How to photograph Jupiter?

Started Apr 25, 2016 | Discussions
Astrozoid
Astrozoid Contributing Member • Posts: 653
Re: How to photograph Jupiter?

mac01 wrote:

Astrozoid wrote:

Light pollution has nothing to do with high resolution planetary imaging. That's all about the seeing.

You need:

1. Good focus.

2. Excellent collimation.

3. Scope mirror completely cooled down.

4. Optimum sampling, which means matching the resolution that the seeing allows to the resolution that your scope is capable of, to the pixel size in your camera. You want to shoot around f/20 for mediocre seeing, and f/30 for outstanding excellent seeing.

You don't just want to blow the image up to get Jupiter as large as possible. Once you go past the point of optimum sampling, you are just getting empty magnification that doesn't record any more detail, and just makes your exposures longer for no reason.

5. "Lucky Imaging" Video recording at 1:1 pixel resolution. This means finding a way to record a small section of the sensor usually by recording Live View. You might be able to get closest with BackYardNikon. Recording video with the "high-definition" normal built-in video will trash the resolution when it downsamples the original resolution of the sensor.

You can get 1:1 pixel resolution if you shoot single still frames, but one frame is not going to look good. You need to stack hundreds or thousands of frames.

Adjust the ISO and exposure so the planet is correctly exposed in the video. This is by trial and error.

On some older Nikons, you can't control the exposure that Live View presents, it just tries to autoexpose the image, and if you can't change the brightness of Live View. With a small bright planet on a large black background, it's going to overexpose Jupiter, and basically you can't do anything about it if you can't adjust the Live View exposure, so you are basically screwed for high-res planetary imaging with some Nikons.

6. Use AutoStakkert! 2 to align and stack about 3 minutes of video. It's much better than RegiStax for stacking. AutoStakkert! 2 will also do some basic sharpening which I find works well. If you want to see if you can get a little bit more, then use RegiStax wavelet sharpening to the stack out of AutoStakkert!

I have a book on high-resolution planetary imaging with DSLRs if you are interested. You can find it on my home page at www.astropix.com

Here's what you can do with a DSLR and Lucky Video imaging with a DSLR:

Jerry

Hey Jerry, thanks for all the info and all I can say is wow...

I'm switching gears from NB deep sky to planetary and trying to build some skill for the upcoming Mars and Saturn imaging sessions next month with a little Orion ccd and C8. Do you use a stepper motor for focusing with a barlow or is focusing planetary done manually?

Thanks again

Chris

Hi Chris,

I used a motorized focuser, it makes things a lot easier, but it's not a requirement.

At extremely high magnifications, the planet (or better a star used for focusing) can move completely out of the field of view due to image shift if you try to focus an SCT with its normal focusing mechanism of moving the mirror.

With a motorized focuser, you can lock the mirror down. This also helps with something like a Celestron Edge for deep-sky, where the back focus distance is critical for the built-in field flattener.

Jerry

RustierOne
RustierOne Veteran Member • Posts: 4,338
Re: How to photograph Jupiter?

RustierOne wrote:

Astrozoid wrote:

Here's what you can do with a DSLR and Lucky Video imaging with a DSLR:

Great advice, Jerry. I'm looking forward to learning how to use Autostakkert!2. Since I haven't yet received my new ZWO ASI290MC color camera, I've just been using Registax for Moon imaging. I'm also hoping to get the ZWO atmospheric dispersion corrector in time for capturing Saturn and Mars next month.

I just got some good news from ZWO Optics in China. They have shipped my new ASI290MC color video camera and UV/IR cut filter. It should be here within a week. I just ordered the filter tonight with a note to ship it with the camera. Almost immediately I got a message from Vanessa at ZWO saying they had a few units of the new camera ready for shipment, and I would be getting one. I'm excited, since I was expecting to wait on into May to get one. Now if I can just get my mitts on one of ZWO's atmospheric dispersion correctors.... That one is supposed to ship before the end of this month from High Point Scientific. I had better get on the ball and start learning how to use Firecapture camera control software and Autostakkert!2 processing software. Will the weather cooperate?

