wimvb

Like I said before, any attempt to save money in AP is doomed to fail.

... and don't forget to tighten the clutches (but not too much). My mount suddenly stopped slewing yesterday due to just that.

Doomed to fail. 😉

Yes, low noise AND high sensitivity.

If you undersample, aperture is your only measure for light gathering. If all the light from an object (star) is captured by one pixel, regardless of which size that pixel is, then the light falling on that pixel in a unit of time, is proportional to the area of the scope aperture. This is the most extreme case of undersampling. In the most extreme case of oversampling, a uniform patch of sky, the formula I gave holds true. For real stars and details in galaxies, the truth lies somewhere in the middle of course, but for most nebulae, you can apply the formula I gave. But this is only the geometry of photon capture. In a real system you need to factor in quantum efficiency/sensitivity and noise. As for Göran's results, he has the advantage of imaging from a very dark site (mag 21.5 or better). His images have no light pollution, other than from weak natural sources, and therefore have very low noise to begin with. Jerry Lodriguss wrote an article about the effect of light pollution, and came to the conclusion that for every unit of magnitude you lose due to LP, you need to increase your total integration time by a factor of 2.5. In other words, if Göran were to move his RASA/ASI2600 to my site (mag 20.5), he would need 2.5 times longer integration time to get the same final result. Imaging from a dark site is more effective than getting a more sensitive camera or buying aperture.

For PS there's a plugin called Hasta La Vista Green. As far as I know, it does the same as scnr in pixinsight.

Neither have I, but I've read reports about it, so I changed to eMMC just to be on the safe side (better safe than sorry). Remember that in a computer, data is written a lot more often than in a camera or mobile device (swap drive, viryual RAM, etc). And eMMC devices are definitely faster than sd cards. When I replaced the sd card with eMMC, I saw a clear difference in performance/speed.

Definitely. One way to place samples is to find an image with the same target online. Crop this image to get approximately the same fov as the image you want to correct. Then use this image to place samples. If you can successfully remove a gradient you will be able to extract more detail where that gradient was most obvious. Sometimes you can only appreciate the difference once you've done dbe.

It's not just the magnitude, but also their scale. The arcs are quite narrow, and the atmosphere/weather really has to play along if you wish to image them.

Yes, eMMC is a lot faster and more reliable than sd. I've had eMMC in my Rock64 for a few seasons now, and I'm very satisfied with the performance.

Very nice. What software do you use? in pixindight I would apply scnr green to reduce the green bias you seem to have.

?? Please elaborate.

Without participating any further in the discussion, I want to share an image that shows how choosing different white references in PixInsight Photometric Color Calibration affects the colours in a stretched image. I used the RGB data of the latest IKI data set. Combined the raw colour masters and applied DBE to even out the background. Note that I checked the "Normalize" tick box in Target Image Correction. This means that DBE does not affect the median image values of the three channels, and as such does not perform a background neutralization. Next I defined a small preview without stars as a reference for Background Neutralization. After that I cloned the image x 12 and applied Photometric Color Calibration with the preview as background reference and different white references. Finally I stretched the image using Arcsinh stretch, which is supposed to best retain colour balance in an image. All images received the same stretch. I resampled the images to get a manageable final image size (integer resample / 4 with average). The tag in each panel indicates the white reference that I used in colour calibration: Star spectral types: (from red to blue) O5V, B0I, A0I, F0I, G0I, K0II, M0III, O5V and Photon Equalization Galaxy types: ASP (Average Spiral Galaxy, the default in PCC), Sa, S0, Sb "Take your pick"

Many of the sensors that go into astro cameras are developed for machine vision (including cars) and security/surveillance cameras. These applications can utilize smaller sensors than consumer cameras (dslr), but still need resolution, while being larger than sensors in mobile devices. Smaller sensors are cheaper because manufacturers get more of them from each silicon wafer. They are also easier to incorporate in systems. Here it isn't consumer's rave that drives the development, but economy. Also, because cmos sensors read out individual pixels, developers can get very creative with read out modes. One of the latest developments is tetrapixel design, where each "ordinary" pixel in an RGGB configuration is actually made up of 2x2 small pixels. These tiny pixels can be read out individually and even exposed individually, giving a much larger dynamic range than ordinary pixels. The ASI294MC camera has this feature. Such a feature is highly desirable in traffic cameras and security cameras which have to deal with a very high dynamic range (for example when identifying a driver in a dark car at night with bright headlights and bad weather). Otoh, with the ASI294 (the mono version), consumers did oddly enough want more pixels. ZWO had locked their camera to bin 2x2 with 4.63 um pixels. But consumers demanded the sensor to be unlocked to allow small 2.315 um pixels, all 47 million of them. Folly, in my opinion, because it degrades the specs.

