April 2015
Financials:
Opening balance March 1 $1784.67
Dues—new members $60.00
Dues—renewing members $30.00
Revenue for subscription for member to Astronomy Technology Today $140.00
Payment to charitable organization registration with Secretary of State $15.00
Subscription for member to Astronomy Technology Today $14.00
Ending balance March 31 $1859.67
Current membership in BAS: 33 members
18 attended this month’s meeting
Virgil’s astronomy news:
Showed picture of category 4 typhoon
April 4 lunar eclipse—total (if not for haze cover)—about half of group watched
Spots have been seen on Ceres; Dawn can’t take pictures right now. Ceres is 2% of mass of moon but 1/3 of its weight. Dawn orbited Vesta. Dawn is the first craft that has orbited 2 objects.
New Horizons is closer now to Pluto than we are to the Sun. Closest approach will be on July 14 and has been plotted down to the second.
Ganymede is the largest moon in the solar system, 10 times the mass of Pluto. It has auroras and inferred oceans.
Mars:
Rover’s view from Mars March 18—2-tone mineral veins. Think these had to have been formed by water over many wet and dry phases.
Have found nitrogen on Mars. Mars is the only planet inhabited solely by robots!
Milky Way: may be 30 percent bigger than we thought it was. Nine new dwarf galaxies have been found in our vicinity near the Magellanic cloud.
Would anyone be interested in solar glasses for eclipses?
Astrophotography 101, Part 2 by Rick Bryant
Rick has been a member of the BAS for 18 years and has 15 years’ experience in astrophotography to share.
His plan for skills to develop for beginners:
February meeting—introduction by Bob Young
April—skills development
June—intro to image processing
Barn Door mounts
Workshop for absolute beginners
More advanced workshop
3 sets of skills needed:
• Learn the night sky
• Learn how to use YOUR equipment in the dark
• Learn YOUR software
Your interests in photography:
Start with what you have
Keep good records
Develop your skills
Determine your interests
Critically evaluate your needs before you spend money
Lessons learned # 1 : Be prepared
Check equipment before you take it to the field
Get the latest information on special astronomical events you want to photograph
Make an equipment checklist
Plan each astrophotograph in advance
Use star wheels and charts
Put charts in a notebook with acetate sheets
Lessons learned # 2:
A universal image does not exist yet!
Lessons learned # 3:
Tracking tolerance
Usually 5-10-15 minutes of exposures
Basic rules of thumb:
600 rule—wide field “good” images
250 rule—high resolution/magnification
Convert lens to full frame size (25 mm)
600/38 = 16 seconds
He uses 350/400.
Lessons learned # 4:
Polar alignment tolerance (see chart from his presentation)
Lesson # 5:
It is easy to over-expose
Lesson # 6:
(Auto)focus
Learn how to manually focus at infinity
Must learn *consistent* manual focus
SLR can focus past infinity
Electronic focus—focus indicator; daylight testing and verification. Verify infinity in full prior to use.
Autofocus is limited to sun, moon, etc.
He marks lens to where infinity focus is.
Lesson # 7: Batteries
They die quickly due to cold, long exposure time and constant drain.
Have extras, fully charged, and keep them warm.
Be prepared to use battery substitutes—AC and/or DC.
(Note: Autoguiding—tracking just that object you want to photograph—is not a part of beginning astrophotography.
Example: photo of crescent moon at 33,000 feet)
Learn how to—
Focus using zoom
How to change batteries and charge your equipment
Use shutter speed
(He showed a picture of Mercury, crescent moon, Venus and Saturn taken with a level 1 camera, remote release, and tripod.)
You can use a fence post or hood of car to balance camera on.
Lots of newer cameras have remote releases
Step it up a notch: Image Processing
He showed a “Level 2” picture of comet Panstaars taken March 13, 2013
First tool to learn how to use: Histogram
With this, use mid-tone stretch; use mid-tone slider. Clip shadows/highlights to bring out more (for example) of the tail in a comet. Black out trees.
Take it up another notch: Stacking pictures
You want to separate the signals from the noise. You want to even out the noise and average it out, then stretch the image to get more detail.
Stack pictures in 10 second time frame 1.3 seconds apart; 6 ½ seconds over a 10 second period
Not all image processing software will let you stack layers.
He showed a “level 2” picture of the Grand Canyon by moonlight. Used a tripod, stacking, basic processing, photo merge. He took slices and stitched them together. Software he uses finds the fit; Photoshop can help you find the fit.
Step it up a notch:
Simple tracking mounts
Longer exposures; manual or motorized
A simple barn-door tracker costs $20.00, but you can get others costing $80.00 or more, shipped.
He showed a “level 3” picture of comet Neat taken with a camera, remote and manual tracking with a 60-second exposure, taken May 15, 2004.
Start tracking, then take picture. This is a skill to learn; you can master it in one night.
He showed a “level 3” picture of Southern Orion, taken with a camera, remote, manual tracker, stacking and processing. Orion is very photogenic!
If you take 20-40 exposures, you get more detail.
You can get free image stacking software; Deep Sky Stacker is one of the best
His philosophy in astrophotography is to remove as much human made noise as you can.
Dark frames (cover lens cap)
Flat frames (use white or light gray card)
Bias frames (fastest shutter speed that you can do)
Learn the scientific side of image processing; learn about light pollution gradients
He showed a “level 3” picture of Comet Lovejoy taken Jan 16, 2015 with camera, remote, motorized tracking and stacking and processing
He showed a “level 3” picture of Orion taken with camera, remote, motorized tracking, stacking and processing
He showed a “level 3” picture of the Milky Way, Cassiopeia to Orion, taken with camera, remote, motorized tracking, stacking, processing and photo merging, covering 100 degrees of the night sky.
Take it up a notch:
Photograph through a telescope. Higher power/shorter exposure time.
Future seminars:
Barn door mounts
Intro to image processing in June
Intro to Pixinsight LE
Intro to Deep Sky Stacker