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Best way for flats

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#1 makeitso

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Posted 17 March 2019 - 08:48 PM

Hi everybody,

 

I’m wondering what the best way to make flats is. I’ve heard several different ways of doing it. I’ve tried a few of them. I’ve tried the t-shirt method. I’ve tried point to the sky in the day time. Neither of those seemed to work that great.

 

I don’t have a computer screen big enough to cover the 8” newt and don’t want to buy one.

 

I thought about getting an el-light but I can’t find one big enough for cheap. If you know of one that would cover an 8”, let me know.

 

I also thought about getting a sketch pad, the kind with the light behind it. Would that work or would it be to uneven?

 

Ir

 

If there’s a way to make one, I’m up for that. Any and all options are on the table. I’ve searched and some stuff but nothing that does what I’m looking for.

 

Thanks, Jack



#2 bobzeq25

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Posted 17 March 2019 - 09:02 PM

Hi everybody,

 

I’m wondering what the best way to make flats is. I’ve heard several different ways of doing it. I’ve tried a few of them. I’ve tried the t-shirt method. I’ve tried point to the sky in the day time. Neither of those seemed to work that great.

 

I don’t have a computer screen big enough to cover the 8” newt and don’t want to buy one.

 

I thought about getting an el-light but I can’t find one big enough for cheap. If you know of one that would cover an 8”, let me know.

 

I also thought about getting a sketch pad, the kind with the light behind it. Would that work or would it be to uneven?

 

Ir

 

If there’s a way to make one, I’m up for that. Any and all options are on the table. I’ve searched and some stuff but nothing that does what I’m looking for.

 

Thanks, Jack

"Best" way without stating a budget gets you the best way, budget independent.  I (and others here) use this, think it's the best.  It's been carefully designed to be just that.  No t-shirts needed, point the scope vertical, put it on top and shoot.  Does a superb job.  Much easier and less fussy than anything else I've tried, and I've tried a lot.  Up to 12".

 

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

 

You did say you were open to any and all options.  <smile> This is not a status symbol.  It merits the highest praise that can be said about any equipment.

 

It      Just     Works


Edited by bobzeq25, 17 March 2019 - 09:09 PM.

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#3 makeitso

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Posted 17 March 2019 - 11:11 PM

bobzeq25,

 

That looks like a great way to do it, probably the best way. $250 is a little more than I wanted to pay though. Is that the only one made? Is there a cheaper, similar item available? For that price, I could get a flat panel monitor which could be useful for other things as well.

 

I will search more.

 

I would like to keep it under $100, less would be better.

 

Thanks, Jack



#4 bobzeq25

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Posted 18 March 2019 - 01:37 AM

bobzeq25,

 

That looks like a great way to do it, probably the best way. $250 is a little more than I wanted to pay though. Is that the only one made? Is there a cheaper, similar item available? For that price, I could get a flat panel monitor which could be useful for other things as well.

 

I will search more.

 

I would like to keep it under $100, less would be better.

 

Thanks, Jack

People use a variety of seemingly similar, often much cheaper panels.  But they're not specifically made for flats, they're art tracing panels and the like.  Their uniformity is suspect.  Best bet is to find one that someone has used for flats, and can vouch for.  But you won't know if they really can tell how good their panel actually is.

 

I've used a monitor.  It didn't seem to work all that well, and was a pain to get setup perfectly perpendicular to the scope, which is necessary.

 

There are threads here.  Here's one.  You can see the variability of opinions and experiences.

 

https://www.cloudyni...ed-or-el-panel/

 

With cheap panels people often use t-shirts.  And/or rotate the panel, say, every 5 frames of 30 total.  I chose to spend the money and not fuss with things like that or worry about whether the panel was good or not.  I've never seen a bad review of the Spike-A-Flat.


Edited by bobzeq25, 18 March 2019 - 01:45 AM.

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#5 ippiu

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Posted 18 March 2019 - 03:03 AM

I usually use it. It does the job. I'm happy with it.

https://www.teleskop...wer-supply.html


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#6 makeitso

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Posted 18 March 2019 - 08:50 AM

Thanks!

 

What do you guys think about this one?

 

https://www.ellumigl...14in-circle-kit

 

Meanwhile, I’m reading a thread.

 

Thanks, Jack



#7 bobzeq25

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Posted 18 March 2019 - 09:29 AM

Thanks!

 

What do you guys think about this one?

 

https://www.ellumigl...14in-circle-kit

 

Meanwhile, I’m reading a thread.

 

Thanks, Jack

It could work fine.  Just don't have enough information.  I'd try to look for reviews.


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#8 makeitso

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Posted 18 March 2019 - 09:41 AM

Thanks, yes that’s a problem. It’s an unknown. I haven’t been able to find any reviews on it. They do have PayPal, so I might be covered. I’m not sure how to find out if it works or not, even if I tried it. I’m still looking.

 

As usual, nothing is simple in astronomy, especially if it involves a camera.

