Capture More Flattering Images For FREE (or maybe $35) - Astrophotography Flat Frames

Flat frames are the simplest way to improve your astrophotography images. They are fast, cheap and easy to add into your work flow. Let's discuss the best ways to take them, how many you should take, and see what improvements they make to your final image.
Electroluminescence Panel: www.aliexpress.com/item/32893...
I use the A4, pink off white on, DC12V inverter version
Timestamps:
0:00 Take Flat Frames
1:06 The Magic Of Flats
2:15 Flat Frame Details
2:46 What Is A Flat Frame
3:58 How To Take Flat Frames - Method 1
6:55 How To Take Flat Frames - Method 2
8:24 How To Take Flat Frames - Method 3
9:01 Exposing Your Flats Correctly
10:14 How Many Flats To Take
10:56 Flat Image Comparison
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[@starpartyguy5605]

I have a c9.25. I made flat frame tool with an el panel. I found an old square edge picture frame. I bought a 1/8 inch milk white plastic to cover the front as a diffuser. I bought a black piece of plastic for the back. I taped the el panel to the inside of the black plastic and mounted the diffuser panel in front. I image at star parties. So I got some black foam board and made a mask for the front. I can take my flats without people complaining about the light.

[@andywray3446]

FWIW: I use a flat panel tracing board set on its lowest level and aim at an exposure time for each filter that ends up with a median ADU of around 13,000; that seems to work well in general. Flats really are the easiest thing to take as they are really short exposures: place the tracing board on top of a scope that is pointing straight up at the end of an imaging session and shoot all of them for multiple filters in probably less time than a couple of imaging shots.

[@JohnMcGFrance]

Although I know many use the paper or t-shirt method, the issue I have with it is the non-repeatability. This means every time you take them you need to work out the correct exposure. Also, the t-shirt can add dust quite easy=ily to the scope so your flats aren’t even accurate compared to the original subs. I’d very much recommend the flat panel of tablet route. So much easier. You can take flats immediately before or after an imaging run regardless of sky conditions and the exposures will be the same duration every time. When you’ve got 4 filters to shoot flats for it saves a huge amount of hassle. And for those that need to take dark flats/flat darks (the debate continues) it means you can have a library of them to use for each filter because the times remain unchanged, so you only need to take them once every few months.

[@AstroWithRoRo]

Agreed. I love using the flat panel, dial in the panel brightness and exposure time and it’s all done. Using the same exposure lengths means the dark library is easy to maintain too. Makes the whole process much easier.

[@Wheeljack678]

I struggled for the longest time taking correct flat frames - to the point that they actually made my images worse. Eventually I stopped looking at every different method and just started chasing the histogram with an android tablet (and a Flat Frame App) on top of my scope. No shirts, papers or anything inbetween. I keep the ISO the same as my lights as well, which lead to my flat frames usually being taken at shutter speed 1/640 for the histogram to peak a little to the left of the middle. I know the ISO doesn't matter, the illuminated field does, but now my flat frames finally work so I'm afraid to change things again. And you're right. We spend hours and hours capturing these images and even more hours processing them. Why not add less than a minute to that process to take your flat frames as well. They really do help alot and are a cheap price to pay for how much they improve the final stack.

[@RigoFromSpain]

Nice and clear explaining RoRo

[@AstroWithRoRo]

Thank you 🙂

[@astrodug]

Great info. I've ignored flats for years. I just rigged up a flat panel on a tripod and a vellum diffuser for my 10inch SCT.

[@AstroWithRoRo]

Good stuff!

[@gagaboul3423]

-some flat panels i used have low frequency illumination and show bands, it required 5sec+ exposure to average them -sky flats if taken at dawn or dusk may capture stars if exposure is long -if flats have long exposure, they should be calibrated with darks

[@DawgcityClev]

Paper? Interesting. I thought long and hard about using paper or even the boards from the dollar store but they seemed not evenly flat when you shine light through them. I might re-think this and give it a try

[@valentinotera3244]

Let me to understend, if my light frame have istogram peak at 25%, my flat frames has to be taken with an istogram around 25%?

[@barthennin6088]

So if one is doing astrophotography with an ALT-AZIMUTH do FLAT FRAMES still help?

[@zubenel01]

Roro Recommendation for a 20” (1/2 meter ) dob😉.…

[@xs4allan]

Interesting flat panel. A lot cheaper than all the "official" ones.

[@AstroWithRoRo]

Yes, in this expensive hobby you have to find ways to keep the costs down!

