Ringed Saturn Visible All Night

[Southwind17]

The biggest improvement to getting the images came when I switched to the delayed shutter release. I thought the vibrations from pushing the button would die out fast enough that they wouldn't affect an image taken with a one second exposure. That was not the case.

If your camera has a cable shutter release I suggest you set it to manual open and use a simple lens cover as your exposure mechanism. Given that you're shooting in the dark you can even just use your hand as a blind - moving it away from the front of the lens after you've opened the shutter and let things settle down for as long an exposure as you require.

 

[davefoc]

If your camera has a cable shutter release I suggest you set it to manual open and use a simple lens cover as your exposure mechanism. Given that you're shooting in the dark you can even just use your hand as a blind - moving it away from the front of the lens after you've opened the shutter and let things settle down for as long an exposure as you require.

Do you think that there is still some motion blue in the images from the shutter even though the shutter was closed ten seconds after I touched the camera? That might be, and your idea would be a way to experiment with that possibility. My Canon SX1 doesn't have a "bulb" feature, the longest exposure is one second. I could still experiment with the idea by holding something in front of the lens and taking it away just after the lens opens but putting it in place just before the lens closes would be difficult.

I don't know why the SX1 doesn't a bulb setting, I've thought it was because they wanted to protect the sensor from damage because of somebody leaving the shutter open in a high light situation, but don't DSLR's have a bulb setting? Maybe they think that people that buy DSLR's are more competent than people that buy high end point and shoot cameras?

 

[davefoc]

Jupiter has 61 known moons and is 318 times more massive than earth.

Good to know. I could only count 53 in my image.

The best way to get a good image of Jupiter is to use a video camera with a telescope and stacking individual video images.

Also good to know. So you can get an even better image of Jupiter's moons if you use a telescope?

 

[Skwinty]

Good to know. I could only count 53 in my image.

Only 4 of Jupiters moons are large and the remainder are small. There is also a trojan asteroid called Achilles orbiting Jupiter.

Also good to know. So you can get an even better image of Jupiter's moons if you use a telescope?

See this image from Mike Salway, one of Australia's top amateur astro-photographers.

http://www.mikesalway.com.au/wp-content/uploads/2009/05/20080530_1528-mikesalway.jpg

He used a 12" reflector and a DMK21AU04 camera capable of 60fps.

This is a great hobby, but can be wallet depleting.

 

[Skwinty]

Do you think that there is still some motion blue in the images from the shutter even though the shutter was closed ten seconds after I touched the camera?

If you were holding the camera in your hand there will definitely be some blur.

The key to sharp, crisp images is to use a tripod or some sort of mount. Even on a top end DSLR you get the option to lift or deactivate the mirror to prevent camera shake.

New DSLR's come without a mirror for precisely this reason.

 

[davefoc]

If you were holding the camera in your hand there will definitely be some blur.

The key to sharp, crisp images is to use a tripod or some sort of mount. Even on a top end DSLR you get the option to lift or deactivate the mirror to prevent camera shake.

New DSLR's come without a mirror for precisely this reason.

Let me assure that I was not hand holding the camera for these images. It turned out that even the amount of shake from pushing the button to take the picture was too much for a clear image. Things got better when I went to the camera's 10 second delay function so the camera released the shutter 10 seconds after I touched it.

The issue I was curious about was whether even the electrically released shutter might have added a bit of blur. There is still some blur left in the image and I wondered if that might have been part of it. But I suspect that most of the blur left has to do with the fact that the image is at the limit of the resolution for the camera. The moons seem to be in the range of ten pixels and I don't expect that ten pixels is going to produce a sharp image.

For the record, I was joking about counting 53 moons. I could see two. I'm going to take another picture tonight. I'm curious about a few things:
1. Will the moons I saw have moved noticeably in one day?
2. Will I be able to resolve the red spot if I reduce the exposure time?
3. Will any of the blur be reduced with Southwind17's idea?

 

[Skwinty]

I would think that the shutter induced camera shake is miniscule and focus and the atmospheric conditions are more likely to be the source of the blur.

The sidereal days of the 4 moons are:

Europa = 3.55 days
Io = 42.4 hours
Ganymede = 7.1 days
Callisto = 16.7 days

A wireless trigger would be better than a cable release.

The more photos you stack, the better the chance of resolving greater detail.

 

[davefoc]

I would think that the shutter induced camera shake is miniscule and focus and the atmospheric conditions are more likely to be the source of the blur.

The sidereal days of the 4 moons are:

Europa = 3.55 days
Io = 42.4 hours
Ganymede = 7.1 days
Callisto = 16.7 days

A wireless trigger would be better than a cable release.

The more photos you stack, the better the chance of resolving greater detail.

I have a wireless trigger for the camera. I might experiment with that if I can find it.

It seems like I might be able to make a guess about which moons I am looking at depending on how much they're moved.

Stacking seems like a cool thing to play with, at first I was thinking that it wouldn't work because the position of Jupiter moves around in my images, but maybe the stacking software is smart enough to deal with something like that?

Do you have some stacking software that you'd recommend?

