Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Filter recommendations for nebula imaging (77mm)?

  • Please log in to reply
21 replies to this topic

#1 Henrik S

Henrik S

    Lift Off

  • -----
  • topic starter
  • Posts: 5
  • Joined: 10 Jun 2020

Posted 20 September 2020 - 05:18 AM

I’ll soon be getting back my Nikon D5500 back from astro modification, and it’ll have a uv/ir-block. I will be using it with my Samyang (=Rokinon) 135mm/f2, mainly from a bortle 3 location, so not much light pollution. I’m looking for a filter to help me press back those pesky stars when imaging nebula centrally in the milky way arm, like the north america nebula etc.

Since I use a Nikon D5500, I haven’t really found any clip-in that I’d want to try. I see that STC optics has soon clip in for asp-c nikon, but apparently, it would need some bending or cutting to get it into place, and I wouldn’t wanna go ”DIY” on something you pay 250$ for 🤔 So the only options I’ve found so far, is 77mm filters for the front of the lens. I’d love to see something like an optolong l-enhance in that size, but the front runner now seems to be the Optolong UHC filter (77mm). Any thoughts, suggestions?

Edited by Henrik S, 20 September 2020 - 05:18 AM.


#2 m_abukhalid

m_abukhalid

    Mariner 2

  • -----
  • Posts: 201
  • Joined: 28 Dec 2017

Posted 21 September 2020 - 12:37 PM

There's an IDAS LPS-D2-N5 which is specifically designed for the d5500 sensor for a good fit. Another option which im following is using stepdown rings with the lens wide open to use any 2 inch filter you like

#3 Henrik S

Henrik S

    Lift Off

  • -----
  • topic starter
  • Posts: 5
  • Joined: 10 Jun 2020

Posted 21 September 2020 - 01:27 PM

Thank you! One thing I haven’t really grasped, is how using step-down rings would affect the image. I understand that it would partly be like stopping down the aperture a bit (which I usually do anyway to sharpen up the stars). But do you think it could also cause some vignetting, since it’s there in the front? I like the idea of a 2 inch filter of course, since then I could use it when I decide to get an apo refractor in the future as well 😎

#4 DubbelDerp

DubbelDerp

    Apollo

  • *****
  • Posts: 1,096
  • Joined: 14 Sep 2018
  • Loc: Upper Peninsula of Michigan

Posted 21 September 2020 - 02:04 PM

Thank you! One thing I haven’t really grasped, is how using step-down rings would affect the image. I understand that it would partly be like stopping down the aperture a bit (which I usually do anyway to sharpen up the stars). But do you think it could also cause some vignetting, since it’s there in the front? I like the idea of a 2 inch filter of course, since then I could use it when I decide to get an apo refractor in the future as well 😎

The step-down rings do increase the amount of vignetting, but flats through the filter do an adequate job of correcting for it. The bigger issue, I think, is uneven diffraction spikes around bright off-axis stars. My personal opinion is that the benefits of shooting emission nebulae outweigh the funny looking bright stars, but others will disagree.

 

Here's an example of an emission nebula shot through a Rokinon 135mm f/2 and Optolong L-eNhance filter mounted over the objective via step-down rings. Note the diffraction pattern around Alderamin:

https://www.astrobin.../full/7zyk81/0/



#5 m_abukhalid

m_abukhalid

    Mariner 2

  • -----
  • Posts: 201
  • Joined: 28 Dec 2017

Posted 21 September 2020 - 02:07 PM

I went back to check and realized I only actually tested it stepped down to 58mm. Stepping down to 58mm didn't give me any increase in vignette but I still needed flats for my D500. This is the image I got out of it (no filter)

117715986 10157078873332391 6205233974558945369 O

 

I chose the 2 inch filter route because I would like to upgrade my camera to a cooled camera at some point. Stepping down to 48mm, if it works as well, would slow down my lens even further to F6.3 but my primary imaging is now on my 6 inch newt. Your lens would become F2.8 I think. The clip in filter would make more sense if you plan to use the same camera with a refractor as it lets you get the most out of your lenses and you can still use it on any telescope with the D5500. Going for 2 inch filters gives you the flexibility of changing the camera without buying a new filter. Hopefully someone on here actually tested this setup with your lens. Even if you get a clip in filter, you can still use the step down rings to stop down your lens to where you see no abherrations at the edge of your image (if thats something you are doing already in camera).