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Best Regards,
Russ

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Juggernaut122
OP Juggernaut122 Contributing Member • Posts: 699
Re: How to photograph Jupiter?

Astrozoid wrote:

Here's what you can do with a DSLR and Lucky Video imaging with a DSLR:

Jerry

Hi Jerry.

Looks like my Nikon D5100 has a 640 x 480 video mode available.  I am using a scope that is f/5.9.

I had thought that using my camera aperture set to 1.8 would be ideal to let more light in (afocally), but you seem to suggest that I want to use a smaller aperture.  Should I use a camera aperture somewhere around f/3-f/4?

Thanks!
Juggernaut

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Astrozoid
Astrozoid Contributing Member • Posts: 653
Re: How to photograph Jupiter?

Juggernaut122 wrote:

Hi Jerry.

Looks like my Nikon D5100 has a 640 x 480 video mode available. I am using a scope that is f/5.9.

I had thought that using my camera aperture set to 1.8 would be ideal to let more light in (afocally), but you seem to suggest that I want to use a smaller aperture. Should I use a camera aperture somewhere around f/3-f/4?

Thanks!
Juggernaut

Hi Juggernaut,

Unless the Nikon is cropping the images down to the center 640x480 pixles out of the 4928 x 3264 pixles on the sensor, then 640x480 video mode would be the worst thing you could use.

What you need is 1:1 pixel resolution off the sensor. None of the built in video modes is going to give that to you.

I think you are misunderstanding exactly what is needed for high-resolution planetary imaging.  It's not the aperture of your camera lens. It's the aperture of your scope that determines the resolution it is capable of in a given seeing condition.

You need to magnify the image by increasing the focal length of your scope / camera lens combination so that the effective focal ratio of the entire system is somewhere between f/20 and f/30.

Jerry

RustierOne
RustierOne Veteran Member • Posts: 4,338
Re: How to photograph Jupiter?

Astrozoid wrote:

Juggernaut122 wrote:

Hi Jerry.

Looks like my Nikon D5100 has a 640 x 480 video mode available. I am using a scope that is f/5.9.

I had thought that using my camera aperture set to 1.8 would be ideal to let more light in (afocally), but you seem to suggest that I want to use a smaller aperture. Should I use a camera aperture somewhere around f/3-f/4?

Thanks!
Juggernaut

Hi Juggernaut,

Unless the Nikon is cropping the images down to the center 640x480 pixles out of the 4928 x 3264 pixles on the sensor, then 640x480 video mode would be the worst thing you could use.

What you need is 1:1 pixel resolution off the sensor. None of the built in video modes is going to give that to you.

I think you are misunderstanding exactly what is needed for high-resolution planetary imaging. It's not the aperture of your camera lens. It's the aperture of your scope that determines the resolution it is capable of in a given seeing condition.

You need to magnify the image by increasing the focal length of your scope / camera lens combination so that the effective focal ratio of the entire system is somewhere between f/20 and f/30.

In other words you get the higher f-numbers by increasing the telescope's focal length, NOT by stopping down the optics. That way you still get the full aperture light-gathering and resolution needed for planetary imaging.

You mention afocal imaging. With a removable lens camera you are better off attaching camera directly to telescope without the camera lens in there. You can use a Barlow lens or eyepiece projection to get the image scale you desire.

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Best Regards,
Russ

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Juggernaut122
OP Juggernaut122 Contributing Member • Posts: 699
Re: How to photograph Jupiter?

RustierOne wrote:

In other words you get the higher f-numbers by increasing the telescope's focal length, NOT by stopping down the optics. That way you still get the full aperture light-gathering and resolution needed for planetary imaging.

You mention afocal imaging. With a removable lens camera you are better off attaching camera directly to telescope without the camera lens in there. You can use a Barlow lens or eyepiece projection to get the image scale you desire.

Hi,

Ok, so the only way to do it is by connecting my camera to a computer and taking the image from the live-view to the computer?

If I connect the camera directly to the scope with the barlow, my zoom is still alot less than if I use an afocal approach through the camera lens with my scope lens and barlow.  Am I still better off attaching directly to the scope without the camera lens even though the zoom will be alot less?

