G2V calibration - Will it make that much difference?

[swag72]

Tonight I have spent my evening doing a G2V calibration with my existing SW 120ED, Atik 314L and Baader RGB filters. I have come up with the following ratio's

R:G:B 1.11 : 1 : 1.04

As I understand it, this means that if I take a 300 sec exposure for the green filter, I will be looking at the following exposures

333 : 300 : 312

To me, these look like very small amounts, so my question is this - Will it really make that much difference?

I also have another question about the importance of atmoshperic extinction, but that can wait!!!

[RobH]

In my experience it doesn't make much difference TBH .....atmospheric extinction will be changing the ratios depending upon the altitude of the target too, so it's not static.

I tend to go more by the chip sensitivity, and roughly balance my exposures that way, as at least it's constant, and colour balance isn't hard to adjust in processing.

Rob

[swag72]

So my evening has been wasted?!!

[RikM]

Not at all. You have just learned that you already have a well corrected imaging system.

[swag72]

I tend to go more by the chip sensitivity, and roughly balance my exposures that way, as at least it's constant, and colour balance isn't hard to adjust in processing.

Stupid question then - Do you do something similar to determine chip sensitivity? I just take the same length exposures, is there a better way?

@Rik - That's a well corrected imaging system?

[ollypenrice]

My concern would be the amount of moonlight present. Almost full moon. I really don't know what effect that would have. If the moon reflects a full spectrum then it might not matter, but does it? Anybody?

Olly

[swag72]

Ahh, I did it all before the moon came up!!!! I know that because when I walked down the obsy steps I nearly fell down them as I couldn't see

[ollypenrice]

Too much Fundador!!!!!!

Olly

[RobH]

Stupid question then - Do you do something similar to determine chip sensitivity? I just take the same length exposures, is there a better way?

You should be able to find the technicval data for chip sensitivity online Sara although I just had a quick look and can't find it!....Contact the guys at Atik...they'll have it.

TBH, it's not worth getting too hung up on these sort of things as it's easy to end up chasing your tail!

Rob

[Davey-T]

I have an Atik 314L+ and enquired about the colour response of the chip on the Atik

Forum but never got an answer so I guess nobody new (or cared)?

Davey T

[swag72]

Cheers both - Shame Davey T that Atik never answered

[RobH]

I know the response of the 285 chip in the 314L is greater than the R & B.

With my 16HR (same chip), I tend to go for, say 280 secs green, 300 secs red and 360 secs blue, whatever that is in percentages!

It seems to give me decent star colour and I tend to have to deal with light pollution casts, rather than a bad initial colour balance.

There's very little science behind those ratios, just lots of trial and error.

Rob

[MikeD]

I think it becomes more usefull to do G2V calibration if you are useind an LP filter, I don't at the moment but am going to give it another go.

Mike.