69 replies to this topic

[rob.0919]

Thankyou for reviewing this Denis.

It looks a thing of beauty.

 

I've often wondered how they perform, and when i brought my TEC140  back in 2018 i noticed they are listed in the TEC 'accessories' section.

 

Could it help me spot the elusive Sirius B 'pup star'  ? Maybe but its an expensive way of finding out......

[noisejammer]

... Could it help me spot the elusive Sirius B 'pup star'  ? Maybe but its an expensive way of finding out......

The 'Pup' isn't actually that difficult with my 6". I find that contrast is the crucial factor but there are several field stars of similar brightness (11^m), so it helps to know where to look.

 

This chart may help - it's dated but you can advance 25 years from 1999 and you'll find Sirius B is about 10 arcsec NE of Sirius A. (The orbital period is 50 years, so you can also go backward to 1974.)

 

It's useful to have a pretty good idea how large 10" appears in your scope. It's about 1/4 the diameter of Jupiter at opposition or about half the diameter of Saturn.

 

Of course, you also need a steady, transparent sky. I can't help with that.

[vicuna]

is this only for planets / moon?

[Sarkikos]

No way I would pay $5,447 or $4003 for this gizmo.  $1482 is closer to what I'd spring for, but still extravagant.  It would probably make more sense to put that money toward a larger aperture with better optics.

 

Mike

[noisejammer]

is this only for planets / moon?

Chromatic aberration - whatever its source - is most obvious on bright objects. That does not mean it does not occur when observing faint objects at lower elevation. It principle then, you may get a boost in apparent brightness when observing stars at fairly high magnification. An example might be when chasing close doubles.

 

The real issue is whether you can resolve the chromatic aberration. This plot comes from the technical notes supplied with my ADC by Pierro-Astro. This was measured at sea level.

 

 

The point is that even at an elevation of 30 deg, you will see a blur corresponding to 1 arcsec. If you can resolve this, the energy is being spread over a larger area and a star will be dimmed. On the other hand, if you live under the jet stream, the atmosphere will usually stir things up more than 1.5 arcsec and there's no benefit.

 

For reference, almost everyone can resolve 1 arcsec at about 120x, so dispersion is pretty much always there if you have a steady sky.

[Jan-S]

No way I would pay $5,447 or $4003 for this gizmo.  $1482 is closer to what I'd spring for, but still extravagant.  It would probably make more sense to put that money toward a larger aperture with better optics.

 

Mike

It's certainly in the realm of diminishing returns. But some people may have limited-aperature scopes for a variety of reasons, other than financial, and seek to extract the most out of them. I have to carry the OTA a few stairs up, out into the garden, and then onto a pier. So, anything larger than a 16 cm or so apo is not likely to get used much. There are other factors too: a larger scope cools slower, it is affected more by less-than-perfect seeing, and, I believe, need longer F-ratios to achieve the same optical excellence if it's a refractor.

 

I found ADCs a bit rough mechanically, and hence hard to get right, but the Gutekunst certainly is not. Very robust and very smooth in use.

[Sarkikos]

It's certainly in the realm of diminishing returns. But some people may have limited-aperature scopes for a variety of reasons, other than financial, and seek to extract the most out of them. I have to carry the OTA a few stairs up, out into the garden, and then onto a pier. So, anything larger than a 16 cm or so apo is not likely to get used much. There are other factors too: a larger scope cools slower, it is affected more by less-than-perfect seeing, and, I believe, need longer F-ratios to achieve the same optical excellence if it's a refractor.

 

I found ADCs a bit rough mechanically, and hence hard to get right, but the Gutekunst certainly is not. Very robust and very smooth in use.

I understand the size constraints for observers who live in cities or live in condos or apartments with no private yard.  But I've always seen more surface detail on planets and the Moon with larger aperture.  If the seeing is so bad that it would seriously limit the potential of a telescope, I don't bother with planets that night.  I observe deep sky instead. 

 

Mike

Edited by Sarkikos, 30 May 2024 - 11:14 AM.

