152 replies to this topic

[Jerry Lodriguss]

I've put together a web page with tips and techniques for shooting the upcoming total solar eclipse on August 21, 2017.

 

http://www.astropix....lipse_2017.html

 

If you haven't started yet, now is the time to get your game plan together and start practicing!

 

Jerry

 

 2017_Eclipse.jpg   143.73KB   14 downloads

Edited by Jerry Lodriguss, 05 July 2017 - 04:55 PM.

[SteveRosenow]

Jerry, I note you are headed to Madras?

Perhaps we'll cross paths and meet up. I'll be there with my wife capturing it for the Eclipse Megamovie team.

[Jerry Lodriguss]

Hi Steve,

 

Maybe we will if we can find each other in the mass of people who are supposed to be there.

 

Jerry

[REC]

I've put together a web page with tips and techniques for shooting the upcoming total solar eclipse on August 21, 2017.

 

http://www.astropix....lipse_2017.html

 

If you haven't started yet, now is the time to get your game plan together and start practicing!

 

Jerry

 

2017_Eclipse.jpg

Wow, between you and Foxxwood, we should all get great results!

[Jerry Lodriguss]

 

I've put together a web page with tips and techniques for shooting the upcoming total solar eclipse on August 21, 2017.

 

http://www.astropix....lipse_2017.html

 

If you haven't started yet, now is the time to get your game plan together and start practicing!

 

Jerry

 

2017_Eclipse.jpg

Wow, between you and Foxxwood, we should all get great results!

 

Thanks, lets hope so!

 

Jerry

[charotarguy]

Wow, thank you Jerry this is awesome   , wish Christie was this generous with our NJ budget, beaches and state parks    .

[Jerry Lodriguss]

Wow, thank you Jerry this is awesome   , wish Christie was this generous with our NJ budget, beaches and state parks    .

Thanks!  You are very welcome.

 

Jerry

[jforkner]

Just read your updated page and was curious about one of the parameters in your Exposure Sequence, specifically ISO.  Why ISO 200, not 100 during partial phases?

 

I get why you’d want a higher ISO to shorten shutter speeds during totality—more images.  But during partial phases, I'm curious about the need for speed?

 

Thanks for the helpful info & insight.

 

Jack

[torn8o]

Wow, your site is an awesome resource... I plan to scour it thoroughly.

[Jerry Lodriguss]

Just read your updated page and was curious about one of the parameters in your Exposure Sequence, specifically ISO.  Why ISO 200, not 100 during partial phases?

 

I get why you’d want a higher ISO to shorten shutter speeds during totality—more images.  But during partial phases, I'm curious about the need for speed?

 

Thanks for the helpful info & insight.

Hi Jack,

 

I'm not using 200 during totality just to get higher shutter speeds. The difference between exposures, most of them over 1/2 seconds, are going to give you a trivial amount of extra time to shoot extra frames. For all practical purposes you are not going to shoot any more frames because all of the overhead is in sending the control info like shutter speed changes over the USB. That takes 3 seconds. Using a higher ISO for shorter shutter speeds actually takes longer because in terms of signal-to-noise ratio, you need 2 frames at the higher ISO and that increases your USB overhead. So for the same signal to noise ratio as a lower ISO you would need twice as many frames and that would kill your framing rate.

 

For me, for my camera, it was a complicated technical set of considerations balancing readout noise, quantization effects and dynamic range. There's no one perfect ISO, I just though 200 was the best compromise for my camera for this particular subject with a huge dynamic range, and seemingly plenty of light in the bright inner corona, but faint outer corona fading into the sky background.

 

I also have a holdover feeling, maybe you could call it a superstition now days, but there were weird things, like banding noise, that used to happen at ISO 100. 

 

The partial phases are, let me see how I can say this without offending any of the lunar population... kind of a joke at a total solar eclipse. Something to pass the time until the real show begins.. No one cares about the partial phases. I'm really just shooting them for a time-lapse and maybe a multiple-image composite. But with a filter, there isn't really much dynamic range you have to deal with so using the lowest ISO doesn't really gain you anything much here at all. I'm not really going to be resolving any sunspots at 420mm, so I'd rather go a little high to get an over one-thousandth of a second exposure just in case of wind or vibrations. There ain't going to be much to see at 420mm with a filter during partial phases, so the ISO doesn't really matter much to me here. 

