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equipment questions. ASI294MCPro vs Saturn-c?

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#1 Northernguy

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Posted 04 February 2024 - 11:39 AM

I plan to use my Lunt universal 80 mm scope, so I can image h-alpha before and after totality, and then switch to white light using a DIY Baader solar film filter to image during totality. Hopefully will not take more than a few minutes to switch out the etalons and blocking filter. 

 

I am thinking I should use a color camera to capture the corona, do you agree? For color, I have an ASI294MCPro and a Saturn-C SQR. Any advice on which, if either would be the best? I do also have a digital DSLR camera (Cannon Rebel 6Ti) and an intervalometer, if it would be better to go old school. 

 

since this will be my first total eclipse, the plan is to set up exposures ahead of the event, and just let it go so I can focus on experiencing the eclipse and observe by eye alone (with eclipse glasses of course). 

 

astronomy_tools_fov.jpg


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#2 banjo1000

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Posted 04 February 2024 - 01:06 PM

In part, it depends on what you want to capture. The ZWO camera is cooled and it has a larger diagonal so it would be better for the corona. The PO camera has smaller pixels so it’s better for prominences and chromosphere. Since you have a Lunt, you see prominences all the time, but one can only see the corona during an eclipse. That would tip the scales for me.

One can control timing better with the Rebel for diamond ring, but the Astro cameras can do well enough if you are clever about setting up FireCapture. Your model Canon has a faint dark pattern that will drive you to distraction if you try to bring out faint corona details.

I bought a used Canon 5D Mark IV body for the Exmouth eclipse. Full frame cameras are better for an eclipse to catch the corona. You might also consider Used Canon 6D bodies. They both have better dark noise than the cheaper rebel line.

The only filter you want is an IR/UV cut from 30 secs before totality to 30 seconds after. Don’t look through viewfinders when the solar filter comes off. Please check the ZWO specs for your camera. I think the protective window on a ZWO cooked color camera may act as the cut filter.

Joe
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#3 Northernguy

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Posted 04 February 2024 - 03:53 PM

Thanks Joe, that is extremely helpful. Yes, the corona is what I'm after.

I'm actually much more comfortable with Sharpcap than Firecapture, so will stick with that. I plan to figure out the scripting language between now and the eclipse so it can take a number of different exposures for me. I'll make sure to include a UV/IR filter in the imaging train.

 

thanks again and clear skies

Rick 


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#4 CreatorsHand

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Posted 05 February 2024 - 02:52 AM

I plan to use my Lunt universal 80 mm scope, so I can image h-alpha before and after totality, and then switch to white light using a DIY Baader solar film filter to image during totality. Hopefully will not take more than a few minutes to switch out the etalons and blocking filter. 

 

I am thinking I should use a color camera to capture the corona, do you agree? For color, I have an ASI294MCPro and a Saturn-C SQR. Any advice on which, if either would be the best? I do also have a digital DSLR camera (Cannon Rebel 6Ti) and an intervalometer, if it would be better to go old school. 

 

since this will be my first total eclipse, the plan is to set up exposures ahead of the event, and just let it go so I can focus on experiencing the eclipse and observe by eye alone (with eclipse glasses of course). 

 

