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best filter for nebula

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#1 wheelers4life

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Posted 29 October 2019 - 08:23 PM

I have a celestron edge hd 8. I hust recieved my .7x reducer today. I am looking for a filter that I can use to try out on nebula. I have read many differnt types of filters. Most seem to say for visual. What would be good for EAA I was thinking about a skyglow, narrowband filter or ultra contrast filter. I have been looking at the ring, lagoon, viel, orion, and horsehead filter. have been looking at some clusters as well. I need the 2 inch that will go on my zwo asi 294 pro mc cooled

Thanks



#2 Umasscrew39

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Posted 30 October 2019 - 04:01 AM

By far the best is the Optolong L-eNhance filter for nebulae.  I use it on my C11" EdgeHD with my ZWO ASI294MC Pro for emission nebulae and have gotten excellent results. 


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#3 NaNuu

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Posted 30 October 2019 - 05:32 AM

I agree, if observing in heavy light polluted areas, a dual- or tribune filter is a very good thing. There are different brands (i.e. I'm experimenting with an IDAS NB1 filter, essentially the same thing), so you might search for "dual band filters".

 

But be aware that these filters cut out much of the light hence usually you will need much longer single frame exposures to get something to see. 


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#4 sudeepban

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Posted 30 October 2019 - 06:28 AM

I feel like the Optolong L-eNhance filter is the one I most consistently hear of people using with success, and I've considered it as a next step for improving my EAA setup (8SE, 294MC Pro, f/6.3 reducer) given the light pollution an hour north of NYC. I had a couple of questions about adding it:

1. Would this be useful for imaging nebulas only? No use for galaxies?
2. Where in the optical train does it go exactly? Could it impact backfocus for the reducer?
3. Are these useful for visual as well as imaging? I have 1.25" filters and eyepieces, do I need to go for 2.00" for use with the camera?

#5 Umasscrew39

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Posted 30 October 2019 - 07:01 AM

I feel like the Optolong L-eNhance filter is the one I most consistently hear of people using with success, and I've considered it as a next step for improving my EAA setup (8SE, 294MC Pro, f/6.3 reducer) given the light pollution an hour north of NYC. I had a couple of questions about adding it:

1. Would this be useful for imaging nebulas only? No use for galaxies?
2. Where in the optical train does it go exactly? Could it impact backfocus for the reducer?
3. Are these useful for visual as well as imaging? I have 1.25" filters and eyepieces, do I need to go for 2.00" for use with the camera?

I also suffer from LP and bad humidity just north of Orlando.  So, I know what you mean.

 

1- I have tried it on M31 and some star clusters.  It is ok but not great.  Suggest you try something like the Optolong L-Pro, the IDAS LPS D-1 (has worked well for me in the past), or one of the many UHC filters on the market.  Frankly, I've not found many to help much on galaxies.

 

2- Depends on your setup.  I use a filter wheel which goes before the reducer which connects directly to the scope.  So, it is camera-filter wheel with filter-reducer-scope using appropriate spacers to meet backfocus requirements.  This does not impact backfocus requirements.  Other options for filter placement are in the ZWO instructions.

 

3- I never tried it for visual.  Both sizes work well with a camera.  


Edited by Umasscrew39, 30 October 2019 - 08:34 AM.


#6 Clouzot

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Posted 30 October 2019 - 08:25 AM

Jim Thompson started a very interesting comparison of LP filters for EAA in this forum. You may want to check it out!

I recently got two different LP filters: the ubiquitous Optolong L-Enhance (mentioned above), and the IDAS LPS-D2. Both came as 2" filters, which I can easily thread into my Hyperstar.


My current setup: C9, ASI183MC uncooled, Hyperstar v4, Sharpcap.

 

I ran some quick comparisons with and without the IDAS fiter, on the same night. My sky is probably between Bortle 6 and 7 (the Milky Way is not visible).


Here is a side-to-side comparison of M33 with either the IDAS, or no filter at all.

In both captures:

- No flats, as can be seen from the vignetting.

- Gain 118, 30s subexposures

- no Sharpcap enhancements applied

- Sharpcap livestack histogram autostretch for both captures.

- no general histogram stretch

 

The only difference is the resulting histogram: the IDAS cuts a lot of light, so at this gain and exposure, there's little signal. I had to balance whites manually to compensate for the filter's tendency to put everything off, but the IDAS image retains its greenish cast...

 

Total integration time: 18min30s with IDAS, 20min with no filter.

 

Interestingly, the IDAS brings lots of detail that are barely visible in the no-filter shot. It also cuts stars (which an IR/UV cut would do as well I gather). On the negative side of things, it also gives that unnatural colored look to nebulas.

 

M33_compare.jpg


Edited by Clouzot, 30 October 2019 - 08:26 AM.

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#7 Clouzot

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Posted 30 October 2019 - 10:49 AM

Here's a comparison shot of part of the Cygnus Eastern Veil (NGC 6992 etc) between IDAS LPS-D2, Optolong L-Enhance and no filter, all done with the same setup as above. This was the first light of both filters, so please bear with me!

 

No filter: 20x30s = 10 min total

Optolong: 20x30s = 10 min total

IDAS D2: 17x15s = 4m15s total

 

I realize that shooting 15s subs with the IDAS instead of 30s and integrating twice less wasn't my best move (at least for comparison purposes) grin.gif

 

It's really, really hard to compare apples to apples with these filters, as the histogram black/mid/white points and the white balance will always be different from capture to capture.

 

What is again evident is the contrast you can gain by using this type of filter. But they really need longer exposures, probably more like 45s or 1 minute even at f/2. It's already a bit too much

That, in turn, implies a better mount, a better polar alignement... Not something you want to fiddle with during an EAA session.

NGC6992_comp.jpg


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#8 wheelers4life

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Posted 10 November 2019 - 06:46 PM

Quick question. My zwo asi 294 has what looks like an adapter that holds a 1.25 filter and screws in very close to the sensor. Has anyone seen this. Would it be ok to use. I can knock off a heft amount going with 1.25 filters instead of 2"

#9 donstim

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Posted 10 November 2019 - 10:27 PM

Yes, that is an adapter for a 1.25 inch filter. It puts the filter very close to the camera sensor. I feel it works well, and that it what I've been using.

#10 Ptarmigan

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Posted 10 November 2019 - 10:38 PM

Quick question. My zwo asi 294 has what looks like an adapter that holds a 1.25 filter and screws in very close to the sensor. Has anyone seen this. Would it be ok to use. I can knock off a heft amount going with 1.25 filters instead of 2"

I have a ZWO ASI294MC Pro and I have used the adapter that allows 1.25 filter to be close to the sensor. I have had no trouble with it and I use the Lumicon Deep Sky filter.



#11 wheelers4life

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Posted 10 November 2019 - 11:43 PM

Thanks. Yall are awsome
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