Thanks David. FocusMax sounds very good. I have Maxim DL so I'll look into it for initial focus. I have a few ideas as well to focus M prime Pentax lenses with your system when imaging at 150mm and longer.
I think I've worked it out now. Very cool. Trying tonight on a real star. I like your tensioning belt system. Did you use bearings for the rollers or just straight shaft in the alu blocks?
PS: If you've got the part# for the cogs and width of the belts. There's a lot of this stuff on eBay but not sure on your dimensions. 11mm?
Here's a graph a mate of mine did from a demo. The steps were set to 500 counts and I was holding the external temperature probe in my hands. Perfect linearity.
Last edited by multiweb; 24-10-2013 at 10:42 AM.
Reason: Position vs. Temperature
Pleased you like the WF rig, I really like WF imaging as you end up seeing all sorts of interesting objects that are generally not imaged individually.
With reference to the WF rig setup :
I used pillow bearing blocks to carry the drive shaft. The blocks have little ball races embedded into them. The drive shafts are made from 3mm stainless steel with 3mm pillow bearings to match. The same arrangement was used for the drive and idler block. I made the aluminium spacers used to raise the drive axis to the mid point of the lens.
With the belt wrapping around the lens it's analogous to gripping the lens with your hand an rotating exerting almost no lateral force only rotational.
The belt used was a HTD timing belt with 140 teeth. It just so happened that the tooth pitch on the belt exactly matched that of the rubber grip on the lens so there is absolutely no danger of slip. The pulleys are 12 tooth HTD aluminium with a 3mm drive shaft aperture.
To support the lens I used 100mm guide rings, one of which I had to turn down in order that it fitted the rear of the lens correctly.
Got to try Focusmax with the SharpSky Pro last night. Connected the QHY9 via MAXIM DL as an ASCOM camera. The mount connected with Gemini.net ASCOM Driver as well. Then fired up Focusmax and connected to the SharpSky Pro focuser. Clicked 'new wizard' and sat and watched whilte the V-Curve generation happened. 5min later I had an absolute position and it was focused. Pretty cool.
Tonight I'm going to try again the temperature compensation as I have a couple of logs now to get a good step value. Seeing was terrible. I got a FWHM of 4 to 4.5 but in normal conditions without focusing aid I would have got 5 or more.
Marc, I thought you might enjoy the FocusMax/Maxim combination. Several chaps up here top side are using it and have been getting really nice repeatable results - certainly as good and more often better than using a mask and once the V-curves are done very quick/repeatable.
Hi Lewis .... yes your wait of eleven days is a little excessive and unusual. Maybe your unit was subject to a customs spot check ? This has caused delivery delays in the past. Generally delivery from the UK down under takes about seven working days.
Very pleased you like the equipment and am looking forward to seeing an image or two of the fitted solution
Talking of images here are a couple of links to a Ha images taken with the Nikkor 180mm ED f/2.8 lens and WF rig posted earlier :
i bought a GSO two speed focuser for the saxon ED80 i have, my problem is not knowing how to attach the sharpsky. I bought this new from a member here on IIS, he got it only a few weeks ago, but there are a few bolts short of the full quid which i will have to get, that's not the problem. it is how i attach it to the focuser? see the pic of the new focuser.
Dave I have mine on the genuine SW 10:1, mainly because it takes the SW focal reducer. If I get a chance at the weekend I'll have a look at the GSO focusser, I took one off my ED80 and still have it around somewhere.
Dave I have mine on the genuine SW 10:1, mainly because it takes the SW focal reducer. If I get a chance at the weekend I'll have a look at the GSO focusser, I took one off my ED80 and still have it around somewhere.
thanks Phil. I think a bag of nuts an bolts went missing - the three that connect the plate to the other plate that connects to the sharpsky. but how i connect to the focuser and keep it solid?
Dave, my best guess is to make a curved and slightly offset bracket on the top of the focusser, shouldn't be too difficult with a piece of Aluminium, a drill and some filing (MacGyver one up....). Imagine a flattened out question mark.
On the other side of the focusser, a little forward of the focus mechanism and before the flange, there are two small Allen grub screws that are just blanking mounting holes for findersope mounts. On my focuser you can see the dome headed screws I bought to replace them. They're a commonly available thread (may even be the same as some used on the Meade stuff), I took one of the grubscrews out and in to my local Nuts & Bolts shop and matched with some stainless dome head screws.
Make sure you don't get them too long as the drawtube will hit them if they're too long. The countersunk screws hold the roller mechanisms that the drawtube rolls against, I don't think they adjust so you may also be able to use them with the right length screws. If you're going down that route it may be worth taking the drawtube out and doing some fine tuning, mine is way too smooth and the focusser slipped easily.
If you need some small bolts to join the bracket to the Sharpsky, I have plenty, complete with locknuts that should fit, just holler and I'll send some up.
Last edited by acropolite; 14-12-2013 at 07:15 PM.
Dave, my best guess is to make a curved and slightly offset bracket on the top of the focusser, shouldn't be too difficult with a piece of Aluminium, a drill and some filing (MacGyver one up....). Imagine a flattened out question mark.
On the other side of the focusser, a little forward of the focus mechanism and before the flange, there are two small Allan grub screws that are just blanking mounting holes for findersope mounts. On my focuser you can see the dome headed screws I bought to replace them. They're a commonly available thread (may even be the same as some used on the Meade stuff), I took one of the grubscrews out and in to my local Nuts & Bolts shop and matched with some stainless dome head screws.
Make sure you don't get them too long as the drawtube will hit them if they're too long. The countersunk screws hold the roller mechanisms that the drawtube rolls against, I don't think they adjust so you may also be able to use them with the right length screws. If you're going down that route it may be worth taking the drawtube out and doing some fine tuning, mine is way too smooth and the focusser slipped easily.
If you need some small bolts to join the bracket to the Sharpsky, I have plenty, complete with locknuts that should fit, just holler and I'll sens some up.
wont say no to those Phil - thanks. making a bracket will be interesting and i can see what you are talking about
Trying tonight on a real star. I like your tensioning belt system. Did you use bearings for the rollers or just straight shaft in the alu blocks?
AND THE FOCUSER