#6 Henrik S

Henrik S

    Lift Off

  • -----
  • topic starter
  • Posts: 5
  • Joined: 10 Jun 2020

Posted 21 September 2020 - 02:54 PM

The step-down rings do increase the amount of vignetting, but flats through the filter do an adequate job of correcting for it. The bigger issue, I think, is uneven diffraction spikes around bright off-axis stars. My personal opinion is that the benefits of shooting emission nebulae outweigh the funny looking bright stars, but others will disagree.

Here's an example of an emission nebula shot through a Rokinon 135mm f/2 and Optolong L-eNhance filter mounted over the objective via step-down rings. Note the diffraction pattern around Alderamin:
https://www.astrobin.../full/7zyk81/0/


Really nice elephant trunk nebula! 👍 Your results are really great. I actually tend to get some uneven-ness in the diffraction spikes of the brightest off-axis stars even without a filter anyway. What f-stop did you use there in the lens? Or was it fully open and stopped down with just the filter in front? Do you think vignetting/uneven spikes would theoretically be tamed down a bit by stopping down the lens a bit more so that the lens stops down more than the filter does? If that makes any sense.. 🙂

#7 DubbelDerp

DubbelDerp

    Apollo

  • *****
  • Posts: 1,096
  • Joined: 14 Sep 2018
  • Loc: Upper Peninsula of Michigan

Posted 21 September 2020 - 04:30 PM

Thanks! I left the aperture wide open and let the step down ring do its thing. I thought about stopping it down so that the internal aperture blades were limiting the light to see if it improved the star shapes, but the new moon came around and I haven’t had moonlit skies to justify trying. But I think it’s worth giving it a shot.
  • PollAirUs likes this

#8 PollAirUs

PollAirUs

    Sputnik

  • -----
  • Posts: 35
  • Joined: 30 Apr 2020
  • Loc: Minas Gerais, Brasil

Posted 21 September 2020 - 05:51 PM

I'm in the exactly same situation as you are! I have a Nikon D5300 and a Rokinon 135mm F2 as well.

I'm also afraid of using step down rings to use 2" filters. They're much easier to find and we'd be able to use in any apo telescope in the future, but I fear use it in front of the objective lens. Also 77 to 52mm is a big step down, but if those diffraction spikes in some bright stars is the only issue, It doesn't seem to be such a big risk. Of course vignetting is also a considerable issue, but I wonder if DubbelDerp used a software plugin to remove it in processing, such as Gradient Xterminator or if only the flats are enough to avoid vignette.



#9 DubbelDerp

DubbelDerp

    Apollo

  • *****
  • Posts: 1,096
  • Joined: 14 Sep 2018
  • Loc: Upper Peninsula of Michigan

Posted 21 September 2020 - 06:00 PM

I'm in the exactly same situation as you are! I have a Nikon D5300 and a Rokinon 135mm F2 as well.
I'm also afraid of using step down rings to use 2" filters. They're much easier to find and we'd be able to use in any apo telescope in the future, but I fear use it in front of the objective lens. Also 77 to 52mm is a big step down, but if those diffraction spikes in some bright stars is the only issue, It doesn't seem to be such a big risk. Of course vignetting is also a considerable issue, but I wonder if DubbelDerp used a software plugin to remove it in processing, such as Gradient Xterminator or if only the flats are enough to avoid vignette.


I can post some raw lights and some calibrated lights tomorrow. In my case, the flats worked just fine without any additional processing. Other than removing light pollution gradients, that would be present regardless.
  • PollAirUs likes this

#10 PollAirUs

PollAirUs

    Sputnik

  • -----
  • Posts: 35
  • Joined: 30 Apr 2020
  • Loc: Minas Gerais, Brasil

Posted 21 September 2020 - 06:46 PM

I can post some raw lights and some calibrated lights tomorrow. In my case, the flats worked just fine without any additional processing. Other than removing light pollution gradients, that would be present regardless.

That would be awesome! I just realized that I've been following you on astrobin for a long time.



#11 DubbelDerp

DubbelDerp

    Apollo

  • *****
  • Posts: 1,096
  • Joined: 14 Sep 2018
  • Loc: Upper Peninsula of Michigan

Posted 21 September 2020 - 07:02 PM

That would be awesome! I just realized that I've been following you on astrobin for a long time.

