Philip Terry

But it is fantastic when it's running to specification. I've had zero issues until recently, and I think the ZWO team have been very responsive to user concerns in the past, I expect the same again. And I'm still using it, even with occasional glitches.

Yep, my OAG is giving me grief, it seemed to be working fine until recently.

I've been getting the same problems with PA and calibration, using a single rig.  Fine until January. These problems seem to be coming up on various discussion boards, I'm waiting in the hope that ZWO are going to address these issues in the next update soon. Meanwhile, I'm plugging on with PA supposedly no better than 90", and ignoring a lot of the error messages! I can generally still get decent 240 sec subs with the wackiness ignored. My biggest gripe has been failures to lock on to guide stars when there seems to be a screen full of them, but maybe that's coincidental and just me. Anyone had that?

Thanks Andy, the CN thread looks very relevant. But I'll hold off from adjusting any lens cell screws for the time being, I might go for a "cold weather mask" in the short term and see how that works out. Interesting to see how common this issue is! Thanks again for all of the advice; Phil.

Thanks Andyy and Nicolàs. It certainly seems to be temperature-dependent; I tried Nicolàs's experiment of imaging straight after taking the scope outdoors, and there was no sign of the dark beams. They crept back subtly as the night progressed. No trefoil-ish shapes either. Fits with the late Summer images being free from the effect. I won't mess with the cell screws, I'm not looking for perfection!

Excellent - thanks for your insights Nicolàs, interesting stuff. I'll try the "no cool-down" routine that you suggest as a test. I won't be too concerned if the optics show pinching, I'm still happy with what I'm getting from the scope.

Thanks Nicolàs - very helpful advice and a really interesting article. I wonder if it might be pinching; on your recommendation I've gone back and looked at images from late summer, and the effect is much diminished or absent. On the night of imaging the Orion nebula the temperature was around zero Celsius (I've finally found  a purpose for that thermometer in the ZS focus knob!)  - the coldest I've imaged in so far. Attached is a photo of tne Sadr region nebulosity, from mid-August, and I can't see the dark beams here. They do indeed become more obvious as the year advances. This raises another question - wouldn't it be expected that a dew heater band on the ojective would ameliorate this? Admittedly, I switched mine on after the scope had been sitting outside for a while,  but shouldn't it offset the pinching caused by low temperature, at least to some extent?

Thanks Tom - good to know that this is the case for very high-end scopes too!

Hi All:

I've been taking images over the last few months and I've just noticed some undesirable spike sillhouettes in my images of bright stars, particularly when I do a close crop to expand the image. It was really striking  a couple of nights ago on a shot of M42; I attach a blow up of a region where the brightest star in the field shows 2 "dark beams" shooting out of it. The telescope is a Zenithstar ZS73 with 0.8 FF/FR and the camera  is a Canon 600D.  (The flattener probably needs a bit of adjusting, corner stars on the full-field image are a bit elongated and streaky). This is a stacked image of 24 x 90 sec exposures, ISO 800 unguided, processed throughout using Affinity. I'm not desperate to produce perfect images, and I'm really pleased with what I've taken so far, but I'd like to solve this. I've used a torch to peer up the optical train but can't see anything untoward. There are a couple of machined notches in the rim of the flattener towards the midpoint, but these look part of the item and face forwards so it would seem odd if these are having an effect. Any suggestions would be welcome! Thanks, Phil.

Thanks Paul - I was out that evening,  mainly to test a new smartphone holder on the telescope, and I took a near-identical photograph. After your post I went back and identified all the features you highlight, first time in 40 years! Great match with the Cambridge atlas photo, my atlas wasn't up to it (much as Iike it - Wood & Collins).

I had a go last Saturday when we had a rare spell of clear weather. First is a single image taken by eyepiece projection (26 mm) through my old 200 mm SCT using the "Night Mode" on my Samsung Galaxy S10. The second is the result of stacking 8 similar images using Deep Sky Stacker and faffed around a bit on the phone's photo editor. I was surprised to pick up blue and red colour, and the trapezium is only just overexposed (effectively the exposure time per shot is 20-30 sec). 

It seems to me that planetaries and clusters are well-suited to simple smartphone shots. Here are a few recent ones. Not as good as M27 a while ago (some are very small!) but fun to image them. In order: M76, (Little dumbbell), Caldwell 22 (blue snowball), NGC6826, NGC40. I also reprocessed my old M27 shot, stacking 4 shots and Photoshopping it a bit more on the phone (last shot). All taken with an ancient 8" SCT and a Samsung Galaxy S10.

Yes, my phone was fixed at the eyepiece and the scope tracked via a Heq5-pro mount. I used to do untracked photos of the moon on an old alt-az mount, but this would be stretching it too much for DSO's. Eyepiece projection at x77.

I've tried to image this before, to no avail, but last night the imaging gods were on my side. This is a single shot, with minimal on-phone processing (I will stack and tweak more later, maybe). Amazing what these phones can do - even the pink/red shell is just coming tbrough. Meade LX200 8" SCT (circa 1992) plus Samsung Galaxy S10 in "Night mode" (about 20 s automated exposure).

Not as spectacular as M13 a few nights ago, but comes up nicely with Samsung Galaxy S10 and an 8" SCT. Conditions were a bit iffy.

Hi John  - Thanks! The Night mode is a standard feature on the S10 phone. It seems to take extended duration shots for as long as it deems necessary; interestingly, the timing does seem to vary a fair bit, even for the same object. I believe that there are apps that can do this or give you more control.

Hi everyone - Despite moonlight and some haze last night I thought I'd try a speculative shot of M13. 8" SCT on HEQ-5 Pro with Samsung Galaxy S10 in night mode, single shot, no fancy stuff. Came out quite well. I normally photograph the moon; I attach an old shot from that great period of weather back in April-June. The scope was undriven on an old alt-az mount, and the phone hand-held for that one.

Very good indeed - I look forward to seeing more! 😊