michael8554

We often have an Airbus A400 cargo plane fly over on it's way to Salisbury Plain for maneuvers. Comes around half a dozen times at low altitude. I always wave, such a cool aircraft. I haven't seen Tom Cruise hanging on though......... Michael

5.6um x 5.6um Michael

"Since moving over to the OAG I haven't managed to get PHD2's guide assistant to run successfully, due to Dec backlash not giving enough movement South." The GA run was successful. The optional final measurement, you didn't have "Measure Dec Backlash" ticked. Because I guess you already knew that previous GA runs had advised the backlash was too large to measure. Need to adjust that. "Dithering I was working on the assumption that with the OAG the guide camera & imaging camera had the same pixel size then I should use a setting of 1 in Astro Photography Tool" Well the figure you set that to depends on how much dithering you need, 12 pixels is a commonly quoted figure. "Another suggestion I read about, was to increase the size of the box around the guide star in PHD2. When the scope is pointing at lower altitudes I sometimes get large deviations which make subs unusable." That will only work if the "large errors" are moving the star out of the box - shouldn't happen. Michael

Looking at the star shapes of the 10s exposures, I'd agree that more backspacing is required. The 180sec exposures will have guide errors, so don't judge the backspacing using those. Looking at the GuideLog for the 19th: The Calibrations had warning messages after the Cals, and again in the Guide Assistant results: "Last Cal Issue = Rates," "Norm rates RA = 17.6"/s , Dec = 14.3"/s; ortho.err. = 7.6 deg" "GA result- Recommendation: Consider re-doing your Calibration (Prior alert)" Which you seem to be ignoring ? You would get better Cals if you pulsed north until the guide star moves consistently, showing that Dec Backlash had been taken up. THEN Cal. Near south and near Dec = 0 if possible, but Dec = 28 isn't too far out. It would be worth Binning the guide camera, to improve sensitivity and pixel scale. Your Dithers are only a maximum of about 6 pixels on the imaging camera. Pretty much the same errors on the 25th. Michael

"450D, 600D, 60D, 700D, 70D, 2000D, maybe the 800D or the 80D" Canon DSLR's are grouped by the number of digits in the model number, nnnnD to nD. So the 2000D is a budget camera, the 6D is a prosumer camera. But often a nnD is a nnnD with the same electronics in a metal case and with a few more switches. If you run tethered to a PC, the 550D is the same as a 600D, but without the flip screen, and is usually overlooked so cheaper. Michael

Hi Dave Not much info on your setup and exposure duration. I assume these are "long exposures" ? IMO both shots display guiding errors - all the stars are elongated in the direction top left to bottom right. I would eliminate guiding errors, then test. Look at a single short exposure, stretched if necessary. 0.4RMS means nothing if individual RA and Dec errors are not similar. Michael

Diagnosing what happens post-flip will requuire the GuideLog. Michael

I said: "Once the mount has done a "Goto Zero Position" I never said to loosen the clutches to send it there. Michael

Vliav Happy-kat's link addresses many of your DSLR video objections: https://www.astropix.com/html/equipment/canon_one_to_one_pixel_resolution.html Michael

"one of the reasons I bought a planetary camera was because with a digital SLR the image scale was far too small" A planetary camera with the same size pixels as a DSLR will have exactly the same image scale. For instance, 2000D 3.72um, ASI 120MM 3.75um. With your 500mm FL scope the image scale of both is approximately 0.75arcsec/pixel Barlowed, 1.50arcsec/pixel without. Perhaps you mean the FOV was too large ? But as I said, crop the DSLR and you have the same size image in pixel width and height as the planetary cam. "Also if the image is just a dot on the DSLR screen, it will be difficult to achieve correct focus." Agreed. You can try the 10X mag on LiveView, or attach to a laptop which will have a much larger display. Michael.

Hi Ciaran PHD2 will guide well on 1 star when correctly set up. It will guide even better with MultiStar and fast exposures that would normally be classed as "Chasing the Seeing". And "9 to 12 stars" with an OAG is pretty good going. I still think that changing the OAG may only be marginally better, and may well give you disappointingly similar guiding results. Because I think your lack of round stars is down to mount and PHD2 settings, you admit to the mount being "sticky." Concentrate on the real problem. Michael

Hi Ags You'll have to explain what you hope this will achieve. Michael

Don't worry too much about the Barlowed image only being a "dot". Whether you use a large-chip DSLR, or a tiny-chip Planetary camera, the image size on the chip is the same. The Planetary camera isn't magically producing a larger image. By the time you've cropped the DSLR image it will be a similar pixel width and height as a planetary camera's output. Michael

Hi Ciarán "although Phd2 still apparently manages to pick up close to 12 guide stars while doing multi-star guiding" I take it you mean PHD2 is capable of choosing up to 12 stars. "the aperture of the OAG stalk is actually really small. It's only a circle of about 5 or 5.5mm in diameter," Your ASI290mm has a sensor 5.6mm x 3.2mm, so a pretty good match for the stalk, I can't see any need for a different OAG. Is the guidecam well focused, what HFD do you typically get ? What exposure are you using ? You could post a PHD2 GuideLog that includes the "Star Lost" situations. Michael

Hi Matt When you image galaxies, nebulae etc, with the mount set to Sidereal, there is no drift ? With the same image scale ie same camera, the sun drifts when the mount is set to Solar rate, same with the moon on Lunar rate ? Michael

Try "On Camera" for the PHD2 Mount selection. With or without the Aux mount selection, Whichever works, but with is best. Michael

I bought the Amazon panel too. In A3 to accommodate my 200mm SCT. What size is your OTA, you didn't say ? It didn't dim enough on its own dim settings, so I tried a PWM dimmer . But at a low enough setting it flickered. So I ditched the PWM dimmer and added 3 layers of ND 0.6 filter. That gave me 0.8 to 1 second exposures on the DSLR AV setting. Michael

Bolt the Canon Tripod Ring Mount to the Vixen Style dovetail bar with a long Tripod Bolt. 3/8-16 or 1/4-20 are the common sizes. A single fixing can easily rotate, so I would drill an extra hole in the ring mount, to take a smaller diameter bolt and nut. Michael

It would seem the Flats aren't correctly correcting the Subs. Post a jpeg of one of your subs, and of one of your flats. Michael

Strange. If you click "Stack checked pictures", then it will Register first, then it will Stack without an additional click. Michael

"I initially saw movement and it is like the mount is trying to re-centre." Okay, was that seen in the eyepiece ? And in which axis was it moving ? For planets the other tracking rates may hold the view for long enough. Michael

How would I know if it was on the Alt or Az side? Well is the jerking showing in images, or something you heard, or something you saw ? If in images, Az is up and down, Alt is left and right. If you can hear it you'll have to use your ear close to each drive. Michael

I've stretched the 1 second exposure to show the stars, okay would you say ? A 5 sec or 10 sec exposure may be clearer. Michael

All those earlier subs show the same elongation in the centre of frame. If you have eliminated collimation, then it's PE and PA. A single short exposure should settle the argument. Michael

Is the jerk in Alt or in Az ? Does the jerk occur when tracking in Sidereal and in Moon Rates ? I don't know the 5SE's motor drive, but if it occurs in all modes, that fast a repetition could be grit or damage to one of the faster moving gears in the gearbox. Michael