M106, OSC

[lensman57]

HI,

Taking advantage of a clear spell early on, here is the result of 14 X 900s subs. Very noisy and with wind blowing like mad the star shapes are not great but that is how it is. SW 100ED, TV TRF 2008 and Idas D1 fiter.

Thanks for looking,

AG

[kalasinman]

I like the color. Sorry if a little off topic, but I've heard the IDAS LPF filters a great and free from color cast, but increase exposure times. As they pass over 90% of desired WL, is the increase in exposure times based on getting the same histogram per unit of time? If so then the exposure times to equal brightness of target should be the same, plus having better contrast, or have I got it wrong?

[lensman57]

I like the color. Sorry if a little off topic, but I've heard the IDAS LPF filters a great and free from color cast, but increase exposure times. As they pass over 90% of desired WL, is the increase in exposure times based on getting the same histogram per unit of time? If so then the exposure times to equal brightness of target should be the same, plus having better contrast, or have I got it wrong?

Thank you for your kind words. There is a general increase of exposure time with any LP filter, with this one is about an F stop in the old money. The pass band of the filter or the percentage of a specific  band is just that a percentage ie 92% in Ha and Oiii of the remaining light  for example. The issue of colour balance is a tricky one as any  blocking of the visible portion of the spectrum will unbalance the colour. IDAS filters seem to suffer less from a colour shift compared to an Astronomik CLS which is in fact a narrowband LP or Nebula filter.

Regards,

A.G

[kalasinman]

I find getting color in my images difficult, probably as I am just starting guiding for one thing and haven't taken full advantage yet.

I get the one f stop equivalence. That's 50% of the light. So if the filter passes 92% of what we want, and we're losing 50%, doesn't that imply that we lose 8% of what we want and the rest is what we don't want? So 42%  is ok to get rid of?

[lensman57]

I find getting color in my images difficult, probably as I am just starting guiding for one thing and haven't taken full advantage yet.

I get the one f stop equivalence. That's 50% of the light. So if the filter passes 92% of what we want, and we're losing 50%, doesn't that imply that we lose 8% of what we want and the rest is what we don't want? So 42%  is ok to get rid of?

I think that it is simpler to think of it this way. To get the same signal as an unfiltered image you have to give it twice as much exposure or thereabouts.

A.G