Thanks!
Juggernaut

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Allien
Allien Contributing Member • Posts: 516
Re: How to photograph Jupiter?

Juggernaut122 wrote:

RustierOne wrote:

In other words you get the higher f-numbers by increasing the telescope's focal length, NOT by stopping down the optics. That way you still get the full aperture light-gathering and resolution needed for planetary imaging.

You mention afocal imaging. With a removable lens camera you are better off attaching camera directly to telescope without the camera lens in there. You can use a Barlow lens or eyepiece projection to get the image scale you desire.

Hi,

Ok, so the only way to do it is by connecting my camera to a computer and taking the image from the live-view to the computer?

No, you could do it afocaly as well, just as you are. Record the video to your camera in that small video mode.

If I connect the camera directly to the scope with the barlow, my zoom is still alot less than if I use an afocal approach through the camera lens with my scope lens and barlow.

Correct, although the small video mode you guys are discussing will help offset this, to some degree.

Am I still better off attaching directly to the scope without the camera lens even though the zoom will be alot less?

"Better off" depends on your goals and quality of optics used between the camera and mirror. I prefer Jupiter in prime focus on my 750mm newt, but it is really small. I can use a Barlow or small sensor video camera to make it larger, but the Barlow trashes the image and the video is complicated, relatively speaking. (Also higher "proper" focal lengths may need a tracker for video, which presents it's own challenges.)

Thanks!
Juggernaut

The planets are bright in your eyepiece, so if you are doing "afocal" you can probably stop your lens down or decrease your exposure time.  Regardless of the amount of frames, keep the total session to around ~40 seconds to minimize rotational blur.

For whatever reasons, folks don't seem to do the afocal thing very much, I think it's a snobbery thing more than anything else. (And fiddly, but they do have mounts to attach to the scope to hold the camera for you.)

Really it's almost a matter of semantics. The name of the game for planetary is to get the biggest image on your sensor possible, with acceptable quality of course.

Technically speaking, I think a lot telescope imaging configurations would be "afocal" by definition, both amateur and professional.

rnclark Veteran Member • Posts: 3,957
Re: How to photograph Jupiter?

Astrozoid wrote:

rnclark wrote:

Seems to me it depends a lot on the video processor and what it does to down sample the sensor. I just checked my 7D2 on a Moon video I did last year and comparing the same physical area on the Moon, I get within 1% of the same S/N whether video or still.

Hi Roger,

You got within 1% of the resolution from a 1080p video as from a full-frame still? That is hard to believe.

No, that is not what I said.  I said for the same angular spot size, I got the same S/N for a single frame of 1080p video as a single still frame.

I've done extensive tests on this and the resolution in 1080p video is absolute trash compared to a full-res still.

But, S/N is not the same thing as resolution is it?

Also, shooting at 1:1 means one is susceptible to the errors in Bayer deconvolution and effects from the blur filter. Seems like a 2x2 bin would be better for resolution than 1:1.

It's not true 2x2 binning, it's downsampling ,or decimation and downsampling. I'm pretty sure decimation is involved, and I don't think you can recover lost resolution from that. But you are the planetary scientist so I could be wrong.

If the camera actually took the 4 pixel Bayer group and created one super pixel, like DeepSkyStacker, that might be good if you don't mind shooting at f/60, but if the camera is throwing away every other line it seems like it would have to debayer each individual pixel first, so I don't see how software binning is going to help with debayerization errors.

You are assuming all cameras just do down sampling by throwing out data.  That may have been true in older cameras with slower processors, but with the push for better low light capability and faster processors, new model cameras could well be averaging (binning).  That appears to be the case with the 7D2.  The 7D2 has dual fast digic 6 cpus.

I'll do a full planetary test when I get some time.

Form those who just want to try and use their DSLR it can be a viable option.

Roger

Astrozoid
Astrozoid Contributing Member • Posts: 653
Re: How to photograph Jupiter?

rnclark wrote:

You got within 1% of the resolution from a 1080p video as from a full-frame still? That is hard to believe.

No, that is not what I said. I said for the same angular spot size, I got the same S/N for a single frame of 1080p video as a single still frame.

Hi Roger,

How do you measure the S/N for a spot size?

Jerry

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