michael8554

"I am powering from the mains." But how ? The spec is "11 to 15V @ 2amp." Users are recommending 13.8V @ 5Amp. And it needs to be a Regulated power supply. Michael

1. FF = Field Flattener, FR = Focal Reducer. These require the correct Backfocus, or coma will result . 2. "Askar isn't a lens, but it doesn't behave like a typical refractor." Whatever, interesting that altering Flange Distance while still able to infinity focus does change the coma. 3. So "Too thin spacer - still coma, but smaller". If going thinner improves the coma, then try an even thinner spacer, or no spacer ? Michael

1. "Yes correct, the motors seem to be fine." You don't agree the clutch is okay ? 2. "I can hear the motor trying to track" Perhaps the motor has enough oomph to start a high-speed slew. But not enough to overcome the friction of the system, bearings etc, when tracking. Are you able to remove the motor and worm assembly, and check the worm runs quietly without a load ? And that the wormwheel rotates freely without binding or much resistance ? What power supply ? Michael

The "brass rod" is the worm, meshing with the shiny wormwheel. If the mount slews in Az with the hand controller, then the clutch and motor must be working - right ? Is it tracking in Az as setup in the image ? Put a finger mark in the grease on the wormwheel adjacent to the worm, and check that the wormwheel has moved after 10 minutes. Michael

1. "why my Askar denies the following rule?" That rule is for FF and FR, not necessarily for lenses. You can test whether altering the Backfocus does actually make a difference to the coma, not just the infinity focus. I doubt it will. 2. 30 sec exposures are showing some central elongation, try 10 secs and stretch the jpegs, they are good enough. Michael

Hi Vroobel Backfocus is only of concern if you have a FF or FR. All a lens needs is to be the correct Flange Distance from the sensor, in order to reach infinity focus. The Canon Flange Distance is 44mm. So you raise an interesting thought that reducing the lens to sensor distance has similar effects to altering the Backfocus from a FF or FR. Have you started at 44mm Spacing ? Michael

PHD2 likes to Cal where the stars are "moving ' the fastest ie near Dec = 0 Michael

Depends how you are Polar Aligning. With a polarscope, most have a year scale for compensating for Polaris's shift. If you run out of years then you can guesstimate. After all the polarscope is only really good enough for visual. If you have a PC based tool, I don't know if they even use Polaris. Michael

What is the worm end-float like when loaded ? Michael

Time to say what your equipment is - mount, focal lengths, pixel sizes. Lets say you have one of those tiny guidescopes that give 6arcsec/pixel. And you're imaging at 2arcsecs/pixel. A 12 pixel dither on the imaging camera is 2 x 12 = 24arcsecs. How many pixels does the guidecam have to Dither to make the imaging camera Dither 24arcsecs ? 24/6 = 4 pixels. If the NINA setting is for the guidecam, your 7 pixel Dithers are too much, and probably increasing Settling times. If the NINA setting is for the imaging camera, then you should try 12. Michael

Was that 7 pixels of the imaging camera, or the guide camera ? 12 pixels of the imaging camera on every image is common. Michael

"Stars didn't look tight in test shots," 2 arcsec/pixel may be Under Sampling, leading to enlarged stars. Or poor focus ? "cuiv the lg" ? Beats me. Closest I could find was Cuiv, The Lazy Geek Michael

You haven't said which camera ? Dithering, Darks, and Flats. Michael

1. Can't see the settings as the screen grab is overexposed. If you hit the print screen or Prnt Scrn button at the right of the top row of your keyboard you get a copy of the screen in the Clip Board that you can paste. 2. Everything is green on the status bar. RA = 0.29, Dec = 0.20, Tot = 0.35 look good. As long as your Imaging scale is larger than about 0.4arcsec/pixel you should have round tight stars. 3. "i can't change the scale from pixels in phd2 its greyed out" I can only suggest you reload PHD2. Don't erase it, you will loose your settings. Just reinstall, it will overwrite. Michael

At 1626mm FL you'll need a guidecam with big pixels, to get a sensible pixel scale. The Costar is 5.2um, the ASI 220MM only 4um, a LodeStar has 8.2umx8.4um pixels. Perhaps the ASI 220MM Binned 2X or 3X would do. But the guidecam sensor needs to be a good size-match for the 10mm x 10mm prism, the ASI 220MM is only 7.68mm x 4.42mm. Probably there are better matches out there. Michael

For really accurate focusing, I use "Bahtinov Grabber "on my PC, with the Bahtinov mask on the OTA. It gives a reading of how accurately you have aligned the spikes. Michael

Yep, you just stepped down your 360mm lens to f/115. The "camera obscura" concept is very old. A rich Victorian might have a special darkroom in his mansion for his camera. The novelty was the production of an (inverted) image with no lens. Why ? lead to the discovery of the wave/particle duality of light. Michael

Generally speaking a mount in the northern hemisphere starts off pointing north, and points south in the southern hemisphere. Towards the celestial pole for that hemisphere. An Alt/Az mount should be levelled. I have seen that the left or right attachment is important, but I don't know whether the hemisphere affects that choice. Michael

I won't say my imaging expectations are up to Olly's standards. But many do DSO's with wedge-mounted SCT's, including myself. The older Meade and Celestron wedges are flimsy, which is why I went for the AE MegaWedge. The main problem is the time taken to setup if you don't have a permanent rig. I would expect that the challenges are similar on a EQ mount at 1500mm FL. Michael

My Bad, I misread that you were testing the round plug on the battery pack. Michael

If that is the correct D-cell pack for the mount, you have proved that a centre positive supply is needed. Michael

I have a print of "Portrait of the Moon. Pastel drawing by John Russell 1795", hanging in our house. Amazing detail. Gift from our daughter, who was a curator at The History of Science Museum in Oxford. Michael

Yes it would help to know which mount you have. My AE MegaWedge is made from 15mm steel. "Could this be accurate enough to allow tracking?" If you only want to track, you don't need a wedge, the Alt/Az mount will do that already. If you want to guide, then Polar Mode on a wedge is best. You will need a method of adjusting the Alt and Az of the wedge, even if it's made to sub-millimeter tolerances. To get a PA error of no worse than 5 arcmins. Michael

If you're using PHD2 to guide, the PHD2 Calibration Assistant will slew the mount to near south and Dec = 0 before Calibration starts. PHD2 will then automatically adjust the RA guiding to match the higher Dec of the target you eventually GoTo. So if the guidescope is pointing considerably far off Dec = 0 when the mount is at Dec = 0, that might affect how well PHD2 guides RA on the target. Pointing the guidecam at Dec = 0 will still confuse, as PHD2 will still calculate based on the Dec of the mount. Michael

Thanks kobu, I'll try that newer driver on my LodeStar X2, weather permitting :-< Michael