dawson Posted July 18, 2013 Share Posted July 18, 2013 I've had a few pints so sorry if there are more typos than usual. Is the focal point, actually a point? As in a point of light? And, is prime focus at that point (and if so how does a point of light (if that is what it is)) fill the whole sensor o a camera? If not at the focal point (which may or may not be a point), is it the telescope side or the other side of this? Thanks leigh for the drinks, but not for showing my ignorance once again We both waves at saturn so should feature in the new cassini image of earth. Night Link to comment Share on other sites More sharing options...
Brantuk Posted July 18, 2013 Share Posted July 18, 2013 The focal point is the point at which the telescope comes to focus (i.e. produces a clear and sharp image) - just like focusing a daytime camera so the picture's not blurred. The scale of the image on a camera sensor will depend on how much you magnify the focused image (e.g. using a 2x, 3x, 4x, etc barlow). You can of course work out the correct combination of scope and camera to fill the camera sensor at the telescopes prime focus (i.e. without a barlow). Link to comment Share on other sites More sharing options...
tuckstar Posted July 19, 2013 Share Posted July 19, 2013 I've had a few pints sorry if there are more typos than usual.Is the focal point, actually a point? As in a point of light? And, is prime focus at that point (and if so how does a point of light (if that is what it is)) fill the whole sensor o a camera? If not at the focal point (which may or may not be a point), is it the telescope side or the other side of this? Thanks leigh for the drinks, but not for showing my ignorance once again We both waves at saturn so should feature in the new cassini image of earth. Night Sorry to wee wee on your bonfire but the cassini photo will be taken today!!! Im sure cassini waved back though ;-) Link to comment Share on other sites More sharing options...
Guest Kheldar Posted July 19, 2013 Share Posted July 19, 2013 (edited) Yes, focal point is a point I'm not sure the EP/CCD sits at this point, I think it sits behind it? Edited July 19, 2013 by Kheldar Link to comment Share on other sites More sharing options...
xanthic Posted July 19, 2013 Share Posted July 19, 2013 (edited) So would that be the focal plane, as a point is of no use to a retina or sensor. Edited July 19, 2013 by xanthic Link to comment Share on other sites More sharing options...
dawson Posted July 19, 2013 Author Share Posted July 19, 2013 Interesting.Thanks all. Yes I'd realised we got the Cassini thing wrong; Tibbz told me Leigh, fancy sitting outside the pub again tonight to try to get in the picture I'm not sure Mrs Leigh will let you out again, she didn't look too happy when we rolled back to yours after hours. Oops. Haha JD Link to comment Share on other sites More sharing options...
Guest Kheldar Posted July 19, 2013 Share Posted July 19, 2013 Interesting.Thanks all. Yes I'd realised we got the Cassini thing wrong; Tibbz told me Leigh, fancy sitting outside the pub again tonight to try to get in the picture I'm not sure Mrs Leigh will let you out again, she didn't look too happy when we rolled back to yours after hours. Oops. Haha JD Anti social buggers, there's a meet on at Belper! Link to comment Share on other sites More sharing options...
Daz Type-R Posted July 19, 2013 Share Posted July 19, 2013 Mrs Leigh (Miranda) is one to talk, the time she has rolled in some nights!!!!!!! (just to clear any confusion here I work with Miranda, nothing more!!!) Link to comment Share on other sites More sharing options...
xanthic Posted July 19, 2013 Share Posted July 19, 2013 Interesting.Thanks all. Yes I'd realised we got the Cassini thing wrong; Tibbz told me Leigh, fancy sitting outside the pub again tonight to try to get in the picture I'm not sure Mrs Leigh will let you out again, she didn't look too happy when we rolled back to yours after hours. Oops. Haha JD Haha, you've forgotten that we got back to my house to find my car alarm going off. Was that last shandy one too many? Link to comment Share on other sites More sharing options...
dawson Posted July 19, 2013 Author Share Posted July 19, 2013 I can walk to Leigh's in under 2 minutes; Belper is a bit more of a trek, and it's not even going to be dark! If we were mid August I'd be there for sure with some kit. You won't miss me, you'll be up to your neck in wires anyway, and trouble shooting Sheila JD Link to comment Share on other sites More sharing options...
Tweedledee Posted July 19, 2013 Share Posted July 19, 2013 Many focal points make up the focal plane. I think these diagrams show focal points, the focal plane and their positioning well... Link to comment Share on other sites More sharing options...
dawson Posted July 20, 2013 Author Share Posted July 20, 2013 I'm on my phone so can't see the images well. I've ordered a copy of opticks, but its only a paperback so no idea if i've ordered the correct version. James Link to comment Share on other sites More sharing options...
Tweedledee Posted July 20, 2013 Share Posted July 20, 2013 I've ordered a copy of opticks, but its only a paperback so no idea if i've ordered the correct version.James You fancied a bit of light reading then Just seen a 1704 original for sale online for nearly £42000.00! Link to comment Share on other sites More sharing options...
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