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Neximage 5 - more questions


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Hello, just have one night of experience with my Neximage 5 and 2.5 weeks of experience of ever owning a telescope.

So, ya, I have questions!

here are a few...I'm using Icap that came with the Neximage 5 for capture, mucking about with Sharpcap also...

1. what is binning with regards to video capture? When do I use it?

2. Should I dial back framerates for planetary capture? It keeps defaulting to 30+ when I change resolutions in icap (but doesn't seem to capture at that anyways, I am guessing that is hardware based)

3. Less exposure and more gain or vice versa to have better stacking quality?

4. What codec should I use, or uncompressed? Registax keeps choking on my uncompressed ones...and some codecs are causing errors. I'm thinking uncompressed but keeping it under a gig file is the answer?

5. Resolution? Does a lower resolution use more pixels per object as it's filling more of the screen/using entire detector for the planet or better higher resolution/finer pixel depth? My mind says use the 640x480, but I am unsure.

6. Can you use a Bahntinov Mask for focusing on planets as well as stars? Haven't tried it yet.

7. RGB 24 vs 32...seems to make easier to manage files using 24, I'm guessing this is color depth. The Y800 appears to be B and W?

Thanks! Here's my first neximage shot from last night...still trying to process the other vid files but I may need to cut them down - they're choking Registax

Saturn, Neximage 5

Jeremy In NY

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I originally posted this in the wrong area I think :p Hello, just have one night of experience with my Neximage 5 and 2.5 weeks of experience of ever owning a telescope.

So, ya, I have questions!

here are a few...I'm using Icap that came with the Neximage 5 for capture, mucking about with Sharpcap also...

1. what is binning with regards to video capture? When do I use it?

2. Should I dial back framerates for planetary capture? It keeps defaulting to 30+ when I change resolutions in icap (but doesn't seem to capture at that anyways, I am guessing that is hardware based)

3. Less exposure and more gain or vice versa to have better stacking quality?

4. What codec should I use, or uncompressed? Registax keeps choking on my uncompressed ones...and some codecs are causing errors. I'm thinking uncompressed but keeping it under a gig file is the answer?

5. Resolution? Does a lower resolution use more pixels per object as it's filling more of the screen/using entire detector for the planet or better higher resolution/finer pixel depth? My mind says use the 640x480, but I am unsure.

6. Can you use a Bahntinov Mask for focusing on planets as well as stars? Haven't tried it yet.

7. RGB 24 vs 32...seems to make easier to manage files using 24, I'm guessing this is color depth. The Y800 appears to be B and W?

Thanks! Here's my first neximage shot from last night...still trying to process the other vid files but I may need to cut them down - they're choking Registax

Saturn, Neximage 5

Saturn - first neximage night

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Binning means that a grid of 2x2 pixels are combined to effectively give a larger, more light sensitive pixel. The native resolution of the sensor is then reduced to lower resolution with a bigger pixel size.

I would assume then that binning will give less detail overall then, but a larger object image?

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I would assume then that binning will give less detail overall then, but a larger object image?

Much depends on the optical resolution of the telescope. For planetary imaging an imaging resolution of about 3 pixels per arcsecond of the telescopes'

resolving power is required to achieve the best image (imaging at numbers higher than 3 pixels doesn't give more detail, only a bigger image). By binning the pixels it would be possible to achieve this ratio at a more useful focal length than using the camera unbinned, normally this results in a focal ratio of about f25.

The formula to work out the optimum focal length looks something like this:

(206.265 x P) / F = A/3

206.265 is a constant to convert angular units

P = pixel size in microns

F = focal length (mm)

A = optical resolution of telescope ( 116 / aperture (mm) )

F = (206.265 x P) / (A/3)

If the pixels are small the focal length is shorter, resulting in a smaller disc. Bigger pixels require a longer focal length resulting in a bigger disc.

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Last night was awesome, tried a focal reducer/corrector, lost the star diagonal too. Haven't messed with it a lot yet, only processed one of the vids, but I am VERY PLEASED.

Saturn May 15 2013 (week 3)

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Hi - I'm a Neximage 5 user - thought I would tell you about the Y800 Codec. Although its gray scale it can actually be converted to colour either when you use registax or in software like PIPP.

When you use the RGB setting the Neximage 5 has to make up all the pixels for each colour that are between each individual coloured pixel array. This is called Bayer Interpolation. Because it does it quickly the algorithm isn't too great. Y800 Codec outputs the raw values for each pixel and you can get Registax/PIPP to fill in the gaps of the Bayer array, which it can take more time over so will produce better results.

So worth having a try at in my opinion. I have just got mine to work in Y800 and the final colour image looks more detailed.

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Hi - I'm a Neximage 5 user - thought I would tell you about the Y800 Codec. Although its gray scale it can actually be converted to colour either when you use registax or in software like PIPP.

When you use the RGB setting the Neximage 5 has to make up all the pixels for each colour that are between each individual coloured pixel array. This is called Bayer Interpolation. Because it does it quickly the algorithm isn't too great. Y800 Codec outputs the raw values for each pixel and you can get Registax/PIPP to fill in the gaps of the Bayer array, which it can take more time over so will produce better results.

So worth having a try at in my opinion. I have just got mine to work in Y800 and the final colour image looks more detailed.

Thanks for that will try that out on my next session.

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Hi Danny

+1 for the lose the green video

I like your tip about using the different codec, I saw your image of Jupiter in the planetary thread the other day and did think how much more details you had managed to get, a very nice capture in my humble opinion. I also have the neximage 5 and will give this a go next clear night. It has taken me a while to get the thing running anywhere near I struggled to get the frame rate above 20fps for ages until I discovered that the external hard drive I was saving direct to was causing a bottle neck. Managed to get it up to 46fps by saving direct to the PC instead. I assume you used the C11 for that capture, very nice. What frame rate have you managed to run at with the different codec

John

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@Redbird - yes I had problems with the NI5 on one PC, however it wasn't an AMD, it was some sort of pentium chip (on a DELL). I think it may have been to do with the USB driver - I just borrowed a work laptop and used that instead (a HP) 

@John: Make sure you have a large chunk of free space on your hard drive. You can do a defrag too - that will help with write speed on the drive.The C11 is what was used yes.

I am soon to run some experiments using different debayer algorithms to see what is best for Jupiter. I will publish the results on one of the conferences soon.

If you do use Y800 its a bit fiddly, but worth the results. you need to set the Y800 setting in 2 places in ICAP or it wont work. You need to use GR as the setting for the debayering technique used. Here is a useful link: http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/6225130/Main/6186642

Aboove all guys, what is needed for as good capture is a night of good seeing. We spend so much time pointing our scopes at turbulent skies and sometimes blaming other things for the blurry images. The most useful think I have read to date is the following article, it took a few reads to get it to sink in but its a big time saver and very enlightening:

http://adsabs.harvard.edu/full/2006JBAA..116...11P

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