Best LPR filter for imaging around here ?

[Ian]

Yes, Narrow band is one way forward but thats generally used by people who have an exceptional amount of LP and I'm not sure that I'm in that category. 

I don't think Paul has that problem, but it is a different sort of imaging. I'm not sure that stacking filters as you've suggested is not going to stop more light than a good set of narrowbands. I would expect the total cost to be lower too.

But I'd do what John says, at least to start with. I think the images he posts lend a lot of credibility to his words...

[RobertM]

Yes you're probably right, but I'll try that filter that Chris has kindly offered to let me try first.

On the Starlight message group I saw that someone has suggested using G2V stars to balance - maybe this needs further investigation.  It would certainly seem sense to balance the RGB exposures against a known stellar source from each image and would take a lot of guesswork out of the process.  Maxim allows white balance to ba achieved by clicking on either the background or a stellar source and it does seem to work very well if you choose the right star.   Whether it's a practical proposition identifying that 'right star' is another matter...

[Ian]

I tend to set colour balance against other peoples results... Not rigorous, or scientific but I'm still trying to make pretty pictures rather than photometrically accurate representations.

That'll come, but I have enough fun just getting the faint fuzzy on the ccd and keeping it there...

[JohnP]

Ian - Exactly - I normally do final colour balance by searching for similar images on the web.... John

[Rocket Pooch]

wow what a thread,

i'm with mike on the cup and mug issue here

Robert I would not stack the filters, there not parfocal and you will be messing about with focus all the time

I also agree with john, if the bandwith with the CLS cuts partial wavelength just expose more or balance the weaker signal when processing, but as ian points out you will never get a true lrgb with any of these filters because something goes missing.

personally i just fiddle with the colour balance until it looks nice?

for real LRGB we all have to hike to the south a few miles

your truly, board from canada

but the sushi is excellent

[RobertM]

The stacking filters idea was just just an idea, in any case my Atik is barely wide enough for the filters I have let alone stacking.  I take your point about colour balancing though but there are just so many things to tweek, fiddle and fudge anway.  Wouldn't it be nice if someone out there made RGB filters with just the right cutoffs for an LP site, the Astronomiks do rather take the ideal world approach which is excellent for dark skies.  Now there's a thought ... dark skies ... I see the next DSC is on 7th Dec, I might actually go if I can get my act together.

Chris, if you haven't already then try soft shell crab dipped in Terayaki sauce, now that is yummie ...

[JohnP]

Robert - did you ever get a filter in the end - if so which one? Cheers,  John

[RobertM]

Hi John,

Yes, I got the Baader Neodymium, my choice was based on it letting more target signal through (according to the graphs).  It was cheap (£18 second hand) but seems to be quite good, both the M81 and M101 images were taken with it.  I've yet to see how it mixes with colour channels but it seems to do what it says on the tin

Hope that helps
Robert

[JohnP]

I have one of those as well (bought it ages ago - only 1 1/4 inch though) - I must try it again sometime - I guess this is the 'moon & skyglow' filter..???

John

[RobertM]

Yes, it's the Moon and Skyglow filter.  My SXV-H9 chip is only 2/3" size so the 1.25 filter is not a problem for me.

[JohnP]

SXV-H9 chip is only 2/3"

I would die for a chip that big - the Atik 16ic is 1/4 inch...

Thks for your help.... John

[MarkS]

Are you sure its 2/3" ?

The Starlight Express homepage says about the SXV-H9:
"Large, high resolution 'Exview' CCD chip, with 1,447,680 x 6.45uM pixels in a 9 x 6.7mm array "

In the end the only way you're going to find out which filter is best around here is to do a side-by-side comparison.  And it will vary from area to area depending on what type of streetlighting (or floodlighting!) is used in your neighbourhood. Yes, something like the Baader UHC-S or the Astronomik CLS is very severe in what it removes (and increases the necessary exposrue time) but it might still give a better overall result.

I'd certainly like to give a Neodymium a try versus an Astronomik CLS versus no filter and see what happens.

[RobertM]

Yep, I'm sure it's 2/3" - 8.8 x 6.6 mm are the standard dimensions for that size according to DPreview.

I agree about the side by side comparison for the conditions but that was too expensive an option for me.  Some do manage to work their way through filters to decide what's best but I decided to take an educated guess and it seems ok for now.  I see something that produces better results for where I am then I'll consider it.

I'd be more than happy to loan you my filter Mark but I only have one and never know when I'll need it   Chris did mention something about having one he doesn't use thought so it might be worth a PM.

[Rocket Pooch]

I have:

Neodium 1.25"
Astronomik CLS 1.25"
Baader UHC-S 2"

The CLS is the best where I live but the other two are less severe.

If you want to borrow one let me know.

Chris