[@user-dr8ug3gs3c]

WOW! I knew Rhett Shull Did Guitar Video's on youtube but I did not know he did Astrophotography also. lol. You really look like him. Check it out.

[@skyboy98046]

This is a very interesting way to make a video lesson. Lol 😛

[@Tekytek]

I've just stumbled upon your channel, not sure why you haven't shown up in my feed earlier, given your following. slowly going through all your vids. It's weird at first, expecting a non Aussie accent on YT.. but great to see a local Sydney person. For this video, you don't mention Flat Darks.. how come? Cheers John.

[@AstroWithRoRo]

Thanks Teky! I'm slowly making my way through all the different calibration frames types. I have it in my list of videos to create and will definitely get onto it soon. I plan to have flat darks and bias in the same video.

[@astrodojo1]

could you tell me what is the drop rate from the fake end of the video? I checked the time on the video just before leaving, great video btw, thanks!

[@AstroWithRoRo]

4% of total viewers drop between the 45s and 1m 10s mark. Less than I was expecting to be honest. 😅

[@syeduddinacmacgma9734]

Waiting for your video on portable power set up ..

[@AstroWithRoRo]

It will be out next week so make sure to keep an eye out for it or hit that bell icon! :)

[@syeduddinacmacgma9734]

@@AstroWithRoRo Thanks mate. Also I am from Brisbane and I like your videos. Keep up the good work.

[@AstroWithRoRo]

I have just released my portable power/battery video, hopefully it is of use to you :)

[@MethiasZa]

How do you decide on the target ADU for your camera? The imaging tools can auto adjust the flats to hit that target ADU, im not sure how to pick the right ADU

[@AstroWithRoRo]

In general you can just aim for 50% ADU brightness to keep it easy and simple. Just be careful of banding or exposing for too short of a time.

[@MethiasZa]

@@AstroWithRoRo Thanks, would you use the full 16bit ADU to do this (typically what the FITS files are saved as) or do you need to try and translate your cameras 12 or 14bit adu somehow?

[@AstroWithRoRo]

Using the 16bit ADU is fine.

[@MethiasZa]

@@AstroWithRoRo Perfect, thanks so much.

[@williamcaldwell9431]

I too think flat frames are essential to good AP photos and take them in the morning post imaging. I do have one question , you and others have stated that the imaging train must remain unchanged from lights to flats, this includes the focus, however I use autofocus throughout the night to compensate for temperature changes...etc.. The incremental change in focus positions is small but does occur several times during the night. My flats do seem to work well, but do you feel this is an issue?

[@AstroWithRoRo]

I don't have an autofocuser myself, so haven't had any experience with how small the changes in focus are with that method. I would suggest keeping the focus changes to a minimum so the flats are as accurate as possible. Another option could be to work out a way to automate your flats, so if the focus changes you can capture new flats for each bump of the focuser.

[@gagaboul3423]

I use an autofocus on a C11 at F6.3 and F2 (hyperstar) and dont have problems with both focal ratio and sometimes i take flats later the day after. Actually the outside temperature during nighttime is causing the a physical change on lens and mirrors and the autofocus keeps the focus from drifting. From my experience, even a 10-20 degrees delta between the coldest moment of night and temperature in morning or even noon did not cause problems. A good test would be to take flats during another night and at noon and compare effects on stacked image.

[@foxglovemead]

Nice tutorial. You are lazy and you wake up, do a few flats and you are done capturing... do you run into problems with the weather - it rains? Or your gear goes walkabout? Are you sleeping under the stars (or at least one foot out of the window)? If you are using a computer and the computer goes to sleep/crashes or is unplugged, does the scope crash into the mount?

[@AstroWithRoRo]

My gear lives on a balcony which is mostly covered from the rain (also means not much sky view). If the forecast is for rain, I just make sure to get up early and cover it over before the rain hits. When I take my gear out to dark sky spots I set up my tent right next to it, and I would definitely wake up and hear if someone tried to move it or take it. You will want your computer to stay awake so it can keep imaging and controlling the mount, but you can set mount limits in the mount which will not require a computer.

[@foxglovemead]

@@AstroWithRoRo Can you set limits in the mount or in EQASCOM? I would be wary of using EQASCOM to directly control the mount because without a computer the mount will just continue in RA. With ASCOM to the HC to the mount, the HC may limit the movement e.g. do a meridian flip, so you lose one sub, but that is all.

[@valentinotera3244]

Flat your damn images out folks. That's it. It's all about flat frames.