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Light pollution filter for astrophotography?

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#1 smithers3

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Posted 21 January 2013 - 09:38 PM

I have an unmodified Canon t3i. I'm wondering which light pollution filter would be the best. Orion has a skyglow that is specifically designed for astrophotography. However, I'm not sure how different it is from their regular skyglow (other than the fact that it's far more expensive).

But, are there others that would be better? I don't have a lot of light pollution now, but I'm going to be moving in the next year to a place with more, and I'd hate to stop astrophotography just when I'm getting going.

Thanks!

#2 mmalik

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Posted 21 January 2013 - 09:58 PM

I use this.... Thx

#3 piaras

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Posted 21 January 2013 - 10:26 PM

Here is a 50 minute stack using my unmodded T3i with a Astronomik Clip in EOS CLS-CCD on an Orion 80ED scope. This was taken 1 1/2 miles due West from Buffalo NY, in my back yard.
I also have Lumicon Deep Sky Filter. The Astronomik is a new purchase so not much experience with it. It will allow me to use my EF lenses for wide angle stuff as well as on the scopes.

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#4 ky1duck

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Posted 21 January 2013 - 10:40 PM

here are two shots 1st on a 60sec without filter and the second one is a 60sec with orion skyglow both taken with my unmoded t3i and orion st 80mm.

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#5 ky1duck

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Posted 21 January 2013 - 10:40 PM

2ed also the skyglow takes out some of the purple halo from my cheap 80mm ST i was using.
just my 2 cents worth.

robert

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#6 piaras

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Posted 21 January 2013 - 11:06 PM

I use a LP filter basically all the time. It helps remove the remaining sky glow that is present even at dark sites.
My back yard is 18-19 on the Unihedron due to Buffalo in the East, so I shoot from zenith to west to avoid the majority. At the observatory the reading is usually 21-21.5 most nights, but like I said I still use a filter and it does make a difference even there.
Pierre

#7 smithers3

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Posted 22 January 2013 - 12:06 AM

Robert, are you using the regular skyglow filter or the special astrophotography one?

#8 ky1duck

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Posted 22 January 2013 - 12:22 AM

just the skyglow broadband. looked at the astrophotography one but couldnt see spending the extra money. only thing is the astrophoto one allows 575-590nm(yellow) and 615-630nm(orangish) to pass through.and also blocks 472-480nm part of blue area. The numbers are close going off orions charts. as for what these changes would do to photos i aint sure. but i am sure someone here could tell you that.


robert

#9 Samir Kharusi

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Posted 22 January 2013 - 01:13 AM

To the original poster. First get the camera modded and only thereafter worry about filters. Spend your $ where it matters. When you are ready for filters study this link carefully.

#10 harbinjer

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Posted 22 January 2013 - 01:17 AM

I have a Astronomik CLS clip filter. It definitely works on reducing light pollution, and natural skyglow. While it reduces all light, it does pass H-alpha light well, so even an unmodified camera can do a bitter better in that realm. It made shooting the north american nebula possible, not great, but possible. I don't know which is best, but I know mine works.

#11 SteveRosenow

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Posted 22 January 2013 - 04:21 AM

My only wish is that they offered them for Nikons. It's cost-prohibitive for me to switch camera brands (that and I don't intend to, as I'm a Nikon-only guy).

#12 astroricardo

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Posted 22 January 2013 - 11:40 AM

Everyone will have a different opinion on this and here's mine. Modding your camera will enhance *some* of your pictures, a LPF will enhance *all* of your pictures. I'd go with an LPF but that's what I just did. I'm trying out the Celestron UHC/LPR also currently on sale for about $75 and I have to say I'm impressed. I was looking at the Orion because of everyone saying that it doesn't affect the color balance, but I'm doing all kinds of processing anyway.

#13 bluedandelion

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Posted 26 January 2013 - 02:39 AM

Everyone will have a different opinion on this and here's mine. Modding your camera will enhance *some* of your pictures, a LPF will enhance *all* of your pictures.


LP filters are not so good with low contrast subjects like galaxies. They do a good job on H-alpha regions. It's not just opinion. That's what the transmission curves yield.

Samir's article is an excellent reference.

Ajay

#14 astroricardo

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Posted 26 January 2013 - 06:48 PM

My point was that it's a matter of opinion which to do first.

Yes, everyone wants to mod their camera. But will I spend 200-300 now while my camera is under warranty or spend $75 on an LPF? For the stuff I'm taking pictures of, limited time I have and where I have to do it (my driveway) a LPF made a lot more sense.

#15 Tonk

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Posted 26 January 2013 - 09:04 PM

a LPF made a lot more sense


Sure it will change the colour of the backgroud sky - but until you mod the camera it will not improve capture of H alpha - so I suggest sticking to globs, open clusters, bright galaxies and such like until you do

This is not an opinion its optical physics

#16 bluedandelion

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Posted 27 January 2013 - 03:41 PM

My point was that it's a matter of opinion which to do first.


Oh, I misunderstood. Yes and it is also a matter of budget.

Ajay

#17 Toxic Coolaid

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Posted 27 January 2013 - 09:50 PM

Without my Astronomik CLS filter I could not take subs long enough to image anything that is not pretty bright. I'm in a Red Zone and usually limited to 45 second subs without the CLS. However with the filter I can extend my times to 120 seconds. Obviously the answer get BOTH the mod and the LP filter. But which 1st? IMHO, unless you have very little light pollution, get the filter first. When I drive to a Green Zone where I can have 600+ second exposures, I don't use the LP filter unless I'm imaging west towards Bristol which is 15 miles away. My 1st modded camera was a self modded $150 1000D (only 10MP). I've even shot targets like Orion and the Veil Nebulae mainly with a T2i, then shot some with the 1000D and combined the images in PS later. Either way your images will better :)

The Veil 120 seconds with Astronomik CLS filter from my Red Zone

Posted Image



The Veil 120 seconds with with no LP filter. And yes there is a picture here.

