Filter Advice - Colours + LP Filter?

[Hailfire101]

Hi guys.

I'm looking at getting some filters.
At the moment I'm using a DSLR, with a SW Coma corrector...
I was wondering a few things.

Can I get filters that screw into the SW Coma Corrector?  Are they the 2" ones?
My 2nd question is, if I buy a set of colour filters, would I actually need a LP filter too?  Or would the other filters remove the LP anyway?

Any brand/filter reccomendations?
I am also, in the future looking to upgrading to a CCD/CMOS astro cooled camera, so would like the filters to be future proof too.



Thanks
Mike

[newbie alert]

Some narrowband filters will cut out the LP such as HA,POO

Look into the new cmos cooled camera's as they're more suited to l.p. areas with shorter exposures

[geordie85]

Unless your DSLR is mono then there won't be any advantage to shooting through rgb filters.

A 2" idas light pollution filter will be your best course of action at the moment and it will screw into the end of your coma corrector. 

[Hailfire101]

Thats probably what I wanted to hear.   

Which one of these would be good for me?
https://www.firstlightoptics.com/light-pollution-reduction-imaging.html

I'm not sure of the differences between them.

 

[geordie85]

I'd personally go for this one and I did which is why I have 2. Stupid really as I've only got 1 scope.

https://www.firstlightoptics.com/light-pollution-reduction-imaging/idas-p2-light-pollution-suppression-filter.html

[Hailfire101]

I thought that maybe the case.

I think the D1 maybe better for me, as I have a Baader modded DSLR.

Whats the difference between the standard one and the QRO version though?
Cant find anything online that suggests the differences?  Is it reduced reflection on brighter stars?

 

[Hailfire101]

Edited previous post.

[geordie85]

I couldn't tell you as I've never had the d1 version. FLO website states that the d1 is optimised for OSC  

[ollypenrice]

Going back a step, your DSLR already has colour filters in place. Each pixel has either a red, green or blue filter placed over it in a pattern called a Bayer matrix. In fact it will have two green-filtered pixels for every red and blue one.

If you use an Ha filter only the red filters can let the Ha light through, Ha being deep red. The problem is that the DSLR is also filtered to pass only the visible spectrum between red and violet. This filter often intrudes into the Ha part of red, blocking it. Later cameras are often rather less affected than older ones. They can be modified so that this intrusive filter is removed or replaced by a more appropriate one.

Olly

[Oddsocks]

20 hours ago, Hailfire101 said:

Whats the difference between the standard one and the QRO version though?

The English language sales literature on many of the web sites selling IDAS filters is rather out of date and has been copied from the European importers release notes, the German language sales notes are rather more up to date. A recent sales note for unmounted IDAS filters contains a useful comparison graph between the D1 and  P2 and can be found in English here:

http://www.teleskop-express.de/shop/product_info.php/info/p6997_Hutech-IDAS-LPS-P2-Light-Pollution-Suppression-Filter--unmounted--31-mm-diameter.html

D1 is for OSC and DSLR cameras, it does not pass the deep red SII band which is only weakly detected by these cameras. D1 is designed for a good colour balance of the raw camera image and requires little adjustment in post processing.

P2 is for mono cameras and passes the SII band which mono cameras record.

The new QRO versions have a tapered ring mount for the filter assembly that is said to reduce edge reflections, these are the coloured stripes that flare across the image at the field edge due to bright stars just on or over the field edge where the star is focused on the filter mount, not the glass, or just straddling the boundary of the two. Unmounted versions of the IDAS filters do not suffer this edge flare as much but because the IDAS filters are not edge blackened it can still occur in some filter wheels and hand painting the filter edge with matt-black helps prevent these border-edge reflections.

Both D1 and P2 in plain or QRO versions suffer from star halos to some extent as do many interference filters.

If you are planning to upgrade to a mono camera at a later stage then the P2 is the obvious choice but you will need to colour balance the image from a DSLR or OSC in post processing as it will appear red biased.

Note that light pollution filters such as the IDAS are becoming less usefull as time goes by. Most LP filters are optimized to remove the emission lines from low and high pressure sodium street lights (orange and yellow-white) and mercury (green-blue) mainly used in commercial and industrial sites. Most councils and many commercial-industrial sites in the UK are in the process of replacing their sodium and mercury lamps with wide band LED lamps and LP filters are not effective at combating LP from these sources.

When you do upgrade to a mono camera and filters the size and mount choices are many and will depend on the size of the camera sensor, how many filters you want in the filter wheel and the focal ratio of the telescope, 1-1/4", 2", 31mm, 36mm, 50mm round or square, mounted or unmounted etc, so trying to anticipate future needs and making a choice of LP filter size and mount type now is always going to be difficult.

