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

Best Hydrogen alpha filter (1.25") for < $100?

  • Please log in to reply
12 replies to this topic

#1 DecepitconFromOrion

DecepitconFromOrion

    Lift Off

  • -----
  • topic starter
  • Posts: 22
  • Joined: 05 Oct 2018

Posted 07 December 2019 - 12:21 AM

Hi all! I'm looking to get started with solar imaging soon (with a proper solar filter first obviously) and am wondering if there are any decent Ha filters (1.25") for less than 100 USD? I have a Celestron 8SE with focal length reducer, in case it matters. Thanks!


  • PirateMike likes this

#2 Napp

Napp

    Vanguard

  • *****
  • Posts: 2,438
  • Joined: 26 Jul 2015
  • Loc: Florida, USA

Posted 07 December 2019 - 12:42 AM

Sorry, but photographic filters are not narrow band enough for solar photography.  Solar telescopes have filtering with a bandwidth of less than an angstrom.  You have to spend big bucks for hydrogen alpha viewing and photography of the sun. 


  • PirateMike and drd715 like this

#3 PirateMike

PirateMike

    Mercury-Atlas

  • -----
  • Posts: 2,960
  • Joined: 27 Sep 2013
  • Loc: A Green Dot On A Blue Sea

Posted 07 December 2019 - 12:59 AM

I don't do solar imaging and I know almost nothing about it. One of the main reasons that I'm not doing it now is that some of the equipment is different than regular deep sky imaging equipment and I haven't the money to get started (yet).

 

Solar imaging does not seem cheap to start doing.

 

 

Miguel   8-)

 

.



#4 Napp

Napp

    Vanguard

  • *****
  • Posts: 2,438
  • Joined: 26 Jul 2015
  • Loc: Florida, USA

Posted 07 December 2019 - 01:15 AM

The cheapest entry to solar observing and photography I am aware of is the Meade Coronado PST for about $700 new (cheaper used) not including mount.  And it is not ideal for photography though some experienced photographers get decent results.  The really beautiful photos you see here in Cloudy Nights are usually made using DayStar Quarks or larger models of Lunt or Meade Coronado hydrogen alpha scopes.


Edited by Napp, 07 December 2019 - 01:20 AM.


#5 17.5Dob

17.5Dob

    Fly Me to the Moon

  • ****-
  • Posts: 6,754
  • Joined: 21 Mar 2013
  • Loc: Colorado,USA

Posted 07 December 2019 - 01:20 AM

There is no such thing.......to get "real" solar Ha images, you need a sub angstrom filter something like this...




At bare minimum, expect to spend  $3,000-5,000 to get your 8SE up to solar viewing in Ha.....


It would be far cheaper to just buy a small Solar scope like this !!

 


Edited by 17.5Dob, 07 December 2019 - 01:27 AM.

  • guyroch likes this

#6 FlankerOneTwo

FlankerOneTwo

    Viking 1

  • *****
  • Posts: 890
  • Joined: 30 Aug 2017
  • Loc: Vegas, baby!

Posted 07 December 2019 - 05:02 AM

Sorry to say but solar h-alpha imaging can't really be done inexpensively. Solar h-alpha imaging requires extremely narrow bandpass filters, typically 0.5 Angstrom (0.05nm) or less. This can be achieved with a type of interference filter called an etalon. These come in two main varieties, the air-spaced ones such as are used in solar h-alpha refractors such as those by Lunt and Coronado and can be had generally in etalon apertures up to 90mm (although the scope aperture may be larger if the etalon is internally mounted), and mica spaced ones such as in the Daystar Quark / Quantum and Solar Spectrum products. Air spaced etalons are typically front or internally mounted and require a separate blocking filter, typically incorporated into a diagonal. The Daystar and SolarSpectrum mica-spaced etalons are intended to be mounted at the rear of the scope in place of an eyepiece and incorporate a blocking filter into the design, however these filters are not adequate by themselves once aperture gets above 120mm or so. This is the type of device you would need if you intend to image with your 8SE. Those of us imaging with scopes much above 150mm are typically using a full aperture energy rejection filter (ERF) and maybe even an additional  filter such as a Baader UV/IR or R-CCD. A full aperture ERF is not inexpensive in large sizes such as you would need for your 8SE - a 180mm Baader D-ERF is $1300 (and you also need a filter cell to hold it on the scope, $334 from Baader); many of us use ones produced by Aries in the Ukraine which I have found to be excellent, and the vendor can be contacted here in the Solar Observing and Imaging group. The etalons are not inexpensive either; a Daystar Quark is $1195 new, the tighter guaranteed bandpass Quantums are significantly more ($8500 for the lower grade 0.4A SE, $12650 for the research grade 0.4A PE). Of course you can find used ones for less in the Classifieds (but not $100).

