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Flatfield EL panel options


strutsinaction
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Hi

I'm after a flatfield EL panel to use with my FSQ85 + QSI690. Any recommendations and what I should avoid?

I see that the Widescreen Centre sell the 160mm Gerd Neumann Aurora flatfield panel for £65. I think this is a popular choice although the cabling seems to be a weak point and it doesn't have a dimmer.

As a cheaper alternative, has anyone considered something like this:

http://www.amazon.co.uk/gp/product/B00J3NRAV2/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A23HHFRIW02ZZW

This retails for £36 and is dimmable, and powered via USB.

Thanks for any advice!

Regards

John

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I use one for my DSO images with my modded DSLR camera and it is excellent - far better than the LED lightbox that I made and used originally.  The only problem that I have heard of is that it may not be suitable for narrowband imaging as it may not produce an evenly distributed spectrum.  No doubt someone will be able to confirm this.  When I look at the histogram of mine (in RGB) it does give three more or less equal strong peaks. one in each colour.

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John


The aurora panels are reasonable value and you can custom build a box around it to suit your telescope setup and imaging needs.



You can spend a lot more...





There was some mention that HitecAstro may be bringing out a range of light panels but not sure if this is still ongoing.


Mike 

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I've used the Lightbox from amazon on my C8 SCT. It does work though you need a lot of flats due to the PWM dimmer. Even on maximum brightness there are light/dark stripes, I take a few hundred frames and the even out and produce a nice flat frame.

James

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Thanks, folks! Some interesting info here.

I've used the Lightbox from amazon on my C8 SCT. It does work though you need a lot of flats due to the PWM dimmer. Even on maximum brightness there are light/dark stripes, I take a few hundred frames and the even out and produce a nice flat frame.

James

Thanks James. The issue with PWM dimming has put me off this option somewhat.

Roger

I use one for my DSO images with my modded DSLR camera and it is excellent - far better than the LED lightbox that I made and used originally.  The only problem that I have heard of is that it may not be suitable for narrowband imaging as it may not produce an evenly distributed spectrum.  No doubt someone will be able to confirm this.  When I look at the histogram of mine (in RGB) it does give three more or less equal strong peaks. one in each colour.

Do you also see light/dark stripes in your flats when using the Amazon panel?

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I use a netbook. Open up paint and then make it full screen. Gives a very consistent light across the whole screen.

Peter

Hi Peter

I like this idea and have heard of other doing this too. I don't have a permanent setup and will be doing my flats indoors so this would work well for me. I can try my iPad screen and see how that performs. I assume the panel needs to be right up against the OTA?

Regards

John

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Hi

I'm after a flatfield EL panel to use with my FSQ85 + QSI690. Any recommendations and what I should avoid?

I see that the Widescreen Centre sell the 160mm Gerd Neumann Aurora flatfield panel for £65. I think this is a popular choice although the cabling seems to be a weak point and it doesn't have a dimmer.

As a cheaper alternative, has anyone considered something like this:

http://www.amazon.co.uk/gp/product/B00J3NRAV2/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A23HHFRIW02ZZW

This retails for £36 and is dimmable, and powered via USB.

Thanks for any advice!

Regards

John

A good EL panel suitable for AP flat fielding must have its RGB aligned. If there is colour bias it will cause all sorts of problems in NB and RGB imaging.

A.G

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A good EL panel suitable for AP flat fielding must have its RGB aligned. If there is colour bias it will cause all sorts of problems in NB and RGB imaging.

A.G

Hi A.G

Well, I do intend doing NB in the future so maybe the Aurora will be the better choice for my setup.

I have a QSI690 WSG-8, with all filters in place, sealed and currently spotless. For LRGB, I was hoping to get away with capturing L flats only rather than having to do L, R, G and B. Is that a valid approach? I think I read in another thread that this is what Ollie does. Similarly for NB, is it fine to capture just the Ha flats and use the master flat for OIII and SII. Again, is this a valid approach?

Regards

John

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Hi A.G

Well, I do intend doing NB in the future so maybe the Aurora will be the better choice for my setup.

