| Planetary Photo Techniques (page 5, Updated 3/24/08) This page continues with the Skynyx Camera & Lucam Recorder |
Collecting and processing planetary photo exposures into good images is not a
"luck-of-the-draw" proposition. The sky conditions that you operate under is not entirely under
you're control, but you can reduce wasted time by going outside only when the forecast shows
good potential. Since the best planetary photos happen when the seeing is at it's best, keep up
with the latest forecasts. Check the seeing forecast at the Clear Sky website
(http://cleardarksky.com), the 300mb (jet stream) wind speed forecast at the Unisys website
(http://www.weather.unisys.com; look at the Grf long range, and NAM/Wrf short range models,
you want the lowest wind speed, pinkish/red on the 300mb chart), and the flight level 300
(30Kft/300mb) winds at the Aviation Weather Center website
(http://adds.aviationweather.gov/winds). It is actually worthwhile to also look at the lower, and
higher, level winds at both the Aviation Center and Unisys sites (check levels from 1000mb to
225mb). You really want low winds (short vectors) at all levels.
If the seeing forecast calls for mediocre conditions, you may see a reduction in turbulence at
the day/night, and to a lessor extent, the night/day boundaries. Look at stellar scintillation just
after the sun sets, and again around sun up (I find the effect to be more noticeable around
sunset). This effect, if present some evening, may only last 1/2 to 1hr.
Summary
Whether you're using a simple RGB webcam, or top of the line "machine vision" camera, there
are a few things that need to be done if you want "good" planetary photos. These include:
1) Don't waste your time if the seeing isn't good, go do something else. If the transparency is
terrible (reducing the planet magnitude by more than 1 or 2 magnitude), you might want to skip
the session too.
2) Use a mount that can keep the planet in the camera FOV for at least a few minutes.
3) Defrag your hard drive before you start, and remember were the record files are going.
4) Use a focal length long enough to come close to nyquist sampling blue light, at least green.
5) Learn how to focus. Use a nearby star for best focus, then return to the planet.
6) Choose an exposure that fills the histogram, or exposure meter to 1/2 or 3/4 (on your capture
program). Once you have this exposure selected, you'll have the upper limit on the frame rate.
If you can reduce the exposure slightly, and achieve the next higher frame rate, do so.
7)Set your frame limits so that the planet doesn't rotate more than 1 or 2 pixels during the
record. Try to get as many frames as possible, the more the better (remember that Registax may
have problems on sequences greater than 1GB, typically a couple thousand 8b frames).
If you do these, you'll get a good set of frames, then it's a matter of aligning, stacking,
sharpening, and final color processing. Get a copy of Registax, (PixInsight is good too)
Photoshop, or Photoshop Elements to help with these steps.
Remember, It's the Seeing that counts, not how many thousands you spend on the
equipment!
More ramblings concerning the Lumenera Skynyx camera and LRGB long focal length imaging
to follow. I'll provide more detail on Lucam Recorder camera settings for the Skynyx 2-0M when
working with planets, processing AVI/SER sequences with Registax V4, other programs like IRIS
& PixInsight (IRIS offers stacking, and both of these programs offer some very useful image
processing routines), and PS CS2 planetary LRGB layer processing.
"luck-of-the-draw" proposition. The sky conditions that you operate under is not entirely under
you're control, but you can reduce wasted time by going outside only when the forecast shows
good potential. Since the best planetary photos happen when the seeing is at it's best, keep up
with the latest forecasts. Check the seeing forecast at the Clear Sky website
(http://cleardarksky.com), the 300mb (jet stream) wind speed forecast at the Unisys website
(http://www.weather.unisys.com; look at the Grf long range, and NAM/Wrf short range models,
you want the lowest wind speed, pinkish/red on the 300mb chart), and the flight level 300
(30Kft/300mb) winds at the Aviation Weather Center website
(http://adds.aviationweather.gov/winds). It is actually worthwhile to also look at the lower, and
higher, level winds at both the Aviation Center and Unisys sites (check levels from 1000mb to
225mb). You really want low winds (short vectors) at all levels.
If the seeing forecast calls for mediocre conditions, you may see a reduction in turbulence at
the day/night, and to a lessor extent, the night/day boundaries. Look at stellar scintillation just
after the sun sets, and again around sun up (I find the effect to be more noticeable around
sunset). This effect, if present some evening, may only last 1/2 to 1hr.
Summary
Whether you're using a simple RGB webcam, or top of the line "machine vision" camera, there
are a few things that need to be done if you want "good" planetary photos. These include:
1) Don't waste your time if the seeing isn't good, go do something else. If the transparency is
terrible (reducing the planet magnitude by more than 1 or 2 magnitude), you might want to skip
the session too.
2) Use a mount that can keep the planet in the camera FOV for at least a few minutes.
3) Defrag your hard drive before you start, and remember were the record files are going.
4) Use a focal length long enough to come close to nyquist sampling blue light, at least green.
5) Learn how to focus. Use a nearby star for best focus, then return to the planet.
6) Choose an exposure that fills the histogram, or exposure meter to 1/2 or 3/4 (on your capture
program). Once you have this exposure selected, you'll have the upper limit on the frame rate.
If you can reduce the exposure slightly, and achieve the next higher frame rate, do so.
7)Set your frame limits so that the planet doesn't rotate more than 1 or 2 pixels during the
record. Try to get as many frames as possible, the more the better (remember that Registax may
have problems on sequences greater than 1GB, typically a couple thousand 8b frames).
If you do these, you'll get a good set of frames, then it's a matter of aligning, stacking,
sharpening, and final color processing. Get a copy of Registax, (PixInsight is good too)
Photoshop, or Photoshop Elements to help with these steps.
Remember, It's the Seeing that counts, not how many thousands you spend on the
equipment!
More ramblings concerning the Lumenera Skynyx camera and LRGB long focal length imaging
to follow. I'll provide more detail on Lucam Recorder camera settings for the Skynyx 2-0M when
working with planets, processing AVI/SER sequences with Registax V4, other programs like IRIS
& PixInsight (IRIS offers stacking, and both of these programs offer some very useful image
processing routines), and PS CS2 planetary LRGB layer processing.
