Dujon
13-06-2006, 12:34 PM
Firstly the success. I managed to (I think - see later) collimate my Newtonian. As it happened the clouds of the last week or so cleared and allowed me to cart it and its mount on to my back balcony for a quick look around and a check of the optics.
Having drifted around Crux for a while I decided to wait until Jupiter had cleared the guttering of my house and have a dekko at it. Talk about bright, I nearly went to get my sunglasses. The seeing wasn't all that good and the Moon was climbing quickly after it - the equatorial bands were drifting in and out of sight - but three moons were easily visible. One had only just cleared Jupiter's limb; at first I thought it might have been a background star. After a while it crept away slowly from the planet but then started to disappear and, until the penny dropped, I thought the atmospheric conditions were conspiring against me. Then I realised that it might be being eclipsed. A quick trip back to the house (and blinding light) plus reference to the latest info. on Jupiter told me that it was indeed an eclipse of Ganymede. It was still visible but quite faint but I didn't stick around to see what would happen as it was getting close to kick-off time in the football (soccer).
Sorry about that, but it was so pleasing to have the new toy performing reasonably well. I won't post such stuff again . . . honest injun.
A couple of questions though which could well be related. I hope that some of you more experienced ladies and gentlemen might be able to help me out.
I wear glasses and, particularly in my right eye, suffer from astigmatism.
I use my left eye for viewing.
If I star test by defocussing each side of a reasonably bright star then on one side of the image I see a dark centre circle surrounded, not by rings but a series of radial lines; it's almost like an iris surrounding a pupil. On the other side of focus I see a three-lobed apparition - it almost looks like a round winged moth. That is, it has two major lobes and a shorter ovalish extension in one direction at right angles to the other two. If I move my head relative to the eyepiece it follows my eye around. I'm assuming, but am not too sure, that this is the result of my own astigmatism rather than that of the telescope's optics.
Possibly related is that when I collimated the 'scope I used a visual method in the first instance and then followed that up by using a laser collimator. The laser's red dot fits nicely into the centre of the return path in the collimating tool itself. However, when I then look down the focussing tube at the secondary and primary mirrors I see the primary mirror's three holding mounts and a single secondary mirror mount centred in the field of view as well as the four spiders of the secondary's mount. The reflection of my eye in the focussing tube though is off centre. By that I mean that it's like looking at the focussing tube from 'the other end' but at an angle.
I'm a bit confused. Can laser collimation give one a false reading? Do I need only to do a bit of tweaking? Have I lost the plot?
To those of you who view whilst wearing spectacles: Do you suffer from glare when viewing bright objects? Whilst viewing Jupiter I found it jolly annoying as it's like looking through a slightly misted pane of glass. Taking off my specs would clear the problem but, obviously, degrade the image.
Err, sorry, that's a bit of a long post.
Having drifted around Crux for a while I decided to wait until Jupiter had cleared the guttering of my house and have a dekko at it. Talk about bright, I nearly went to get my sunglasses. The seeing wasn't all that good and the Moon was climbing quickly after it - the equatorial bands were drifting in and out of sight - but three moons were easily visible. One had only just cleared Jupiter's limb; at first I thought it might have been a background star. After a while it crept away slowly from the planet but then started to disappear and, until the penny dropped, I thought the atmospheric conditions were conspiring against me. Then I realised that it might be being eclipsed. A quick trip back to the house (and blinding light) plus reference to the latest info. on Jupiter told me that it was indeed an eclipse of Ganymede. It was still visible but quite faint but I didn't stick around to see what would happen as it was getting close to kick-off time in the football (soccer).
Sorry about that, but it was so pleasing to have the new toy performing reasonably well. I won't post such stuff again . . . honest injun.
A couple of questions though which could well be related. I hope that some of you more experienced ladies and gentlemen might be able to help me out.
I wear glasses and, particularly in my right eye, suffer from astigmatism.
I use my left eye for viewing.
If I star test by defocussing each side of a reasonably bright star then on one side of the image I see a dark centre circle surrounded, not by rings but a series of radial lines; it's almost like an iris surrounding a pupil. On the other side of focus I see a three-lobed apparition - it almost looks like a round winged moth. That is, it has two major lobes and a shorter ovalish extension in one direction at right angles to the other two. If I move my head relative to the eyepiece it follows my eye around. I'm assuming, but am not too sure, that this is the result of my own astigmatism rather than that of the telescope's optics.
Possibly related is that when I collimated the 'scope I used a visual method in the first instance and then followed that up by using a laser collimator. The laser's red dot fits nicely into the centre of the return path in the collimating tool itself. However, when I then look down the focussing tube at the secondary and primary mirrors I see the primary mirror's three holding mounts and a single secondary mirror mount centred in the field of view as well as the four spiders of the secondary's mount. The reflection of my eye in the focussing tube though is off centre. By that I mean that it's like looking at the focussing tube from 'the other end' but at an angle.
I'm a bit confused. Can laser collimation give one a false reading? Do I need only to do a bit of tweaking? Have I lost the plot?
To those of you who view whilst wearing spectacles: Do you suffer from glare when viewing bright objects? Whilst viewing Jupiter I found it jolly annoying as it's like looking through a slightly misted pane of glass. Taking off my specs would clear the problem but, obviously, degrade the image.
Err, sorry, that's a bit of a long post.