Hey, so you’re the one! Sorry about most of the images I post... grin.gif


  • PollAirUs likes this

#12 mmalik

mmalik

    DSLR camera modifications

  • *****
  • Vendors
  • Posts: 10,971
  • Joined: 13 Jan 2012
  • Loc: USA

Posted 21 September 2020 - 08:01 PM

There's an IDAS LPS-D2-N5 which is specifically designed for the d5500 sensor for a good fit.

Where is this filter listed? I don't find it at Hutch listing. Regards

 

 

Edit: There is one LPS-D1-N5 listed...


Edited by mmalik, 21 September 2020 - 08:03 PM.


#13 DubbelDerp

DubbelDerp

    Apollo

  • *****
  • Posts: 1,096
  • Joined: 14 Sep 2018
  • Loc: Upper Peninsula of Michigan

Posted 22 September 2020 - 08:21 AM

So here's my camera set-up. H-a modded Canon 600D, with APS-C sensor. Rokinon 135mm f/2 lens, 77-49mm and then 49-48mm step-down ring, Optolong L-eNhance filter:

Annotation 2020-09-22 091451.jpg

 

Here's a 300-second light frame, uncalibrated, highly stretched in APP to show the vignetting:

Annotation 2020-09-22 091601.jpg

 

Here's a single flat frame, uncalibrated, highly stretched in APP:

Annotation 2020-09-22 091726.jpg

 

Here's the calibrated Master Flat, background neutralized and highly stretched in APP:

Annotation 2020-09-22 091842.jpg

 

And here's the calibrated light frame, calibrated with the Master Flat and Master Dark, highly stretched in APP:

Annotation 2020-09-22 092019.jpg

 

Edit - My guess is that this would be a problem on full frame. But it does appear to be effective with a crop sensor camera.


Edited by DubbelDerp, 22 September 2020 - 08:22 AM.

  • 2ghouls and PollAirUs like this

#14 Henrik S

Henrik S

    Lift Off

  • -----
  • topic starter
  • Posts: 5
  • Joined: 10 Jun 2020

Posted 22 September 2020 - 10:35 AM

Thank you, that’s really valuable input! 🙂 The vignetting doesn’t seem that much worse than when shooting without filters @f/2.0.

#15 Linwood

Linwood

    Viking 1

  • -----
  • Posts: 848
  • Joined: 09 Jul 2020
  • Loc: Ft Myers, Florida, USA

Posted 22 September 2020 - 10:49 AM

https://www.astronomik.com/

So here's my camera set-up. H-a modded Canon 600D, with APS-C sensor. Rokinon 135mm f/2 lens, 77-49mm and then 49-48mm step-down ring, Optolong L-eNhance filter:

attachicon.gifAnnotation 2020-09-22 091451.jpg

 

Here's a 300-second light frame, uncalibrated, highly stretched in APP to show the vignetting:

attachicon.gifAnnotation 2020-09-22 091601.jpg

 

Here's a single flat frame, uncalibrated, highly stretched in APP:

attachicon.gifAnnotation 2020-09-22 091726.jpg

 

Here's the calibrated Master Flat, background neutralized and highly stretched in APP:

attachicon.gifAnnotation 2020-09-22 091842.jpg

 

And here's the calibrated light frame, calibrated with the Master Flat and Master Dark, highly stretched in APP:

attachicon.gifAnnotation 2020-09-22 092019.jpg

 

Edit - My guess is that this would be a problem on full frame. But it does appear to be effective with a crop sensor camera.

So I have not tried anything like this for astro, but I use nice wide fast lenses with wide apertures a lot for terrestrial sports shooting, and occasionally am shooting through openings in fences and protective barriers that are a bit smaller than the lens opening.  What I've found is vignetting is not per se an issue, but that the occlusion will reduce overall contrast.  In daylight it is worse if the occlusion has color or is lit, not something you have with stepdown rings of course.  This is not like (say) a bad lens hood on a longer, slower telephoto, where you definitely see vignetting.  F2, F1.4 - those apertures, with stuff near the glass, are just plain different.

 

I know zip about this in AP-land, but if it were me and I wanted to test the impact, I'd also take the filter off (just the filter) and shoot with and without the stepdowns for the same exposure, and see what FWHM and similar measures look like.  Maybe there's no impact (like I said -- no color, dark, very round no shape -- maybe no impact except a slight light loss). But... maybe. 

 

I am interested because I have an 85/1.4 I'd like to try, and it takes a 77mm if I recall. 