 

If you decide you would really like to do solar Ha, probably the best way to get started is to pick up something like a Lunt 60THa. This will run you $1500 - $2200 for a single stacked scope, depending on blocking filter and focuser. It is a lightweight scope with a focal length that is relatively tolerant of seeing conditions (a huge factor in solar imaging), and has enough backfocus to accomodate an imaging train without difficulty. Note that solar imaging with an 8SE is very very sensitive to seeing conditions, and I find that there are maybe 1 or 2 hours during the morning when the sun is both high enough to reduce airmass and the ground has not yet heated up enough for thermal effects to be severe. Later in the day the image often looks like peering into a pot of boiling water.

 

White light solar imaging can be done for quite a lot less, but of course you will not see all the chromospheric features that make h-alpha so fascinating. Currently at solar minimum there is not a lot to look at in white light, but that will change over the next few years.
There are quite a few more experienced folks over in the Solar Observing and Imaging forum. Hope this has been helpful.


  • jerahian and DecepitconFromOrion like this

#7 DecepitconFromOrion

DecepitconFromOrion

    Lift Off

  • -----
  • topic starter
  • Posts: 22
  • Joined: 05 Oct 2018

Posted 07 December 2019 - 10:43 AM

Thanks everyone, sorry for my naivety ... I guess solar photography will have to be a project for later when I have more discretionary $$$. I was hoping that, if not Ha, this would be another narrowband filter that would show fine details, but sounds like the bandwidth has to be tiny and all of these filters will set be back at least a grand. Too bad we are at solar minimum, nothing to see in white light. Oh well! 



#8 Napp

Napp

    Vanguard

  • *****
  • Posts: 2,438
  • Joined: 26 Jul 2015
  • Loc: Florida, USA

Posted 07 December 2019 - 12:05 PM

Thanks everyone, sorry for my naivety ... I guess solar photography will have to be a project for later when I have more discretionary $$$. I was hoping that, if not Ha, this would be another narrowband filter that would show fine details, but sounds like the bandwidth has to be tiny and all of these filters will set be back at least a grand. Too bad we are at solar minimum, nothing to see in white light. Oh well! 

 

No need to apologize.  This question actually shows up fairly often.  Better to ask than just spend the money to find out it doesn’t work.  Cloudy Nights folks have stopped me a few times from wasting my money.  Of course they’ve caused me to spend much more money by giving me new ideas.  lol.gif



#9 MalVeauX

MalVeauX

    Cosmos

  • *****
  • Posts: 7,656
  • Joined: 25 Feb 2016
  • Loc: Florida

Posted 07 December 2019 - 12:20 PM



Thanks everyone, sorry for my naivety ... I guess solar photography will have to be a project for later when I have more discretionary $$$. I was hoping that, if not Ha, this would be another narrowband filter that would show fine details, but sounds like the bandwidth has to be tiny and all of these filters will set be back at least a grand. Too bad we are at solar minimum, nothing to see in white light. Oh well! 

To the contrary, there's plenty to see in white light with a 200mm aperture, if your seeing supports it. You can resolve convection cells with this size scope, which are actually quite beautiful and interesting to image and see. They change rapidly, minutes, so it's never the same. You could get into animating this and showing the changing cells as they come and go in just 30 minutes of real time, structures over 1500km in diameter... You can use a loose 656nm or 610nm filter to narrow things down to have calmer seeing conditions. You just need a solar film filter, full aperture, to thermally control your C8's aperture.

 

For example, here's what you can resolve in white light with a C8:

 

49051337837_4efd65ed91_b.jpg

 

The photosphere can be inexpensively imaged and is actually very interesting with higher resolution, less interesting with course image scales and tiny apertures (just a ball with some texture). But in high resolution with big apertures, if your seeing supports it, there's plenty interesting surface structures in the photosphere that are lovely to see and image.

 

Going to the chromosphere, things get costly. And it would require a full aperture D-ERF for your C8, which is even more costly than the narrowband filters. So if you're interested in the chromosphere (HA, CaK), then I suggest you look at small refractor options (either dedicated scopes like a Lunt, Coronado or a Daystar filter, everything will be $1200 to $2000 basically to start, so that's just the fact of things).

 

Very best,


  • brave_ulysses, phobos2 and Tulloch like this

#10 Tulloch

Tulloch

    Surveyor 1

  • *****
  • Posts: 1,829
  • Joined: 02 Mar 2019
  • Loc: Melbourne, Australia

Posted 08 December 2019 - 01:21 AM

To the contrary, there's plenty to see in white light with a 200mm aperture, if your seeing supports it. You can resolve convection cells with this size scope, which are actually quite beautiful and interesting to image and see. They change rapidly, minutes, so it's never the same. You could get into animating this and showing the changing cells as they come and go in just 30 minutes of real time, structures over 1500km in diameter... You can use a loose 656nm or 610nm filter to narrow things down to have calmer seeing conditions. You just need a solar film filter, full aperture, to thermally control your C8's aperture.

