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Newbie question: How the heck do I use the ZWO ADC?

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#1 Stargazer3236

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Posted 23 May 2017 - 02:49 PM

I see such great pics of Jupiter and Saturn with the ADC and I wonder how you do it? I would love to take images like that, but I cannot figure out how to use my ADC.

 

I have an Ioptron ZEQ25 mount. I know about the horizon alignment, but I cannot figure out how to adjust the levers to get rid of the Red and Blue tinge.

 

Any help would be appreciated.



#2 Guest_djhanson_*

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Posted 23 May 2017 - 07:26 PM

Basically, just keep the ADC level and frequently adjusted (maybe once per hour).  I eyeball my ADC for level by keeping the half-way point between the two knobs at about horizon (others sometimes mount a small level).  I adjust mine using Fire Capture 2.5 with its ADC tuning feature using my color cam ZWO224MC (try to get the red/blue circles as close as overlapped).  This is the step you may be looking for I think.  Generally for low altitudes, the knobs are further spread apart and as my imaging begins gaining altitude (e.g. from 30 to 50 degrees), I will be adjusting the knobs slightly closer together each time I re-adjust and checking via Fire Capture (if this makes sense).  Now I've made markings on my ADC for Jove for say 30 vs 50 degrees so that when I'm shooting mono ZWO290MM.  This works pretty well.

 

At least this method works pretty well for me.  John B. has some great ADC tutorials in the CN archives here.  cheers, DJ


Edited by djhanson, 23 May 2017 - 07:28 PM.

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#3 John Boudreau

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Posted 23 May 2017 - 09:01 PM

I'm not quite sure if your trying it out visually or trying to get it to work with a color camera, so I'll just give you a long-winded basic tutorial. lol.gif

 

The easiest way to get the feel of ADC adjustment is to first practice visually, preferably with an Alt-Az mount as the horizon reference doesn't change through the night.  Since you have one in the NexStar mount, can you put the C8 back on it for ADC testing? ADC use is also easier to learn viewing straight-through (no diagonal) if possible.

 

Once you have hands on experience getting it to work, you should be able to then figure out how to use it with an equatorial mount and diagonal. Many people have a 'eureka' moment and it becomes second nature even with different scope/mount setups.

 

A quick exercise first: Attached is an ADC polarity test image with minor color fringing. Some ADC's are made so that in an inverting scope, their levers should be pointing to the left; others should be pointing to the right. There are examples of this issue from more than one manufacturer. Both ways are correct and work equally well--- it's just that this complicates basic instructions. So looking at your computer screen through the ADC (with the ZWO the rotating scale marks should be facing you), start with the levers together and pointing to the left at the mid point of the lever slot overlap. For reference, rotate the scale ring with the white plastic screw also to the left and in-line with the levers and lightly tighten that white screw. Now spread the levers --- the one closest to you down; the other up. Use the white screw and the ring marks as reference to adjust each lever at equal distances from that white screw and try to find a lever position that eliminates the color fringing. *IF* your ADC is correcting the color fringing, it's what I call a 'left hand' ADC. If it's only making the color fringing worse, then simply rotate the ADC body so that the levers are pointing to the right, and adjust the levers to eliminate the fringing. In this case, the closest lever to you should be adjusted up; the other down. If this way works, it's a 'right hand' ADC.

 

Now onto  the real sky--- Assuming Alt-Az and no diagonal with your SCT, point the scope at Jupiter. Insert the ADC into the scope with the levers and white screw together, and with the levers pointing to whatever L or R direction that worked in the above test. Also make sure the levers and white screw are aligned with the horizon as best you can. The ADC should now be at zero correction--- the view would be similar to one without an ADC. Now spread the levers equally from the white screw as in the above test, and you should start to see the atmospheric dispersion cancel out. You should quickly find a best setting for the given altitude, or at least find yourself getting close to a good setting. The better the seeing, the easier it is to find the 'sweet spot'. If you have an eyepiece that's parfocal with your camera, many times the visual setting will be good enough for imaging. If you have a color cam, then you may want to tweak the ADC adjustment using the excellent ADC adjustment tool in FireCapture.

 

Diagonals complicate matters--- as if not pointed straight up they rotate the apparent horizon, complicating the horizon reference setting. Since diagonals vertically correct the image, they also require you to rotate the ADC--- If without a diagonal your levers were to the left; with a diagonal they should be to the right. Also, with an equatorial mount the horizon reference rotates as the planet traverses the sky. This is why the ZWO ADC has a rotating scale and white reference screw--- so you can update the horizontal reference setting and adjust the levers accordingly from the white reference screw. And remember that the lower the subject, the wider the lever spread to correct the dispersion.

