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Light Pollution Filters and Moving from DSLR to CCD?


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Good morning everyone,

I've been dabbling in astrophotography for about two months now with my Nikon D7100 that I normally use for more terrestrial subjects.  I've had some issues with the RAW (NEF) formatting from the camera into stacking programs and what not, but I think I have stuff figured out for the time being.  (Here's the thread on that endeavor: http://stargazerslounge.com/topic/234995-working-with-star-tools-–-from-nikon-d7100-to-dss-to-star-tools-–-advice/)

I live in a metro area in Minnesota.  The nearest "good" dark sky spot is about 40 miles from my house.  Even from there, I have to compete with a little bit of light pollution in the distance.  Can anyone recommend a good light pollution filter for my 77mm lens?  I'd really appreciate any feedback on the topic and if a filter like that would be worth it.  To my understanding, it'd filter out the LP while keeping the colors of the actual objects I am shooting, am I correct?

Secondly, I've been doing some thinking about moving from my DSLR to a CCD.  My only concern is the cost of doing so.  I've already invested a bit of money for astrophotography with getting a Skytracker, some lenses and what not and would hate to have blown money on things that I won't use anymore.  However, moving to a CCD camera and a scope would allow me to shoot in different formats more suitable for stacking programs and development.  Could I get good results from mounting my camera to a scope and if so, which one?  Or should I save up for a CCD and a scope?

I'm currently saving for a wedding and also paying off one hell of an engagement ring that will be deployed in April so I'm trying to mind the funds atop my photography hobby.

Any feedback is greatly appreciated!

Jake

 

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Hello Jake,

there are several light pollution filters on the market. Usually what people want are nebula filters which is why i refer to them now. The goal of most of those filters is to filter out light created by artificial lightsources and to transmit light originating from atomic transitions (space objects like nebula). An overview of available filters is shown here: http://www.astrosurf.com/buil/filters/curves.htm

In general the filter prize is correlated to the ability of how well it can discriminate "space light" from light pollution. Light pollution filters that are popular include the Astronomik UHC or the Hutech IDAS LP filters. Unfortunately these are pricey. Canon users would have the option of clip in filters from Astronomik which are around 180,- €. 

There are also 77mm screw in filters from Astronomik but they start at around 270,- € (Hutech should be similar). 

These are the options that i`m aware of. There might be cheaper solutions which most likely also lack in performance. The 77mm sizes are a bit uncommon to be honest, because usually people screw there filters between telescope and camera and there 2" size is most often sufficient (which makes it also quite alot cheaper).

One thing to notice is that these UHC filters will change the color of the stars a little bit (the Hutech is better than the Astronomik) and also that for galaxies those filters are counter productive as galaxies usually emit broad band light (just like stars) which results in a color cast and reduced intensity when photographed through a UHC filter. 

Regarding the CCD: Nowadays DSLRs are capable of quite astonishing deepsky photos. Have a look at this guy http://www.astrobin.com/users/fotojerry999/

All of his photos are taken with a Nikon D5300. So i would say for the moment don`t invest in a CCD, but try to improve other aspects e.g. filter, mount etc.

best regards

Matthias

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Hello Jake,

there are several light pollution filters on the market. Usually what people want are nebula filters which is why i refer to them now. The goal of most of those filters is to filter out light created by artificial lightsources and to transmit light originating from atomic transitions (space objects like nebula). An overview of available filters is shown here: http://www.astrosurf.com/buil/filters/curves.htm

In general the filter prize is correlated to the ability of how well it can discriminate "space light" from light pollution. Light pollution filters that are popular include the Astronomik UHC or the Hutech IDAS LP filters. Unfortunately these are pricey. Canon users would have the option of clip in filters from Astronomik which are around 180,- €. 

There are also 77mm screw in filters from Astronomik but they start at around 270,- € (Hutech should be similar). 

These are the options that i`m aware of. There might be cheaper solutions which most likely also lack in performance. The 77mm sizes are a bit uncommon to be honest, because usually people screw there filters between telescope and camera and there 2" size is most often sufficient (which makes it also quite alot cheaper).

One thing to notice is that these UHC filters will change the color of the stars a little bit (the Hutech is better than the Astronomik) and also that for galaxies those filters are counter productive as galaxies usually emit broad band light (just like stars) which results in a color cast and reduced intensity when photographed through a UHC filter. 

Regarding the CCD: Nowadays DSLRs are capable of quite astonishing deepsky photos. Have a look at this guy http://www.astrobin.com/users/fotojerry999/

All of his photos are taken with a Nikon D5300. So i would say for the moment don`t invest in a CCD, but try to improve other aspects e.g. filter, mount etc.

best regards

Matthias

Thank you very  much for getting back to me, Matthias.

I did some looking around at the types of filters you mentioned and came up with this site for the Hutec filters: http://www.sciencecenter.net/hutech/prices/filters.htm .  If you go to the very bottom, you'll see that they make one for the D7000 which is nearly identical to my D7100.  Would it be wiser to go for the Nebula Filter or the Light Pollution filter?

I think I might make the plunge and go for one of the filters that I can drop in and out of my camera for when I want to use it for AP.  I think eventually I would like to get a scope and do some stuff that way, but for now, getting the drop in will allow me to use what I currently have with my tracker and save a little bit of money.

Even with my humble setup, I did manage to get a decent shot of Lovejoy while it was here: http://www.captureminnesota.com/photos/1655678

Your feedback and advice is really appreciated.  Now I just need to get better about reducing coma, improve my stacking, and my processing.  I've been wavering between Pixinsight and Nebulosity.

Thanks again!

Jake

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Hello,

thank for the link of the Hutech Filters. I wasn`t aware of the existance of front filters for Nikon. I`m interested in those myself :)

As to the decision between light pollution and nebula filter. I had a look at the transmission spectra and it seems that the light pollution filter is a bit more versatile although the nebula filter will be even better at suppressing artificial light. But this comes at the cost of color shifted stars.

Personally in this case i would most likely go with the light pollution filter LPS-D1.

Before you buy one make sure that it really fits your camera and also be cautious with the type of lenses you mount with this filter (i think DX lenses like the 18-55 are not compatible because they protrude to far into the camera body).

You can read about this here at the bottom: http://www.sciencecenter.net/hutech/filters/ffilter.htm

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Hello,

thank for the link of the Hutech Filters. I wasn`t aware of the existance of front filters for Nikon. I`m interested in those myself :)

As to the decision between light pollution and nebula filter. I had a look at the transmission spectra and it seems that the light pollution filter is a bit more versatile although the nebula filter will be even better at suppressing artificial light. But this comes at the cost of color shifted stars.

Personally in this case i would most likely go with the light pollution filter LPS-D1.

Before you buy one make sure that it really fits your camera and also be cautious with the type of lenses you mount with this filter (i think DX lenses like the 18-55 are not compatible because they protrude to far into the camera body).

You can read about this here at the bottom: http://www.sciencecenter.net/hutech/filters/ffilter.htm

Ahhh, you're right.  Dang.  I'm going to email them and ask if they have any reference on which lenses will and won't work.  I have a mixture of lenses, but primarily use a 12-24mm lens and an older 80-200mm lens for AP.  I'll see what they say; I'd hate to get it and then not have it work.

I did find this though:

http://www.lumicon.com/store/p/89-77mm-Night-Sky-Hydrogen-Alpha-Filter.aspx

Perhaps I'm too tired, but wouldn't it make the images B&W then or do I need to head back to bed?

Jake

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