Jupiter First Image

[badhex]

Hi all

Thought I'd share my first image of Jupiter. It was really just a test of my kit than a concerted effort so definitely not optimum.

I used a modified Lifecam HD on my Skymax 102 and took a 2 minute video at 10fps - due to driver issues if I film at 1280x720 I can only get 10fps but this can be fixed with other drivers apparently. I used SharpCap for the capture, pretty much on default settings except for a minor brightness adjustment.

With the 1200 frames I got, Registax used 960 odd, and a bit of tweaking the wavelets gave me what I finally ended up with.

It's the first time I've used any of these bits of software, and unfortunately I had some issues (probably codec related) with Registax on my main PC - my old laptop used for the capture just about coped with Registax but it was not a pleasant experience, particularly in the wavelets section!

Now I have a rough feel for the process I'm going to spend some time getting the best out of my Lifecam in SharpCap (London skies permitting), and I'm going to try some other stacking software probably, as despite a very strong background in computers I find Registax a little esoteric for my tastes. Any suggestions welcome.

Watch this space, hopefully I'll have some better results to share in the future!

Thanks

Joe

[Langy]

That's pretty good, probably still even better than my third attempt.

Just an extra tip, after you have finished recording I use another free piece of software called PIPP. That will center your planet / moon on each frame and then you can also set it to crop the frames. Therefore you can end up by no longer needing a 1GB video file as it replaces that with one in the 10's of MB. Same quality video but all that black space has been removed.

Well done.

[Astrosurf]

Good first image! +1 for PIPP. There's also Castrator freeware which crops the avi. I use that and find it excellent.

Alexxx

[badhex]

Thanks all.

I'll no doubt be having another go this weekend, weather permitting. I don't have a Bahtinov so I guess I'll be chasing shimmer, does anyone have any tips to try and get around this?

Moreover, I had issues with the image whiting out and I guess this was mostly the lack of any settings changes (it being just a test), but I had wondered if given the addition of the Revelation 2.5x would reduce the amount of light coming in and be a pro rather than a con in this case?

Joe

[JamesF]

I'd hope that you'd be able to reduce the frame size in SharpCap to give you a much smaller frame.  Even if you're not increasing the frame rate that would probably help a lot.  The 2.5x barlow would certainly give you a larger image, though you might need to increase the exposure time and/or gain to counter the dimming of the image and that may also set a limit on the frame rate.

If you open the histogram window in SharpCap, I'd suggest that you want to increase the exposure and gain to get about 65% to 70% of the way across the histogram.

James

[oldpink]

+1 for JamesF's comment on using a smaller ROI, you will get far better frame rates
also try to keep the gain to 50 or below

[badhex]

Okay thanks.

The issue with the Lifecam is that the standard Microsoft driver doesn't allow you to record at anything above 10fps at 1280x720 - but I can reduce the resolution to increase the frame rate as you guys have pointed out. I'll spend some time playing with the gain etc. and see what I end up with.

Joe

[Langy]

Surely increasing the frame rate just means you have to spend less time recording the video.

Will reducing the resolution not reduce the overall image size, therefore meaning that the best option is a lower frame rate and spend longer time recording with a higher resolution?

[JamesF]

The issue with the Lifecam is that the standard Microsoft driver doesn't allow you to record at anything above 10fps at 1280x720 - but I can reduce the resolution to increase the frame rate as you guys have pointed out. I'll spend some time playing with the gain etc. and see what I end up with.

You're not really decreasing the resolution here in the sense the term is used for imaging.  You're reducing the effective size of the sensor by cropping off the edges so they don't have to be transferred over the USB bus or written to disk.  The amount of detail you can collect does not change as a result.  As the planet doesn't take up anything like the entire sensor that's no big deal (as long as you can keep the planet on the bit of the sensor you are using).

James

[JamesF]

Surely increasing the frame rate just means you have to spend less time recording the video.

Will reducing the resolution not reduce the overall image size, therefore meaning that the best option is a lower frame rate and spend longer time recording with a higher resolution?

No, for the reason above.

Increasing the frame rate (as long as you retain a bright enough image) means you can collect more frames in the same amount of time.  As more frames is generally better when you're stacking images, and you have a limited amount of time because the target planet is spinning (quite fast, too) the higher the frame rate you can get whilst retaining a good quality image the better.

