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ADC Question - What am I missing?

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#1 John Miele

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Posted 07 January 2018 - 03:40 PM

My ADC has a ring with a white screw. This ring can be loosened and rotated to any orientation. I assumed the white screw was supposed to be lined up with the middle of the overlap of the two slots. If that is the case, then why is this ring adjustable? Why wouldnt there just be a fixed marker/screw located in the correct position that you use to orient the prisms parallell to the gorund? Am I missing something fundamantal here? You ar enot suppoed to monkey with the white set screw are you?...Thanks...John



#2 Pitter

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Posted 07 January 2018 - 05:08 PM

Both the white set screws are moved equidistant from each other and are set for the particular altitude of the target.  It's a dance that takes practiced trial and error.   The ADC is pretty much useless below f/10 so hopefully your scope is at least there or higher.



#3 John Miele

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Posted 07 January 2018 - 05:19 PM

I understand that part. I'm talking about how you orient the entire ADC unit in the focuser befroe you start tot move the levers apart. Trying to use the white set screw to be parallel to the horizon but the ring with the white set screw can move!



#4 John Miele

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Posted 07 January 2018 - 05:23 PM

Ok. I guess if I just set the white set screw and ring like this I should be ok?

 

 

Attached Thumbnails

  • 1.25“ADC.jpg

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#5 John Boudreau

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Posted 07 January 2018 - 05:43 PM

>Why wouldnt there just be a fixed marker/screw located in the correct position that you use to orient the prisms parallell to the gorund?

 

That would work well for a leveled Alt-Az mount, as the horizon reference wouldn't change wherever you pointed the scope--- you'd only have to adjust the prism lever spread to adjust the ADC's dispersion to properly counteract that of the atmosphere. However many use an ADC on an equatorial mount, and as an EQ mount moves across the sky it's horizon reference changes. The rotating ring scale and white screw are intended as a way to update the horizon reference now and then to aid in lever adjustment as the EQ mount tracks across the sky. To allow at least a few hours of adjustment before running out of lever slot travel, the lever slots are quite long and have about 60° of overlap.

 

 

>I assumed the white screw was supposed to be lined up with the middle of the overlap of the two slots.

 

It can be set up that way to allow easily referenced adjustment for tracking a target along a path several hours before through several hours after the meridian--- and that's probably a good way to start to familiarize yourself with how the ADC and scale works. But it doesn't have to be set up that way as long as you can assure that you'll have enough lever travel for adjusting the prisms during your planned observation period. Once you get the hang of adjusting the thing it'll become self explanatory.

 

 

Also, it's a good idea to find out if you have what I call a left-hand or right-hand ADC:
https://www.cloudyni...-adc-important/


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#6 phileefan

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Posted 07 January 2018 - 06:20 PM

John,

 

I glued a bubble vial onto the white screw so that I can keep it level. Hope this helps you! 

 

 

 

20170430_114014a.jpg


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#7 Pitter

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Posted 07 January 2018 - 06:25 PM

Yup.  Just like 'phileefan' has it.  waytogo.gif ​ You will have to adjust it from time to time as the mount moves away from parallel.



#8 Pitter

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Posted 07 January 2018 - 06:36 PM

>Why wouldnt there just be a fixed marker/screw located in the correct position that you use to orient the prisms parallell to the gorund?

 

That would work well for a leveled Alt-Az mount, as the horizon reference wouldn't change wherever you pointed the scope--- you'd only have to adjust the prism lever spread to adjust the ADC's dispersion to properly counteract that of the atmosphere. However many use an ADC on an equatorial mount, and as an EQ mount moves across the sky it's horizon reference changes. The rotating ring scale and white screw are intended as a way to update the horizon reference now and then to aid in lever adjustment as the EQ mount tracks across the sky. To allow at least a few hours of adjustment before running out of lever slot travel, the lever slots are quite long and have about 60° of overlap.

 

 

>I assumed the white screw was supposed to be lined up with the middle of the overlap of the two slots.

 

It can be set up that way to allow easily referenced adjustment for tracking a target along a path several hours before through several hours after the meridian--- and that's probably a good way to start to familiarize yourself with how the ADC and scale works. But it doesn't have to be set up that way as long as you can assure that you'll have enough lever travel for adjusting the prisms during your planned observation period. Once you get the hang of adjusting the thing it'll become self explanatory.

 

 

Also, it's a good idea to find out if you have what I call a left-hand or right-hand ADC:
https://www.cloudyni...adc-important/'

Your original post on this was what helped me figure out that mine was a 'Righty'.   Sure sped things up for me after that.  


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#9 Thundermoon1994

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Posted 09 January 2018 - 09:22 AM

John,

 

I glued a bubble vial onto the white screw so that I can keep it level. Hope this helps you! 

 

 

 

attachicon.gif20170430_114014a.jpg

You, Phileefan, are a genius!

 

 

Damien


Edited by Thundermoon1994, 09 January 2018 - 09:22 AM.