[denis0007dl]

I received Gutekuns ADC, Serial Nr. 115, with incredible testreport with Strehl 0.999, love it.

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Edited by denis0007dl, 27 June 2024 - 04:09 PM.

[denis0007dl]

Powermates 2x and 4x ready for ADC usage in T2 system format...

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[turtle86]

All comparisons are valid, fair and above all, instructive. 

 

5000 EU is about $5,447.  Wow.  That's even more expensive than the NVD kit I've been putting off for the last ten years.  I think I'll be keeping my ZWO ADC!

 

At the Gutekunst website, the price of the compact ADC is 3675 EU.  That's about $4003, so a bit less than the average starter setup for NVD.  

 

Mike

 

I had the ZWO for a while myself and thought it was well enough made and got the job done.  But I'm also basically lazy and just didn't feel like having one more gizmo to fiddle with, so after a few times I stopped using it and eventually sold it off. I'm more of a DSO observer than a planet observer anyway.  For my purposes I'm content simply to wait until a planet is better placed in the sky before observing it.  It helps of course that I have good seeing where I observe and I'm at a lower latitude.  If I were more of a planetary enthusiast and lived further north, I probably would've kept the ZWO and would maybe even consider the Gutekunst unit.  It's very expensive but looks to be very well made.  For what it's worth Yuri at TEC really likes it.

[Deadlake]

Is there any comparison of the Gutekunst compact versus the APM adc, https://www.apm-tele...rsion-corrector ?
Apart from the Gutekunst having a larger aperture hard to find out the differences.

[denis0007dl]

Is there any comparison of the Gutekunst compact versus the APM adc, https://www.apm-tele...rsion-corrector ?
Apart from the Gutekunst having a larger aperture hard to find out the differences.

There were few CN posts where users favour Gutekunst both mechanically and optically.

I personally didnt compared them.

 

Denis

[vahe]

The 'Pup' isn't actually that difficult with my 6". I find that contrast is the crucial factor but there are several field stars of similar brightness (11^m), so it helps to know where to look.

 

 

 

I had no problems in seeing the Pup in my 155 F9 with binoviewer at roughly 250x.

 

I had two problems in identifying the Pup, one problem is the intensity of Sirius A which creates a ghost image within prisms of my Zeiss binoviewer, as I try to center the main star a ghost image starts to move in from the opposite direction, once the two are merged the Pup is the only star next to the bright Sirius A and is easy to identify, (the ghost image is almost as bright as the main star).

 

Good seeing is essential, your geographic location (latitude) makes big difference, I am at latitude 29.7 so the Sirius is reasonably high in my sky.

 

Also a minimal glass eyepiece with low scatter is very helpful.

 

The two are currently at about the widest separation therefore increasing chances of seeing the Pup.

.

Vahe

[Bearcub]

Someone who is constantly at 15-60 altitude i think this could benefit. I dont know how much it would help but maybe someday i will save up for it. Great review.

 

Small question: how often were you adjusting the ADC? every 5minutes even at same target?

[denis0007dl]

I had no problems in seeing the Pup in my 155 F9 with binoviewer at roughly 250x.

 

I had two problems in identifying the Pup, one problem is the intensity of Sirius A which creates a ghost image within prisms of my Zeiss binoviewer, as I try to center the main star a ghost image starts to move in from the opposite direction, once the two are merged the Pup is the only star next to the bright Sirius A and is easy to identify, (the ghost image is almost as bright as the main star).

 

Good seeing is essential, your geographic location (latitude) makes big difference, I am at latitude 29.7 so the Sirius is reasonably high in my sky.

 

Also a minimal glass eyepiece with low scatter is very helpful.

 

The two are currently at about the widest separation therefore increasing chances of seeing the Pup.

.

Vahe

Yep, ghost image is provided by Gutekunst ADC, very true!

Same its on both my Mark V and APO SS and Maxbright II binoviewers.

