Jupiter with Focal Extender Explore Scientific

[jsmoraes]

Full Moon, but the sky was very clean.
Total frames for each AVI : 800 frames
Total used frames:200 frames

GSO 305 mm - ASI120MC - AS!2 - Wavelets Registax 6.0 - PS CS3

GSO 305 mm - ASI120MC + Barlow GSO ED 2x mode 1.5x - AS!2 - Wavelets Registax 6.0 - PS CS3

Note: I have a doubt about the information in status bar of ASI120MC and SharpCap when capturing images:

1) it shows two informations: captured frames and dropped frames . What is the difference ? Why there are difference in amount of frames ?

2) manipulation of percentual of USB connection modify the amount of capatured frames and dropped frames. Better set make dropped frames higher than captured frames. Why ?

[michael.h.f.wilkinson]

Very nice result. Dropped frames tells you the number of frames that may have been output by the camera but couldn't be stored on disk, usually because the disk is too slow.

[jsmoraes]

Thank you, michael. I was thinking as you say. My last work, this Jupiter image, showed values that cause some confusion.

With USB around 58 % I had more capturing frame than dropped frames. Ok, the USB was very slow.

With USB around 70 % I had more dropped than capturing frames. If things are as you say (and I was thinking) the AVI has some frames that are only duplication of previous.

This make sense. The AVI has some freezing frames during the play action.

Therefore, use of Sharpcap needs more one set up to pay attention. The best will be when the capturing and dropped frames are equals or with values vary similar.

I don't know if this issue is the same for Firecapture. I will test it.

[Virgoman]

Lovely detailed shots of Jupiter. Nicely coloured and processed. I had this issue with SharpCap dropping frames myself - couldn't understand it - laptop has plenty of grunt. I switched to Firecapture very quickly and haven't looked back.☺. Might be worth defragmenting your HD - I have found this to work in the past.

Best regards,

Ralph

[Kokatha man]

...there really shouldn't be any dropped frames if the laptop is half-reasonable...perhaps not enough RAM available or an almost-full drive. I suggest you switch to FireCapture also!

If you only captured 800 frames I presume the frame-rate was pretty slow anyway...usb2 should have handled that without any problems whatsoever so dropping frames is fairly puzzling...

That second image shows signs of an under-exposed histogram for the ASI120MC...

If you use FireCapture it generates .txt files with every .avi file & this .txt will show aspects like frame-rate, exposure as per the histogram etc. etc...useful when analysing data!

[jsmoraes]

Thank you for comments.

I understand that the problem of dropped frames is with USB speed. I use netbook Lenovo S10-2 - 1 Giga RAM. It isn't a top computer ! The frame rate was about 15 to 20 frames per second. I needed to select the size with 800 or 900 px, because of Io and Ganymede moons.

For exposure I work around gama = 15, brightness = 30, gain = 15 and exposure 35 to 55 ms. I adjust the parameters trying to get the most bright image without saturation of areas.

I will try again the FireCapture. I had problem with it. I donwloaded the last version for test.

I did only 800 frames because of derotation issue. I never tried it in Winjupos. It seems I will need to learn it.

The focal extender isn't a TV Powermate, but it work very well. I liked this my new toy !  Because of the constant intense refraction, I live on the side of the sea with much humidity, I bought a 3x model. Although maybe the best choice should be 4x or a bit more.

I can use my barlow 2x GSO ED to enhance, but this barlow has a medium or poor performance. Much spherical distortion. Hard to get good focus.

From another AVI, the planet cames with some noise, but I liked the moons !

GSO 305 mm - ASI120MC - Focal Extender 3x + Barlow GSO ED 2x in mode 1.5x

200 from 800 frames - AS!2 Registax PS-CS3

Focal Length: 6041 mm - f/19.8

[DrRobin]

The first image is very nice, lots of good detail coming through. You could merge the two to get the moons and detail in one shot?

I worked out at 20 frames per second you were about 40 seconds capture? I use 120 ~ 150 seconds, after that rotation does play a part and I need to use WinJupos. I reckon with your set up you could go to 100 seconds without any problem.

I started using Firecapture a couple of years ago and initially had a problem getting it to recognise the camera, turned out to be a driver problem, but after that it worked well. My C11 with 2x Barlow gives 5400mm focal length at F20, so fairly similar to your set up. In Firecapture with an ASI120MM-S using gain at 50, exposure around 18ms, gamma 50 I can get around 50 fps on Jupiter with no dropped frames.

The -S is USB3.0 so it will do is for a full frame, but my ASI120MM will only do 30 fps for a full frame, it is only USB2.0. 20 ~ 30 fps is still a good rate to get a decent image run and F20 is a good focal ratio for good to excellent seeing. Higher F numbers really require excellent seeing.

I hope this helps.

Robin

[jsmoraes]

Thanks, Robin. And the comment helps. I let aside my planetary activities ( I started with it and mainly with Jupiter when my telescope was in dobsonian mounting  - http://jsmastronomy.30143.n7.nabble.com/Jupiter-2011-td5.html ) because I haven't a good barlow.
Now with this Focal Extender I returned to it.
Planetary is different from DSO. I will need try more times to get experience.

My USB is 2.0, but the computer is a netbook, worse than a notebook. I can get frame rate up to 40 frames per second with small size of image. At this session I wanted to catch the moons, the size was about 800 or 900 px. And so, frame rate about 15 to 20.

The maximum time to capture Jupiter without rotation is very important. Your suggestion of 100 to 120 seconds is welcome.
 

[jsmoraes]

The time of AVIs were around 40 ~ 60 seconds. With 800 ~ 850 frames.

[jsmoraes]

Well, the last AVI of the session. It seems to be the best AVI . The moons were "imported", since they weren't well framed. Only 9 minutes of error for theirs positions.

Focal Extender 3x + GSO barlow ED 2x in 1.5x mode