ADC question

[WbRaDy]

My ZWO colour has bit the dust so was going to take advantage of the black Friday deal on the ZWO 120MM, just wondering if I still need the ADC with the ZWO mono and RGB Filters or do the filters override the need of an ADC?..

Thanks 

[Kokatha man]

No! Atmospheric dispersion affects all cameras, both colour & mono!

Whilst you can see aspects of the dispersion onscreen with a colour camera, the mono images you view with these cameras will not show this - but the real culprit of impaired resolution (aka blurred detail ) is still there. 

A lot of people confuse aspects of this, thinking that if you align the individual channels of a colour image displaying AD (using something like the "RGB Align" tool in Reg6) that you have solved the problem, but you haven't addressed the real issue!

We employ the ADC when we use the mono ASI290MM: at the start of our imaging sessions earlier in the year for Mars (relatively low in Southern Oz) I'd put the ASI462MC (same pixel-sizing as the 290MM & therefore completely parfocal) into the back of the EFW & tune out the A Distortion, take a few colour captures before doing a reset of the levers, then switching in the mono camera.

From then on we'd image with that camera...what you will find is that the ADC is correctly tuned for a wide span of time either side of culmination with the same spacing either side of the null/level point on the 2 levers.  (at home this is from about 44° through to 48° & back down to 44° - hours of imaging time)

What this meant was that we could dispense with the colour camera step completely after becoming aware of the separation required...setting the levels & null-point level (we use an SCT) then advance each lever to their positions we had become familiar with (a minuscule point just past 1 full gradation of the ADC slip ring) & that was that!

After about 3 r-g-b captures I'd reset the null point to level (I have a bubble on that) & move each lever so that the spacing was the same either side of the new null/level point as before & then was good to start imaging again, confident that Atmospheric Dispersion was being corrected!

Btw, I don't know what camera you were using before, but an ASI120MM is a bit archaic nowadays: there are other ways to set a mono camera & an ADC, although they are a tad more difficult tbh... 

Edited November 29, 2020 by Kokatha man

[Davey-T]

There is a handy hints thing on the ZWO site on how to set their ADC.

Dave

[WbRaDy]

Looking at the manual it would suggest a W47 filter or the use of another colour camera, is that what you are referring to Dave? Kokatha man i was using a 290MC before it died and was looking to replace with a mono as i already have a filter wheel i use with a 1600MM for deep, although i think it would be easier to replace with another colour 😀

Thanks for the advice

[callisto]

On 29/11/2020 at 23:53, Kokatha man said:

but an ASI120MM is a bit archaic nowadays:

On the contrary....This is an affordable and very widely used camera nowadays

[Kokatha man]

I'm not saying it isn't capable bro - just a very old model & superceded by several since.....I guess I should know, I received the very first one outside of Mainland China for initial testing etc a long time ago now! ;)

[Davey-T]

10 hours ago, WbRaDy said:

Looking at the manual it would suggest a W47 filter or the use of another colour camera, is that what you are referring to Dave?

No there are specific instructions for using the ZWO ADC somewhere on their site.

Dave