I use paint shop pro. I wonder if the latest version has something like that. I'm going to go look.

I can program my camera to store RAW images. I fooled around with that a bit but I didn't see enough improvement to justify the effort. I think the problems with my photography are probably great enough to mask the subtle improvements possible with RAW images.

ETA: I hadn't thought about it when I wrote the above about stacking, but is the same software used for focus stacking also used for stacking astronomy images? In a quick look around it seems like both paint shop pro and photoshop have some kind of image stacking capabilities. I'm not sure that they would be applicable to astronomical pictures or not where the blur is caused by other factors than focus.

 

[Skwinty]

Which camera do you have?

 

[Skwinty]

You would be better off with jpeg as a raw image has no processing done by the camera so jpeg will give the best results without you having to worry about additional tweaking. If you have a canon then the software for canon will allow you to do composite work. Otherwise try registax. I think that is the name of the software I am thinking of. I don't use stacking as I use a german equitorial and a astrotrac for tracking which allows for single long exposures without the object drifting.

 

[Skwinty]

As long as the software allows you to shift and rotatate the images to line them up and gives you a variety of options for blending the images together then it should be okay. The reason for stacking in astro imaging is to allow a number of short exposure images to be stacked to increase the signal to noise ratio. That way you do not need to worry too much about the earths rotation and objects drifting whilst the shutter is open. If your max exposure is iirc 10 seconds you should be good.

 

[davefoc]

Which camera do you have?

Canon SX1
It is what is called a super zoom (although the super in this camera is much less super than what is available in the newest super zooms).

http://www.usa.canon.com/cusa/support/consumer/digital_cameras/other_powershot/powershot_sx1_is

 

[Skwinty]

Canon's digital photo proffesional will allow for stacking iirc. They call it composite.

 

[Southwind17]

I was reading about stacking last night as it's a totally new concept to me (not that I claim to be a photography expert!). Saw some images of Jupiter post-stacking compared to a single pre-stacked image - amazing difference.

I don't quite get how it works, though. How can a series of individually inferior images be overlaid to generate a much clearer image? Where does the detail come from?

 

[Skwinty]

The idea is to improve the photon signal to noise ratio and dynamic range. A long exposure will gather many photons but you need to have tracking equipment to compensate for the rotation of the earth.

Shorter exposures negate this requirement for tracking but collect far fewer photons, By stacking multiple short exposures and summing or even averaging the value of each individual pixel means that you increase the number of photons collected.

Here is a link to a more detailed explanation.

http://keithwiley.com/astroPhotography/imageStacking.shtml

 

[edd]

Planetary imaging works a bit differently when it comes to stacking. You're not usually so photon-starved, so any individual image has reasonable signal to noise, and your total stack would have way more photons than you'd need for a quality image. What gets you the major gains in stacking lots of very short (fractions of a second) exposures is that atmospheric seeing is a rather dynamic effect. For short periods, the quality of the image you get can be quite exceptional, and by detecting when you have excellent atmospheric conditions and only stacking those you can avoid the worst of the usual effects of atmospheric blurring.

http://en.wikipedia.org/wiki/Lucky_imaging

 

[Skwinty]

Thanks Edd,

I don't do planetary imaging as I use a DSLR and my interest is in wide field deep space photography. A specialised video camera like the DMK21AU04 with filters is more suitable than a DSLR for planetary work.

Planetary imaging is demanding and tracking assists in making stacking easier especially when working at high focal length. The atmospheric conditions are the biggest factor in obtaining a top class planetary image.

As far as signal to noise ratio and planetary imaging is concerned, I understood that for each image stacked there is a huge gain in SNR. If this was not the case, then why not choose the best image afforded by atmospheric conditions and forego the stacking?

PS Your images on flicker are really good.

 

[edd]

Well, yes, I probably understated the benefit of boosting the signal to noise in stacking planetary images.

 

[Skwinty]

Here is a pic of Saturn by Jerry Lodigruss

60 frames per second
1/60th second exposure
ISO 6400
telescope with 11 inches of aperture and 5,600mm of focal length at f/20.
The best 400 frames out of 3,600 total were selected and stacked in AutoStakkert!2 software
Sharpened with wavelet sharpening in Registax.
Individual color channels were registered and color adjusted in Photoshop CS5.

 

[Southwind17]

Well, yes, I probably understated the benefit of boosting the signal to noise in stacking planetary images.

Could you just clarify SNR please - presumably put simply it's a measure of the 'wanted' photons to the 'unwanted'. How does stacking alter the ratio? Does it concentrate the wanted photons, but because the unwanted are more 'random' they don't get so concentrated?

ETA: Instead of being lazy(!) I've just read the linked article above - very helpful. The only thing I don't quite get now is what, exactly, noise is in photography. I get the impression that it's not necessarily stray light from unwanted sources, but more 'contamination' of the wanted light through blurring by the atmosphere and such like. It also seems that the camera itself can introduce noise, presumably by the introduction of light-type effects on the recording mechanism, similar to low-level white noise or 'hiss' in audio equipment, presumably.

Am I on the right track here?