MODEL PFE-1 CCD/TELESCOPE ADAPTER Technical Manual and User’s Guide OPTEC, Inc. OPTICAL AND ELECTRONIC PRODUCTS info@optecinc.com http://www.optecinc.com 199 Smith St. Lowell, MI 49331 U.S.A.
Figure 1-1. Model PFE-1 shown with Lynxx PC and Celestron 8" Telescope.
TABLE OF CONTENTS Revision 6 - January 2000 Section 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. THEORY OF OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Purpose of the PFE-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2.2 Basic Mechanical Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LIST OF FIGURES Figure 1-1 1-2 2-1 8-1 PFE-1 shown with Lynxx PC and Meade 8" Telescope. . . . . . . . . . PFE-1 CCD Photometer System and Accessories. . . . . . . . . . . . . . Cross-Sectional View of the PFE-1 mounted with CCD camera. . . Typical Stepper Control Curcuit Using the SAA1027. . . . . . . . . . . . Page Cover 2 4 20 LIST OF TABLES Table 5-1 5-2 5-3 5-4 6-1 7-1 7-2 8-1 8-2 8-3 Physical Characteristics of Optec UBVRI Filters. . . . . . . . . . . . . .
SECTION 1.0 INTRODUCTION The recent advent of affordable astronomical CCD cameras has opened whole new opportunities in the area of stellar and extended object photometry. The small format CCD cameras now being manufactured by companies such as Meade and Santa Barbara Instrument Group are examples of the new low-cost cooled-chip astronomical cameras.
Figure 1-2. PFE-1A CCD Photometer System.
SECTION 2.0 THEORY OF OPERATION 2.1 PURPOSE OF THE MODEL PFE-1 Two of the most serious limitations to doing photometry with the small format CCD cameras are small field sizes and lack of a convenient way to insert photometric filters into the light path. The PFE-1 provides an off-the-shelf solution to both these problems. The TC-211 CCD chip used in the SBIG ST-4 and Lynxx PC series cameras has an array of 165 pixels by 192 pixels.
2.2 BASIC MECHANICAL DESIGN Figures 2-1 shows cross-sectional views of the PFE-1 when mounted to a CCD camera head. Light enters the PFE-1 through the 1¼ inch telescope adapter and is directed either to the focusing eyepiece or the CCD sensor by means of a flip-mirror. The focusing eyepiece consists of a 1-inch (25.4mm) focal length Ramsden and a reticle with a precisely etched square that defines the CCD field of view. A green LED illuminates the reticle from the side.
On the bottom of the PFE-1 flip mirror/eyepiece assembly is an input jack for the 12 VDC required to provide power to the reticle LED. The external DC power supply adapter should be plugged in before operation. To adjust the reticle brightness on the PFE-1, use a small screwdriver to turn the pot next to the power input jack. The PFE-1A has an adjustment knob to facilitate changing the reticle brightness. For the PFE-1, a two-position filter slider is mounted between the flip mirror and the CCD.
Mounting kit stock number 17614 will adapt the Santa Barbara Instrument Group's Model ST-4 CCD camera to the PFE-1. The 1¼" telescope mount of the ST-4 includes a small cover window and O-ring seal. Mounting kit number 17614 includes a special spacer which contains a replacement cover window and O-ring seal. The stainless steel camera mount then attaches to this spacer and the PFE-1 attaches to the camera mount. Again, all mounting screws and tools are included with the mounting kit.
SECTION 3.0 INSTALLATION PROCEDURES 3.1 MOUNTING THE PFE-1 Installation of the PFE-1 to one of the cameras should be done in a clean area free of dust and other contaminants. The procedure is not difficult and all necessary tools are provided with the mounting kits. However, as with any delicate optical device, care should be taken when handling the camera. For first time buyers who prefer not to attempt mounting the PFE-1, Optec will perform the installation and reticle alignment free-of-charge.
In the telescope, locate a fairly bright extended object such as the moon or a distant street lamp and center it in the reticle. Put the control software in the Focus mode and slightly loosen the setscrews to allow camera rotation. Rotate the camera and make the final X-Y adjustments so that the view within the reticle matches the view on the video monitor. The full-frame focus mode works best. Take your time.
SECTION 4.0 TROUBLE-SHOOTING GUIDE The following common problems and solutions have been collected over the years from our customers and our attempts to solve their instrument problems. Before calling us, read through these and relevant sections of this manual to see if an easy solution exists for your errant photometer. The CCD photometer seems to produce erratic results with the I and R filters but appears to work OK with the B and V filters. Read section 3.1 again.
the S/N ratio will be lowered. Remember, for each 10°C drop in operating temperature a gain of about one stellar magnitude is achieved in limiting magnitude. The focus seems to shift significantly throughout the evening. Focus is a common problem among the Schmidt-Cassegrain type telescopes. With the folded optical path of the SCT, slight thermal changes have a significant effect on the overall focus of the system.