Amp glow is still present with peltier cooling, but it calibrates out with darks. Otoh, you also need dedicated darks to calibrate flats. Newest cmos sensors have no or at least much less amp glow than those from "last year".

Sony announced a few years ago that they decided to stop their production of ccds alltogether. Other manufacturers have followed. With the exception of specialised areas, ccd is being replaced by cmos. Cmos has caught up and surpassed ccd. But beware when you switch to cmos; they have their own quirks.

The OAG-L has a "window" of 11.7 x 8.3 mm. Both the ASI120 and ASI290 have smaller sensors than this. Only the ASI174 has a sensor that covers (most of) the oag's light passing aperture. If you were to pair this oag with the ASI290, you are not using its potential. In my experience, the ASI290 is sensitive enough to give you stars to guide on with the smaller oag. Even this oag has a larger window than the sensor size of the 290. So, unless you need the larger pixels of the ASI175 (5.86 um), I don't think you need the larger oag.

Both the EQM35 and the EQ5 have steel tripods. You can tell from the round legs visible in the image. You could try to find a used EQ5 steel tripod. I believe it will fit an EQ3 PRO. A Star Adventurer lacks the declination axis, and therefore any goto capability. Also, when you add guiding to the mix (eventually you will have to add guiding), a Star Adventurer can't guide in declination. You need declination guiding unless you have zero polar alignment error.

As I wrote before, the aluminium tripod isn’t very stable. If you decide for this mount, keep it as low as possible (don’t extend its legs all the way). I’ve read about people filling its legs with sand to improve stiffness. But when I tried that, the sand just ran out. Too many holes between the plastic parts and the aluminium. Instead I put wooden dowels inside the legs. I believe it improved stiffness. The mount itself is good for lightweight scopes and camera lenses, but definitely not for the Skywatcher 150pds that I had on it. I think that paired with a 72ed, as you suggest, may make a nice portable setup.

It’s the same. I got my numbers mixed up. The goto version is called ”pro” and is based on the eq3-2, which is a further development of the eq3 mount without motors. The eq3 pro is based on the eq3-2 and has motors on ra and dec, and thus goto capability. Confusing? I always thought so.

If you do not have your mount connected to your laptop, it’s easier to connect the guide camera to the guide port (st4) of your mount and to your laptop (usb). But if you have your mount connected to your laptop, then forget st4 and connect only with usb. In phd you need different settings in your profile. Use the profile wizard to set up. Remember that if you use st4, you need to redo calibration each time you select a new target ( if declination is different). With the mount connected to your laptop (eqmod or pulse guiding) this is not necessary, as long as phd gets pointing information from your telescope software.

I have used the eq3-2 pro (goto) with a skywatcher 150pds, and can only advise against using it with a Newtonian telescope. Newtonian telescopes are big telescopes and, while not heavy for their size, act as sails. They need stable mounts. As @vlaivwrote in his first reply, this mount is good for short focal length wide field imaging (I’d say up to about 300-400mm). But then only if you first upgrade the tripod. The tripod in the image you shared is the aluminium version. With any mount, use a steel (or sturdy wooden) tripod. The advantage that this mount has over a star tracker (star adventurer) is that it is goto and allows guiding in declination.

I don't have the large zwo oag, but their standard version with a helical focuser and the ASI290 mini. This works great and so far I've always had a few stars in its fov to choose from. Even multi star guiding works most of the time. Beware that a larger prism must be positioned closer to the main sensor. I mean, if you have the scope's illuminated field (circle) and inside that the area of the sensor (rectangle), then the rectangle of the prism has to fit between the long side of the sensor rectangle and the edge of the circle. If the prism rectangle isn't covered by the circle, you won't be utilising the full area of the prism. And you also have to make sure that the prism is clear of the sensor area, or you will see the edge in all your images. Finally, a larger prism means a thicker stem and therefore a thicker oag. This adds to the "backfocus".

Yes, but it needs to be in a very specific format. https://indilib.org/forum/ekos/6382-weather-watcher-question.html

That's why I went from a 150PDS to a SkyWatcher MN190 Maksutov-Newtonian. But I wouldn't recommend this scope to a beginner. And it DEFINITELY WON'T FIT on a HEQ5 mount. Here are the two next to each other. The MN190 is about the same size as a 200PDS, and if you are imaging from an exposed location, will act as a sail in the wind. With these large reflectors, you should also look into off axis guiding, eventually.