attachicon.gif astronomy_tools_fov.jpg

I have a couple observations for you to consider. First of all, you only have 4 to maybe 4 1/2 minutes of totality, depending on where you are traveling to. That is not a lot of time to switch out the etalons and blocking filter, add the white light filter, possibly find the Sun again and likely refocus, capture your images of totality, and then reverse the process. In doing so, you will most assuredly miss seeing the corona, which is the reason to get into the path of totality, due to messing with the camera and telescope. If you are serious about doing that, set it all up and run through the whole process, and then multiply the time by 1 1/2 to 2, due to the excitement of the day. I would recommend instead using two OTAs, either double-mounted or each on a mount, both set up and focused well before the start of the eclipse, even if you don't use the second one until totality (or just before and after to capture the Diamond ring and Bailey's Beads). I think that you may be better off going the old school method using your DSLR and intervelometer on a second telescope, and using your ZWO camera and Sharpcap with your Lunt for the partial phases. You are more likely to be able to capture the extent of the corona. I used a 7D Mar II and a 500mm f/4L lens in 2017, and I don't think I would have wanted it any tighter. To capture the image in my profile picture, I used 7 bracketed exposures 2 stops apart; that may be easier to do with your intervelometer, as you can set the bracketing and then push the shutter button on the intervelometer while looking at the corona. Unless you can increase the  number of bracketed exposures to 7 (which my 7DII can do), you would need to change the base exposure several times to get the full dynamic range, but you would still have a lot of time to look instead of taking apart and reassembling your telescope. During the last eclipse, I missed most of totality because of equipment problems (my mount messed up and I had to do it on a tripod, which required manually adjusting to match the Sun's movement); this time I am aiming to automate things better, and if something happens, I am more likely to set the equipment aside and not miss what may be my last chance to see totality.

 

Paul


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#5 ch-viladrich

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Posted 05 February 2024 - 06:27 AM

Dynamic range comes first and foremost when it is about corona imaging.

 

The IMX294 has a 13 bits dynamic range while the IMX553 has a 14 bits dynamic range. It does make a difference in the end for corona imaging.

 

I don't know what is the dynamic range of the Canon 6D.

 

On my side, I will be using a Nikon Z7 (13.8 bits dynamic range) because it is easier to take in a plane (no need for a computer). I'll use bracketing (9 different exposure times), preset control (one for the Bailey beeds and one for the main part of toatlity)  and a remote control. So basically all the images  will be taken in "automatic" mode during totality.

 

Don't forget to remove the solar filter for totality ;-) but keep it just before C2 in order to properly focus your telescope in its "white light" configuration.


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#6 Northernguy

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Posted 05 February 2024 - 11:46 AM

I have a couple observations for you to consider. First of all, you only have 4 to maybe 4 1/2 minutes of totality, depending on where you are traveling to. That is not a lot of time to switch out the etalons and blocking filter, add the white light filter, possibly find the Sun again and likely refocus, capture your images of totality, and then reverse the process. In doing so, you will most assuredly miss seeing the corona, which is the reason to get into the path of totality, due to messing with the camera and telescope. If you are serious about doing that, set it all up and run through the whole process, and then multiply the time by 1 1/2 to 2, due to the excitement of the day. I would recommend instead using two OTAs, either double-mounted or each on a mount, both set up and focused well before the start of the eclipse, even if you don't use the second one until totality (or just before and after to capture the Diamond ring and Bailey's Beads). I think that you may be better off going the old school method using your DSLR and intervelometer on a second telescope, and using your ZWO camera and Sharpcap with your Lunt for the partial phases. You are more likely to be able to capture the extent of the corona. I used a 7D Mar II and a 500mm f/4L lens in 2017, and I don't think I would have wanted it any tighter. To capture the image in my profile picture, I used 7 bracketed exposures 2 stops apart; that may be easier to do with your intervelometer, as you can set the bracketing and then push the shutter button on the intervelometer while looking at the corona. Unless you can increase the  number of bracketed exposures to 7 (which my 7DII can do), you would need to change the base exposure several times to get the full dynamic range, but you would still have a lot of time to look instead of taking apart and reassembling your telescope. During the last eclipse, I missed most of totality because of equipment problems (my mount messed up and I had to do it on a tripod, which required manually adjusting to match the Sun's movement); this time I am aiming to automate things better, and if something happens, I am more likely to set the equipment aside and not miss what may be my last chance to see totality.

 

Paul

Thanks for your comments, Paul. I agree, priority one is to not be messing with equipment during the time of totality, except for removing and replacing the solar film filter. I have downloaded the eclipse timer app, and hopefully that will make it easy enough for me not to need to focus on the times. I was not thinking of imaging in h-alpha right up to totality, but actually planning to switch to white light about 20 minutes or so prior. Hopefully that would be enough time to make sure things are assembled correctly and scope is in focus. My (only) mount is very reliable and I use a hinode solar guider, so I believe it will behave itself (fingers crossed). I do need to practice with the night-time setup of the Lunt. I put it together last night for the first time and couldn't figure it out for 30 minutes. I finally realized they had put the connection ring of the night-time focuser on backwards, and had to remove it and flip it around. Doh!

