The exact time might be a little later depending on how the faac Dearborn astrophotography meeting goes tonight.
I could open earlier but I'm probably going to attend the meeting and also will likely eat a snack before opening later. The sky is supposed to be clear tonight, but it will be cold and we will wait and open up a little later than we could to let Jupiter rise higher in the sky. It looks really good. Foe those who can brave the cold in a dark sky site you may see meteors streaming from a meteor shower tonight as well.
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Thursday, December 13, 2012
Backyard EOS AVI capture of Jupiter from last night.
We were open briefly last night. Four of us were out. Mike, Tim Dey, Rick and I were out at the observatory.
Around midnight I captured an AVI and processed it. This was captured using backyard EOS. A nice program for those with canon dslr cameras and live view mode. I had the canon EOS t1i hooked up to the c14 for the capture of Jupiter. Had shutter speed set to 1/80 of a second. Captured 2000 frames. Stacked and processed the AVI file using Registax 6.
Backyard EOS provides 5x video zoom capture from the t1i. The capture of the video was at native f11 focal length of the c14. That being 3911mm. But the 5x digital zoom capture makes it five times closer. So this would be what a 5x Barlow lens would show for a mounted camera looking at Jupiter.
So what is 3911 times 5? That's the focal length of this shot for a t1i. The t1i uses a 3/4 frame chip as well, so it's a little closer than a full frame chip or 35mm film negative would show.
- Posted using BlogPress from my iPad
Around midnight I captured an AVI and processed it. This was captured using backyard EOS. A nice program for those with canon dslr cameras and live view mode. I had the canon EOS t1i hooked up to the c14 for the capture of Jupiter. Had shutter speed set to 1/80 of a second. Captured 2000 frames. Stacked and processed the AVI file using Registax 6.
Backyard EOS provides 5x video zoom capture from the t1i. The capture of the video was at native f11 focal length of the c14. That being 3911mm. But the 5x digital zoom capture makes it five times closer. So this would be what a 5x Barlow lens would show for a mounted camera looking at Jupiter.
So what is 3911 times 5? That's the focal length of this shot for a t1i. The t1i uses a 3/4 frame chip as well, so it's a little closer than a full frame chip or 35mm film negative would show.
- Posted using BlogPress from my iPad
Sunday, December 9, 2012
Observatory will be closed Monday due to bad weather
We are still waiting for clear skies for a Monday scout troop tour.
Weather looks bad tomorrow, so we won't be open for a tour.
Astronomy seems to be a hobby where you truly meet fair weather friends, at least when it comes to observing the stars.
Greg
- Posted using BlogPress from my iPad
Weather looks bad tomorrow, so we won't be open for a tour.
Astronomy seems to be a hobby where you truly meet fair weather friends, at least when it comes to observing the stars.
Greg
- Posted using BlogPress from my iPad
Thursday, December 6, 2012
A quick summary on NTSC video and pixel aspect ratios using Stellacam camera
The Stellacam camera is a video camera for astrophotography.
It produces a video signal for a video monitor. We can record that NTSC video into a video editing program using a card like a Dazzle card and create an AVI file to get images from. This can work well for images like planets and other images as well. We can stack that video and get an image of a planet or the moon, or some other astronomy object and see more details, basically improve seeing by using hundreds of exposures. We do this with programs like Registax. These programs will analyze and select only the in focus frames of an AVI movie or some of the higher quality frame images and stack them or put them together.
The results can be nice, but there can be some problems. One problem is the recording software or Registax may not account for the NTSC video pixel aspect ratio. That is there may be stretched pixel conversions that can appear. This is due to the television and video standards of early television using Non-square pixels, that is pixels that are stretched. Here is what would typically happen.
Round images which use square pixels will be displayed on an NTSC monitor which is not using round pixels. Since the pixels in video are not round the resulting graphic would be stretched and would not look round. People doing graphics on a computer trying to display those graphics would have to use Computer Graphics programs that could calculate and stretch the graphics to display on a stretched pixel format, making the image appear correctly on the NTSC monitor which is not using square pixels.
Now consider what would happen if you took a video camera and made it sensitive to low light for astronomy and wanted it to display it's pixels and images on a tv monitor, that is using an old school monitor and you wanted the image to be correct and display correctly on a video monitor. You would have to add a function to convert and stretch the ccd sensor pixels to NTSC or elongated pixels, so they would display correctly. You would stretch the pixels so they would look correct on video.
The top chart below snows this. Because the tv monitor is not displaying square pixels we stretched them, in the hardware so they will look correct, and the round circle for example the shape of a planet or the moon would look round on the tv monitor.
But wait a minute. What happens when you try to digitize that video signal using something like the dazzle board. The ntsc signal going out the cable is stretched for the long pixels on a video monitor. That video if its not interpreted correctly will end up looking like longer pixels and this will mean that pixels that are supposed to be 1 dot wide will be 1.33 dots wide for the dazzle board to see them.
