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Old 18-04-2013, 02:17 PM
roughy (Mark)
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Flat Field Panels

Hello all

Does anyone have any views or experience with the Aurora flat field panel

http://www.gerdneumann.net/english/a...-overview.html

or the Spike-a flat fielder

http://www.spike-a.com/flatfielders/...FWoxpgodaF4Atw

Price seems to be consistent for both of the same size, up to 12", $200 or around. I'm not interested in a box as I'm always treading on the one I made a couple of years ago.

Cheers

Mark
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Old 20-04-2013, 11:51 AM
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RobF (Rob)
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What sort of camera are you shooting with Mark?
People with shutter cameras can struggle to drop the light intensity enough for sufficiently long exposures on flat panels (I believe).
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Old 20-04-2013, 12:49 PM
roughy (Mark)
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Hi Rob
Cooled CCD with a built in shutter. The Spike-a come with a control for the intensity, the Aurora doesn't.
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Old 20-04-2013, 01:03 PM
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multiweb (Marc)
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If you have a shutter (like a QHY9) and shoot a flat under 1s you might get the shutter shadow in your flat. So you'll need to lower the intensity of your panel. What I do is plug it into a dew heater control and lower the voltage. It will flicker very fast but you get the right levels this way and can shoot 2-4s flats no worries.
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Old 20-04-2013, 01:04 PM
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gregbradley
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I am interested in these as well. I have difficulty in making decent flats for my CDK17 inch scope.

I use a Proline 16803 and it requires 4 second exposures in flats to prevent the shutter showing up in the flat. 5 seconds would be safer.

I'll ask Gerd and post the response.

Greg.
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Old 21-04-2013, 08:22 PM
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strongmanmike (Michael)
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You mean one of THESE Mark..?

I love mine and Gerd can supply you with as many neutral density sheets as you like to dim it down if you want . I currently have one ND sheet in mine for the fast F3.8 12" AG12 and I have a second sheet that I figure I will need once I start using the shallower wells of the SX H694 soon.

The latest Aurora models are round (rather than my square version) too so there is less light leakage at star parties

One good thing I find is that my rear cell cooling fans suck the air out of my tube so when I place the Aurora Panel on the top of the scope it lightly sucks it down and holds it it on, which has proved a god send in my windy environment

Happy Aurora user

Mike
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Old 18-07-2013, 06:58 PM
jase (Jason)
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Bump

Interesting thread, I need more information and people's perspectives on this topic. I have for a long time been a proponent for sky flats. They've always worked well for me with the various scopes and imaging train configurations I've had.

However, I have come to acknowledge that with the new set up with the precision instrument rotator (PIR), I'm going to really struggle getting the needed flats done in the short period of available light at dusk and dawn. The PIR being a necessary evil for long guided images means flats taken at a PA of 0 must also be taken at a PA of 180 to handle meridian flips. This is not news to me and I well knew what I was getting myself into but I was seriously hoping that I could continue to use sky flats with the needed high output of flats.

Based on this I'm on the market for a flat panel. There seems to be a magnitude of vendors these days offering different bells and whistles. Here are my requirements;
  • Must endure the elements of being permanently mounted in the observatory. Its a reasonably clean environment but not pristine. Condensation can be bad at different times of the year. Heat, frost, wind etc. less of a problem
  • Should be easily mountable with the appropriate fittings to support the unit. I don't mind a trip to Bunnings to get other components as needed but I don't want to be making modifications to the unit itself just to mount it. So this is something I expect the vendor to supply. The mount will need to support adjustments so its perpendicular to the OTA
  • Must not require physical intervention to turn on or off. The observatory is operated remotely. I have an eight port remote power switch that I use to turn gear on and off as needed so this isn't too much of a problem providing it is as simple as turning it off and on. If there is some other initialization step that can't be performed remotely, the unit fails to meet this requirement.
  • Should be able to adjust the panel's brightness remotely and support a command line interface for the adjustments so that it can easily be scripted into ACP for automatic flat panel flats. This is a 'should' as opposed to a 'must' as I'm working on the principle that I could install an ND filter so that I reach a happy medium between both broadband and narrowband flat exposure times. Providing I don't get shutter shadow on broadband filters, the narrowband flat exposures can take as long as they need. In addition, at F/9 I'm likely to need all the light I can get.
  • Must be thin. Yeah sounds stupid as they're all thin, but I will emphasise this point as the telescope in the park position I have 4" of room between the telescope and the observatory wall. I may end up having a different flat position but the park location seems most logical. If I mount the panel on the dome itself I would have slightly more room between it and the telescope, however I then need to consider how to power and remotely control it, all on a rotating platform. Running it off the 12v shutter control battery is a less then desirable option (for obvious reasons).
  • Must have good vendor support, preferably a local agent and warranty offered.
Personally I don't think I'm asking much as I'm sure others have walked the path before me and are doing exactly what I want to achieve. I'm looking for unbiased input in order to select a product that matches these requirements.