 

 

Double mounting a second scope is a good idea, if not too much weight. Will certainly consider that. thanks again

 

Dynamic range comes first and foremost when it is about corona imaging.

 

The IMX294 has a 13 bits dynamic range while the IMX553 has a 14 bits dynamic range. It does make a difference in the end for corona imaging.

 

I don't know what is the dynamic range of the Canon 6D.

 

On my side, I will be using a Nikon Z7 (13.8 bits dynamic range) because it is easier to take in a plane (no need for a computer). I'll use bracketing (9 different exposure times), preset control (one for the Bailey beeds and one for the main part of toatlity)  and a remote control. So basically all the images  will be taken in "automatic" mode during totality.

 

Don't forget to remove the solar filter for totality ;-) but keep it just before C2 in order to properly focus your telescope in its "white light" configuration.

Thanks Christian. So, yes I could use the Saturn-C to get 14 bits, if you think that would be superior. 

 

For automation, it looks to me like Sharpcap's Deep space Sequence Planner will work well. It allows as many different exposures as needed. Maybe I would try exposures from 10 msec up to 10 seconds to give me 3 decades of exposure data, and just have it cycle through those for the duration, including C2.

And yes, important to remember to remove the solar filter. Again, hoping the eclipse timer app will remember to remind me. 

 

Clear skies (we hope)



#7 ch-viladrich

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Posted 08 February 2024 - 08:14 AM

Thanks for your comments, Paul. I agree, priority one is to not be messing with equipment during the time of totality, except for removing and replacing the solar film filter. I have downloaded the eclipse timer app, and hopefully that will make it easy enough for me not to need to focus on the times. I was not thinking of imaging in h-alpha right up to totality, but actually planning to switch to white light about 20 minutes or so prior. Hopefully that would be enough time to make sure things are assembled correctly and scope is in focus. My (only) mount is very reliable and I use a hinode solar guider, so I believe it will behave itself (fingers crossed). I do need to practice with the night-time setup of the Lunt. I put it together last night for the first time and couldn't figure it out for 30 minutes. I finally realized they had put the connection ring of the night-time focuser on backwards, and had to remove it and flip it around. Doh!

 

 

Double mounting a second scope is a good idea, if not too much weight. Will certainly consider that. thanks again

 

Thanks Christian. So, yes I could use the Saturn-C to get 14 bits, if you think that would be superior. 

 

For automation, it looks to me like Sharpcap's Deep space Sequence Planner will work well. It allows as many different exposures as needed. Maybe I would try exposures from 10 msec up to 10 seconds to give me 3 decades of exposure data, and just have it cycle through those for the duration, including C2.

And yes, important to remember to remove the solar filter. Again, hoping the eclipse timer app will remember to remind me. 

 

Clear skies (we hope)

Regarding exposure times, you can establish the required exposure times by practising on the Moon :

 

- the full moon has the same luminosity as the inner corrona very close to the solar limb,

- the corona at one solar radius from the solar limb is about 1000x fainter than at the solar limb,

- the corona at 5 radius from solar limb has teh same luminosity as the earthshine.

 

Don't forget the UV-IRcut filter with the Saturn-C camera.


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#8 ch-viladrich

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Posted 08 February 2024 - 12:28 PM

BTW, you can also check some exposure times for the inner corona (and Sloan r' filter) here :

 

http://astrosurf.com...sa/usa2017.html


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#9 Northernguy

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Posted 08 February 2024 - 12:45 PM

Regarding exposure times, you can establish the required exposure times by practising on the Moon :

 

- the full moon has the same luminosity as the inner corrona very close to the solar limb,

- the corona at one solar radius from the solar limb is about 1000x fainter than at the solar limb,

- the corona at 5 radius from solar limb has teh same luminosity as the earthshine.

 

Don't forget the UV-IRcut filter with the Saturn-C camera.

Great advice, thanks again Christian! Now if I could just get one night without clouds to be able to see the moon...





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