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Aurora flatfield panel

flats ELP

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#1 k8jb

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Posted 14 July 2014 - 04:04 PM

Has anyone had experience with the Aurora flatfield panels? They look like a decent solution to finally being able to create good flats.

 

 

John


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#2 Neil

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Posted 16 July 2014 - 02:23 PM

I have one for my TOA130F and it works great. My only minor complaint would be regarding the power supply with dangles from the panel. This has pulled the wires lose and I have had to repair it myself with a soldering iron. That's not a problem for myself but it might be for others.

 

As far as flat fielding is concerned, I have no issues at all.

 

Clear Skies

 

 

Neil.



#3 OleCuss

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Posted 17 July 2014 - 02:19 AM

I'm rather interested in getting one of the flat panels.  Since the weight of the power supply is an issue I may just lengthen the power cord when I get it.  I think some people just fasten the power supply to the back of the panel, but I'm not sure how stiff the panel is and I suspect any bowing could cause some issues when shooting flats.

 

One of my bigger questions is whether the listed size is for the diameter of the mirror or for the diameter of the optical tube.  I'm thinking that for measurement purposes they are talking about the size of the optical tube since different telescope builders may use different sized tubes.

 

The other thing is, I have a number of telescopes ranging in size from 90mm to 12 inches.  They list the panels as being for scopes of less than 420mm or less than 315mm, etc.  But I'm wondering whether a <315mm really would fit well on a 90mm. . .  Especially since if you are shooting flats at a star party you'd want to put a drape over the thing to reduce the obnoxiousness of the light - and I'm wondering if the panel would be bowing under the additional weight over the much smaller OTA?

 

In reality I'd not likely use it on the 90mm OTA - I made a very nice flat panel for that and it works a charm.  But I do have a 102mm refractor and an 8 inch SCT with which I'd like to use the panel - as well as maybe trying some short exposure work with the 12 inch Dob (and maybe the 10 inch LX200).

 

Anyway, I'd appreciate your thoughts.



#4 woolbrig

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Posted 17 July 2014 - 03:40 PM

I bought one of these and made my own light box.  Works great for my SCT.

http://www.glowhut.c...-conne1212.html


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Joe

 

Scopes: Celestron C9.25/Hyperstar, SkyWatcher 80ED Pro, WO Star-71 II Mounts: CGEM (Hypertuned), CG5  Guiding: Orion SSAG/ST80/Mini 50, OAG  Cameras: ASI120MC, ASI174MM, ASI224MC, Canon T3i (Baader Mod), QHY10, QHY23

 


#5 OleCuss

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Posted 17 July 2014 - 04:55 PM

The price is certainly right!

 

Do you happen to have a photo of your lightbox?  Might be nice to see what works.



#6 OleCuss

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Posted 18 July 2014 - 12:48 AM

OK, I did some checking on the sizing questions.  The net effect comes out something along the lines of "buy a size larger than you expect to need".

 

So my 12-inch Dob's outside OTA diameter is 360mm.  The 315mm panel should be understood to have a flatfield diameter of 315mm but the overall physical diameter of the panel is 378mm

 

This means that the flatfield should fit fairly nicely on my 12-inch scope's OTA and that its 315mm flatfield area is larger than is the telescope's mirror.  Well, sorta maybe not quite that simple according to the relevant Gerd Neumann page:  http://www.gerdneuma...s-overview.html

 

The problem is that if I want to use a DSLR or CCD camera with the scope (which is sort of the reason for getting the flatfield panel in the first place), that 315mm panel is actually too small.

 

Determining the needed size for the flatfield area is done by adding the optical diameter of the telescope (305mm in this case) to the diagonal size of the camera (a little over 30mm in the case of my Mallincam Universe and maybe about 28mm for an APS-C sensor?).

 

So with a typical DSLR and superb positioning of the flatfield you actually need a 333mm flatfield.  With my MC Universe I need a minimum of 336mm.  Since positioning with millimeter accuracy is really unlikely it would probably be smart to add about 10mm.

 

So I actually need to get the 420mm panel for a 305mm scope using a typical camera.  If I use a 1/3 video camera I'd have a 6mm diagonal size and would be barely able to use the 315mm panel with the 305mm scope.

 

Much the same logic follows for the 220mm panel.  It was supposedly designed for use with 8-inch scopes, but according to the Gerd Neumann site, the flatfield is too small for use with a typical DSLR with an 8-inch scope.

 

 

It's kind of an odd size recommendation since you put the flatfield panel onto the end of the scope.  If you measure the inside diameter of my 8-inch SCT's OTA, it comes out to around 227mm.  So since the Gerd Neumann site would seem to be recommending the use of a flatfield of at least 233mm with my Mallincam Universe and that 8-inch OTA, they are recommending a flatfield which is larger than the diameter of the OTA!

 

I'm not at all sure the size recommendations make sense.  They seem to conflict with the stated purpose of the panels (220mm for 8-inch scopes, 315mm for 12-inch scopes, etc.) since the sizes don't fit the recommendation for typical use - and the size of the resultant flatfield exceeds the inside diameter of the relevant scope in at least some cases.

 

A little confusing. . .

 

DTVBA



#7 woolbrig

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Posted 21 July 2014 - 01:07 PM

Here are a few shots of the lightbox I built.  I used form board purchased from K-Mart and some white duct tape.  With my SCT I take exposures of .45 seconds.  I recently purchased some tracing paper to dim the light.  I want to try longer exposures to see if the flats are any different.  The nice thing about the tracing paper is that I can continue to add sheets to reach the desired exposure time.

 

I'm going to make another front with a smaller hole for my 80mm scope.  My plan is to just attach it to the front of the existing box with velcro.

 

 

 

Attached Thumbnails

  • LightBox1.jpg
  • LightBox2.jpg
  • Lightbox3.jpg

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Joe

 

Scopes: Celestron C9.25/Hyperstar, SkyWatcher 80ED Pro, WO Star-71 II Mounts: CGEM (Hypertuned), CG5  Guiding: Orion SSAG/ST80/Mini 50, OAG  Cameras: ASI120MC, ASI174MM, ASI224MC, Canon T3i (Baader Mod), QHY10, QHY23

 





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