Placing the ADC before or after the filter wheel?

olav

Hi all,

Will be using my new and first ADC with EFW+ASI290MM.

I understand the ADC should also be of great help dealing with dispersion within each filter's range, but that most users seem to choose a color cam when using the corrector.

Placing the ADC before the filter wheel makes some sense in that I (maybe) would be able to intercept the light path with a flip mirror after the ADC but before the filter wheel, to easier adjust the ADC visually (without looking through filters).

Than again, I'm so new to the ADC concept that I might do the wrong adjustments for all I know, if not looking through the same path/filters.

Or is the optimal ADC adjustment totally independent on the filter colors? Will I find that adjusting by using the camera live window in FireCapture (etc), using the L filter only, will be easy enough?

Has anyone used the ADC with mono and RGB (or other) filters?

Sharing your findings and some ideas of setting up the imaging tain would be much apprediated.

Oh, there's this little idea I have been playing with, after reading a CN thread.

Maybe I also want the ASI224MC, for some purposes.

Now, if I could have this imaging train: scope > barlow > ADC > flip > FW > ASI290MM.

Adapting the ASI224MC to the flip-side might make it even easier to see and adjust the ADC with color.

I mean, it's just a mirror, what could go wrong?

Could maybe even alternate imaging with these two cameras..

Sam@ZWO

I think should after filter wheel

so you can use one filter to adjust the ADC

olav

Thanks Sam,

That's interesting, and I must try to understand the reason for your recommendation.

Does that mean that the introduction a filter-glass in the optical path, with the glass thickness by itself, is enough to require further adjustment of the ADC? (The Astromomik filters are 1,0mm, Baader U and ZWO CH4 a bit more). No, that should not skew anything...(?)

Or do you mean that the RGB filters would benefit from individual ADC adjustments? (someone, please stop the planets from rotating so I don't spend the entire imaging window adjusting!)

Meanwhile, I have almost completed the mentioned optical train (scope&FTFocuser > FFC-Barlow > ADC > flip-diagonal > EFW > ASI290MM), the final adapter should arrive tomorrow.

Some more details:

The Vixen T2 Flip-Mirror will have a wide reticle eyepiece in the 90° output, to both help centering and of course facilitate ADC adjustment. I would think adjustment will be a whole lot easier seeing the full visible spectrum, and adjusting through the mono camera will be a lot harder, even through the luminance filter. But maybe there's something I don't see here.

The EP will be left parfocal with the sensor, using a locking ring with small set-screws, by a first time alignment forcusing at a star high above the horizon, with the ADC zeroed out.

Now let's get rid of these clouds..

Btw, adding the ADC and flip-diagonal is basically easy with the extendible Baader FFC Barlow, but I get forced up to approximately 4x magnification due to the lengthening. Checking the frame in SkyX:

Anyone doing f/40 or more with ASI290MM and various planets?

(Venus should do, but maybe not so great with the UV-pass filter)