Thanks
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Old 25-07-2013, 11:36 AM
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Oscar in Bin (John)
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Flat Field Panels

I recently purchased an Aurora panel from Gerd. Excellent prompt service. I run it on an f7 system with one ND filter and that gives me exposure times in excess of 6secs on colours when binned 2x2.
John
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Old 25-07-2013, 11:51 AM
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multiweb (Marc)
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So you're going to mount the panel on the inside of the dome permanently, park the scope then move the dome to face the aperture in parked position and shoot your flats?
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Old 25-07-2013, 01:18 PM
jase (Jason)
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Quote:
Originally Posted by Oscar in Bin View Post
I recently purchased an Aurora panel from Gerd. Excellent prompt service. I run it on an f7 system with one ND filter and that gives me exposure times in excess of 6secs on colours when binned 2x2.
John
Thanks John. I made contact with Gerd to seek some information on the panels he produces. He made comment that foil based flat panels with adjustable brightness controllers will result in an unreliable light source (foil brightness will vary too much over time). The only way to use these panels is at full brightness and utilise ND filters to drop the intensity as required.

It seems that only the Alnitak (now Optec Inc) flat panels support remote adjustment of brightness control. The important aspect here is that they don't use foil based flat panels. The challenge is the Flat-Man L is a tight fit to illuminating at 12.5" scope. 315mm optic on the 330mm Flat-Man L, so the only option is to go with a Flat-Man XL 18"x18" which is double the cost of the 480mm Aurora flat panel. Seems Gerd's solution is a hands down winner.

Based on your configuration (F/7 2x2 bin), I'd say I will be able to get away with one ND too. I'll purchase two to be sure but at F/9 I doubt I'll need it with the current configuration. Thanks for the input.

Quote:
Originally Posted by multiweb View Post
So you're going to mount the panel on the inside of the dome permanently, park the scope then move the dome to face the aperture in parked position and shoot your flats?
Hi Marc, I'm undecided as to where to mount it. I've highlighted the challenges in the previous post with dome mounting but I'm sure some ingenuity could make it work with an electrical contact between the dome and walls when at a certain position such as home. The wall would be easier but then it still needs to be high enough to ensure the aperture can easily reach it. The current telescope park position would likely meet this requirement but it will need some testing.

ACP 7.0 supports fully automated sky, dome and artificial light flats and I'll sure be looking to leverage this as I do today for sky flats. So what you mention is correct. The script can move both scope (Alt/Az) and dome (Alt) to a preset configuration, turn on the light source, tweak brightness (if applicable) on a per filter basis if desired, take your flats including rotated flats at different PAs), turn off the light source, then park dome and scope before powering all gear off. That would be a dawn scenario. The reverse will be applied for dusk.

My "light on" and "light off" command will simply be a terminal session string to the remote power switch to turn the flat panel power adapter on and off. Basic stuff.

Below is a snippet of the ACP config help to control this.

Flat Panel or Screen Section
Before editing this, run your light control program in a command window and make sure you can control the panel or screen and write down the exact commands given to do that. Testing this now will save you pain later.
    • DoFlatAlt & DoFlatAz - The alt/az coordinates needed for your scope to point at the panel or screen. For the FlipFlat, just pick something semi-horizontal. If these are commented out, the scope will not be moved. This allows you to manually put a light box onto the scope, for example.
    • DomeAz - If your dome needs to be rotated to a particular azimuth for light source positioning, indicate that here (otherwise leave it commented out).
    • PerFilterBrightness - This is a comma-delimited list of numeric values corresponding to each filter in your system. The values are in the same order as the filters. This lets you vary the light source brightness for each filter.
    • LightCtrlProgram - The full path and name for the light command line program for your light source (AACmd.exe for the FlipFlat/FlatMan). If this is empty or commented out, no program will be run to control the light.
    • LightOnCommand - The string to be given after the light control command to turn the light on. For the FlipFlat, include the C command to close the cover so the light source is in front of the optics. You can include #BRT# in this string, and ACP will substitute the per-filter brightness from the PerFilterBrightness list for the current filter.
    • LightOffCommand - The string to be given after the light control command to turn the light off. For the FlipFlat, include the O command to Open the cover so the light source is moved away from being in front of the optics.
    • LightOnDelay - Time in seconds to wait after the light is turned on for its brightness to stabilize. EL Panels especially can take some time to reach full brightness especially when it is cold.
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