#10 phileefan

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Posted 09 January 2018 - 07:23 PM

Damien,

 

I can't take credit for this idea, Kokatha man originally had a post awhile back that showed a bubble vial attached to his ADC. This was just my take on the idea! waytogo.gif  Take care.......................

 

Here's the link to Darryl's post on this: https://www.cloudyni...kokatha man adc

 


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#11 John Miele

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Posted 09 January 2018 - 09:19 PM

I think I get it now! Thanks for the help...now where's my bubble level...that mod looks too good to pass up!



#12 moonwatching ferret

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Posted 09 January 2018 - 11:02 PM

 

>Why wouldnt there just be a fixed marker/screw located in the correct position that you use to orient the prisms parallell to the gorund?

 

That would work well for a leveled Alt-Az mount, as the horizon reference wouldn't change wherever you pointed the scope--- you'd only have to adjust the prism lever spread to adjust the ADC's dispersion to properly counteract that of the atmosphere. However many use an ADC on an equatorial mount, and as an EQ mount moves across the sky it's horizon reference changes. The rotating ring scale and white screw are intended as a way to update the horizon reference now and then to aid in lever adjustment as the EQ mount tracks across the sky. To allow at least a few hours of adjustment before running out of lever slot travel, the lever slots are quite long and have about 60° of overlap.

 

 

>I assumed the white screw was supposed to be lined up with the middle of the overlap of the two slots.

 

It can be set up that way to allow easily referenced adjustment for tracking a target along a path several hours before through several hours after the meridian--- and that's probably a good way to start to familiarize yourself with how the ADC and scale works. But it doesn't have to be set up that way as long as you can assure that you'll have enough lever travel for adjusting the prisms during your planned observation period. Once you get the hang of adjusting the thing it'll become self explanatory.

 

 

Also, it's a good idea to find out if you have what I call a left-hand or right-hand ADC:
https://www.cloudyni...adc-important/'

Your original post on this was what helped me figure out that mine was a 'Righty'.   Sure sped things up for me after that.  

 

 I payed 500 dollars for a set of aluminum rings and put my optics in a solid tube so I can always keep my focuser level if the white screw is turned away from the neutral position then one level will be corectend then the other so in a sence im even still confused. will the white screw ever be placed of set from the neutral position??? still not getting the pic lol im a confused ferret and confusing a ferret can be dangerous 



#13 moonwatching ferret

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Posted 09 January 2018 - 11:08 PM

this is how i feel over the whole thing lol

https://www.youtube....h?v=JGKeTelc3-g

its actualy an ermine



#14 kevinbreen

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Posted 10 January 2018 - 03:10 AM

Mine is a righty, I checked, several times. Two evenings ago I tried imaging the moon shortly after it rose. I moved the ADC levers in accordance with the advice on threads by above posters, but the process introduced colour fringing.

So, what the hell??

I moved the levers too much?
It’s actually a lefty ADC?

It’s a pain in the backside, frustrating doesn’t even come close.

#15 John Boudreau

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Posted 10 January 2018 - 06:24 AM

Mine is a righty, I checked, several times. Two evenings ago I tried imaging the moon shortly after it rose. I moved the ADC levers in accordance with the advice on threads by above posters, but the process introduced colour fringing.

So, what the hell??

I moved the levers too much?
It’s actually a lefty ADC?

It’s a pain in the backside, frustrating doesn’t even come close.

Are you using the ADC straight-through or with a diagonal? What is the typical altitude of the subjects you're observing/imaging? I assume you're using the scopes listed in your sig?



#16 kevinbreen

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Posted 10 January 2018 - 09:32 AM

Hi John. Thanks for the reply. It’s straight through, no diagonal and yes the scope is the Nexstar 8SE.

#17 kevinbreen

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Posted 10 January 2018 - 11:11 AM

I forgot to mention, the altitude was around 20 degrees....

#18 moonwatching ferret

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Posted 11 January 2018 - 01:21 AM

you may want to try moving the levers in the opposite direction that eft and right pic could be confusing. its kind of like polar alignment using drift it confuses me the other night i was moving my mount the wong direction if you leave the levers at neutral and the image looks good then you dont need the adc another thing i personally nticed is in fc adc tuning you have to have the planet in center of roi when the planet drifts to one side the little animation of eric cartman changets. thats what the little red blue white dot looks like to me... one of the south park characters lol. if the image ets better when you move the levers to the short side of the slt rotate the adc 180 degree is backwards.  lastly somebody needs to comment on the cute video i posted a link to it reminds me of how i felt learning or trying my adc for the first few nights **** till daryl set me straight.... just trying to also have some fun around here


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#19 moonwatching ferret

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Posted 11 January 2018 - 01:24 AM

John,

 

I glued a bubble vial onto the white screw so that I can keep it level. Hope this helps you! 

