Any way to determine which filter is being used if not sure of position ???

[teoria_del_big_bang]

Not really done very much LRGB stuff at all but for some reason I am just not really sure whether the Blue and Green filters are crossed over. I was under the impression they were set in what I thought was a logical order:-

1. Lum
2. Red
3. Grn
4. Blu
5. Ha
6. OIII
7. SII

But when I look in my notes I made when I fit them I have written it down as LRBG not LRGB so suspect Green & Blue may be in wrong positions.
I would prefer not to open everything up unless that's the only way as not a quick job with these bolt on spacers so is there an easy way to be sure which order they are in without.

Its only the green and blue that is in doubt.

Steve

[vlaiv]

Take any G or F class star and measure intensity in sub from each filter - green will have higher ADU value if you used the same exposure length.

[teoria_del_big_bang]

Thanks @vlaiv

I can always rely on you for these technical questions 🙂 

Steve

[teoria_del_big_bang]

Not sure when next clear night in north UK will be mind 🙂 

Steve

[david_taurus83]

Would taking a picture of a green or blue object during the day not have the same result @vlaiv ?

[vlaiv]

Just now, david_taurus83 said:

Would taking a picture of a green or blue object during the day not have the same result @vlaiv ?

Yes it would. Also - just imaging white object will do the same - green will be stronger than blue - because QE is less in blue part of spectrum than it is in green.

[teoria_del_big_bang]

26 minutes ago, vlaiv said:

Yes it would. Also - just imaging white object will do the same - green will be stronger than blue - because QE is less in blue part of spectrum than it is in green.

Okay so I guess the one that needs the longer exposure when taking flats to obtain same ADU  is the Blue then ?

 

Steve

[vlaiv]

1 minute ago, teoria_del_big_bang said:

Okay so I guess the one that needs the longer exposure when taking flats to obtain same ADU  is the Blue then ?

 

Steve

Provided that flat panel has nice uniform spectrum and is generally white in color (color of light).

I'm not 100% sure about LED panels though. They seem to have "lump" in blue part of spectrum:

But even with this lump, if light that panel gives is white - it should give you lower ADU reading in blue than in green if your camera has common QE curve - like this:

If it peaks in 500-600 range and is lower in 400-500 range, then blue will definitively be lower in ADU value.