the rotation is simply zero (if you put it into the image train exactly horizontally). Unlike the manual ADCs, you don't need to bother with a bubble level since it will handle a 1 degree off-horizontal component.