The software that captures the video may not have aspect ratio settings that can account for the non-square pixels. It will end up showing a planet that is not round. It looks round on an ntsc monitor, but when its digitized to an avi file, the software may not rescale it.
What youll end up with is a planet that looks oblong.
As you can see below, the programs down stream that use this AVI file will generated a stretched image.
(notice Jupiter looks nice, with good black and white details, but it's stretched a little bit and is out of round.).
The solution is to rescale and reformat the image later on to change it's width back and get rid of the stretch. I'm not showing that step here.
Registax is not expecting non square video sourced files for it's images, it's expecting video from a square sensor, like an astrophotography ccd camera.
How could a webcam work? The webcam uses video and displays and scales it for a normal computer monitor which is using square pixels not NTSC stretched pixels, so the regular webcam video or a camera like the Meade DSI camera would create a video clip with square pixels to begin with.
To make things a little more confusion, Jupiter is actually stretched a little bit in real life, because it's spinning at such a high rate of speed. Liquid and clouds literally fly out around the equator and cause the planet to bulge a little bit. So I wouldn't want to bring it back to a total circle with a perspective correction.
For more information on pixel aspect ratios see:
http://en.wikipedia.org/wiki/Pixel_aspect_ratio
But be aware it's only talking about square pixels being moved to NTSC or other video non square ratios. . . Its not talking about moving from NTSC to digital for digital processing that remains in the computer display realm.
Posted using BlogPress from my iPad
It produces a video signal for a video monitor. We can record that NTSC video into a video editing program using a card like a Dazzle card and create an AVI file to get images from. This can work well for images like planets and other images as well. We can stack that video and get an image of a planet or the moon, or some other astronomy object and see more details, basically improve seeing by using hundreds of exposures. We do this with programs like Registax. These programs will analyze and select only the in focus frames of an AVI movie or some of the higher quality frame images and stack them or put them together.
The results can be nice, but there can be some problems. One problem is the recording software or Registax may not account for the NTSC video pixel aspect ratio. That is there may be stretched pixel conversions that can appear. This is due to the television and video standards of early television using Non-square pixels, that is pixels that are stretched. Here is what would typically happen.
Round images which use square pixels will be displayed on an NTSC monitor which is not using round pixels. Since the pixels in video are not round the resulting graphic would be stretched and would not look round. People doing graphics on a computer trying to display those graphics would have to use Computer Graphics programs that could calculate and stretch the graphics to display on a stretched pixel format, making the image appear correctly on the NTSC monitor which is not using square pixels.
Now consider what would happen if you took a video camera and made it sensitive to low light for astronomy and wanted it to display it's pixels and images on a tv monitor, that is using an old school monitor and you wanted the image to be correct and display correctly on a video monitor. You would have to add a function to convert and stretch the ccd sensor pixels to NTSC or elongated pixels, so they would display correctly. You would stretch the pixels so they would look correct on video.
The top chart below snows this. Because the tv monitor is not displaying square pixels we stretched them, in the hardware so they will look correct, and the round circle for example the shape of a planet or the moon would look round on the tv monitor.
But wait a minute. What happens when you try to digitize that video signal using something like the dazzle board. The ntsc signal going out the cable is stretched for the long pixels on a video monitor. That video if its not interpreted correctly will end up looking like longer pixels and this will mean that pixels that are supposed to be 1 dot wide will be 1.33 dots wide for the dazzle board to see them.
The software that captures the video may not have aspect ratio settings that can account for the non-square pixels. It will end up showing a planet that is not round. It looks round on an ntsc monitor, but when its digitized to an avi file, the software may not rescale it.
What youll end up with is a planet that looks oblong.
As you can see below, the programs down stream that use this AVI file will generated a stretched image.
(notice Jupiter looks nice, with good black and white details, but it's stretched a little bit and is out of round.).
The solution is to rescale and reformat the image later on to change it's width back and get rid of the stretch. I'm not showing that step here.
Registax is not expecting non square video sourced files for it's images, it's expecting video from a square sensor, like an astrophotography ccd camera.
How could a webcam work? The webcam uses video and displays and scales it for a normal computer monitor which is using square pixels not NTSC stretched pixels, so the regular webcam video or a camera like the Meade DSI camera would create a video clip with square pixels to begin with.
To make things a little more confusion, Jupiter is actually stretched a little bit in real life, because it's spinning at such a high rate of speed. Liquid and clouds literally fly out around the equator and cause the planet to bulge a little bit. So I wouldn't want to bring it back to a total circle with a perspective correction.
For more information on pixel aspect ratios see:
http://en.wikipedia.org/wiki/Pixel_aspect_ratio
But be aware it's only talking about square pixels being moved to NTSC or other video non square ratios. . . Its not talking about moving from NTSC to digital for digital processing that remains in the computer display realm.
Posted using BlogPress from my iPad
Monday, December 3, 2012
Jupiter and our moon, in one field of view
The following was taken on 11-28-2012.
This image shows the actual distance between the two objects as they appeared in the wide field of view of the Meade refractor.
