StarMich

I'm aiming for the best possible field illumination for my Explore Scientific PN208 f/3.9 imaging newtonian. The scope is 5 years old now and while doing maintenance I wanted to do something about the design flaws as well. With the current secondary holder design it's impossible to center the mirror beneath the focuser. My question is: is this really an issue when the entire primary is visible? I read about optimal field illumination when the secondary is centered, but this isn't achievable with this telescope. I attached an image showing the (very bad aligned and already degrading) secondary at the moment. This is as far down as I can go, I would need to replace the holder screws with longer threads to go further but I don't know if it would make any difference for field illumination? Thanks in advance, Michael

I'm using Astronomy Calculator 4.8, it outputs images at the actual resolution you can expect voor a given setup and object. I mentioned uncooled to make it more comparable to my current DSLR, cooling is a must if I'm going to upgrade. It's just recently I'm planning to actually buy a new camera, with those CMOS astrocameras popping up the last few years I intentionally waited longer. First part: Didn't think about this, good point! Have to look more into that. Second part: I don't understand this entirely, do you mean if you would crop the ASI1600 image to the same FOV there would still be a benefit in light gathering power (unbinned)? When doing mosaics you indeed have a benefit, but is this also true for single pane shots? I know, it took me years to get the full potential out of my gear. But now I've reached the limit, it seems like it's time for an upgrade. It's also hard to compare shots online made with different cameras as a lot of astrophotographers make use of some sort of noise reduction in their luminance. I personally prefer not to do any noise reduction as you see the traces almost everytime, I prefer a bit more noisy but sharper than smoother with noise reduction.

I have a question about experiences with entry-level CCD / ColdMOS cameras and the selection process for upgrading to one. I have been doing astrophotography for 9 years now, always worked with DSLR (uncooled, color, full spectrum mod). My main telescopes have a focal length of 812 mm (f/3.9) and 1000 mm (f/5). Since about 5 years I started following the CCD world with the idea to eventually switch to a monochrome cooled camera for luminance, with the aim of more light sensitivity and higher resolution. At that time my goal was to save for a camera with the well-known KAF8300 sensor, but in the meantime the CMOS sensors have started to compete more and more with the entry-level CCD cameras. Everywhere these days I see images popping up made with the well-known ASI1600M or QHY163M, the results usually speak for themselves and I had the idea to go for the ASI1600M Pro. I started some research into the specs of the sensor in these cameras (MN34230) and compaired these to the KAF8300, my current DSLR: a full spectrum Canon 1100D and other cameras in the price range ~ €2000 or lower. (< £1700) After some calculations I started to have doubts about the choice for an ASI1600M, this was my reasoning: Light output per pixel and consequently also the exposure time required to capture the signal from deepsky objects can be expressed (fast proxy) as the product of pixel surface and quantum efficiency. This is of course independent of thermal noise and read-out noise, but it seems to me that differences in this are not significant between different manufacturers that incorporate the same sensor into their cameras. If there is anything wrong in my reasoning, feel free to correct me. Below the numbers I obtained: Canon 1100D: 9.1 Canon 450D: 9.5 (is often "monofied" nowadays) ASI183M: 4.7 ASI1600M / QHY163M: 8.5 ASI174M / QHY174M: 26.1 ASI294C: 16.0 Atik 414EX Mono (ICX825 sensor): 22.0 KAF8300: 16.8 The first thing that struck me here was the lower score of the ASI1600M compared to my current camera, of course I compare mono with color here but it makes me wonder if the ASI1600M is worth it in this price range (€300 1100D vs €1100 ASI1600M) uncooled)? Second thing I noticed was that the ASI174M has a higher score than the Atik and it has more pixels. And a third was that the KAF8300 is gradually being overtaken by a price range € 800 lower. The high score of the ASI294C also makes this camera tempting, but I lose the resolution gain of the monochrome there. The above reasoning makes me leaning towards a QHY174M (ASI is discontinued), resolution is then almost equal to the current one with the Canon 1100D and the image field is a lot smaller, but I do see a large potential light gain. The ASI1600M offers me the highest resolution possible for a decent sensitivity, but I still find the score quite low compared to the other cameras. I would like to hear experiences about the above cameras / sensors and whether I would have forgotten another decisive factor in my numerical comparison. Thanks in advance, Michael