Reducing the resolution would reduce the overall image size, but that's not what's happening here.  It would just be cropping off the unused edges of the sensor before transmitting the data.  The resolution of the image would remain the same.

There is a process where the entire sensor surface is used to provide a lower resolution image by combining the sensor data from adjacent photosites.  That's usually called "binning".

James

[badhex]

This is what I thought. More FPS also means more chance of catching a 'clearer' frame as the atmosphere shimmers around, IIRC?

[JamesF]

This is what I thought. More FPS also means more chance of catching a 'clearer' frame as the atmosphere shimmers around, IIRC?

Yes, if we assume that higher frame rates mean shorter exposures which is often the case though the two are not guaranteed to be linked.

James

[Langy]

Thanks, I usually use a higher resolution on my xBox webcam and noticed the frame rate is often as low as 7.5. So I will try a lower resolution of 640 x 480 and push the frame rate up.

I just thought that by using the higher resolution, my final image was bigger.

[badhex]

Ah - looks like I replied at the same time as you James. As you pointed out the size of the CCD is huge in comparison to the size of the planetary image being projected onto it, so I figured I could drop the 'resolution' considerably and get more FPS. I wasn't sure how much the FPS and exposure were linked, but I do understand the principles of trying to get the shortest reasonable exposure time possible for stacking.

[badhex]

One other thought on FPS. Theoretically if there is in any given minute a few split seconds of clarity, the higher FPS is increasing your chance of catching that clear moment, just by law of averages? Obviously exposure time is crucial to the equation, but I'm just musing really.

[JamesF]

I just thought that by using the higher resolution, my final image was bigger.

That would happen if "increasing the resolution" increased the pixel density, but all it does is use more of the total area of the camera sensor.  If you're not using that area then there's no benefit.

If you want a bigger image then you need to increase the focal length of the optical system (usually by adding a barlow) or decreasing the pixel size of the camera sensor (ie use a different camera with smaller pixels).  Both require compromises.  Increasing the focal length increases the area of the sensor covered by the image, but the image becomes dimmer which requires more gain which in turn causes more noise.  Decreasing the pixel size often means reduced sensitivity which also can require more gain.

James

[JamesF]

One other thought on FPS. Theoretically if there is in any given minute a few split seconds of clarity, the higher FPS is increasing your chance of catching that clear moment, just by law of averages? Obviously exposure time is crucial to the equation, but I'm just musing really.

Well I guess there's also the issue that if the image is shimmering, say, and would move ten pixels across the camera sensor in one second then if you image at 5fps with 1/5th second exposures each frame will have a two-pixel "blur".  If you image at 20fps with 1/20th second exposures each frame will only have half a pixel "blur" and you might not see that.

But also, if the air is still for five seconds and you can get a good image then at 5fps you'll get 25 good frames to stack.  At 20fps you'll get one hundred.

When you're stacking, noise reduction varies as the square root of the number of images stacked, so you want as many good frames as you can possibly get.

James

[badhex]

Out of interest, what are people's stacking software of choice for planetary imaging?

[badhex]

Oh, and thanks to all for advice and thoughts!

[JamesF]

Out of interest, what are people's stacking software of choice for planetary imaging?

AutoStakkert!2 for stacking, then Registax v6 for wavelets.

James

[JamesF]

This may be helpful if you're not familiar with AutoStakkert:

http://stargazerslounge.com/topic/184821-beginners-guide-to-stacking-planetary-images-with-autostakkert2/

James

[badhex]

Great. Thanks for the help everyone. I'll see what I can achieve!

[badhex]

Hi all

A bit of playing round with PIPP and linked wavelets in Registax gave me this image from the same source material as the original image. Haven't had chance to get any better material so far this weekend but hopefully will get a bit of a go tonight.

Another thing, when playing with sharpcap settings I couldn't find slider for gain. What am I missing?

Thanks

[oldpink]

on sharpcap the gain is on the right hand side next to the exposure unless they have updated it again

[JamesF]

Another thing, when playing with sharpcap settings I couldn't find slider for gain. What am I missing?

Ah, it may be that the drivers for the lifecam don't offer a gain control, in which case you probably have to do everything with the brightness control instead.  Gain and brightness really aren't the same thing at all, but it's perhaps a simplification aimed at users of the webcam who aren't planning to use it for planetary imaging.

James