 

 

 

attachicon.gif20170430_114014a.jpg

i thought it was level with the horizon as seen in the focuser it changes in a newt on a gem as the tube rotates thats why i bought tube rings for my 16



#20 Kokatha man

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Posted 11 January 2018 - 04:34 AM

For the imaging trains of some folks the comments I made in my most recent thread about making sure you get enough distance between the ADC "output" & the camera sensor is very relevant...this is to ensure the dispersion from the ADC's prisms is wide enough to see good dispersion & correct for it - John Boudreau takes credit for this suggestion btw... wink.gif

 

If you position the camera too close to the ADC output you are not going to get sufficient dispersion a lot of the time & it will seem to make your ADC appear useless!

 

For SCT users, operating their ADC's at f10/11 (ie, native scale) appears very adequate for good ADC performance from the ZWO unit...this means that placing the barlow after the ADC you may be able to control the resultant image scale a bit better - that and a little extra distance to the camera also ensuring that spread I mentioned first...better than having your barlow before the ADC (ie, nearer the focuser) & getting larger amplification because of the distance to the camera from the barlow, which usually means you jam the camera up too near to the ADC output. wink.gif


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#21 kevinbreen

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Posted 11 January 2018 - 09:22 AM

For the imaging trains of some folks the comments I made in my most recent thread about making sure you get enough distance between the ADC "output" & the camera sensor is very relevant...this is to ensure the dispersion from the ADC's prisms is wide enough to see good dispersion & correct for it - John Boudreau takes credit for this suggestion btw... wink.gif

 

If you position the camera too close to the ADC output you are not going to get sufficient dispersion a lot of the time & it will seem to make your ADC appear useless!

 

For SCT users, operating their ADC's at f10/11 (ie, native scale) appears very adequate for good ADC performance from the ZWO unit...this means that placing the barlow after the ADC you may be able to control the resultant image scale a bit better - that and a little extra distance to the camera also ensuring that spread I mentioned first...better than having your barlow before the ADC (ie, nearer the focuser) & getting larger amplification because of the distance to the camera from the barlow, which usually means you jam the camera up too near to the ADC output. wink.gif

Thanks Darryl, I had read that post and the image train was in this order - ADC, DSLR. No Barlow was employed as I was shooting the Moon in its entirety (utilizing a f/6.3 focal reducer also to fit the entire disk on the sensor). So I take it from what you say that maybe there wasn't enough distance from ADC to sensor to allow the ADC to correct the light. In which case, I shouldn't be using the ADC at all for full-disk moon shots....

I nearly tried Jupiter this morning at 6am but it was cloudy on and off, and bitterly cold, so reluctantly (and somewhat relieved) I was able to return to bed for another hour. 

If I'm reading you correctly when you say

 

"this is to ensure the dispersion from the ADC's prisms is wide enough to see good dispersion & correct for it"

 

then it's just not possible to see the actual dispersion if the cam is too close to the ADC, and the image looks "OK",and it's for this reason that some distance has to be introduced to exaggerate the dispersion in order that it can be corrected visually (using FC ADC tuning tool, for ex). Right?

 

And sorry for this quick question - can the ADC can be used to correct the dispersion a star and not just planets? If so I intend practicing on a few at different altitudes.



#22 Kokatha man

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Posted 11 January 2018 - 07:09 PM

<"this is to ensure the dispersion from the ADC's prisms is wide enough to see good dispersion & correct for it"

 

then it's just not possible to see the actual dispersion if the cam is too close to the ADC, and the image looks "OK",and it's for this reason that some distance has to be introduced to exaggerate the dispersion in order that it can be corrected visually (using FC ADC tuning tool, for ex). Right?">

 

What we found was that despite FireCapture's tuner displaying dispersion of the channels no amount of adjusting of the ADC could compensate...John suggested the greater distance from ADC to camera would assist due to the ADC providing greater dispersion over greater distance there - & "yes" the next time we imaged this fact was clearly demonstrated. smile.gifwaytogo.gif

 

I have no idea how the Moon would respond to the ADC...we shot the Moon at only 12° with our vintage f15 80mm Dai Ichi Kogaku refractor the other week without an ADC...you can see it in the "6" & under..." small bore thread here somewhere - no problems but we weren't thinking about colour & were using an ASI174MM camera...as I understand it, trying for colour on the Moon requires really ramping up the saturation in post-processing fwiw - my only understandings thereon...so I have nfi on using a colour camera & ADC on it. wink.gif

 

I see no reason why not re the star testing btw...


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#23 moonwatching ferret

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Posted 11 January 2018 - 10:46 PM

nobody comented on my cute vid of a confused weasel yet aww so cute



#24 John Miele

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Posted 12 January 2018 - 01:51 PM

Hey "ferret"...I loved the video! Reminded me of that little animated critter that is always trying to get a hold of an acorn in the ice age movies! ...John



#25 moonwatching ferret

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Posted 12 January 2018 - 06:22 PM

it reminds me of all those nights trying to figure my adc lol




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