Do I take flats without a filter or with each filter?
Narrowband Flats with or without a filter?
With each filter. There might be dust on each individual filter and you want to catch that in your flats.
I've been doing NB images since 2006 with 6,5 and now 3mn filters. Have never needed to do flats.
Buy some think it's good to do flats with all filters.
Buy some think it's good to do flats with all filters.
Take flats and dark flats for each filter. They don't take very long to take at all. It's the darks for the lights that take forever.
How can you take a narrow band flat, if you don't do it with a narrow band filter. It then would become a luminance flat.
YES, all filtered flats need to be taken with the corresponding filter. The shorter the focal length, the more crucial the flat subtraction becomes.
What you are asking is "can I use a Luminance no filtered flat for my narrow band images?" I would say no.
Lynn K.
YES, all filtered flats need to be taken with the corresponding filter. The shorter the focal length, the more crucial the flat subtraction becomes.
What you are asking is "can I use a Luminance no filtered flat for my narrow band images?" I would say no.
Lynn K.
Its always better to take flats.
Take flats with each filter you image.
If you rotate the camera or change anything in the optical train redo the flats.
CS
Rouz
Take flats with each filter you image.
If you rotate the camera or change anything in the optical train redo the flats.
CS
Rouz
Concise
Many people get very nice images without using flats, but they would get even better images if they did use flats.
Well Written Respectful
Bob Lockwood:
I've been doing NB images since 2006 with 6,5 and now 3mn filters. Have never needed to do flats.
Buy some think it's good to do flats with all filters.
Bob,
You must have very clean filters! Just remember that flats do three things:
1) Removes the effects of vignetting, which includes dust motes. (Maybe not a big deal for your system)
2) Removes radiometric fall off. (Happens in ALL systems)
3) Minimizes the effects of PRNU. Modern CMOS sensors are pretty good but this is still something to deal with. (Occurs in ALL sensors to some degree.)
John
Helpful Concise
I wouldn't consider processing an image without flats.
The larger the sensor the more important.
Also, faster optics will need flats even more.
You can stretch the image much more with a well calibrated flat.
What's not critical are darkflats IF you have a clean sensor.
I don't use darkflats with the IMX571 and 455 but its was needed for the IMX183 with amp glaw.
CS
Rouz
The larger the sensor the more important.
Also, faster optics will need flats even more.
You can stretch the image much more with a well calibrated flat.
What's not critical are darkflats IF you have a clean sensor.
I don't use darkflats with the IMX571 and 455 but its was needed for the IMX183 with amp glaw.
CS
Rouz
Helpful Concise
My question regarding this tho is: Are you saying you are running out and doing flats every 2 hours (if that is the case), BETWEEN filters? Because how would get correct focus for them/each later, in that of course doing a refocus with each (and they then would all be different…) … unless you watched your AIS-Air/etc and made note of the EAF position for each? Then recreate later? You cannot do flats the next day of course, in that no stars to refocus on for each filter (unless you had the numbers, to recreate)
Marty Anderson:
My question regarding this tho is: Are you saying you are running out and doing flats every 2 hours (if that is the case), BETWEEN filters? Because how would get correct focus for them/each later, in that of course doing a refocus with each (and they then would all be different…) … unless you watched your AIS-Air/etc and made note of the EAF position for each? Then recreate later? You cannot do flats the next day of course, in that no stars to refocus on for each filter (unless you had the numbers, to recreate)
Take flats at the end of the imaging session for each filter. Your filters need to be generally parafocal, but critical focus for each filter is not necessary. I just take the flats at the last focal position I had the imaging train on before putting it back to zero.
Well Written Concise
FLATS rules
Take flats and dark flats for each filter.
Maintain the same focus and rotation as light frames.
temperature does not ' matter.
Take flats and dark flats for each filter.
Maintain the same focus and rotation as light frames.
temperature does not ' matter.
can't seem to take proper flats with asi 294mm
hello, so recently I made a big upgrade and bought a asi 294mm pro with chroma 1,25" filters (LRGBSiiHaOiii), and also I control everything from the eagle 5 s. this is my first time imaging with a mono camera, and also been using Nina for a few ...
Discusses flat-taking procedures with multiple filters on astronomy camera.
Dust Motes on Flats
When I take flats at home they have 0 to maybe 2 dust motes. I keep my camera sensor and filters very clean and when I do clean them I am very careful and the results are good. My new remote setup has flats that are showing 10-12 dust motes. Obviousl...
Addresses flat-frame quality issues and filter/sensor cleanliness concerns.