fwm891

Hi Graham, The subs were circa 100s, that's determined by the mount's firmware. I'm using the original firmware which when I connect the camera to the 'snap' socket on the mount gives - fits header says 99.4s. Note: the bloating round the stars is caused by primarily two things: the condition of the lens and the full spectrum mod on the camera making it more sensitive to IR/UV which doesn't focus to the same point as the visual spectrum.

I decided last night to try my S.A. with an old 400mm Tokina 400mm f5.6 lens on a Nikon D5100 mono modified body. Although I have the Pro version of the mount I decided to just mount the camera/lens on a ball head rather than the the dec shaft and counter weight. I pointed the lens at M51, focused by zooming the image on the camera's live-view screen. I set the iso at 1600, shutter to bulb, connected a shutter release cable to the 'snap' socket on the mount which gave me circa 100s sub frames. There is a firmware update which allows other variations but I'm using as supplied at present. The image is a central crop of the frame. 45 frames were shot and 34 selected via PI's blink viewer taking out frames with aircraft/satellites etc. No darks, bias or flats have been added. No DBE to even the background. Frames integrated and histogram adjusted. Will try again with the lens/camera mounted on the dec shaft with everything balanced out.

Just bought a CEM60 standard and tri-pier (where's that postman...) ?

Steve - responded to your message - thanks. Francis

Will you be getting the CEM 60 standard model in - approx. when please Francis

Looking very Tudor - black woodwork?

If your saving the sono tube then yes it would be difficult, might do it adding multiple layers as poly sheet will slide against itself quite easily, or put a cloth layer round the sono, then a poly layer...

Wrap the sono in polythene tightly first that will give you a smooth barrier between the sono and the CF. Or I think TS do a CF tube for 10 inch optics. https://www.teleskop-express.de/shop/product_info.php/info/p10113_TS-Optics-Carbon-Composite-Tube-Upgrade-for-GSO-254-1250-mm-Newtonian.html They do others

A telescope is computed to operate at infinity only - therefore in general that's it at it's best . Camera lenses are computed to work over a range and therefore not at best at any distance. Go with a scope everytime

Welcome to SGL. Great start and 3 M's in the 1st photo ?

Look at the Canon EOS M100 too

Managed to get a short run with the Lodestar installed last night (need to look at SharpCap settings!), anyway sequence of 50 frames shot with a gap of 4 secs between frames. I've stacked the first and last frames in Photoshop CS3 with an image of M1 to approx. same scale (not my image). The arrow shows the drift in 4 mins 7 sec (from timestamp). Drift is mainly due to poor north alignment. I made no adjustments later when viewing M1 at x62 (1250 fl with 20mm ep) for 5 mins. So need to sort the north alignment and fine tune the tracking speed (Oh and remember to re-set the platform when it ends a run... ?)

Thanks ALL. Out again briefly, again rain stopped play but at least I was able to confirm the variable drive rates through an eyepiece. When (and if!) there's a longer spell of clear stuff I'll pop my Lodestar in and capture a short animation. Biggest problem I think is going to be getting a good north when I put the platform down. Might try and make a little jig to take the right-angle finder, or a wooden tripod to fit the rocker-box foot holes with a finder on top... Life would be so much simpler if I didn't keep thinking up things to do!

New controller arrived today and installed. Works fine, from mega slow to see it rotating! ? Soon as I could see a couple of stars I set the platform up, rotated to Vega being the brightest to get a initial speed indication. Let it drift then pull it back in with the controller. Adjust the controller to give me a tracking speed. Kept Mars in the centre of fov for a good while at x180 - strated to rain so further test will need to wait... ?

Just run some calcs on the controller - it's giving me x1.3 the correct PWM pulse width required for sidereal motion whether set to max or min potentiometer settings... Kaput I think. It was a cheapie of the bay. Just ordered something more substantial. TBC.

It cleared for a while and things started well @ circa x180 (14mm + x2 barlow & 1250 mm fl) I started making pot adjustments, turning drive off then back on, increasing speed to recentre stars, adjust down to track ? - then there was this distinct 'POP' from the PWM controller ? speed output went to max regardless of the pot's position. Mmmm back to *bay for another controller or something better? TBC...

Looking good Dave - I have a 750x750 screw-driven WorkBee - great machines ?

Electrics now in place and tested. I've timed it over measured distances on the sectors - waiting for some clear sky now to try it in anger. The push-to-break switch is very sensitive and stops everything as soon as pressure is applied. Two blocks come together to set the beginning of travel point. Still debating the pivot point, whether to stay with the ball bearing or switch to something more positive. The flashing led is quite dim so shouldn't cause any headaches.

Just had to try it out....

Aluminium rod arrived today so I've got the two main rollers machined up. The brass stub shaft's need finishing to length but I wanted to have a dry fit first. The motor drops into the recess and will have a fixing plate to hold it in position and fine adjustments. Few photos:

Sorting out the electrics today while waiting for the metal to arrive. I'll run this off a small 7Ah 12VDC battery - need a couple of push-to-break switches. There will also be an on/off switch and a (dim) red led. Not sure whether to put the led in the hand speed control or at the power entry... Make some short legs to go under the baseboard to bring the eyepiece height up a bit. Then sort out a seat, then...

Set-up a temporary pivot and edges to simulate the drive and idle shafts so I can see the extent of the platform tilt in either direction. Initially I wanted a 45 min travel but I have enough for 60 mins plus. The level is set at ±8° the pencil marks show there is a cushion either side I can set switches on to cut power should it be left un attended. The aperture for the motor has been cut allowing some wiggle room. The holes to take the baseboard's feet have also been bored. Waiting on some metal rod now to make the two shafts and 2mm sheet to make the motor mounting plate. TBC...

Tried the motor and PWM controller to confirm the speed range. On max it didn't quite get to the 2 rpm stated (though driving direct from the battery it did!) so I turned the controller back to it's mid point and made a few measurements. I now get at this setting 1 rev in 70 seconds. Given that I'm running through a 40:1 I can increase the drive shaft diameter to compensate for the slower revs. Drive shaft now 23.14mm OD which is good as it will allow better (shallower) contact between the drive shaft and the segment. Pleased I didn't assume the PWM controller would give me full speed.

My thoughts at the moment on the drive shaft and motor. Mounted it with the worm vertical so I can rotate the drive shaft around the worm shaft to fine tune the shaft contact with the curved segments. The motor come below the ground board so I will need a waterproof cover to protect the electrics (not shown)