michael8554

To me, the bottom left corner is the only place where the stars are round in both images !! Anyway, the rotation shows that the sensor is tilted Michael

Do you have the 5SE and the finderscope aligned to each other ? Then you can centre Sirius in the finder, then in the 5SE. Michael

Edge damage to the belt might indicate the cogs are offset. Michael

APS-C has a roughly 30mm diagonal, so a 31.7 adapter sounds okay. A 2" adapter might be more rigidly mounted, the less adapters the better. Michael

You didn't mention your power supply. Michael

Lights taken before and after Meridian flip ? Michael

Tony also rotated the image 90 degrees, to show The Monkey Head looking left. Michael

Hi Neil So the mount is actually slewing eastward, rather than RA just stopping. Might be an intermittent slew button. Try exercising them a few times. In the menus reverse which way the left/right slew buttons move the mount, and see if it then intermittently goes westward ! Random slews can be caused by power supply problems. Michael

I hadn't heard that before. What I have read is that as refractor FL increases, Chromatic Aberration becomes less apparent. Flatteners serve a different purpose that may still be necessary at 800mm FL. Michael

Yes Clarkey, decent rings and The purpose-made focus extender enables the camera to achieve focus without over-extending the focuser draw-tube. Hopefully corrects the ST80's floppy focuser. Michael

Hi Bill There isn't a Calibration or Guide Assistant run in your Log, but Calibration and PA seem to be good. Dec guiding is good, Dec = 0.32arcsecs RA is twice that, RA = 0.66arcsecs. Your RA tracking has a significant 10 second period spike that is often seen in belt-drive mounts: PHD2 will find it very hard to guide out such a fast transient. Not a EQ6R-Pro user, but from what I've read it may be a matter of belt tension adjustment, and/or moving the belt a few teeth on the cogs. And PHD2 Predictive Periodic Error Correction (PPEC) for the RA Guide Algorithm, at a fixed setting of 10 secs. Hopefully EQ6R-Pro users can provide clarification. Michael

To guide a long-focus OTA at a reasonable image scale ratio, a long-focus guidescope is often required. And the problem is flex in the relatively long, heavy, guidescope, often mounted in adjustable guide rings, with a guide camera held by lock-screws instead of threaded connections. We're talking flex of only microns. Hence the need for OAG's. You can add SCT mirror flop to the list of Diff Flex generators. Michael

This is a puzzle. Here's a zoomed out view of the same part of the graph I posted yesterday, with the Star Mass displayed in white. See how the camera output doesn't change during the 400arcmin RA excursion. Here's a zoomed-in view : See how Dec (red) recovers, but RA (blue) disappears eastward, with PHD2 applying Max correction pulses (blue). Point C from yesterday is now apparent in both views . At point C, RA miraculously returns, but immediately returns to where it was, heading eastward. I think this must be a reporting problem, as the mount and guidescope can't behave like this without loosing the guide star. Upload the PHD2 GuideLog AND DebugLog on the PHD2 Help Forum. Asking them to examine the section 02:57:00 onwards. Details on how to Upload are in the PHD2 Help menu. Make sure the date and time in the filenames are relevant. Michael

Note at point A how RA and Dec are both heading off, not due to a Dither. Dec recovers, but RA continues eastward at what must be many times guide rate, probably at slew rate. And that would surely result in a Lost Star situation, but there's no message. Star Mass hasn't been enabled on the graph so I can't tell what's really happening. At point B, RA appears to have returned, I can't see the guide pulses so I can't tell how it's been corrected. Only then is there a Star Lost message. And what's the blue line at point C ? Best to post a PHD2 GuideLog. Michael

Hi Derek Set the 600D up just like you'd use it during the day, with a lens on, and check LiveView is working. Then put it on the OTA, LiveView should work. Michael

Hi Derek Why are you using LiveView ? During the day you find focus using the visual viewfinder on the back of the DSLR. Did you make the measurement I suggested, instead of trying those random movements ? You can use the diagonal while you're trying to see if focus is possible, but it's best to remove the diagonal when imaging, as every unnecessary lens/mirror/prism in the light path attenuates the light reaching the camera. Michael

Hi Derek The ST102 has a focal length of 500mm. That means that the images you want to capture are in focus 500mm back from the lenses at the front of the telescope. So roughly measure 500mm with the diagonal removed. The 600D has a sensor that is 44mm back from the lens mounting flange. Assuming you have bayoneted a T2 Adapter to the flange, the sensor is now 55mm back. So 500mm - 55mm = 450mm gives you roughly the position the front of the T2 adapter needs to be positioned. You'll probably find you need a long T2 threaded spacer. They come in standard lengths, so juggle lengths with the focuser roughly half way out. Michael

Ignoring the images that show small round stars (with diffraction spikes ???) , this could be due to many things. What are the actual RA and Dec guide error figures ? Are the guiding exposures too fast, causing "Chasing the Seeing" ? Is the Minimum Move setting too high ? Maybe you should post a PHD2 GuideLog. Michael

From the document calculating_different_magnifications_with_the_vip_barlow.pdf "If the sensor is 64 mm away from the upper end of the Barlow element, you're working with double focal length. If you are using a DSLR with a standard T2-adapter, the distance is always 55mm. Thus, if you screw the Barlow- element directly into the T-ring, the distance to the sensor is 50 mm, and you are working with 1,8x magnification." To me this suggests you need around 50 to 60mm between the barlow element and the sensor. But as you have found, this will result in insufficient in-focus. Unless you mount the Barlow between the focuser and the wedge ?? Michael

Garbled description, so post an image of the part. Michael

Your "DSC_0151" single sub has almost zero data. The "M41 only lights" stack is actually worse than the sub ! 3/4sec exposures just are just too fast, so stacked and stretched results are very noisy. A 1250mm OTA on a non-tracking tripod is not going to work. Successful images from Tripod mounted scopes have much shorter focal lengths. Michael

Your 3 minute sub has little or no tilt, but does show guiding errors, all the stars are elongated at 45 degrees to the horizontal. You need a short exposure, stretched if necessary, to show star shapes without guide errors. Michael

The latest 24th Feb GuideLog has more data than the previous 24th Feb log, including those attempted Cals at Cal steps up to 10,000. But although they definitely moved RA, they failed to move RA enough. With 2000ms step it moved about 8arcsecs (or pixels, I'm not sure what the scale reports) : With 10000 step it still only moved a max of about 8arcsecs, so there's no correlation between moves and Step Size: In between the two Cals above there was this third one at 750ms. Why has the RA direction moved 90 degrees ? Was there a flip after the first Cal, then a flip back ? Or is the guidescope or guidecam loose and rotating ? I'm not familiar with the Star Adventurer, but perhaps it's not in the correct mode for guiding. You could check the ST-4 cable isn't faulty. Michael

What focal length ? Is "1/1.3" the shutter speed, so about 3/4 second ? That may be way too fast, and may explain the very noisy image after stretching. Let's see that single Light. Michael

Or this one ? https://www.astroshop.eu/reduction-rings-adaptors/ts-optics-adapter-sc-female-thread-to-m48-male-thread/p,56580 Michael