 

Thanks, Jack



#9 saguaro

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Posted 18 March 2019 - 10:19 AM

Hi Jack,

 

I use the larger (A2) version of this one for my 14-inch SCT, but the A3 version which is smaller would work for an 8-inch scope: https://www.amazon.c...00?ie=UTF8&th=1

 

It works great, since it uses a 3-step brightness control (not continuous brightness control, which results in rolling horizontal bands when taking flats). I use it on the lowest brightness setting. I added some layers of translucent paper found at an Art Supply store (Canson Opalux Translucent Paper) to dim the brightness even further (since I need to take flats at F/2). You may not need the extra layers if you are working at a slower focal ratio.


Edited by saguaro, 18 March 2019 - 10:27 AM.

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#10 OleCuss

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Posted 18 March 2019 - 10:29 AM

Thanks!

 

What do you guys think about this one?

 

https://www.ellumigl...14in-circle-kit

 

Meanwhile, I’m reading a thread.

 

Thanks, Jack

 

I have the kit but it is important to realize that what you are getting is a suitable EL panel which is not supported and not designed to fit on your OTA.  It is not stiff and should not be expected to work without doing at least something to it.

 

I'm planning on using a styrofoam ring (meant for wreaths) and then use plexi-glass-type material and foam cutting gear to come up with a sort of light box to fit onto the OTA.  I'm sure it will work but it is not like getting a Spike-A where it is already set up for you.

 

Do note also that OPT Corp sells the GERD Neumann set of Aurora flat field panels:  https://optcorp.com/...ns/gerd-neumann  You can get one to fit.

 

One other thing?  If you get the EL panels and make your own system for fitting to your OTA you can make one which scatters very little light about.  That means you could be in a star party and do your flats without bothering others much (or at all).


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#11 makeitso

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Posted 18 March 2019 - 11:40 AM

seguaro,

 

Thanks for the link! Those are some of the ones I’ve been looking at. You are using this and it works good? That’s basically is on the top of my list now. My 8” newt is an f5 so it should work good.

Do you use it at star parties? Have you masked it so it doesn’t bother other people?

 

OleCuss,

 

Thanks for the reply and information! So it is just the el light and the power adapter? I would put it in something like cardboard to make it stiff or do what you’re doing with the craft foam. I saw one that had been put in a foam column that fit over the end of the scope. The problem with that is when the light is on the whole column glows.

 

The ones on optcorp are a little costly for me.

 

Thanks, Jack



#12 OleCuss

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Posted 18 March 2019 - 12:50 PM

Yes.  You get the power adapter and the EL panel.  That's it.

 

Do note that if you find that you have a disturbing glow coming through the foam you can simply paint the thing or put duct tape all over it.

 

For that matter, I'll put the thing together (some day) using only glue and tape - and maybe only tape.  If you use some of the glow tape from Duck Tape you'll find it easier to find and orient the thing when you want to do your flats.


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#13 makeitso

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Posted 18 March 2019 - 12:57 PM

Duct tape and another one of its many uses!

 

I think I’m setup now, just have to decide for sure which one I want to go for. If anyone else wants to chime in, I’m listening.

 

Thanks, Jack



#14 saguaro

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Posted 18 March 2019 - 02:45 PM

seguaro,

 

Thanks for the link! Those are some of the ones I’ve been looking at. You are using this and it works good? That’s basically is on the top of my list now. My 8” newt is an f5 so it should work good.

Do you use it at star parties? Have you masked it so it doesn’t bother other people?

 

Yes, I use the larger one and it has worked great for taking flats. I would not recommend it at a star party after dark unless you are in an area where other folks are doing EAA using monitors to display images and so dark-adaptation is not an issue. If you do want to use it at a star party, you can probably use it after sunset but before the sky is fully dark, so it would not interfere too much with folks who are trying to preserve their dark adaptation. Also, if you can leave your camera set up on your scope between sessions, you won't have to take another flat (unless you change filters or make some other change to the imaging train).

 

You could also throw a small light-blocking blanket or similar over it when you’re using it and that would probably work at star parties.


Edited by saguaro, 18 March 2019 - 03:10 PM.

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#15 makeitso

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Posted 20 March 2019 - 09:38 AM

Yes, I use the larger one and it has worked great for taking flats. I would not recommend it at a star party after dark unless you are in an area where other folks are doing EAA using monitors to display images and so dark-adaptation is not an issue. If you do want to use it at a star party, you can probably use it after sunset but before the sky is fully dark, so it would not interfere too much with folks who are trying to preserve their dark adaptation. Also, if you can leave your camera set up on your scope between sessions, you won't have to take another flat (unless you change filters or make some other change to the imaging train).

 

You could also throw a small light-blocking blanket or similar over it when you’re using it and that would probably work at star parties.

I ordered the a3 sized one. I figure I can use this out of the box at home and modify it so I don’t bother others at star parties. I’m thinking it will work on any of the scope I have. I only use the 8 and 6” with a camera. The achromatic doesn’t take good pictures. 

 

Thanks, Jack



#16 39.1N84.5W

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Posted 29 March 2019 - 06:08 PM

Another CN guy takes live flats for free just before sunset. Using the sky. I have yet to try it but will do so soon.
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