alan holmes founder and president new products at sbig
TRANSCRIPT
Alan HolmesFounder and President
New products at SBIG
SBIG is Now Part Of Aplegen
• New Management intends to:– increase astronomical product research
and development– adds new cameras with features suited
to life sciences applications such as:• Gel Imaging• Fluorescence microscopy
• New CEO is Ron Bissinger, known for amateur exoplanet measurements
Past SBIG Cameras over the last 23 years
• ST-4 (my baby)• ST-6• ST-5/ 237/ PixCel 237• ST-7/ 8/ 9/ 10/ 2000 line• STL-11000/ 6303/ 1001 line• STX-16803/ 6303• ST-402/ 1603/ 3200• SG-4
New Camera Models in Last Year
• ST-I• ST-8300 and STF-8300• STX-6303
ST-I is a new Guider/Planet Camera
ST-I Features
• 640 x 480 pixel interline CCD• 7.4 micron square pixels• Exposures as short as 1 millisecond• 16 bit A/D converter• 10 electrons read noise• powered off USB port• Shutter for automatic dark frames• Fits in 1.25 inch eyepiece tube
ST-I Comes with a Case and Software
A Guiding package is Available that is all Most Users Need
Planetary Imaging is also Possible
(Not the best but it’s mine!)
ST-8300 is our most Popular Camera
• Features– 8.3 million pixels – 16 bit A/D– 38 degree C cooling– 5.4x5.4 micron pixels - good for refractors– EXCELLENT low dark current– Just went on sale at a great price - $1795 US
5 (and 8) Position Filter Wheels are Available
The ST-8300 is capable of Great Images!
Peter Clausen
Peter Clausen
New STF-8300 Provides Faster Readout
10 Megapixels / Second Full Frame Image Buffer Readout and Download Simultaneously Download Full Frame < 1 sec. User Rechargeable Desiccant Plug Internal Image Processing – Raw or Processed
Even-illumination (Photometric) Shutter 32-bit and 64- bit drivers for all Windows O/S Equinox Image and Equinox Pro for Mac Base Price $2495 US
STX-16803 is our largest CCD Camera
•4096x4096 pixels
•9 micron pixels
•Excellent Cooling
Martin Pugh
STX Images -Johannes Schedler - Austria
M97-Owl Nebula (too far north for Santiago!)
More STX Images from Johannes
NGC 5033
New STX-6303 is Excellent for Narrow Band Imaging and Faint Objects
Adriana Sherman, Guatemala
New Accessory Products at SBIG
• Differential Guiding • ST-8300 Off Axis Guider
Differential Guiding Solves a Difficult Problem
• When guiding at long focal lengths with a guide scope, the scope-to-scope alignment drifts due to:– Gravity direction changes– Thermal effects– mirror flop– mechanical shifts
• Differential guiding eliminates all of these
SBIG’s New Technique: Differential Guiding *
• An artificial star is created near the imaging CCD focal plane
• Beam of light from artificial star exits telescope
• Beam is retro-reflected into guide scope• Guide scope views both artificial star and
background star• Separation of artificial and real stars is
maintained by guiding* Patented
Differential Guiding Diagram
Main Scope
Guide Scope
LED
Guide Camera
Retro-Reflector
Imaging
Camera
Guiding is Adjusted to Maintain X and Y Offsets Constant
Guide Star
Artificial Star
X
Y
Retroreflector is Derived from Corner Cube and Dove Prism
Corner CubeDove Prism
Beam is exactly retro-reflected, and displaced to outside the telescope aperture. Retro-reflected angle is insensitive to small mechanical misalignments.
Testing was Performed in my Backyard
A Celestron Edge 14 was used for the Test
Retroreflector Assembly and Guide Scope (Hutech 50 mm F/5)
ST-8300 and Artificial Star Generator
Conventionally Guided Image - 30 minutes
Differential Guided Image - 3 x 30 Minutes - no Shifts!
It Works Great! (ST-8300C Data Added)
New Off-Axis Guider for ST-8300
Guider Ray Trace Diagram
• Allows guiding in front of the filters• Also provides focal reduction for 2X
more area
Imager CCD ST-I
CCD
It uses an ST-I and Mounts to Filter Wheel
Low Profile – Adds only 19mm backfocus to camera and filter wheel (total about 58mm)
Built-in relay lenses and 0.7X reducer doubles the field of view of the ST-i
Guide camera can be mounted at 90 degrees x 4
St-I Guider Image at F/3.5! Stars are excellent for guiding
Celestron Edge 14 Image using OAG With ST-8300
Alan Holmes
OAG Makes Guiding Narrow Band Images Easy
Peter Clausen
-Astrophotography Hints-
Stray Light and Flat Fields
An Example of the Problem - An Expensive Refractor with an ST-8300
• Center to edge variation = 6%• There is NO vignetting in either image!• “Hot Spot” is caused by glints off internal cylindrical
surfaces near CCD Camera
Green Flat Field IR (940 nm) Flat Field
Measuring Stray Light: My “CCD View” Pinhole Camera
• Chamber window of ST-3200 replaced with a tiny lens
View of my office through a short 1.25 inch nosepiece
Looking into that High-End Refractor
Actual Aperture!
Bad Stuff!
Problem is glints off of “black” anodized surfaces. Total Stray Light is 8% Green, 18% IR
$5 Million Peso (!) RC Scope
Green - 13% Stray Light Near IR - 37% Stray Light
Aperture Edge
Why is this important? - Astronomical Features have very Low Contrast against the Sky Background
9% contrast
1% contrast
(Images are from a Dark Site)
Tony Hallas
Stray Light is also a Serious Problem for Photometry
Vignetting Stray Light Sum
Using a flat field to correct an image with stray light incorrectly increases brightness of stars near edge of field
(Looks like vignetting but it’s not)
A Collection of “Black” Objects Imaged at Near Infrared Wavelengths (940 nm)
White Business Card
Black Felt (79% reflectivity
Black Paper
Flat Black Paint
Flat Black Paint can solve this Problem - User Flat Field Images
STL-11K - Flat Field with Moonlite Focuser and ribbed draw tube
Flat field after painting draw tube with flat black paint
How to detect the problem yourself
• Point your telescope at a flat field screen
• Put your eye at the point where you usually insert the camera
• Look into the tube
What can you do?
• Paint black anodized surfaces Flat Black– I prefer barbeque black - low temperature paints may use
dyes that are transparent beyond 700 nm• Add thin shim rings to work as knife edges baffles• Do NOT use incandescent bulbs for flat fields
– Use white LEDS instead – Better, but still not perfect
• Sky flats may help - matches spectrum better for LRGB imaging• Use flat field for each color if doing RGB images• Photometrists should map response by moving stars around in
field to detect problem
It is Worth the Effort!
Tony Hallas
Particularly with Huge Mosaics (Rogelio Bernal Andreo - 19 APODs!)