 

DJ has given you excellent advice for once you're imaging with the ADC. To many people constantly fiddle with ADC adjustment as the planet moves through the sky. When the target is near the meridian, it's not uncommon to be able to go an hour in between adjustments--- after all, even a 90% correct setting is pretty tough to tell from a 100% setting. As a planet is on the rise or on the way down and well away from the meridian, it's altitude changes more quickly and you may find yourself needing corrections every 15 or 20 minutes or so.

Attached Thumbnails

  • ADC polarity test.jpg

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#4 Stargazer3236

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Posted 23 May 2017 - 09:21 PM

John, I tried your method and my ADC is a lefty. But other than that, I cannot, for the life of me, figure out how to get the blue and red merged, instead of separated.

 

So, I start out the the white set screw aligned with the horizon, the levers are situated on  top of each other over the set screw. And I separate the levers to get the blue and red tinges to merge, correct?


Edited by Stargazer3236, 23 May 2017 - 09:30 PM.


#5 John Boudreau

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Posted 23 May 2017 - 10:08 PM

John, I tried your method and my ADC is a lefty. But other than that, I cannot, for the life of me, figure out how to get the blue and red merged, instead of separated.

 

So, I start out the the white set screw aligned with the horizon, the levers are situated on  top of each other over the set screw. And I separate the levers to get the blue and red tinges to merge, correct?

Yes. Separate the levers evenly, in your case with the lever closest to you down and the scope-side lever up (move both towards the longer part of the lever slots, not their overlap area). This is assuming there is no diagonal or other erecting optic before the ADC. The mid-point between the levers should point along the horizon from the ADC's body. This can be referenced by the white screw on the rotating scale ring.

 

If you're setup for imaging and using FireCapture's ADC tool, be aware that it's quite sensitive--- especially to seeing. It's rare to get the ADC tool's colors perfectly aligned and steady in our typical NE seeing--- they are always bouncing around.

 

With Jupiter still reasonably high in the sky, your levers should not have to be spread very far apart. You will have to spread them noticeably further apart for Saturn though.


Edited by John Boudreau, 23 May 2017 - 10:11 PM.


#6 Stargazer3236

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Posted 23 May 2017 - 10:47 PM

In the optical train, where should I place the ADC?

 

As my current setup goes, I use a 2" visual back, with a 1.25" Rotolock adapter, then I place my filter wheel next followed by my Baader 4 EP turret, then my crosshair EP and two camera's. Should I place the ADC before the Filter wheel?



#7 John Boudreau

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Posted 24 May 2017 - 02:26 AM

In the optical train, where should I place the ADC?

 

As my current setup goes, I use a 2" visual back, with a 1.25" Rotolock adapter, then I place my filter wheel next followed by my Baader 4 EP turret, then my crosshair EP and two camera's. Should I place the ADC before the Filter wheel?

Yes. After your Rotolock, you should be using a 1.5 to 2x Barlow or telecentric amplifier, ADC, filter wheel, then camera/eyepiece. But some successfully put the ADC after the filter wheel, and some even put both the Barlow/telecentric amplifier and ADC after the filter wheel. The Baader turret may be adding too much projection distance to a Barlow, that's where a telecentric amplifier like the 1.25" 2x Explore Scientific Focal Extender or 2.5X Televue Powermate is a better choice as the magnification is more stable over longer projection distances. You could then probably use your turret without an issue. Ideally you want to shoot for about f/20 at the focal plane for a 3.75 micron pixel camera for proper planetary sampling--- a bit more is OK, but certainly no more than f/25. A 2.5x Televue Powermate actually decreases a bit in magnification as the projection distance increases.

 

However, you still should be seeing the ADC work well with the f/10 to f/12 you apparently have been working with. The lever spread will have to be more at those f-ratios vs. the ideal f/20 or so, but it should still work OK.



#8 gfstallin

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Posted 24 May 2017 - 10:39 AM

Thank you folks for asking and answering this question! Santa brought me an ADC last Christmas (how did he know?!?) and I tried it once, saw dancing circles, and placed it back in the imaging case. I've been sort of looking for instructions on figuring whether I have a lefty or a righty (will test later today) or what I was doing wrong (nothing, apparently).

 

George



#9 Chris Watts

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Posted 25 May 2017 - 01:32 PM

Basically, just keep the ADC level and frequently adjusted (maybe once per hour).  I eyeball my ADC for level by keeping the half-way point between the two knobs at about horizon (others sometimes mount a small level).  I adjust mine using Fire Capture 2.5 with its ADC tuning feature using my color cam ZWO224MC (try to get the red/blue circles as close as overlapped).  This is the step you may be looking for I think.  Generally for low altitudes, the knobs are further spread apart and as my imaging begins gaining altitude (e.g. from 30 to 50 degrees), I will be adjusting the knobs slightly closer together each time I re-adjust and checking via Fire Capture (if this makes sense).  Now I've made markings on my ADC for Jove for say 30 vs 50 degrees so that when I'm shooting mono ZWO290MM.  This works pretty well.