 

The show is totality, that's what I really care about.

 

Jerry

[johnpd]

Jerry,

 

  Is it ok to use an Alt-Az mount for the totality phase. You would get some field rotation but over 2 minutes (@480mm F/L) would it be prohibitive?

 

JohnD

[jforkner]

Hi Jack,
 

 

There ain't going to be much to see at 420mm with a filter during partial phases, so the ISO doesn't really matter much to me here. 

 

The show is totality, that's what I really care about.

 

Jerry

 

That was my thought exactly, hence the question.  But I understand why you chose ISO 200---the camera.

 

Thanks for the thorough response.

 

Jack

[Jerry Lodriguss]

Jerry,

 

  Is it ok to use an Alt-Az mount for the totality phase. You would get some field rotation but over 2 minutes (@480mm F/L) would it be prohibitive?

 

JohnD

Hi JohnD,

 

You will get trailing at a certain point from the Earth's rotation with the alt-az mount. It depends on the pixel size in your camera as well as the focal length, and how much blur you are willing to put up with.

 

You will also get some field rotation, but you probably won't see it in a single exposure. It's only if you want to put together an HDR composite that it might be a problem.  For normal long exposure deep-sky, if you had field rotation from frame to frame, the stacking software can correct for it by aligning on multiple stars in the frame to de-roate the stack. But with the eclipse, you won't have any other stars to align on. Some of the planetary image processing programs may do de-rotation, but I don't know if they would work in the special case.

 

If you're just shooting single frames, I don't think you have to worry about field rotation.

 

At 480mm, I'm guessing you can shoot exposures about as long as 1/15th to 1/8th of a second, if you have a tripod that is solid as a rock. If you want fainter stuff that requires longer exposures, you could use a higher ISO and shoot multiple frames to stack, but with this short of an eclipse, you're going to be limited in how many multiple frames you can get.

 

Jerry 

[geothomas]

Jerry,

 

I just did a couple of test shots with my newly modified D5300. The solar filter I got from Thousand Oaks must be stronger than the one you used in coming up with your planned sequence. You suggest 1/1000 sec at F8 for ISO 100 during partial phases. However, when I shot at F8 and ISO 200, I needed to expose at 1/250 to get the red portion of my histogram onto the right side. 1/500 looked ok too, but it had things just right of the middle.

 

I'm thinking if I change my ISO from 200 to 100, and I change my shutter speed from 1/250 to 1/125 that this would be my starting point for partial phases and then I adjust my shutter speeds for Diamond Rings and Bailey's Beads accordingly to be 1/15 and 1/1000 respectively.

 

Does this look right? 

 

First pic shows 1/500, F8, ISO 200

 

Second pic shows 1/250, F8, ISO 200

 

Much thanks.

 

 

Attached Files

•  Sun1.jpg   89.34KB   5 downloads
•  Sun2.jpg   100.38KB   3 downloads

[Jerry Lodriguss]

Yes, the second pic looks better, none of the channels are clipped so you are good.

 

I found that with the DayStar filter, it was two stops less than the Baader.

 

I trust the Baader to be ND5.  I don't know what the DayStar is supposed to be.

 

I can tell you that the Baader produced much sharper results than the DayStar too.

 

Jerry

[geothomas]

Yes, the second pic looks better, none of the channels are clipped so you are good.

 

I found that with the DayStar filter, it was two stops less than the Baader.

 

I trust the Baader to be ND5.  I don't know what the DayStar is supposed to be.

 

I can tell you that the Baader produced much sharper results than the DayStar too.

 

Jerry

Thank you. I had a 1.4x teleconverter on here, which I don't think I will use, also didn't take much time on getting my focus spot on. Will try that in the upcoming days. Maybe I'll look into the Baader filter.

[johnpd]

Jerry,

 

  I will be using a Nikon D90 on an 80mm f/6 telescope mounted on a Skywatcher AZ-EQ6 mount. Eclipse Orchestrator gives me corona bracketing of 3 sets of exposures over just under a one minute span (it has a 40 second delay before starting corona exposures). The exposures range from 1/800 to 1.6 seconds. All exposures except the 1.6 second ones are @ ISO 200. The 1.6 second ones are at ISO 320.

 I have the option of setting up the mount as EQ or ALT/AZ, the latter being easier to do as it has a built-in solar alignment capability.