Posted Image


finial image

Posted Image

#18 fco_star

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Posted 28 January 2013 - 12:15 AM

+1 Toxic
I have the same experience, before I couldn't go over 45sec. same issue (wash out pictures), I first bought the CLS-CCD filter and I could go easy to 5-8 minutes with no issues, then I bought the IDAS LP filter and I get easy 5-8min. Then I decided to buy a Mod camera, it definitely enhance the result of my pictures, I'm in an red zone and I'm very please with the results. I have a friend of mine that could not believe my personal stories related to my success with the filters but I guess it is because he is a genius and he probably will not believe it until he try it by himself.
hope this help you.

#19 Toxic Coolaid

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Posted 28 January 2013 - 01:01 AM

I agree the LP filters are amazing. I also have a UHC-E that cuts out more than the CLS. I'll have to it out on the 60Da because it doesn't cut enough IR for the full mod on my T2i. I have to use the CLS-CCD on the full MOD T2i. But from my initial test it is impressive. I think everyone should get the CLS-CCD no matter the mod. I was able to bring out the Horsehed and flame with only 40 x 2 second lights with the Hap Griffin Full Mod with the CLS-CCD and the Moon out yesterday. Its cool to be able to do day time photography with auto focus using the OWB filter, IR photography with the Pro planet 742, and AP photos with the CLS-CCD or L filter. I can control exactly what wavelengths get to the sensor. Hap put up good explanations and examples here. I think he's running a beta special for the full mod with single glass replacement to retain full autofocus.

http://www.imagingin...llspectrum.html

https://plus.google....835624624833...

now I can't wait to get the Pro Planet 742 and do some IR imaging

#20 Jerry Lodriguss

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Posted 28 January 2013 - 02:41 AM

Sure it will change the colour of the backgroud sky - but until you mod the camera it will not improve capture of H alpha - so I suggest sticking to globs, open clusters, bright galaxies and such like until you do

This is not an opinion its optical physics


Hi Tonk,

I'm sorry, I'm going to have to disagree with you here.

A light-pollution filter like the CLS, LPS or Deep-Sky will definitely help with recording Ha nebula with an unmodified camera.

Please see:

http://www.astropix....ROP/DSLR_HA.HTM

scroll down to the section "Secrets Finally Revealed" :-)

Compare the North America nebula shot with an unmodded camera with and without a deeps-sky filter.

The comparison images have the same total exposure time.

The reason these filters help, even with an unmodded camera, is that by filtering out the skyglow and light pollution, they allow longer exposures that record more Ha light for a given sky background brightness.

It is this contrast improvement that makes using a filter on an unmodded camera work with Ha.

Jerry

#21 jsines

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Posted 28 January 2013 - 02:41 PM

I have an unmodified Canon t3i. I'm wondering which light pollution filter would be the best. Orion has a skyglow that is specifically designed for astrophotography. However, I'm not sure how different it is from their regular skyglow (other than the fact that it's far more expensive).

But, are there others that would be better? I don't have a lot of light pollution now, but I'm going to be moving in the next year to a place with more, and I'd hate to stop astrophotography just when I'm getting going.

Thanks!


When you say "regular skyglow", I'm assuming you're referring to their SkyGlow Broadband LP filter. There is a difference between the two. Take a look at their transmission graphs - the Broadband LP filter blocks everything from about 540-625, while the Astrophotography LP filter doesn't block everything between 540-625.

I bought the Orion SkyGlow astrophotography filter, and it's constantly attached to my t-adapter. I shoot from a white zone, but I'll keep it on even when shooting from a dark zone, per Jerry's suggestion. I did a lot of research, read Samir's article, and decided on the Orion rather than the more expensive filters because it has about the same transmission graph as the more expensive filter, and I could always return it if I didn't like it.

It has allowed me to image at least twice as long - I was getting washed out at about 60 seconds, 400 ISO before, now I go to 2-3 minutes at 400 ISO. I don't see a strong blue cast to the image like I've heard from other filters. I'm very happy with it.

#22 jgraham

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Posted 28 January 2013 - 06:16 PM

Until I started using a light pollution filter color imaging from my red-zone back yard was pretty much a waste of time. Boadband filters designed for visual weren't much better; they pulled down the skyglow, but whacked the color. The Hutech IDA LPS2 made a tremendous difference, reducing sky glow and preserving the color information. The Orion imaging sky glow filter gives similar excellent performance. I now use both the Hutech and Orion filters in their 1.25" format and I just bought a 2" Orion filter.

#23 Dan Watt

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Posted 28 January 2013 - 11:00 PM

Another comparison with my CLS-CCD filter from a almost dark site (green zone). This is a 180sec exposure @ 1600ISO without the filter. Camera used is a full spectrum modded Canon T3 on my 8" f4 newt.

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#24 Dan Watt

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Posted 28 January 2013 - 11:01 PM

And here is a 300 second exposure @ 1600 ISO with the CLS-CCD filter in place. Quite a difference.

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#25 avarakin

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Posted 02 February 2013 - 09:19 PM

To OP:
I suggest getting 12nm Ha Astronomik Clip In. Even though your camera is not modified, it does have some sensitivity to Ha, so you will be getting much better Ha signal.

Here is a thought which would be interesting to prove or disprove: assuming that your image S/N is limited not by noise of sensor but by Light Pollution, then it does not really matter if camera is modified or not modified: the in-camera filter will be reducing both Ha signal and LP signal, thus keeping S/N ratio the same. The only drawback of non-modified camera with Ha filter would be that one needs much longer exposures.
It would be interesting to test this theory.

Alex






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