 

[Hailfire101]

8 hours ago, Oddsocks said:

The English language sales literature on many of the web sites selling IDAS filters is rather out of date and has been copied from the European importers release notes, the German language sales notes are rather more up to date. A recent sales note for unmounted IDAS filters contains a useful comparison graph between the D1 and  P2 and can be found in English here:

http://www.teleskop-express.de/shop/product_info.php/info/p6997_Hutech-IDAS-LPS-P2-Light-Pollution-Suppression-Filter--unmounted--31-mm-diameter.html

D1 is for OSC and DSLR cameras, it does not pass the deep red SII band which is only weakly detected by these cameras. D1 is designed for a good colour balance of the raw camera image and requires little adjustment in post processing.

P2 is for mono cameras and passes the SII band which mono cameras record.

The new QRO versions have a tapered ring mount for the filter assembly that is said to reduce edge reflections, these are the coloured stripes that flare across the image at the field edge due to bright stars just on or over the field edge where the star is focused on the filter mount, not the glass, or just straddling the boundary of the two. Unmounted versions of the IDAS filters do not suffer this edge flare as much but because the IDAS filters are not edge blackened it can still occur in some filter wheels and hand painting the filter edge with matt-black helps prevent these border-edge reflections.

Both D1 and P2 in plain or QRO versions suffer from star halos to some extent as do many interference filters.

If you are planning to upgrade to a mono camera at a later stage then the P2 is the obvious choice but you will need to colour balance the image from a DSLR or OSC in post processing as it will appear red biased.

Note that light pollution filters such as the IDAS are becoming less usefull as time goes by. Most LP filters are optimized to remove the emission lines from low and high pressure sodium street lights (orange and yellow-white) and mercury (green-blue) mainly used in commercial and industrial sites. Most councils and many commercial-industrial sites in the UK are in the process of replacing their sodium and mercury lamps with wide band LED lamps and LP filters are not effective at combating LP from these sources.

When you do upgrade to a mono camera and filters the size and mount choices are many and will depend on the size of the camera sensor, how many filters you want in the filter wheel and the focal ratio of the telescope, 1-1/4", 2", 31mm, 36mm, 50mm round or square, mounted or unmounted etc, so trying to anticipate future needs and making a choice of LP filter size and mount type now is always going to be difficult.

 

Wow, this is a fantasic post!
Thank you for this infomation... I'm sure other newbs will read it too and love this info.

I have a Baader modded DSLR, so that I believe lets more of the Ha Spectrum in (?)  So I think the D1 is certainly looking like a good option for me for now.
When I go for the CCD/CMOS  I'll probably buy with a kit of filters and wheel at the same time. I've see these on FLO before.

Thanks again for you help.
Regards
Mike

[GeorgeLiv]

Concerning the LED blue spectral band and the implications on how skyglow is created in good clear-night conditions, these IDAS notched broadband type filters (mainly the LPS-D1 and LPS-P2) are a rather poor choice in 2018.

[Hailfire101]

On 5/19/2018 at 21:26, GeorgeLiv said:

Concerning the LED blue spectral band and the implications on how skyglow is created in good clear-night conditions, these IDAS notched broadband type filters (mainly the LPS-D1 and LPS-P2) are a rather poor choice in 2018.

I now own the new IDAS D2 filter, and upto now... it's been outstanding!

[GeorgeLiv]

Well, the LPS-D2 is a proper broadband filter and not a notched filter, in fact, mimicking a swan-band type filter which is the WISEST choice for LED cities. (Hint: The blue-green transmission window is shifted towards the yellow). Part of my Appendix3 is attached.

[Adam J]

On 09/05/2017 at 12:35, Hailfire101 said:

Hi guys.

I'm looking at getting some filters.
At the moment I'm using a DSLR, with a SW Coma corrector...
I was wondering a few things.

Can I get filters that screw into the SW Coma Corrector?  Are they the 2" ones?
My 2nd question is, if I buy a set of colour filters, would I actually need a LP filter too?  Or would the other filters remove the LP anyway?

Any brand/filter reccomendations?
I am also, in the future looking to upgrading to a CCD/CMOS astro cooled camera, so would like the filters to be future proof too.



Thanks
Mike

It depends on what you want to image,

For Emission Nebula - Astronomic UHC Filter.

For Galaxies - IDAS D2 (currently only available in 2 inch), or Astronomic CLS (if on a budget, but will make color correcting very hard). 

Color filters are only used in dedicated mono astronomy cameras and would actually make things a whole lot worse if you stuck one on a DSLR. 

Beyond those two a Ha filter can be useful.  

 

EDIT: Wait a second how old is this thread!!

[newbie alert]

On 09/05/2017 at 12:52, newbie alert said:

Some narrowband filters will cut out the LP such as HA,POO

Look into the new cmos cooled camera's as they're more suited to l.p. areas with shorter exposures

That should read HA,OIII...

Damn phone