 

JohnD

[dghundt]

How many exposures are in your bracket from 1/800 to 1.6?

[charotarguy]

Jerry, based on the above, is it a good idea to increase the iso to get shorter exposures (thus saving time, plus get more exposures, possibility of stacking) or keep the iso as low as possible to get less noisy images? I will be using Sony A7x cameras which unfortunately do not have any automation support so will be mostly manual.

[dghundt]

Which A7 are you using?  What focal length?

 

The original A7r, which I have, is prone to vibrations at certain shutter speeds and focal lengths unless you actively dampen it or mount the camera directly to a ballhead/plate.  I plan to leave mine at home for my telephoto focal length imaging.

 

You still have a wired cable release?  You should be able to to quickly dial out your shutter speeds.  

How quickly does it write to your card.  Mine is kinda slow.

[charotarguy]

Which A7 are you using?  What focal length?

 

The original A7r, which I have, is prone to vibrations at certain shutter speeds and focal lengths unless you actively dampen it or mount the camera directly to a ballhead/plate.  I plan to leave mine at home for my telephoto focal length imaging.

 

You still have a wired cable release?  You should be able to to quickly dial out your shutter speeds.  

How quickly does it write to your card.  Mine is kinda slow.

Yeah I have both A7 and A7Rii, I've tested both over a few weekends when it was clear, I did not see any vibration issues you mention but it's possible it might be there but I am not experienced enough to see it. Will be using both during the eclipse, as mentioned earlier there is no software support so will have to go manual, the focal length will be 1000mm for one and 450-500mm for another (both will be used on refractor). 

[Jerry Lodriguss]

Jerry, based on the above, is it a good idea to increase the iso to get shorter exposures (thus saving time, plus get more exposures, possibility of stacking) or keep the iso as low as possible to get less noisy images? I will be using Sony A7x cameras which unfortunately do not have any automation support so will be mostly manual.

Shorter exposures at a higher ISO don't really save you any time. In fact, they take more time because you have more frames, you have more time between frames.

 

The question is, is your setup solid enough so you don't get vibration on long exposures.

 

You really need a wired cable release at a minimum.

 

I'm' going to bet that even though you don't think you see it, you're getting some loss of sharpness from vibration from the mirror flopping open and the shutter opening.

 

Can you keep the mirror locked up with your camera?

 

Jerry

[charotarguy]

 

Jerry, based on the above, is it a good idea to increase the iso to get shorter exposures (thus saving time, plus get more exposures, possibility of stacking) or keep the iso as low as possible to get less noisy images? I will be using Sony A7x cameras which unfortunately do not have any automation support so will be mostly manual.

Shorter exposures at a higher ISO don't really save you any time. In fact, they take more time because you have more frames, you have more time between frames.

 

The question is, is your setup solid enough so you don't get vibration on long exposures.

 

You really need a wired cable release at a minimum.

 

I'm' going to bet that even though you don't think you see it, you're getting some loss of sharpness from vibration from the mirror flopping open and the shutter opening.

 

Can you keep the mirror locked up with your camera?

 

Jerry

 

Well these are mirrorless cameras so there is no mirror lock to deal with and yes I will be using a wired cable release to fire the exposures the only issue is I have to manually set the exposures as there is no scripting capability with any software for Sony (except maybe gphoto2 which I played with and did make it work on windows 10 under cygwin but it is still not idea for eclipse imaging)

Edited by charotarguy, 12 July 2017 - 03:37 PM.

[charotarguy]

How quickly does it write to your card.  Mine is kinda slow.

With the card I have on A7Rii I am able to fire about 5-6 images (drive mode) after that I start getting lag as it is ofloading the data to the SD card on A7 it is about 15-20 images, I might look into the new hi speed cards that Sony came out which are about 3-4x times faster then what I have.

[dghundt]

Your Sonys should be fine as far as the shutter vibration issue that troubles the A7r v1 with telephoto focal lengths.

It is not the mirror, it is the mechanical shutter that caused a problem.

 

The Sony should have an auto-bracket feature so you can press and hold the remote release or press it one image at a time.  I've never used it myself to know how wide a range you can use, but it should be faster than dialing a new shutter speed and waiting a couple seconds for the vibrations you induced to settle down.

 

Find out if you can take advantage of a faster card.  I'd get one if that's the case.

 

Definitely get an eclipse timer and practice your session until you know you have it down and aren't missing frames.