vlaiv

I was always much more attracted to the idea of best value over best possible performance.

There is always 294mm

There you go - those are truly pictures worth more than thousand words.

I was trying to point out that if you don't need several nights with new OSC camera - you certainly won't need it with same sensor mono version.

By the way, I would not do it like that If I wanted dual tone image - I would use Duo band filter + Ha filter on mono camera as fastest option instead of using Ha + OIII filters.

That is even better - real life example, especially if you used the same cameras.

We can actually calculate the difference between the two. We just need realistic data representation and good way to model cameras. In nutshell - you capture for 8 hours with OSC - but you get only 1/4 of pixels for Ha and 1/2 for OIII with normal qe and additional 1/4 of pixels with half QE. All of that is with QE reduced by about 10% with respect to mono.

That really depends on whether you need to commit to several nights in order to get same quality as OSC.

If it is down to lanthanum - we would need to wait some time to detect it only 0.1% of lanthanum is that radioactive isotope and it has half life of about 10 ages of universe - so we would need quite some time for one to decay, even if there is substantial amount of the stuff in the glass.

yes, discussed before (same conclusions):

Not a fair comparison by any means. KAF8300 is low QE, 4/3 size, high read noise CCD, while 2600 is opposite of that - high QE, APS-C size and low read noise. There is 2600MM that can be compared to 2600MC and it is more expensive even if you don't include filters and filter wheel

Hi and welcome to SGL. I'm sure that such sticker is probably just formality. In some cases - glass is doped with some elements to produce better performing product - for example Lanthanum glass. Element lanthanum has radioactive isotope. Maybe there is no way of separating that radioactive isotope from element and there might be some traces of it left. Such elements are used in traces in glass - so overall these pose no issues to health - but regulative requires such sticker to be used. Alternative is maybe something similar used in plastics on the eyepiece. In either case - I'm sure it is not really hazardous to use, but regulative forces manufacturers to use such sticker.

New generations of sensitive OSC CMOS sensors have Mono equivalents and mono will always have edge for imaging over OSC - regardless of filters used. OSC has advantage only in convenience factor (and price).

These values are mix of empirical and theoretical. Theoretical framework is used to relate FWHM of star in images to needed sampling rate to record all the detail in image having stars of said FWHM. Again theoretical framework is used to estimate what sort of FWHM one can expect given certain aperture, usual seeing values and guiding performance. Empirical values of actual FWHM values measured given seeing, scope and mount performance confirm above. You can for example measure your maximum sampling rate given certain scope - by simply measuring your average FWHM (ones you are most likely to get - on average, or even good night - depends on what you aim for - good sampling on average night or good sampling on best of nights). Optimum sampling rate is x1.6 lower than FWHM in arc seconds. If you for example measure 3.2" FWHM of stars in your image - you need to sample at 2"/px (3.2 / 1.6 = 2) to record almost all detail (difference is imperceptible to human eye). This value is derived from Gaussian approximation to star profile, it's Fourier transformation and Nyquist sampling theorem. Expected FWHM values can also be estimated - and are usually "right" - or rather under estimated as usually seeing is worse then we expect. If we estimate FWHM values on most nights with usual mounts - we get this sort of "spread" of working resolutions: less than 80mm - needs sampling lower than 3-2"/px 80-100mm - is good for 2"/px to 1.8"/px 100mm - 150mm is good for 1.5-1.8"/px you need 8" or at least 200mm to attempt going below 1.5" - down to 1.2". In very rare cases you can maybe try 1"/px with 8" aperture, but it needs perfect skies and very good mount. It is however best done with apertures above 8". I don't think any amateur aperture can hope to get below 1"/px at least 99.99% of time - there could be that one night in several years that will allow for less than 1"/px - but not by much.

I see that you have ASI120mm in your kit list - you can use that to do some mono shots of Jupiter and Saturn. Moon and Venus are also fair game for trying out planetary type imaging. All of these can be imaged with barlow and ASI120mm, and that is probably the best way to get into planetary imaging - just to try it out and see how you fare.

Depends on your mount. I'd say that you should aim for 1.5-1.8"/px and with ASI2600 that would mean ~420 - 500mm of FL. Say that you are using x0.8 FF/FR and you have F/7 refractor - that would mean around 500 - 600mm native FL. And the winner is https://www.firstlightoptics.com/stellamira-telescopes/stellamira-90mm-ed-triplet-refractor-telescope.html + suitable FF/FR https://www.firstlightoptics.com/stellamira-telescopes/stellamira-2-08x-reducer-flattener-for-90mm-ed-triplet.html

That works good for planets but it is questionable thing for smaller deep sky targets. Do keep in mind that imaging planets require very different approach to imaging DSOs. It is so called lucky imaging technique - where one captures tens of thousands of frames in rapid succession (much like movie - and is often referred as to movie) - exposures are kept very short - like 5ms or so - all with goal of freezing influence of atmosphere in mind, and eventually choosing only the best frames out of all captured (often as few as 5% of total). With DSO imaging - atmosphere is dominant component of possible resolution and here you can't really circumvent its influence like in lucky imaging. That often means that you'll get larger but blurry image when using a barlow - much like using "software zoom" - or just enlarging image in software. Adding barlow to scope will increase working resolution by factor of x2 (in case of x2 barlow) - as focal length of system is extended by factor of x2. If we go by "aperture at resolution" as being speed - we can easily see that this combination will be "slower" simply because we changed resolution part. This has to do with above - do you really need higher resolution - or to put it more precisely - can you achieve that higher resolution given your sky conditions and mount performance? As is - you are already very high with resolution. Your camera has 3.72µm pixel size and 8" F/5 scope has 1000mm of FL - that gives you 0.77"/px. That is already much more than your mount and sky support. With 8" in most circumstances you'll be able to achieve say 1.5"/px - 2"/px. On very special nights - you'll go below 1.5" - but how much really depends on conditions and your mount performance. With premium mounts one can hope to achieve 1-1.2"/px on the best nights - but not below that. Adding x2 barlow will just make image larger without any real detail. From above you can conclude: For planetary - yes, it's sort of mandatory given that your scope is F/5, for DSO imaging - no, as you are not exploiting pixel scale that you already have (and you need to bin data to get best results from your setup).

