alacant Posted July 31, 2023 Share Posted July 31, 2023 (edited) Hi everyone A positive from Ritchie's 3 hour plate using the 23-1/2" f4 at Yerkes in 1901 alongside our -far less of an achievement- 3 hour 2023 attempt with a 6" f5. Love the twentieth century stars, sadly lacking in our effort. Edited July 31, 2023 by alacant 7 Link to comment Share on other sites More sharing options...
AstroMuni Posted July 31, 2023 Share Posted July 31, 2023 1 hour ago, alacant said: Love the twentieth century stars, sadly lacking in our effort. Nice one. We just need to reduce our stars less using software 😉 and possibly not use the narrowband filters...Otherwise you would get something similar to Yerkes is my guess. Link to comment Share on other sites More sharing options...
alacant Posted August 1, 2023 Author Share Posted August 1, 2023 (edited) On 31/07/2023 at 15:15, AstroMuni said: filters Hi Yes, exactly that. Our cheepo UHC destroys the stars; colour, brightness... everything. I think the only way for a realistic star field would be to take unfiltered frames. Cheers. Edited August 1, 2023 by alacant 1 Link to comment Share on other sites More sharing options...
GTom Posted August 9, 2023 Share Posted August 9, 2023 You need those early 1900's skies and L-frames. Link to comment Share on other sites More sharing options...
tomato Posted August 9, 2023 Share Posted August 9, 2023 Great images both. I’m assuming the Yerkes photo was guided in 1901, who stood there for 3 hours? Link to comment Share on other sites More sharing options...
alacant Posted August 10, 2023 Author Share Posted August 10, 2023 On 09/08/2023 at 09:40, tomato said: who stood there Dunno. Here's George Ritchie -the guy responsible for the 1901 plate- looking into a large telescope. There's also a guide telescope pictured. I'm by no means certain, but I believe they had quite good tracking and guided by observing a star via a second telescope then using mechanical connections to the mount, the aim being to keep the cross hairs over that same star for as long an exposure as you needed. or I suppose until your patience ran out. I see you can still purchase cross hair eyepieces these days. I wonder if anyone here has tried guiding like that? Presumably back then, one got only one go at getting it right. Cheers Link to comment Share on other sites More sharing options...
tomato Posted August 10, 2023 Share Posted August 10, 2023 Thanks for the info. I have manually guided many times back in the day with a reticle eyepiece and a hand controller, I used to manage 15 min exposures on emulsion film but when it was -5 deg C that was quite enough. 2 Link to comment Share on other sites More sharing options...
alacant Posted August 10, 2023 Author Share Posted August 10, 2023 43 minutes ago, tomato said: reticle eyepiece Is it a case watching a star for the duration? Presumably you'd issue NSEW via the handbox if the star moves away from the cross hairs. Link to comment Share on other sites More sharing options...
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