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Equipment Discussions >> Electronically Assisted Astronomy

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greg
scholastic sledgehammer


Reged: 01/25/05

Loc: Central Ca.
Re: The new Universe is in and working new [Re: mallin]
      #5461497 - 10/09/12 12:53 AM

Quote:

John,

You misunderstood my post. A output of 3" or more is required to avoid vignetting. When I tested on a SCT, the baffled draw tube where the mirror rides on is simply too small and too long in some case thus creating vignetting. But when I tried on on a Ritchey-Chretien optical tube (VRC 10), it has a 3"+ output at the rear where no vignetting were present. We tested the same on a TeleVueis and results were spectacular to say the least.

Hope this clear the misunderstanding.

Regards,
Rock Mallin




So output does mean output... Thanks for clearing that up Rock.
I used 3" focuser (output) for this same reason... the wide light cone of my f3.3 would cause vignetting with a 2" focuser.

GregW

Edited by greg (10/09/12 01:17 AM)


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nytecam
Postmaster


Reged: 08/20/05

Loc: London UK
Re: The new Universe is in and working new [Re: greg]
      #5461590 - 10/09/12 03:35 AM

Quote:

Quote:

John,You misunderstood my post. A output of 3" or more is required to avoid vignetting. When I tested on a SCT, the baffled draw tube where the mirror rides on is simply too small and too long in some case thus creating vignetting. But when I tried on on a Ritchey-Chretien optical tube (VRC 10), it has a 3"+ output at the rear where no vignetting were present. We tested the same on a TeleVueis and results were spectacular to say the least.
Hope this clear the misunderstanding. Regards,
Rock Mallin


So output does mean output... Thanks for clearing that up Rock.I used 3" focuser (output) for this same reason... the wide light cone of my f3.3 would cause vignetting with a 2" focuser.GregW


Ummm...So we need an expensive Ritchey-Chretien (VRC 10), TeleVue or equal with a 3" aperture focuser to avoid vignetting via the x0.5 FR

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greg
scholastic sledgehammer


Reged: 01/25/05

Loc: Central Ca.
Re: The new Universe is in and working new [Re: nytecam]
      #5462056 - 10/09/12 12:44 PM

I think it depends on back focus, If (big IF) I understand it right, the problem (Which is common) is the long tube that the primary mirror slides in and out for focusing an SCT OTA. I don't have that problem with a Fast Newtonian.
I think this another case of trade off's which often happens when we mix and match equipment. With so many types of scopes, adaptors, camera's, and so on.... Trade off's are unavoidable.

GregW


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Dwight J
scholastic sledgehammer
*****

Reged: 05/14/09

Loc: Lethbridge, Alberta, Canada
Re: The new Universe is in and working new [Re: nytecam]
      #5462241 - 10/09/12 02:34 PM

Thinking of purchasing a Universe Nytecam?

Edited by Dwight J (10/09/12 02:35 PM)


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Jack Huerkamp
Vendor - Waning Moon


Reged: 10/13/05

Loc: Louisiana
Re: The new Universe is in and working new [Re: greg]
      #5462313 - 10/09/12 03:16 PM

Greg,

I am working on getting an adapter from Dean at Starizona for my 11" HyperStar. The FOV will be 1.5x2.5 degrees at f/2. Deam mentioned that the maximum diagonal chip size for the 11" HS is 27mm, but the Universe has a 28.4mm diagonal CCD sensor. Dean says it will work.

More to follow.

Jack


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wolfman_4_ever
Pooh-Bah


Reged: 07/15/11

Loc: El Segundo, Ca, So. Cal
Re: The new Universe is in and working new [Re: mallin]
      #5462563 - 10/09/12 05:31 PM

Quote:

Hi,

The ccd sensor used is a Sony ICX413AQS scientific grade class 0 only. Nothing else is used. Standard ICX413AQ is fine but does not have the sensitivity and low noise of the ICX413AQS. These sensors are very difficult to obtained.

Rock M.




Ah that's right... THE CHIP DUMMY! (referring to me).. Very nice.. The science grade chips are sweet.. And class 0 to boot? Excellent.....(As Mr. Burn's would say.....)


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GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: The new Universe is in and working new [Re: wolfman_4_ever]
      #5462744 - 10/09/12 07:42 PM

Vignetting with focal reducers has two primary sources.