 

At least this method works pretty well for me.  John B. has some great ADC tutorials in the CN archives here.  cheers, DJ

Where in Fire Capture 2.5 is this ADC tuning feature???



#10 Chris Watts

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Posted 25 May 2017 - 01:41 PM

disregard my query, i found it....thanks....   Still however am not sure what i am aligning with the horizon???    The white nob and scale or the two bar sliders?  It is just not clear to me...sorry.



#11 Steve OK

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Posted 25 May 2017 - 03:34 PM

The white knob.  A line drawn from the white knob that passes through the center of the ADC should be horizontal:

 

ADC horizontal.png

 

The two long "arms" are not shown in the diagram, but will be symmetrically located on either side of the horizontal.

 

Steve

 


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#12 John Boudreau

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Posted 25 May 2017 - 03:55 PM

disregard my query, i found it....thanks....   Still however am not sure what i am aligning with the horizon???    The white nob and scale or the two bar sliders?  It is just not clear to me...sorry.

Chris, I had just posted to your ZWO ADC? thread:

 

https://www.cloudyni...-adc/?p=7903083

 

The reason why a horizon reference is important is because atmospheric dispersion occurs vertically, along a line perpendicular to the horizon. So for a rotating prism system to also create it's counter-acting dispersion along that same vertical line, the ADC levers need to be adjusted against a horizon reference.  



#13 moonwatching ferret

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Posted 26 May 2017 - 04:43 PM

I belive the horizontal line in the scope referes to how the horison apears in the focuser without an eyepiece . I heard the white nob needs to pe paralel to the actual ground which is when i see images of adc with a buble level on the white nob... dang these do hickies are confusing but i seemed to have mastered mine thank god.

 

 I also have a nice thread on the same topic



#14 GeorgeInDallas

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Posted 31 May 2017 - 02:24 PM

Can I just use a level next to the ADC to determine the horizontal setting of the ADC? I have no clear view of a horizon from my imaging location.

 

I have a C14 on a CGE Pro mount.

 

Where does the ADC go in the imaging train. My current setup is scope>Optec Focuser>Filter Wheel> 3x Barlow > ASI174MM camera. 

 

Placing the ADC between the Barlow and Camera will significantly increase the magnification of the Barlow. What is the width (space) required by the ADC?

 

George


Edited by GeorgeInDallas, 31 May 2017 - 02:31 PM.


#15 moonwatching ferret

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Posted 31 May 2017 - 05:12 PM

with 13 replies i assume you worked things out by now.. If y want to see where the horizon is in your scope take the eyepieces out and point it at your neighbors roof or an object that is parallel to the horizon, dont try and put your eye right up to the focuser but ull back  whatever is in the scopeds field of view should come into focus you can then see where your horizon is 



#16 John Boudreau

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Posted 31 May 2017 - 07:15 PM

Can I just use a level next to the ADC to determine the horizontal setting of the ADC? I have no clear view of a horizon from my imaging location.

 

I have a C14 on a CGE Pro mount.

 

Where does the ADC go in the imaging train. My current setup is scope>Optec Focuser>Filter Wheel> 3x Barlow > ASI174MM camera. 

 

Placing the ADC between the Barlow and Camera will significantly increase the magnification of the Barlow. What is the width (space) required by the ADC?

 

George

Yes, I use a level regularly as my roll-off observatory is on a slope.

 

The ADC should be after the Barlow. The ZWO ADC body is about 30mm long and has female T-thread at both ends.

 

If your 3x Barlow is a problem at that projection distance, then you may want to look at a telecentric-type focal extender. These usually keep about the same multiplying factor over fairly long separation ranges. The only one I know of that doesn't is the TeleVue 5x Powermate, all other Powermates are fairly consistent over a good range of separation. The only 3x telecentric type I know of is the 3x Focal Extender from Explore Scientific. Here is a link to the power chart for the Powermates:

http://televue.com/i...werIncrease.jpg

 

I have not used any of the Explore Scientific Focal Extenders nor do I know of a magnification chart for them, so I don't know if they vary much over different separations. Another option perhaps is either a 2x or 2.5x Barlow, with the added projection distance giving you about 3x. Here is the TeleVue Barlow power chart:

http://televue.com/i...werIncrease.jpg


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#17 Steve OK

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Posted 01 June 2017 - 02:47 PM

My 2x Barlow becomes about 2.8x with the ADC in the path.  That puts me just over the line into oversampling with my ASI120mc on my C11, I think.

 

Steve


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#18 lgwong

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Posted 02 June 2017 - 04:21 AM

Do you need to refocus after adjusting the ADC?