I have a QSI690 WSG-8, with all filters in place, sealed and currently spotless. For LRGB, I was hoping to get away with capturing L flats only rather than having to do L, R, G and B. Is that a valid approach? I think I read in another thread that this is what Ollie does. Similarly for NB, is it fine to capture just the Ha flats and use the master flat for OIII and SII. Again, is this a valid approach?

Regards

John

Olly's system is more or less sealed so if yours is just as clean then a Lum flat will do so long as the ADU values are not widely different. This may mean adjusting the illumination level by some means. I am not a fan of using copy machine papers so reduce the light level as most of these although appearing white to eye actually have a vey heavy blue bias due to bleaching.

A.G

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Thanks, A.G. Yet another variable to consider ;-)

Gerd Neumann supplies ND foil that fits inside the Aurora to reduce the brightness (shame there's no dimmer dial). Iwonder ow many layers would I need to get within 20k-30k ADU for the very sensitive QSI690.

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Thanks, A.G. Yet another variable to consider ;-)

Gerd Neumann supplies ND foil that fits inside the Aurora to reduce the brightness (shame there's no dimmer dial). Iwonder ow many layers would I need to get within 20k-30k ADU for the very sensitive QSI690.

With a 690 the life should be easy as it has an electronic shutter that can go down to 1/1000th of a second so you adjust the exposure to get the ADU to about 20000, as long as the frequency of the inverter is not around 1/1000th. The problem is with cameras with mechanical shutter such as a 383L that needs a minimum of 3 seconds for taking flats otherwise the shutter will throw a shadow on the flat frame.

A.G

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With a 690 the life should be easy as it has an electronic shutter that can go down to 1/1000th of a second so you adjust the exposure to get the ADU to about 20000, as long as the frequency of the inverter is not around 1/1000th. The problem is with cameras with mechanical shutter such as a 383L that needs a minimum of 3 seconds for taking flats otherwise the shutter will throw a shadow on the flat frame.

A.G

Cheers, A.G. I think I'll order the Aurora 160mm and see how I get on. I may also add an ND foil too (they're cheap). I'll see what Gerd has to say too.

Once again, thanks for the excellent advice!

Regards

John

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Quick update and thanks for all the advice.

In the end I ordered the Aurora 160mm flatfield panel from Gerd Neumann with a couple of ND foils and a cigarette lighter plug (rather than the banana plugs). Possibly overkill (iPad or laptop screen *may* have been ok). Looking forward to taking some decent flats soon!

Regards

John

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Quick update and thanks for all the advice.

In the end I ordered the Aurora 160mm flatfield panel from Gerd Neumann with a couple of ND foils and a cigarette lighter plug (rather than the banana plugs). Possibly overkill (iPad or laptop screen *may* have been ok). Looking forward to taking some decent flats soon!

Regards

John

Hi John,

The practice of using ipad or laptop for flat fielding illumination is not something that has appealed to me. Considering the number of times that I have dropped the EL panel on the grass I would have been in dire straights had these been an ipad or else so I think that you have made the right decision. Once you get your Gerd Nuemann panel please do take precautions to make sure that the flimsy connection wires to the foil are protected from being ripped off just in case you drop the heavy inverter or the panel. Good luck.

A.G

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The Aurora panel arrived earlier this week. I'm using it with a 0.9 ND filter and it works really well.

Taking flats is so easy with the SGPro Flats Calibration Wizard. I specified a mean ADU of 30000 for filters L, R, G and B and let the wizard do its thing. The wizard takes a series of test exposures for the first filter, adjusting the exposure time until the mean ADU is 30000 +/- 500. The required number of flats are then taken at that exposure. This is then repeated for the next filter, and so on. Finally the filter specific-exposure times are then saved to the profile. Great stuff!

The flats showed that I had vignetting in all 4 corners (to be expected I guess). So, I decided to recalibrate a recent set of M45 subs using the flats since I hadn't moved the camera or focus. I was amazed at the difference this made to the final image which I have posted to the Imaging - Deep Sky thread if you're interested (http://stargazerslounge.com/topic/234541-m45-in-lrgb/).

Regards

John

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One minor clarification to my last post. The SGPro Calibration Wizard doesn't take the flats, it simply works out the optimum flats exposure time required for each filter and binning level. To take the flats you add the appropriate events to a sequence. The exposure time is automatically updated depending on the filter and binning level selected.

Regards

John

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