Dynamic range is irrelevant when doing astrophotography. We increase dynamic range of the image many fold when doing stacking. Saturation is not important either as no camera can capture true dynamic range in any target in single exposure. Just think about it - it can easily happen to have 15 mags of difference in stars in your image (you can have mag4 star next to mag19 star). That is one million times brightness difference. Even 10 mags of difference will give x10000 in brightness - that is hard to record with even 16 bit camera if you want to have any sort of SNR on fainter star (say SNR of 5 - that would make signal at least 25 and 10000 stronger is 250000 which needs ~18bits to be recorded. When we want to capture full dynamic of the image - we do "HDR composing" - using exposure time to capture both faint (long exposure) and bright detail (short exposure) and then combine the two.

Somewhat. Not sure if this is relevant metric. Impact of read noise depends on other noise sources and one can control it with single exposure length (as it is per exposure). That way you can get same total read noise per session between cameras (adjusted for pixel size or not - either way it is controllable quantity). This for example should be taken into account when planning on binning the data as software binning increases read noise. Amp glow just looks ugly - but it really does not add much dark current and hence noise. I've measured amp glow in several cameras and amp glow tends to be 1-2e higher than surrounding dark signal - so noise impact is negligible. Granted, dark current is stronger in ASI183, and quite so compared to ASI553, but both cameras have very low dark current to begin with. ASI183 has ~0.003e/s/px at -20C. In 10 minute exposure - dark current will be 1.8e and corresponding noise will be 1.34e - less than read noise. Overall, I'd say that these two cameras are very similar in performance if we take peculiarities into account. Some might prefer not to have to think about amp glow and binning, while others will appreciate flexibility of small pixels and possible different binning factors depending on their setup. I would not declare "clear winner" either of them.

Maybe try one MNML processing effort - go by "less is more" moto See what you can make out of this image simply by stretching the data. Leave out all other stuff out - don't denoise, don't sharpen, don't do star reduction - nothing fancy, just simple stretch

Here is another interesting idea that I came up recently. Haven't implemented or tested it yet, just wanted to share the idea and discuss it a bit. Mipmaps in computer graphics are pre calculated progressively smaller images that are easier to handle / take up less space and can be applied to object if it is smaller - as they contain less detail. This is usually done in 3d graphics with large scenes where object can be far and thus small and close and thus large - think for example of 3d space simulator and you approaching space station. At first, space station is far away and you don't see / need much detail to be drawn. As you approach - you need more detailed view of it and you use higher quality texture. What does this have to do with stacking? Well, it has to do with binning and resolved detail. Imagine you have following scenario: You have SNR map and your bin x1 stack. SNR map tells you SNR for each pixel in the image. You proceed to create x2 binned version of the image, x3 binned version of the image and x4 binned version of the image. You then resize all of those to original size by some resizing algorithm (in reality - this binning and resizing will be done at stacking stage by using sift bin and resampling to match original size). In the end - you combine final image like this: You set thresholds at some points - say >10, 5-10, 2-5, <2. For each pixel with SNR>10 you keep original pixel value - of bin 1 image For each pixel with SNR in 5-10 range you replace it with corresponding bin x2 image pixel Similarly you do for 2-5 and <2 pixel values replacing them with bin x3 and bin4 images. This will create very smooth looking image in background and very detailed image where you have enough signal. It is like denoising step performed during stacking stage.

How come? ASI533 has 80% QE while ASI183 has 84% peak QE

As far as I can tell - those are the same ones I linked single motor RA drive and dual motor without guide port. They do seem rather expensive though? (maybe with VAT added and shipping - they end up being cheaper then in TS?).

Check out this video for installation procedure (I'm sure there are others on youtube if you search for "EQ5 motor kit" for example):

Star adventurer won't be cheaper option when you add all of it together (tracker, counter weight kit, tripod, etc) and EQ5 is more future proof, but, it really depends on you getting DIY part - that means research on your part of what is best to use depending on your budget. If you don't want to fiddle with motors yourself - then you can get (a bit more expensive) kits for EQ5: single motor: https://www.teleskop-express.de/shop/product_info.php/info/p396_Skywatcher-automatic-stepper-motor-tracking-for-EQ5-NEQ5.html dual motor: https://www.teleskop-express.de/shop/product_info.php/info/p399_Skywatcher-Dual-Axis-Stepper-Motor-Tracker-for-EQ5.html Or dual motor with auto guider port: https://www.teleskop-express.de/shop/product_info.php/info/p7293_Skywatcher-Dual-Axis-Stepper-Motor-Controller-for-EQ5.html Do be careful with these upgrades - as in the long run, you can spend more money then purchasing EQ5 goto version right away. With DIY - you'll be able to reuse components, but here you'll be purchasing upgrade after upgrade whenever you decide to get an improvement. Here is another interesting little mount that has motors and goto and all. It is small mount however, much smaller than EQ5. It's probably somewhere in between of Star Adventurer and Eq5 in payload - which means that it will carry maybe very small scope like 70mm one: https://www.teleskop-express.de/shop/product_info.php/info/p11151_Explore-Scientific-iEXOS-100-PMC-Eight-WiFi-GoTo-Mount---up-to-7-kg.html