#19 james7ca

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Posted 03 June 2017 - 05:30 PM

One of the problems I've had with my ZWO ADC is that just as I get near to having the color fringing removed I hit the end of the slot that allows you to rotate the levers. I wonder if this is because the ADC was adjusted incorrectly by ZWO? Or, maybe it's the left side versus right side issue, since I think I've always used mine on the left side (I may have tried the right side once, but rather quickly and I didn't see much change in the behavior). On my last attempt, when using FireCapture's ADC alignment feature I found that the levers where nearly together and both right next to the end of one of the slots. But, it seemed that was all of the correction I needed since FireCapture was showing just a few units of displacement (bouncing around 0 to 1 or sometimes higher but intermittently going to zero). I've also never seen that much separation between the levers and in fact there is never much room to move them since one is always very near to the end of its slot.

 

In any case, it always seems that I'm right up against the range of travel although I've never tried to use it when Jupiter is low in the sky (which would seem to be an even worse situation as far as the allowed range of travel).



#20 Steve OK

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Posted 04 June 2017 - 09:33 AM

Do you need to refocus after adjusting the ADC?

Focusing is the last thing I check before starting to capture.  And check, and check.....

 

Steve



#21 james7ca

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Posted 22 July 2017 - 11:38 PM

I think I found my problem(s) with adjusting and using the ADC. I definitely have a right handed unit and thus the levers have to be on the right (most of the times I tried to use it on the left). Also, it looks like when using the ADC adjustment utility in Firecapture I can never get the indicator to show a low dispersion, but I think that is because my scope has residual chromatic aberration and to Firecapture that looks just like uncorrected atmospheric dispersion. I've always suspected that the Tele Vue NP127is isn't that well corrected for color, IMO it's more like a flat field ED scope rather than a true APO. This may just be another confirmation of that issue (with the scope).

 

However, when I used the ADC on my Celestron C6 I was able to adjust it so that Firecapture showed very little dispersion (on Saturn). So, at least I know that the ADC is working correctly.


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#22 Billytk

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Posted 23 July 2017 - 09:12 AM

One thing some people may need to keep in mind is if you are using a diagonal, you have to reverse your left/right hand orientation. My ADC is a right hand one, but if I am using my diagonal, I have to insert it in a left handed orientation for it to work. This may be messing people up thinking their ADC is not working when all along is that they have not taken account for the diagonal mirror flip. Also I have an Explore Scientific Focal Extender and it works like a Powermate and not like a Barlow.



#23 Stargazer3236

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Posted 20 August 2017 - 11:29 PM

Well, just to let you all know, I sold my ADC because after employing it numerous times, I could not get it to work or I didn't know how to properly use it or I could not tell the difference between a good image or a bad image. It was all too confusing for me and I would just get frustrated trying to use it, so I did the next best thing and gave it to someone else for a fair price.

 

Thanks for all your help just the same.



#24 James Cunningham

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Posted 21 August 2017 - 06:01 AM

Is the ZWO ADC, is it right sided or left sided on an SCT without a diagonal?  Thanks.

Jim



#25 Stargazer3236

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Posted 21 August 2017 - 06:46 AM

It depends. Use the chart above. Look through your ADC and follow the instruction below:

 

 

 

A quick exercise first: Attached is an ADC polarity test image with minor color fringing. Some ADC's are made so that in an inverting scope, their levers should be pointing to the left; others should be pointing to the right. There are examples of this issue from more than one manufacturer. Both ways are correct and work equally well--- it's just that this complicates basic instructions. So looking at your computer screen through the ADC (with the ZWO the rotating scale marks should be facing you), start with the levers together and pointing to the left at the mid point of the lever slot overlap. For reference, rotate the scale ring with the white plastic screw also to the left and in-line with the levers and lightly tighten that white screw. Now spread the levers --- the one closest to you down; the other up. Use the white screw and the ring marks as reference to adjust each lever at equal distances from that white screw and try to find a lever position that eliminates the color fringing. *IF* your ADC is correcting the color fringing, it's what I call a 'left hand' ADC. If it's only making the color fringing worse, then simply rotate the ADC body so that the levers are pointing to the right, and adjust the levers to eliminate the fringing. In this case, the closest lever to you should be adjusted up; the other down. If this way works, it's a 'right hand' ADC.

 

Diagonals complicate matters--- as if not pointed straight up they rotate the apparent horizon, complicating the horizon reference setting. Since diagonals vertically correct the image, they also require you to rotate the ADC--- If without a diagonal your levers were to the left; with a diagonal they should be to the right. Also, with an equatorial mount the horizon reference rotates as the planet traverses the sky. This is why the ZWO ADC has a rotating scale and white reference screw--- so you can update the horizontal reference setting and adjust the levers accordingly from the white reference screw. And remember that the lower the subject, the wider the lever spread to correct the dispersion.

 

 

 

Then you can determine how to use the ADC the way it should be used.




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