Histogram question using H-Alpha filter for solar photos using DSLR... - Forums

Topic starter

Nov 16, 2023 · Edited: Nov 16, 2023

Hi everyone!

I have a Canon 90D (astro-modified) and an Astronomik 6nm H-Alpha clip filter. I'm using a Tokina 400mm f8 lens. I've got the ISO set to 100. The exposure is currently at 1/60s. I also have a solar filter mounted on the lens. Everything appears to work well, but I'm having issues with the histogram and how much I need to adjust my exposure. The light on the histogram is nearly to the left all the way. I think I'm under-exposing, but I want to see what others think.

Any advice or tips are appreciated. I pasted a screenshot of the histogram from Pixinsight. EDIT: Forgot to mention, the histogram below is from one of my light frames in RAW format, unedited.

-Crimsus

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Oscar

Nov 16, 2023

I think you should post an image of the stacked image unedited (assuming you have already stacked the individual frames together). But I think, at first glance, your histogram does not look right for the sun.

Crimsus

Topic starter

Nov 16, 2023

I think you should post an image of the stacked image unedited

I had a moment of frustration and realized I deleted the folder, so all I have left is the screenshot of the histogram.

You mentioned it doesn't look right for the sun (and I agree something is wrong, but I don't have much experience with solar photos yet). What do you suspect is wrong? How should the unstretched histogram look for the sun?

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Oscar

Nov 16, 2023 · Edited: Nov 16, 2023

What do you suspect is wrong? How should the unstretched histogram look for the sun?

Well that histogram looks like the histogram of a deep sky object linear image which doesn't make sense to me. I assume the histogram should be wavy and long(er) for bright objects like the sun and moon.

I had a moment of frustration and realized I deleted the folder, so all I have left is the screenshot of the histogram.

Do you have any light frames to show at all? All I need is one, if they all look the same.

Crimsus

Topic starter

Nov 16, 2023

Do you have any light frames to show at all? All I need is one, if they all look the same.

Nope. They're gone, blown away, destroyed by the Death Star.

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Crimsus

Topic starter

Nov 16, 2023

I was able to find another light frame from when I was testing out my SolarQuest. There's only one RAW image. I attached the RAW file. Below is the screenshot of the unstretched histogram. Here is the link to the RAW file.

andrea tasselli

Frequent contributor

Nov 16, 2023

It probably would do with a bit more exposure but if you are stacking a stream of raws that won't matter much to the final result. I see, however, that you are both underexposing and out of focus and don't forget to take flats!

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Crimsus

Topic starter

Nov 16, 2023

andrea tasselli:
I see, however, that you are both underexposing and out of focus and don't forget to take flats!

It's a light frame from testing my SolarQuest, so I wasn't too concerned about the focus or flats at the time. I typically have a small number of test shots whenever I get new equipment that eventually go in the trash. I just hadn't had the chance to go into my equipment test shot folder to clean out junk.

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Thomas

IOTD Staff

Nov 16, 2023

Are you using an Ha clip in filter combined with a white light solar filter?

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Crimsus

Topic starter

Nov 16, 2023

Thomas:
Are you using an Ha clip in filter combined with a white light solar filter?

I'm using the H-Alpha clip in filter with the solar filter at this link: https://www.seymoursolar.com/store/p246/Helios_Glass_Threaded_Camera_Solar_Filter.html#/

Thomas

IOTD Staff

Nov 16, 2023

So the Ha clip filter is for DSOs, not solar. The solar Ha is something completely different and a way smaller bandwidth than the clip in filters. We are talking angstroms, not nanometers. The filter you have for the lens is designed for "white-light" solar imaging and on its own will let you see sunspots and surface granulation. I would try removing the clip filter and go from there.

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Crimsus

Topic starter

Nov 16, 2023

Ugh! Ok, I now realize that a white light solar filter and H-Alpha clip filter don't work. I was following what seemed to be a very detailed and informed thread from a YT influencer on CloudyNights. I had to send my SolarQuest mount back to Skywatcher this morning when I discovered that after powering it off, the mount was still running despite the red power LED being off. So if anything, I have time to plan!

Oh well, at least nothing was damaged.

I guess the correct solution for DSLR would be to pick up a dedicated Lunt or Daystar solar telescope with the correct adapter(s) to hook up my Canon 90D. Any recommendations to make that setup work?

Thomas

IOTD Staff

Nov 16, 2023

One other thing/DIY hack for you. I used to do solar with a dslr and lens with a filter on the end of the lens as well. You can easily create your own solar filter way cheaper than buying one. Get a step-up ring for your lens size. So if you have a 55mm filter size, get a 55 to 58 or a 55 to 60 step-up ring. Then get a UV filter in the larger size and cut a piece of solar filter paper to fit between the step-up ring and the UV filter making sure it completely covers the 55mm diameter. Now you have a screw on solar filter. I used thousand oaks solar filter material.

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Thomas

IOTD Staff

Nov 16, 2023

Ugh! Ok, I now realize that a white light solar filter and H-Alpha clip filter don't work. I was following what seemed to be a very detailed and informed thread from a YT influencer on CloudyNights. I had to send my SolarQuest mount back to Skywatcher this morning when I discovered that after powering it off, the mount was still running despite the red power LED being off. So if anything, I have time to plan!

Oh well, at least nothing was damaged.

I guess the correct solution for DSLR would be to pick up a dedicated Lunt or Daystar solar telescope with the correct adapter(s) to hook up my Canon 90D. Any recommendations to make that setup work?

You can easily and quite successfully do white light solar with what you have. Youll get good shots of sunspots and granulation from it. It's an excellent way to start working on solar. Them yes, progress to something like a Daystar Quark or Lunt for h-alpha solar imaging.

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Crimsus

Topic starter

Nov 16, 2023

Thomas:
One other thing/DIY hack for you. I used to do solar with a dslr and lens with a filter on the end of the lens as well. You can easily create your own solar filter way cheaper than buying one. Get a step-up ring for your lens size. So if you have a 55mm filter size, get a 55 to 58 or a 55 to 60 step-up ring. Then get a UV filter in the larger size and cut a piece of solar filter paper to fit between the step-up ring and the UV filter making sure it completely covers the 55mm diameter. Now you have a screw on solar filter. I used thousand oaks solar filter material.

Interesting, however, I already own a solar filter so I probably won't invest more money and time into making one.

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Thomas

IOTD Staff

Nov 16, 2023

There are adapters where a Daystar can work with a camera lens, done it myself, but it works better with an actual telescope. You will need to get a t-mount adapter for your camera though if going either Daystar or Lunt route.

Thomas

IOTD Staff

Nov 16, 2023

Thomas:
One other thing/DIY hack for you. I used to do solar with a dslr and lens with a filter on the end of the lens as well. You can easily create your own solar filter way cheaper than buying one. Get a step-up ring for your lens size. So if you have a 55mm filter size, get a 55 to 58 or a 55 to 60 step-up ring. Then get a UV filter in the larger size and cut a piece of solar filter paper to fit between the step-up ring and the UV filter making sure it completely covers the 55mm diameter. Now you have a screw on solar filter. I used thousand oaks solar filter material.

Interesting, however, I already own a solar filter so I probably won't invest more money and time into making one.

That was more of if you ever wanted one for a different thread size. I had 3 different sizes i used so just made sense to make my own.

Thomas

IOTD Staff

Nov 16, 2023

Here was a Daystar setup I had used at one point. This was a Canon lens, ZWO Canon EOS adapter, M42 extensions (I think?), Daystar Quark, tilt corrector, ZWO camera. You could easily swap the ZWO camera for a DSLR.