I. Double ep search and targeting setup Last Sunday (6/8 - 6/9), I tested a double eyepiece search and targeting setup on the Ealing for visual observing. A flip mirror and right angle was used to provide a search ep at 52mm (32' TFOV) and an observing ep at 25mm (15' TFOV) with the option of rotating in DSO filters on the observing ep. This setup may be of interest for Ealing star party operators. Double targeting setup - photo http://gallery.utahastronomy.com/main.php?g2_itemId=11501 Double targeting setup - component schematic http://gallery.utahastronomy.com/main.php?g2_itemId=11503 The default SLAS 32mm 2" ep provides a TFOV of 20'. This can be a dauntingly small TFOV for searching for and centering on targets. An alternative setup would be to use two sets of 2" eps on the flip mirror - 52mm search and 32mm-25mm 2" ep for observing. A second Lumicon T-2" adapter for that setup arrived in the mail after last Sunday. The following is rough layout of a dual 2" search and target setup. Double targeting setup - 2" variant http://gallery.utahastronomy.com/main.php?g2_itemId=11505 II. Targeting testing and focuser tube flop I also did some testing with a 12mm reticule ep (7' TFOV) to roughly characterize the targeting and tracking tolerances for the Ealing. I wanted to explore possible reasons the Ealing is so hard to target(IMHO and at least for me). Arcturus was transiting. Using the reticule ep, Arcturus was centered and all the finders were centered as precisely as possible (within 20'). Even with the best adjustments, there was a small offset between the ep centering and the Mak finder that had to be memorized. Then I executed a meridian swap and attempted to center the bright star in the ep using the telrads. The star was no where to be found. Increasing the TFOV by inserting progressively lower power eyepieces, Vega was found just outside the AFOV of the 52mm ep. Then I recentered Vega and recentered all the finders. A slew to M57 was performed without difficulty using the finders and the 52mm search ep. A second test was done by merdian swapping back to Arcturus. The same problem was found. After a long slew, the finders were no longer aligned to the target. A third test was done by slewing by to Alberio, recentering the finders and then star hopping to beta Sct and then on to M27. After recentering on Alberio, the slew to M27 was done without any difficulty and was particularly satisfying. In the 15' TFOV observing ep, M27 crisply slewed into view and filled the entire ep AFOV. The amount of finder error after a meridian swap was roughly measured during the test described above. The bright star would be centered in the 12mm reticule and then the corresponding index error in the telrads and Mak finder noted. In general the index error was between 1/2 deg (30') and 3/4 deg (45'). This performance characteristic explained to me why the Ealing finders always seem to be out seriously of the alignment when the scope is first started up and why the scope is always hard to target. Using a 32mm ep with a TFOV of 20', swapping the scope and trying to align on based on the finders can result in being off the target by two or three ep fields or one to one and one-half fields using a 52mm ep with a 31' TFOV. I looked for the cause of the finder index error. I listened for mirror flop during a swap and tracked through the ep while moving the scope across the transit line. No significant swap was found. Finder flop was discounted. The error was seen in ridgedly fixed telrads and in rigid ring secured finders. The source of the problem appeared to be the well-known Ealing's focuser tube flop. When the scope is on one side of the meridian, the focuser tube is leaning to one side. Moving the scope, even on the same side of the meridian but across large 50 degree declination sweeps, causes the focuser tube to lean to one side, causing the apparent misaligning of the focusers. Armed with this knowledge, I tested the principle on M11 and M26. I always slewed to a nearby bright star and recentered all the finders. Then right angle slewing to a target supplemented by the Mak finder worked as expected. Even so, search targeting with a 32mm ep had some level of difficulty. The wider field 52mm ep provided a good targeting bridge between the Mak finder and the small TFOVs of the observing eps at 32mm and lower focal lengths. A fix for the tube flop might be to invest and upgrade the aged rack and pinon focuser on the Ealing with a modern, more stout, Crayford focuser. A Moonlight Crayford focuser illustrates one of many possibilities. JMI NGF Focuser http://www.jimsmobile.com/buy_ngf.htm Moonlight 2.7" Crayford focuser http://www.focuser.com/cgi-bin/dman.cgi?page=productdetail&plugin=dstore.cgi... Astophysics Focusers http://www.astro-physics.com/index.htm?products/accessories/focus_adap/focus... I located an Austin Texas astronomy club newsletter discussing that club's Ealing scope. They replaced their focuser with a JMI NSF model with a motorized focus control. The newsletter also indicated that they had an Astrophysics focuser and an automated JMI tracking control. Austin Texas newsletter https://webspace.utexas.edu/cannonea/www/aas/stnl/ST200212.pdf Although the Skywizard was not working on 6/8-6/9, in a prior session, I concluded the easiest way to use the Wizard in conjunction with bright stars on meridian flip was to just slew to one of the Skywizard named alignment bright stars. Regardless of whether the bright alignment star is in the eastern or western sky, just press "mode", "alignment" and align to the bright star. This dispenses with having to reference and enter the obscure Skywizard "ST" star numbers found in the Ealing Skywizard handbook. The take-away point is that due to focuser tube flop, best practices for targeting are: 1) Do a meridian flip 2) Bright alignment star center in smallest TFOV ep or with reticule 3) Realign all the finders to compensate for the focuser tube flop 4) Resync the Skywizard 5) Enter the DSO target into the Skywizard 6) Use the Skywizard right-angle slew indicator to move within 1 degree of the target 7) Search the 1 degree TFOV in the Mak; tune alignment 8) Search with the 1/2 degree TFOV 52mm ep 9) Finalize targeting with the 20'-15' observing ep III. Tracking testing and RA speed calibration Rough track testing for bright stars was done in various parts of the sky using the 12mm reticule ep. The Ealing tracking rate is variable depending on altitude. You can hear a changed escapement rate when the scope is about 65 degrees altitude. I followed the tracking rate error in the 12mm ep while centered on a transiting bright star and adjusted the sidereal rate calibration knob on the Ealing motor controller. Tracking error was minimized when in "sidereal mode", the calibration knob was set to its lowest setting - all the way to the left. However, the calibration knob did not have a sufficent slow range adjustment to minimize the tracking rate error. I do not know if there is a supplemental right ascension adjustment potentimeter on the back of the controller box. If so, Ealing tracking could be improved by centering the default right ascension rate so that the calibration knob is centered. That would give enough rate calibration adjustment so stars could be tracked with a minimized tracking error. The take-away point for Ealing operators is that the best tracking rate will usually be in sidereal mode with the rate calibration knob turned all the way to the left. I did not have the time to quantify the tracking rate error with star drift imaging, but will attempt to do that in a future session. Regards - Kurt