1) The far field obstructor. Examples include the inner opening on SCT primary baffles, or Newtonian secondary mirrors. Due to their considerable distance from the focus, any vignetting they introduce is seen as a more gradual fall-off in illumination, beginning immediately from the edge of the circle of full illumination.

2) The near field obstructor, which here is the reducer's clear aperture. The vignetting introduced here is of a more rapid fall-off somewhere near the field edge, the 'sharpness' of the shadowing being due to the relative nearness of the the reducer to the focus.

A reducer in a cell of 2" OD does *not* require a 3" rear opening on the scope. Even a 2" opening is good. In fact, said rear aperture need be hardly larger than the reducer's clear aperture. Remember, the only light getting through to the focus is that which enters the reducer's front aperture; light outside this is of no account.

The Universe's 28.4mm diagonal demands of a reducer working at 0.5X a clear aperture of *at least* 2" if near field vignetting is to be minimal. This is impractical for most scopes. And so there is a sharp fall-off near the edges on the long dimension. But the component of far field vignetting, upon which the near field vignetting is superimposed, is not itself affected by the reducer, beyond the expected reduction in scale of the illumination profile. That is, whether a 0.5X reducer has a small or large clear aperture, the far field vignetting is the same, but the too-small reducer aperture superimposes its own component of sharper fall-off inside the field edge.


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mallin
Vendor - Mallincam Video


Reged: 01/27/11

Loc: Ontario Canada
Re: The new Universe is in and working new [Re: nytecam]
      #5462761 - 10/09/12 07:52 PM

Quote:

Quote:

Quote:

John,You misunderstood my post. A output of 3" or more is required to avoid vignetting. When I tested on a SCT, the baffled draw tube where the mirror rides on is simply too small and too long in some case thus creating vignetting. But when I tried on on a Ritchey-Chretien optical tube (VRC 10), it has a 3"+ output at the rear where no vignetting were present. We tested the same on a TeleVueis and results were spectacular to say the least.
Hope this clear the misunderstanding. Regards,
Rock Mallin


So output does mean output... Thanks for clearing that up Rock.I used 3" focuser (output) for this same reason... the wide light cone of my f3.3 would cause vignetting with a 2" focuser.GregW


Ummm...So we need an expensive Ritchey-Chretien (VRC 10), TeleVue or equal with a 3" aperture focuser to avoid vignetting via the x0.5 FR




Hi,

That depends of you telescope choice. Make sure if you use large sensors that your scope will be compatible to it. many SCT have a small and long mirror draw tube and cause vignetting to camera when used with a focal reducer. Just makes sense here. If you go too wide (field of view) some undesirable effect may result thus choosing the right telescope for the job is necessary. Good planning good judgement is key before spending all kind of money on stuff that may not be compatible to your telescope.

Low cost telescope = money saved. But will have to spend again to get it right with many new cameras on the market today. Its all up to you and about your budget.

At least we come forward saying "you need at least 3" of rear optical output".

Rock M.


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johnnyha
Postmaster
*****

Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: The new Universe is in and working new [Re: mallin]
      #5508813 - 11/07/12 06:21 PM

Any more updates, reports or news about the Universe?

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nytecam
Postmaster


Reged: 08/20/05

Loc: London UK
Re: The new Universe is in and working new [Re: johnnyha]
      #5510250 - 11/08/12 04:59 PM

Quote:

Any more updates, reports or news about the Universe?


Agreed - it's a month since the last report

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Lorence
scholastic sledgehammer


Reged: 09/15/08

Re: The new Universe is in and working new [Re: johnnyha]
      #5510328 - 11/08/12 05:46 PM

Quote:

Any more updates, reports or news about the Universe?




I've started using a script that combines the Universe software with Deep Sky Stacker Live. Really enhances the video like aspects of the camera. I'm very pleased with the results.


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geminijk
scholastic sledgehammer


Reged: 04/03/08

Loc: TN
Re: The new Universe is in and working new [Re: Lorence]
      #5515176 - 11/11/12 10:16 PM

Quote:



I've started using a script that combines the Universe software with Deep Sky Stacker Live. Really enhances the video like aspects of the camera. I'm very pleased with the results.




So anything to share with us? Any video of that working?

john


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Raginar
Postmaster
*****

Reged: 10/19/10

Loc: Rapid CIty, SD
Re: The new Universe is in and working new [Re: geminijk]
      #5515337 - 11/12/12 12:11 AM

I think they're posting them all in the Mallincam forums. I'd recommend heading over there. It would be nice to have a larger discussion on CN though.

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