 

Denis

[adamckiewicz]

I use a Pierro-astro mk3 adc.
The scope is a 16” f4 dobsonian.
I use :
- powermate x4 with t-ring, to reach F/D 16, for the ADC works best between F15 and F20
- adc (t2)
- baader Quick changer, that allows the orientation of the binoviewer
-denk2 with t-adapter (I use takahashi 32mm abbe, panoptic 24, ES 14mm 82°, delite 11mm)

The adc is a real game changer with Saturn being low above the horizon!!

Edited by adamckiewicz, 13 September 2024 - 10:24 AM.

[denis0007dl]

I use a Pierro-astro mk3 adc.
The scope is a 16” f4 dobsonian.
I use :
- powermate x4 with t-ring, to reach F/D 16, for the ADC works best between F15 and F20
- adc (t2)
- baader Quick changer, that allows the orientation of the binoviewer
-denk2 with t-adapter (I use takahashi 32mm abbe, panoptic 24, ES 14mm 82°, delite 11mm)

The adc is a real game changer with Saturn being low above the horizon!!

That, same for Jupiter and Mars!

Edited by denis0007dl, 13 September 2024 - 01:34 PM.

[Solar storm]

I’m sold.  I’m getting one 

[adamckiewicz]

Here is a sketch with the set up , August 22, poor seeing, Saturn at 20° above horizon. Magnification 300x.

 

All these details were not visible without the ADC.

[C0rs4ir_]

Its funny how much money people spend on Apo refractors for the last bit of color correction and then use these apos without adc, turning the precious scopes effectively into china ed refractors.

You forgot to mention the ADK from Greatstar, which is of similar quality and principle, but with only 17mm of clear aperture. I have one of these and can confirm your findings compared with the cheap ones. Just logic if the observed object stays on the optical axis + excellent quality prisms.

Edited by C0rs4ir_, 02 October 2024 - 11:47 AM.

[dcornelis]

I have the Greatstar ADK sold by APM, the BIG advantage of the Greatstar and Gutekunst when used on non coma free designs like classic SCT, Classic cass, and even corrected DK types is that they keep your already small well corrected field over your small chip and dont make you move to a lesser corrected part of the focal plane. It can also be seen as tilting of the fov in the cheaper versions. I use the greatstar with excellent result in my Mewlon 300. 

[adamckiewicz]

I have the Greatstar ADK sold by APM, the BIG advantage of the Greatstar and Gutekunst when used on non coma free designs like classic SCT, Classic cass, and even corrected DK types is that they keep your already small well corrected field over your small chip and dont make you move to a lesser corrected part of the focal plane. It can also be seen as tilting of the fov in the cheaper versions. I use the greatstar with excellent result in my Mewlon 300.

Even with newtonians , this adc will avoid the coma. And it works better than the standard adc with focal ratio faster than f15. That means you can use it with f3 big dobsonian and powermate x4

[vicuna]

can someone please explain the limitations of 17mm clear aperture vs 24? (i'd be using it visually only)

 

is the quality of the prisms similar with the Greatstar and Gutekunst?

 

ease of use?

 

tyty!!!

[C0rs4ir_]

can someone please explain the limitations of 17mm clear aperture vs 24? (i'd be using it visually only)

 

is the quality of the prisms similar with the Greatstar and Gutekunst?

 

ease of use?

 

tyty!!!

 

17mm aperture means you are limited to eyepieces with a field lens diameter of 17mm (or camera chipsize of max 17mm). Since the ADC usually is used with higher magnifications i personally dont feel very limited by this (im using the Greatstar ADC). And if you use a barlow before the ADC this limitation gets even smaller and one should be able to use eyepieces with even larger field lenses (havent tried).

 

"is the quality of the prisms similar with the Greatstar and Gutekunst?"

 

I assume so.

 

"ease of use?"

 

Dont know what difficulties with an ADC can arise, but with the Greatstar or Gutekunst you have one lever less to handle, so i guess even easier then the ZWO versions.

 

Youre welcome.

[Stewc14]

I’m thinking of selling the stowaway to be able to buy expensive adc.