wimvb

If you destroy the diffraction of two opposite vanes, you can figure out which need adjusting. Just wrapping something around two vanes should do the trick.

Chromatic aberration is a focus position shift between filters (colours), but stars stay round. Astigmatism will give elongated stars. https://www.britannica.com/technology/aberration#ref61613

Good you have it sorted. I was about to suggest astigmatism from the cc. In that case you should see a difference in focus between R and B, with the help of a Bahtinov mask, for example.

Removing the battery and using a mains adapter helped some to keep the camera temperature down. Long exposures drain and heat up batteries.

I understand the feeling. What is equally frustrating is a clear sky for weeks on end, but too bright to do any imaging. Not even narrow band up here, atm.

Idon't use Maxim DL, nor do I have an AP mount, but my guess is that Maxim talks to the mount through an ASCOM interface. AfaIk, the ASCOM interface allows you to store pec data and should have a tracking mode called sidereal + pec. This mode can be accessible through Maxim. Some high end mounts even have a pec curve stored internally from the factory. Unfortunately I can't help you any further because I'm not familiar with either system. I'm a linux/INDI person. 😉

My guess is that you will see the banding more in shorter exposures. Normally this banding is related to the read step of the sensor. If you expose longer, there is more signal to drown this pattern, and it should be less of an issue. Such was the case with my images from a pentax dslr before I moved on to a cooled cmos camera. Other things that you can experiment with is saving images on the cameras sd card vs downloading them directly to a computer, and using a battery in the camera vs a power adapter and the camera battery removed. I've read that data download, and heat from the battery have caused artefacts in peoples dslr images.

fixed with CanonBandingReduction in PixInsight. It would need a little more tweaking to completely clean up the banding. Dithering would help, but probably won't remove all of the banding. In my experience, longer exposures will drown this pattern, as will increasing the total number of subs.

For simple raw image processing straight from a dslr, RawTherapee does a very good job, and it’s free.

Skywatcher synscan (goto) mounts have an all star polar alignment feature. So do Celestron mounts, afaIk. You put the (eq) mount in a position where it roughly points at Polaris. Use a compass and your latitude. Do a two- or three-star alignment. This will tell you your polar alignment error. You can then use the synscan polar alignment function. If your mount doesn't have this feature, you can always do a drift alignment. For that, you need clear view to the South and East or West. There are good tutorials on line that will explain the procedure. Once you have the mount polar aligned, permanently mark the exact positions of the tripod legs on the ground. This will help next time you set up.

Mono rgb filters are generally designed to block the light from sodium and mercury lamps. That is, the pass bands from the red and green filters don't overlap. This gives mono rgb imaging a slight advantage over osc. Otoh, if you want to do lrgb imaging, you lose this advantage, because the L filter passes all colours. However, as LED lights with their wide spectrum become more common, the advantage of designed rgb filters disappears. What you can do of course, is to use a good light pollution filter with your camera, be it osc or mono.

Web browsers can't show tif images. If yours are finished, processed images, you might want to upload them as jpeg or png, so others can enjoy them. Cheers,

Thanks, Alan. I am very pleased with it, although it needs more integration time. Maybe next season. Iwould need one serious piece of pier extension to get my scope that high. Or maybe rent a few sqm on the platform of the space elevator which China is planning? 😁

A few days ago, I got a link to this Hubble image in my news feed. https://www.nasa.gov/image-feature/goddard/2021/hubble-glimpses-a-galactic-duo I remembered that I imaged the Perseus galaxy cluster last November, so I had a look which part of the cluster the Hubble telesscope had targeted. Sure enough, it was in the frame of my image. With a little tinkering in PixInsight, I framed the Hubble fov in my wide field. NASA can relax, a SkyWatcher Mak-Newt situated in Sweden is no threat to their school bus sized space telescope. Not even if said telescope developes a computer glitch. 😉

ZWO have released the unbinned mode of this sensor: 2.315 um pixels in stead of 4.63, so 1"/pixel if you have a 470 mm FL telescope. 😉

The 2600 has a larger sensor (aps-c), higher full well capacity, lower read noise (and therefore higher dynamic range), higher quantum efficiency, and 16 bit adc. The 1600 is known to have trouble with very bright stars, where diffraction from the chip's microlenses can show up. If you can afford it, go with the 2600. The asi294 is a step up from the 1600, with the same size sensor. Like the 2600 it has a 90% qe, and works with 1,25" or 31 mm filters.

Simbad cites two distance measurements, 470 and 559 pc. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%402313487&Name=NGC++6124&submit=display+all+measurements#lab_meas

Congratulations, winners! Well done.

I also have a similar pattern in the RGB flats. But I got new unmounted RGB filters together with the camera, and the filters have non treated edges, so I can’t rule out reflections or scattering from those. I will get a set of ZWO filter rings before I set up my rig again, and do a proper flats study.

I’ve also taken pleasing images with my ASI294, but I can’t get the same even flat background that I got with my ASI174 (although, that camera has a smaller sensor). And that won’t allow me to go as deep as I’d want.

The problem is that the section of gain settings is just at the sweet spot of where you want to image: low read noise, high dynamic range. I compared the specs to those of my old camera (ASI174MM-Cool), and without the hdr setting, the 294 has higher read noise than the 174, and barely higher dynamic range at gain 0, despite its 14 bit output. I've looked at flats I took in April at gain 0. 0.5 seconds flats with an Optolong L filter in place, looked fine, while flats taken at gain 120 with an Ha filter had a weird pattern. I will take new flats for Ha at gain 0, or thereabout.

I'll be following this thread with interest since I also have an ASI294MM. I'm also not happy with the uneven flats that won't correct the light subs properly. We have summer recess up here untill mid/end of August, but I will start testing later this month or early August.

That explains a lot. Your guidescope should never move relative to the imaging scope. Also, I’m a bit confused regarding how you have the clutch. When released, the mount should move freely. Correctly balanced, it should stay in any position. If either end falls down, you have an imbalance. During imaging, you tighten the clutch, but not overtighten it.

AfaIk, collimation isn't as critical for visual use as it is for AP, and as long as collimation isn't too far off, you can just enjoy the scope as is. But if you want to improve collimation, you can use a defocused star (polaris doesn't move as much in your fov, so is easier to use) to collimate your scope in the field. No center spot needed.

It took a while, but here it is Some time ago we hired someone to do help with rough landscaping in our garden to be. The boulders that were blocking the path to my obsy were removed and I put some granite slabs in place. Then filled up with gravel. So now I have a safe path to the observatory. No more broken knee caps hopefully.