We could see these inside the same field of view with a 40mm or 60mm eyepiece.
Because the moon and Jupiter were above and below in their orientation, my Vixen binoculars could not see both fully in the same field of view. Perhaps earlier in the evening I would have seen both in the vixen binoculars. I could only see part of the moon and Jupiter with the vixen binoculars.
This photo was taken actually as two exposures. One was dimmer and showed the moon clearer, the other brighter photograph showed Jupiter but the moon looked overexposed. By layering both photos together in a simple photo processing application, like Filterstorm for iPad I was able to easily put both together and make it look more like our eye would see them.
We could see a few moons of Jupiter while looking through the eyepiece at both, but I don't think that's visible in this photo.
I sharpened the photo a bit in Filterstorm for iPad as well.
- Posted using BlogPress from my iPad
This image shows the actual distance between the two objects as they appeared in the wide field of view of the Meade refractor.
We could see these inside the same field of view with a 40mm or 60mm eyepiece.
Because the moon and Jupiter were above and below in their orientation, my Vixen binoculars could not see both fully in the same field of view. Perhaps earlier in the evening I would have seen both in the vixen binoculars. I could only see part of the moon and Jupiter with the vixen binoculars.
This photo was taken actually as two exposures. One was dimmer and showed the moon clearer, the other brighter photograph showed Jupiter but the moon looked overexposed. By layering both photos together in a simple photo processing application, like Filterstorm for iPad I was able to easily put both together and make it look more like our eye would see them.
We could see a few moons of Jupiter while looking through the eyepiece at both, but I don't think that's visible in this photo.
I sharpened the photo a bit in Filterstorm for iPad as well.
- Posted using BlogPress from my iPad
Saturday, December 1, 2012
Ever wonder if the observatory is open.
Observatory hotline: 313-444-5850
The above number rings the observatory phone and a couple of phones to volunteers who open up the observatory.
Last week we were open, but I only opened for a couple hours and wanted to focus on getting some photos taken. I invited some of the Faac club regulars but didn't spend the time to announce the observatory as being open as it was a last minute decision to open up.
If it's clear out and we are at the observatory we will answer the phone.
If you call ahead I may be able to tell you if we will be open, but I can't always know for certain with Michigan weather.
As for this weekend which is half over I was unable to open up Saturday afternoon for e brief hours of sunlight we had.
According to the clear sky chart tonic and tomorrow will be cloudy, so we won't be open. Forecasts predict rain, so it's unlikely we will have clear skies. The clear sky chart is actually blank for Sunday night. I'm not sure why it's actually not predicting any weather at all. If it's clear Sunday night we might be open.
I can say if we are open Monday evening it will be for a scout troop and it's still dependent on the forecasts. Right now it doesn't look good for another Monday. Maybe our third Monday night cancellation due to poor weather.
Also we may be open for middle school children Wednesday and Thrusday, all day long, for solar astronomy, but the priority will be with the school children and we probably won't have time Wednesday or Thrusday for any visitors.
So from what I can gather, although we may be open chances are most nights and days for the next six days we will be closed to the public.
I'll try to post more when I know more. . . The weather plays a big factor in this and I have other family things at times that keep me away from the observatory.
During the past week I tried to get a good photo of Jupiter to process, with little success. I did get a photo of e moon and Jupiter in one field of view when they were close to each other. I still have to review that photo.
Greg
- Posted using BlogPress from my iPad
Observatory hotline: 313-444-5850
The above number rings the observatory phone and a couple of phones to volunteers who open up the observatory.
Last week we were open, but I only opened for a couple hours and wanted to focus on getting some photos taken. I invited some of the Faac club regulars but didn't spend the time to announce the observatory as being open as it was a last minute decision to open up.
If it's clear out and we are at the observatory we will answer the phone.
If you call ahead I may be able to tell you if we will be open, but I can't always know for certain with Michigan weather.
As for this weekend which is half over I was unable to open up Saturday afternoon for e brief hours of sunlight we had.
According to the clear sky chart tonic and tomorrow will be cloudy, so we won't be open. Forecasts predict rain, so it's unlikely we will have clear skies. The clear sky chart is actually blank for Sunday night. I'm not sure why it's actually not predicting any weather at all. If it's clear Sunday night we might be open.
I can say if we are open Monday evening it will be for a scout troop and it's still dependent on the forecasts. Right now it doesn't look good for another Monday. Maybe our third Monday night cancellation due to poor weather.
Also we may be open for middle school children Wednesday and Thrusday, all day long, for solar astronomy, but the priority will be with the school children and we probably won't have time Wednesday or Thrusday for any visitors.
So from what I can gather, although we may be open chances are most nights and days for the next six days we will be closed to the public.
I'll try to post more when I know more. . . The weather plays a big factor in this and I have other family things at times that keep me away from the observatory.
During the past week I tried to get a good photo of Jupiter to process, with little success. I did get a photo of e moon and Jupiter in one field of view when they were close to each other. I still have to review that photo.
Greg
- Posted using BlogPress from my iPad
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