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Solar Photography


TrekRover

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I started going down a rabbit hole recently when I started researching Solar photography. I ended up getting a solar filter with a mylar film to filter white light. However I found out something called an H-alpha filter that filters out light except those from hydrogen.

Has anyone used an H-alpha filter before? If yes, what did you use for your Sony camera? and how was the experience of using an H-alpha filter?

I found a company that makes clip-in intermediary filter for placement right in front of the sensor, instead of the usual threaded/lens cap type. However the site states its not for solar viewing.... but to capture the red of deep space nebulas...: https://www.astronomik.com/en/clip-filter/clip-filter-fur-sony-alpha-7r-7s.html?zwl=232

 

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@tonygale TLDR: I ended up ordering the H-alpha clip-in filter. Though still debating if I should risk using it on my a7RIV yet 🤪 As the saying goes...."Do it for science!" lol

Details below to save people time on researching:

Disclaimer: I'm not a science/astronomy person. The below is based on my interpretation of astronomy terminology

After hours of research, I did finally find out why the H-alpha clip-in filters aren't suitable for Solar photography/observation. Most available "cheap" H-alpha filters only filter a specific narrow bandpass/wavelength bandwidth on the light spectrum. These "cheap" H-alpha filters are between 6nm(nanometer) and 12nm.

Whereas H-alpha filters for Solar specific applications require 0.03 nm to 0.07 nm (or 0.3 - 0.7 Angstrom in the astronomy terminology) Most H-alpha filters you will find on astronomy websites will use the Angstrom measurement. (0.03nm allows you to see more contrast and details than 0.07nm).

The problem is astronomy H-alpha filters are extremely expensive and they're mostly designed for telescopes only. The only company that ever designed something for camera applications (Non-astronomy cameras) is Daystar's Quark filter.

However, these products were only designed for the Canon/Nikon DSLR applications and not mirrorless cameras/Sony. If one were to get the quark they we need an adapter converter to convert the Canon/Nikon adapter to fit the DayStar Quark to your lens and Sony camera. 

Additional Thoughts and Side notes: For Solar Photography, there are a few other types of filters in addition to the H-Alpha. The other type is Calcium? and something else, and the white light filter(mylar film). Depending on what you want to see on the Sun the different filters will allow you to see the different layers of the Sun. For example, if you wanted to see the chromosphere/texture of the sun, you would use H-alpha. If you wanted to see the sun spots, you can use the white light filter (cheapest). There is another filter for viewing the Prominence and solar flares.

Astronomy sites/articles have a different terminology Solar Observance vs Solar Imaging. Observance is through a telescope which usually have lens and mirrors, reflectors/refracters, etc. which is why they will emphasize the danger of viewing without proper protection and filters. 

Imaging is the astronomy term for photography astro objects. There are specific astronomy cameras that attach to telescope. Generally lower MP and monohrome. I believe they use RGB and other types of filters to merge colors via stacking and post processing. 

Alternatives:
There are specifically purpose built telescope for solar viewing/observance. These can be "cheap" (~800-1K USD) but can be really expensive (most expensive one I saw was $83K USD 😖). However, their only purpose is for solar observance and not for any other astronomy purpose. 

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As an alternative method, I think I might try using the ND 100,000 (5.0) 16.6 stop filter (whenever the backorder gets fulfilled) with the H-alpha 6nm clip-in filter along with the 200-600mm lens and 2x TC on crop mode. 

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  • 1 month later...
On 5/17/2023 at 3:34 PM, TrekRover said:

As an alternative method, I think I might try using the ND 100,000 (5.0) 16.6 stop filter (whenever the backorder gets fulfilled) with the H-alpha 6nm clip-in filter along with the 200-600mm lens and 2x TC on crop mode. 

The ND filter will not protect the sensor, it only stops lightwave in 1 dimension (if angled perfectly). The light will lose energy (amplitude) but will maintain the same wavelength. And so will the photons and phonons, those are the culprits that could damage the semiconductor sensor. And semiconductors are sensitive to wavelength.

Have you tried stacking the clip-on with the cheap filters?

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5 hours ago, LensBrew said:

The ND filter will not protect the sensor, it only stops lightwave in 1 dimension (if angled perfectly). The light will lose energy (amplitude) but will maintain the same wavelength. And so will the photons and phonons, those are the culprits that could damage the semiconductor sensor. And semiconductors are sensitive to wavelength.

Have you tried stacking the clip-on with the cheap filters?

I am going to try stacking once the 16.6 stop filter arrives. I'll first start with a couple NDs on top and UV and in addition to the H-alpha 6nm wavelength filter, I hope it will be enough. I read a couple articles saying the 16.6 stop for the ND filter is supposed to be the minimum for solar photography. Hope its true. I read most H-alpha filters for solar imaging and observation is supposed to be at 0.03nm. Very tough to find a H-alpha filter.

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  • 3 weeks later...
On 7/6/2023 at 4:34 PM, TrekRover said:

I am going to try stacking once the 16.6 stop filter arrives. I'll first start with a couple NDs on top and UV and in addition to the H-alpha 6nm wavelength filter, I hope it will be enough. I read a couple articles saying the 16.6 stop for the ND filter is supposed to be the minimum for solar photography. Hope its true. I read most H-alpha filters for solar imaging and observation is supposed to be at 0.03nm. Very tough to find a H-alpha filter.

You have a lot of time to experiment. Look for companies that modify sensors for astro photography. They might have an idea where to get them or they might have something in house to help.

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