 

For example, here's what you can resolve in white light with a C8:

 

Very best,

Wow, that's really impressive! 

 

If I understand you correctly, images of the sun (like this one) can be obtained by putting something like a "Celestron Eclipsmart SCT Solar Filter" (or equivalent) over the end of the tube, then maybe some extra filters? (Not as good as yours of course, but something similar after months/years of practice).

 

How do you align the scope with no stars to point at? Or do you just do a simple 1-star alignment and point it at the sun to align?

 

Thanks in advance, Andrew


Edited by Tulloch, 08 December 2019 - 01:53 AM.


#11 MalVeauX

MalVeauX

    Cosmos

  • *****
  • Posts: 7,656
  • Joined: 25 Feb 2016
  • Loc: Florida

Posted 08 December 2019 - 05:59 AM

Wow, that's really impressive! 

 

If I understand you correctly, images of the sun (like this one) can be obtained by putting something like a "Celestron Eclipsmart SCT Solar Filter" (or equivalent) over the end of the tube, then maybe some extra filters? (Not as good as yours of course, but something similar after months/years of practice).

 

How do you align the scope with no stars to point at? Or do you just do a simple 1-star alignment and point it at the sun to align?

 

Thanks in advance, Andrew

Simple Baader Solar Film can be put over a large aperture and you can image with a 610nm Baader filter (cheap, but good) can be used on tubes like reflectors or SCT easily and inexpensively. No need for years of work, just takes good seeing conditions which is usually in the early morning (not mid-day).

 

You can align the night before, or lots of mounts can do solar system alignment these days. Lots of options. My mount is permanently setup and aligned in an observatory.

 

Very best,


  • Tulloch likes this

#12 Tulloch

Tulloch

    Surveyor 1

  • *****
  • Posts: 1,829
  • Joined: 02 Mar 2019
  • Loc: Melbourne, Australia

Posted 08 December 2019 - 10:42 PM

Simple Baader Solar Film can be put over a large aperture and you can image with a 610nm Baader filter (cheap, but good) can be used on tubes like reflectors or SCT easily and inexpensively. No need for years of work, just takes good seeing conditions which is usually in the early morning (not mid-day).

 

You can align the night before, or lots of mounts can do solar system alignment these days. Lots of options. My mount is permanently setup and aligned in an observatory.

 

Very best,

Thanks for the info, my local shop had a deal on the Celestron Eclipsmart Solar filter (at half price) so I snapped it up for my 6". I liked how it fitted neatly onto the end of the OTA with extra velcro straps so it doesn't fall off. I don't have a 610 nm filter, just the standard #25 Red that cuts in at about 580 nm, should be sufficient for a first try. I assume you change the hue of the final images to get it looking yellow?

 

I assume that keeping my ZWO UV/IR cut filter in the train is a good idea also. Will this combination be OK for visual observing as well, or is the UV transmission still too high? Really don't want to make any mistakes with this one ... bugeyes.gif

 

It looks like my mount has a 1-star align, so I'll start with that using my DSLR to see if I can get the whole disc ...

 

Thanks again,

 

Andrew



#13 MalVeauX

MalVeauX

    Cosmos

  • *****
  • Posts: 7,656
  • Joined: 25 Feb 2016
  • Loc: Florida

Posted 10 December 2019 - 04:11 PM

Thanks for the info, my local shop had a deal on the Celestron Eclipsmart Solar filter (at half price) so I snapped it up for my 6". I liked how it fitted neatly onto the end of the OTA with extra velcro straps so it doesn't fall off. I don't have a 610 nm filter, just the standard #25 Red that cuts in at about 580 nm, should be sufficient for a first try. I assume you change the hue of the final images to get it looking yellow?

 

I assume that keeping my ZWO UV/IR cut filter in the train is a good idea also. Will this combination be OK for visual observing as well, or is the UV transmission still too high? Really don't want to make any mistakes with this one ... bugeyes.gif

 

It looks like my mount has a 1-star align, so I'll start with that using my DSLR to see if I can get the whole disc ...

 

Thanks again,

 

Andrew

Heya,

 

Any long wavelength filter that is visible spectrum will work best for seeing conditions with a larger aperture visually, and for imaging. You will find daytime seeing is really, really bad, so longer the wavelength the better. The UV/IR block filter may or may not help much, it greatly depends on the solar filter you're using if it already blocks UV and long IR or if it just reduces transmission but passes full spectrum. So you can use a UV/IR block filter of course as it shouldn't harm anything as long as it's not blocking the wavelength you're imaging in (such as long IR wavelength, but that's not the case here). It should be safe visually simply from the solar filter standpoint, so look into that primarily. I would bet the transmission is super low, so it should be quite safe visually, and very dim for imaging, so limited to course image scale, low resolution (with a dSLR).

 

Very best,


  • Tulloch 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