SECTION 5.0 JOHNSON UBVRI FILTERS The UBVRI filter system established by Johnson is generally followed today and defines color bands in the spectrum interval from 300 to 1200 nm. Table 5-2 lists the filter-detector responses of this system as originally established by Johnson. Filter-detector response is defined as the normalized product of filter transmission times detector response for each wavelength interval.
nm U B V R I 300 310 320 330 340 350 360 370 380 390 400 410 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860 880 900 920 940 960 980 1000 1020 1040 1060 1080 1100 1120 1140 0.00 0.10 0.61 0.84 0.93 0.97 1.00 0.97 0.73 0.36 0.05 0.01 0.00 ------------------------------------------------------------------------------------------------------------------------------------------------- ------------------------0.00 ----0.11 ----0.92 ----1.00 0.94 0.79 0.58 0.
nm U B V R I 300 310 320 330 340 350 360 370 380 390 400 410 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860 880 900 920 940 960 980 1000 1020 1040 1060 1080 1100 1120 1140 0.00 0.00 0.00 0.13 0.33 0.50 0.77 1.00 0.92 0.53 0.00 0.00 0.00 ------------------------------------------------------------------------------------------------------------------------------------------------- --------------------0.00 0.02 0.10 0.22 0.42 0.60 0.72 0.87 1.00 0.76 0.
nm U B V R I DET. A/W* 300 310 320 330 340 350 360 370 380 390 400 410 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860 880 900 920 940 960 980 1000 1020 1040 1060 1080 1100 1120 1140 0.00 0.00 0.00 0.16 0.28 0.37 0.48 0.49 0.39 0.17 0.00 --------------------------------------------------------------------------------------------------------------------------------------------------------- --------------------0.00 0.04 0.14 0.28 0.41 0.50 0.55 0.60 0.57 0.
SECTION 6.0 WING FILTERS With the cooperation of Dr. Robert F. Wing of Ohio State University, Optec has designed three filters for the SSP-3 photometer which are useful in measuring the absorption of TiO (titanium oxide), and the true color temperature of late type stars such as Miras. These 1 three filters labeled MA, MB and MI comprise a subset of the Wing 8-color system . See Table 6.1 for filter specifications.
SECTION 7.0 STRÖMGREN FILTERS The Strömgren uvby is the most widely used intermediate-band photometric system and is often used instead of the Johnson UBV system. The letters u, v, b, y refer to the colors ultraviolet, violet, blue and yellow respectively.
The u filter is made from 2 pieces of Schott colored glass. The first glass of UG11 defines the red side of the pass band and the WG345 defines the blue side. The small amount of red leak of the UG11 glass beyond 700 and 750 nm should not be a source of error except for very red stars. The surface of the UG11 glass has poor resistance to weathering (humidity) and must be protected in a manner similar to the vby filters.
SECTION 8.0 PFE-1A AUTOMATIC OPTION 8.1 PHYSICAL CHARACTERISTICS The PFE-1A CCD photometer allows for automatic selection of filters using the 6-position filter sliders. A small 4-phase stepper motor is located below the flip mirror of the camera head and provides the torque and positioning accuracy needed to exactly center the desired filter. A bevel gear arrangement connects the stepper to the filter slider.
8.3 CONNECTING & OPERATING STEPPER MOTOR If the SSPCARD and associated cable are purchased with the PFE-1A, this section can be disregarded. A 9-pin AMP connector is supplied with the PFE-1A for those wishing to design and build their own stepper controller or computer interface. Table 8-2 lists the pin numbers of the 9pin connector which are connected to the motor and the proper step sequence that these lines must follow. FUNCTION MOTOR WIRE COLOR PIN NO. FOR PFE-1A CONN. STEP SEQUENCE C.W. ROT.
PIN NUMBER 15-PIN 9-PIN SUB-D CIRC. 1 1 2 3 3 7 4 2 5 5 6 6 7 4 8 8 9 9 CABLE COLOR Red Orange Purple Brown N/A White Blue Black N/A FUNCTION +12 Volts DC Q4 - Pin #11 on SAA1027 Q3 - Pin #9 on SAA1027 Q2 - Pin #8 on SAA1027 Not Connected +12 Volts DC Q1 - Pin #6 on SAA1027 Power Ground Not Connected Table 8-3. Pin Number and Function for the Motor Control Cable Connector. Figure 8-1. Typical Stepper Control Circuit Using the SAA1027.
APPENDIX A PFE-1 MOUNTING KIT INSTRUCTIONS MOUNTING KITS FOR THE SPECTRASOURCE INSTRUMENTS CAMERAS The Lynxx PC, Lynxx MC, Lynxx 2, and Lynxx 2000 camera heads are shipped with a combination 1¼"/2" telescope coupler which must be removed. Loosen and remove the coupler by removing the three socket cap screws holding the coupler to the camera face. Install the stainless steel mounting plate with the dovetail mount away from the camera face using the three 1/4" long flat head socket screws.
MOUNTING KIT FOR SBIG ST-5C AND CELESTRON PIXCEL 237/255 CAMERAS The Celestron PixCel 237 and 255 cameras use a three piece mounting kit for attaching to the PFE-1. SBIG sells the PixCel 237 camera directly as the Model ST-5C. The purpose of the three piece mount is to allow easy disconnect of the PFE-1 and attachment of either the MAXfield 0.33X or WideField 0.5X telecompressors to the CCD camera. Optec part number 3486 is required.
Next, attach the PFE-1 to the dovetail by tightening each of the four setscrews on the PFE-1. Roughly center the camera by looking down the 1¼" coupler. You may need to flip the mirror out of the way and remove the filter slider. You may now proceed with the reticle alignment (Section 3.3).
