Last updated: 31 October 2007
Subject: Look at the size of those things...25x100's Sent: Friday, October 26, 2007 08:27:26 From: PETER SMITH (email@example.com) Not Really ETX related but I suppose I am not the only person who dreamt of scanning the heavens with some super-sized binoculars! Think these two pictures really give you a better sense of scale and the true size of 25x100 binoculars! www.btinternet.com/~psmithuk/Bino_mount/Relaxing.JPG www.btinternet.com/~psmithuk/Bino_mount/Scanning.JPG Here's a brief description of the "home made" mount... They 25x100's mounted on a parallel action counter-balanced mount and a heavy duty tripod which I have rushed together just to be able to try the binoculars out - but since they have arrived we have had 100% cloud cover and there is rain and high winds forecast for the next few days - isn't it always the same. The tilt-pan-roll mount is a Manfrotto 141 RC tripod head that I just happened to have lying around. The main tubes are square section aluminium 30x30x2mm about 1.5m long pivoted 1/3 rd of the way along this means the balance weight stays close to the tripod and needs to be around twice the mass of the binoculars and other hardware at the "business" end. It also means that the binoculars can got from the floor to around 2m into the air allowing for "relaxed" viewing from a reclining chair or use standing up and still giving direct overhead capability. The joint plates are 4mm aluminium, the bolts holding it all together are 6mm 8.8 High Tensile. The tripod is 30x10mm flat black iron bar again because it was at hand and I could weld together the top boss. The plan is to either source or fabricate and aluminium tripod or possibly use a surveyors tripod instead of the temporary lash up - which works really well considering there is over 45lbs mounted on it - levelling is by means of 12mm bolts through nuts welded onto the ends of the tripods legs that have a slot in them so they can be turned with a screw driver and then locked off using a locking nut. The counter-balance needed for the Zhummel 25x100s if 11kg made up of 2 and 1kg weight lifting discs on a 1 inch steel tube that can be adjusted for perfect balance by moving them back and fore before locking in place with collars. the swivel bush is machined from 2.5" naval brass which again I had lying around. the "friction" can be adjusted by tightening the bolts through the joint plates but when properly balanced the whole things can be moved around with 1 finger and will hover above your eyes without being held. It took about 7 hours to build (including making up the design as I went along...) and cost (not including the mafrotto head) around $70 If anyone is interested in more information in the short term they can contact me by e-mail and I'll try and help them out.
Subject: First Clearish Night out with the 25x100s Sent: Wednesday, October 31, 2007 11:08:02 From: PETER SMITH (firstname.lastname@example.org) Had first clear spell (only a few hours) so did a back yard test with the 25x100's and the ETX105 both being used at the same time. The ETX with the green laser was use to point at various objects my main target being M31 from my light polluted back yard. I was reasonably impressed with the binoculars but boy do they dew up quickly and the eyepiece lenses are a pain with your breath misting them really quickly until the glasses are in place. Think heaters might be essential fro them. Also need to get the reflex sight fitted properly on them to make "pointing" easier. Had an attempt at imaging M31 using the DSI with the 0.5X field reducer fitted here's the image... www.btinternet.com/~psmithuk/AstroPhotos/m31/m31_5.bmp Don't know what happened to the colour all he other images were orangy...like the others in the same directory... The home made heaters worked flawlessly the corrector plate and eyepiece remaining really clear all night just got to tone down the leds on the switches they are way too bright and I have got to get 2 parafocal eyepieces setup for the DSI now one for it with the focal reducer and one without - would be nice to try and match the FOV with them as well.... Any tips on focusing on "fuzzies" - I suppose a bright star in the vicinity is a good palce to start with a hartman mask and then go back to the "fuzzy". Cant wait for decent clear skies and Orion to make an appearance at a decent hour... Regards, PeterMike here: Yep, Hartman Mask.
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