 

I'm still waiting on a drop in filter (40.5mm) that is being made -- Astronomik will make filters to order, by the way.  I didn't find it expensive (compared to similar sizes), though I also am still waiting for it so no comment on quality, etc.  Though they seem to have a good reputation. 


Edited by Linwood, 22 September 2020 - 10:50 AM.


#16 erictheastrojunkie

erictheastrojunkie

    Viking 1

  • *****
  • Posts: 846
  • Joined: 15 Jul 2016
  • Loc: Salt Lake City

Posted 22 September 2020 - 12:05 PM

You're shooting from a bortle 3 zone, the only filters I'd consider are one of the duo or tri-narrowband options if you'd like to explore some pseudo-narrowband imaging with your modified camera. Otherwise don't use any filters at all, they won't help you in any capacity. 



#17 mmalik

mmalik

    DSLR camera modifications

  • *****
  • Vendors
  • Posts: 10,971
  • Joined: 13 Jan 2012
  • Loc: USA

Posted 22 September 2020 - 12:09 PM

Or use one listed in the Edit; it is a front filter (...goes behind the lens that is). Regards

 

Edit: There is one LPS-D1-N5 listed...



#18 Henrik S

Henrik S

    Lift Off

  • -----
  • topic starter
  • Posts: 5
  • Joined: 10 Jun 2020

Posted 22 September 2020 - 01:07 PM

You're shooting from a bortle 3 zone, the only filters I'd consider are one of the duo or tri-narrowband options if you'd like to explore some pseudo-narrowband imaging with your modified camera. Otherwise don't use any filters at all, they won't help you in any capacity.


Yeah, it’s mainly a pseudo-narrowband effect I’m looking for, together with pressing back the stars. If I go with a 2 inch filter, it’ll probably be an l-extreme or l-enhance. Then I could play around with splitting channels, color assigning do some HOO-like stuff and pseudo-SHO 😎 I will start out filterless with my new camera so I’ll get to know it well before adding any filters. It’ll hopefully be quite a step forward from my old unmodded D3100 to a modded D5500.

Edited by Henrik S, 22 September 2020 - 01:08 PM.


#19 m_abukhalid

m_abukhalid

    Mariner 2

  • -----
  • Posts: 201
  • Joined: 28 Dec 2017

Posted 22 September 2020 - 04:59 PM

Where is this filter listed? I don't find it at Hutch listing. Regards

 

 

Edit: There is one LPS-D1-N5 listed...

I saw it here:

https://www.ontariot...e.com/d2n5.html


  • mmalik likes this

#20 PollAirUs

PollAirUs

    Sputnik

  • -----
  • Posts: 35
  • Joined: 30 Apr 2020
  • Loc: Minas Gerais, Brasil

Posted 29 September 2020 - 08:56 AM

So here's my camera set-up. H-a modded Canon 600D, with APS-C sensor. Rokinon 135mm f/2 lens, 77-49mm and then 49-48mm step-down ring, Optolong L-eNhance filter:

attachicon.gifAnnotation 2020-09-22 091451.jpg

I'm sorry but If 2" means 50.8mm, wouldn't it fit better in a 77-51mm step-down ring?

I'm asking because I'm thinking about buying an 2" filter to use the same way as you did here
 



#21 DubbelDerp

DubbelDerp

    Apollo

  • *****
  • Posts: 1,096
  • Joined: 14 Sep 2018
  • Loc: Upper Peninsula of Michigan

Posted 29 September 2020 - 09:26 AM

2" filter is an inaccurate description. When we're talking about 2" filters, it's actually an M48x0.75 thread. There are some oddball thread pitches out there, so check with the particular filter you're buying, but the majority of them are M48x0.75.



#22 Linwood

Linwood

    Viking 1

  • -----
  • Posts: 848
  • Joined: 09 Jul 2020
  • Loc: Ft Myers, Florida, USA

Posted 29 September 2020 - 09:52 AM

2" filter is an inaccurate description. When we're talking about 2" filters, it's actually an M48x0.75 thread. There are some oddball thread pitches out there, so check with the particular filter you're buying, but the majority of them are M48x0.75.

The guy that invented the 2"x4" board size in the US also named the 2" filter. smile.gif

 

It answered so many questions when I found out that 2" filters were M48.  A lot of descriptions of people's imaging trains suddenly made sense.


  • DubbelDerp likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics