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ADC- essential for planetary?


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Just now, Moonshane said:

Would it improve low doubles like Sirius and Antares?

Yes. In theory the target is not relevant. However, optical quality will matter as will scattered and stray light.

Regards Andrew 

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Just back from another superb seeing evening with the planets and did a few comparisons of with and without the ADC. This is the last time i’ll do such a thing as there is really no point in looking a

I couldn’t resist a little mod. 😁 The Altair doesn’t have a bubble level so thought I would add one so bought a rifle scope bubble level with a 40mm bore which fits the ADC perfectly. Just for Alt

I was clouded out, as usual. However I now have this awesome light-sabre-contraption ready for next time. I just need to find a step ladder to be able to look down into it!

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11 minutes ago, Moonshane said:

Would it improve low doubles like Sirius and Antares?

yes- it really tightened up antares at the weekend and i “think” i split it but it was still noisy and i can’t be sure- need further confirmatory observation - if only it were summer...

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On 12/07/2020 at 13:12, markse68 said:

I’ve been playing with my Atmospheric Dispersion Corrector the last couple of nights and getting the clearest views I’ve ever had. I’m coming to the conclusion that it is an essential piece of equipment for planetary observing- at least while they’re low. Jupiter and Saturn were incredible last night with it-  very very sharp. Mars is looking more like a planet than an orange blob and the icing on the cake was Venus rising- without the adc a rainbow crescent but with it a tight crisp mini moon bar the wobbly atmospherics. It’s really been quite an eye opener! 

I guess the extra glass must take something away from the image but if the image is already blurred by AD then what it subtracts is more than made up for by what it corrects. Mine has uncoated prisms  so with my 18m bco on Jupiter I get 4 reflected jupiter’s around the edge but the glass being planar and angled these are off to the edge so don’t affect the important central image. I guess coated prisms would be better. shorter fl eps the reflections are out of view anyway. I’m using it with a 2x barlow.

Mark

Do you have the ZWO version (the Altair version appears similar), or one of the much more expensive Gutekunst versions.

I find that my ZWO helps a bit on Jupiter, in particular through my 14in Newtonian,  but would not say that it makes a dramatic difference, although possibly I'm not setting it up correctly. I also find that a Baader Neodymium filter helps on Jupiter, as otherwise the very bright image through my 14in, washes out a lot of the detail in the cloud belts.

John 

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I find my ZWO essential on low Jupiter and very beneficial on low Saturn.  Without ADC, low Jupiter in C8 is a mess, and blurry in Tak. Borg can take them on without ADC. For UK altitudes anything but the smallest refractor is just too much dispersion for my taste. I am 7 degrees to the south of you and I find it obtrusive in the past two years.

A brief overview of my recent comparison of ADC vs bino here https://www.cloudynights.com/topic/717134-c8-vs-4-inch-frac-binomono-on-planets/

Next time I will try bino with ADC. Will certainly be more difficult to pull off than with Gutekunst, but worth a try. 

The bigger the aperture the more I need it. ADC beats aperture - I find it better to look through C8 and ADC on Jup then through 12 inch dob without ADC.

The amount of correction is dependent of the altitude and focal lenth of the scope. So Tak with PM2.5 in front of the ADC needs as much correction as C8 with ADC only.

 

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2 hours ago, johnturley said:

Do you have the ZWO version (the Altair version appears similar), or one of the much more expensive Gutekunst versions.

Those Gutekunst ones are a bit erm pricey aren’t  they 😳
I figured I would have focus issues with any of them without major rework of my scope so I made my own.

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1 hour ago, markse68 said:

Those Gutekunst ones are a bit erm pricey aren’t  they 😳
I figured I would have focus issues with any of them without major rework of my scope so I made my own.

The Pierro Astro one isn't exacvtly cheap either

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I just ordered the Altair one too. Will be interesting to see how well it works. If nothing else it will give me more impetus to observe!!

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The prices of the others puts into perspective how amazingly affordable much great quality telescope gear is these days when you compare what you get for the price you get it for.

And still we moan 😂😂

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1 hour ago, markse68 said:

Those Gutekunst ones are a bit erm pricey aren’t  they 😳
 

HOW MUCH !!!! Just looked on APM website, are they layered in Gold 🙀

Edited by bomberbaz
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31 minutes ago, bomberbaz said:

HOW MUCH !!!! Just looked on APM website, are they layered in Gold 🙀

I expect you’d pay similar for a nicely engineered gear driven  Risley prism from an optical house- it’s really a luxury item that a few on the other forum seem to own. It’s USP apart from ease of use is the doublet prisms with planar faces that seem to mainly prevent image wander when adjusting but you’re putting another piece of glass in there too 🤷‍♂️ I have to keep nudging the dob anyway so simple prisms work fine 😉

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It's probably only really bought by professional OBS and people with £30k scopes, then it's a cheap part of the chain😵

Does anybody have any idea please how long the path is through the Altair or zwo units?  

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i think 40mm

Edit- sure i read that somewhere and thought it was too high but looking at specs of the ZWO unit i think it must be closer to 60mm. They say the body height is 30mm but then you’re shifting the ep out further with the ep adapter. Strange neither of them spec for this

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DE88B15D-9075-4E35-8093-5DC51D35997F.jpeg

Edited by markse68
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There are a lot of very helpful contributions to this thread that have got me wondering if I've been using my ADC optimally, next time I'm out I'm going to try some different approaches and pay closer attention to what I'm doing.

If I've been using it incorrectly that will be embarrassing but on the plus side it would also mean I've got some more improvements in the views to look forward to!

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6 minutes ago, Paz said:

There are a lot of very helpful contributions to this thread that have got me wondering if I've been using my ADC optimally, next time I'm out I'm going to try some different approaches and pay closer attention to what I'm doing.

If I've been using it incorrectly that will be embarrassing but on the plus side it would also mean I've got some more improvements in the views to look forward to!

You did say what scopes you're using Paz but I can't remember but the other thing to bear in mind is they suffer quite bad distortions in faster scopes from what I heard- recommendation seems to be f10+ and in faster to use a barlow. Mines f8 and I'm using 2x barlow

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4 hours ago, bomberbaz said:

The Pierro Astro one isn't exacvtly cheap either

The main difference is it uses fused silica prisms rather than BK7 or equivalent which are more expensive but is transparent into the UV.  So it is better for Venus UV imaging unless you have UV eyes.

Regards Andrew 

Edited by andrew s
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4 hours ago, bomberbaz said:

The Pierro Astro one isn't exacvtly cheap either

Yup but that MK3 looks fine with single button adjustment, makes me wonder whether it is easier to use than ZWO.

3 hours ago, johninderby said:

Look forward to finding out what apertures and focal lenghs get the greatest benefit from the ADC. 🤔

More aperture - more dispersion but I really do not thing it is user friendly in a dob. ZWO says get it over f/10, so PM 2.5 in Tak before ADC and without barlow in C8. The shorter the f/l the more astigmatism is introduced.

3 hours ago, Paz said:

There are a lot of very helpful contributions to this thread that have got me wondering if I've been using my ADC optimally, next time I'm out I'm going to try some different approaches and pay closer attention to what I'm doing.

If I've been using it incorrectly that will be embarrassing but on the plus side it would also mean I've got some more improvements in the views to look forward to!

Check out whether it is a left-handed or right-handed one. Here's a useful info on how to check your orientation (mine is right-sided but in a refractor and SCT with a diagonal the white knob goes to the left).

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3 hours ago, markse68 said:

i think 40mm

Edit- sure i read that somewhere and thought it was too high but looking at specs of the ZWO unit i think it must be closer to 60mm. They say the body height is 30mm but then you’re shifting the ep out further with the ep adapter. Strange neither of them spec for this

64BD1A22-B5E8-4176-8B10-93A60862FD65.jpeg

DE88B15D-9075-4E35-8093-5DC51D35997F.jpeg

I've read somewhere that it is approx 50mm. Useful info if you are using a PM or a barlow in front or a binoviewer after the ADC in order to calculate the resulting mags.

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The Altair ADC uses CDGM's H-K9L glass instead of BK7 but apoarently it is the same formulation just a different manufacturer.

Should work well in the CC8” f/12. 🤔

83042563-8458-450B-B547-EC1F760F26C1.jpeg

Edited by johninderby
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9 hours ago, johninderby said:

The Altair ADC uses CDGM's H-K9L glass instead of BK7 but apoarently it is the same formulation just a different manufacturer.

Should work well in the CC8” f/12. 🤔

83042563-8458-450B-B547-EC1F760F26C1.jpeg

It will work very well, indeed. Just make sure to check whether it's a righty or a leftie.

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23 hours ago, Stargazer McCabe said:

I bought mine after having a cuppa with a friend of mine, Es Reid. One afternoon we were discussing planetary observing (before lockdown brought a stop to our regular face to face natters) and he asked whether I used one. When I confessed that I didn't he explained what a considerable difference he felt his had made to his observing through a number of telescopes and from a number of locations. Given his eminently more qualified eyes and his opinion that he wouldn't  observe the planets without it now, I bought my own and can also appreciate the difference they make... 

I had the exact same conversation with Es when he was servicing one of my scopes! I should really try one but I have the same concerns as some of the other members on this thread i.e. something else to faff with and I only use binoviewers so even more back focus required and more prisms in the optical chain.

Edit: I also saw on the FLO website that the recommendation for the ZWO unit is to get the ADC as close to the eyepiece as possible, which I wouldn't be able to do with a binoviewer. Eye placement when using binoviewers is also key for me. If I am not dead on it is easy to introduce unwanted colour so I may be chasing that with an ADC also.

Edited by astro_al
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