vlaiv

This is the technique I used on several scopes and it works fine.

Don't bother with drizzle part at all. Drizzle is (questionably) useful when you are quite a bit under sampled. It tries to recover detail otherwise present but not captured due to low sampling rate. I maintain that it is not working in amateur setups as original algorithm was developed for Hubble and had precise pointing as requirement (like exact 1/3 pixel aligned dithers). Amateur setups can't do that and any dither is random in nature. I'm not convinced that random dithers in combination with drizzle algorithm in fact have any benefit of original algorithm. In fact, if you are at 0.9"/px - I would advise you to do the opposite - use x2 binning instead. It is very likely, and judging by the image above that you are over sampled at 0.9"/px and that just wastes SNR.

Reported size of the image is 6708 × 5056 and 383L has less pixels than that. You also mention 2x2 bin. Did you by any chance use drizzle? Image is grossly over sampled and you should in fact aim for lower sampling rate not higher. This is 1:1 or 100% zoom but it should have something like quarter of current size - like so when viewed 1:1

Good point about filter wheel and darks. That makes using non cooled camera a viable option, but then again - one in principle can go without darks and flats for EEVA. I can see filter wheel with mono camera being very useful - not in terms of color, but rather in terms of filters like IR pass, UHC or multiband filters for nebula and now of course - blank for darks.

If you want to have 2"/px resolution, then you can either: Get a scope with about 600-650mm of focal length or go with double that and bin x2, so 1200-1300mm Not much of choice in 600-650mm region - you are limited to 5" scope there, maybe 6" F/4. Alternative would be too look for decent refractor with about 1000mm FL and use 0.6" FF/FR from Long Perng? With 1200-1300mm you have much more options - you can easily get that with 10" F/5 newtonian, or 8" RC reduced by x0.8

Out of interest - what made you choose that particular camera?

I'm not sure if high prices are here to stay. Once things get back into normal - there will be plenty of second hand items and demand will go down. This will force prices to go down as well. I remember HDD prices skyrocketing after floods in Taiwan that put several factories out of work. That created temporary raise in prices - but things got back to normal after a year or two: (2009 - 2017 HDD prices per GB)

You seem to have issues with calibration in that image: OIII data is very faint and your flat calibration has issues that are higher intensity than intensity of data itself.

@Stu1smartcookie I think that market is self regulating entity. We can certainly talk about the reason for price increase or decrease and we can even express our like or dislike of the state of affairs. Ultimately - we, who pay for the items are in part responsible for prices. If something is too expensive in your view - then there is really simple course of action for you. You can either: a) purchase same/similar item from competition (be that retailer or vendor) b) accept that something has realistic price if all competitors offer item at that price or - get into the game and offer item at lower price than that and make your fortunes that way

I don't use anything for collimation of my dob - just a star. Secondary stays in place very well and with open tube design it is very easy to align it properly. Primary you can adjust just by looking at the out of focus star pattern. These images show how can you tell if telescope is out of collimation. Just make sure star is in the center of the field of view (best to use Polaris as it will not move) and use high power eyepiece. Do slight defocus and if rings are not concentric - you need to fix the collimation. As soon as you move primary mirror - you'll see the change in star pattern - move so that you make circles concentric.

I had both of these mounts. EQ2 was not very stable with larger 130mm F/7.9 Newtonian but it was usable. It is EQ type mount so you'll have to learn polar alignment to use it properly (not hard thing to do - you need to point it to Polaris / North pole - for visual it needs to be approximate). It is a bit more awkward to use than AltAz mount in the way scope moves - but once you understand how it moves - you won't have problems pointing it and using it. AZ3 is more stable, but it has a few issues that really annoyed me. I don't think it is suitable for long scopes. - slow motion controls need to be "rewinded" after you use them - they are not continuous and have certain amount of back and forth. If you track the sky - you'll reach the limit and will need to unwind them in the opposite direction to be able to track - mount has issues when observing near zenith - best place to observe since there is least atmosphere and light pollution there. Scope is nearly impossible to point straight up and longer the scope - more problems you'll have. Out of the two - I'd go with EQ2 version although I prefer AltAz for simple observation.

Mike, I'm totally with you regarding experience of using equipment and observing. This is primarily thanks to good software that you are using. Software in general should remove all the complexities of operation and just present you with good image. I'm not disputing that small sensor is also able to render small targets adequately. I advocate large sensor for two reasons: 1. Large sensor is faster than small sensor when paired with appropriate optics. Here is example of M13 being observed with Lodestar X2 and with ASI294MM for example. First is using 8" scope and second is using 16" scope. If we bin x4 ASI294MM we will also get 2"/px. We thus have same sampling rate, same FOV and x4 light gathering capability. Which one do you think will be closer to "real time" observing? 2. OP said he is interested in larger DSO objects as well. You simply can't observe larger objects with small sensor. You can most of the galaxies except for few largest ones - but not larger DSOs like California nebula This way you get to see only small piece of it. But with large sensor - you get to see more of it. You also get the chance to view large objects very fast - you can bin 4x4 for resolution of almost 5"/px - that is going to present you with decent image of nebulosity in less than a minute. If someone wants these additional "features" and budget is allowing for that - why not?

I don't see where our views differ except for maybe resulting image size. You also have the setup that I recommended 8" F/4 scope sampling at 2"/px. Your camera has 8.3µm pixel size and you don't need to bin in order to get 2.11"/px. It does not have cooling so you probably don't apply darks, or take darks at the beginning of each session - which is not going to be convenient for remote setup. I just pointed out that 1000 x 600 image might be preferable to 750 x 500 one and that larger sensor is faster sensor (when properly utilized). We might not agree on preferable image size, but I think we agree on everything else?

Problem with small sensors is that they give too small image size for reasonable sampling rates with larger telescopes. Say you want to use ASI224 - which is excellent small sensor for EEVA. It is 1304 x 976 with pixels of 3.75µm. Pair that with larger telescope of about 750mm of focal length (6" F/5 newtonian for example). That combination will give you 1"/px - too high for EEVA (and even too high for regular imaging if you as me). You therefore want to bin that to at least 2"/px. Resulting image size is: 652 x 488 That is on smaller size of things, would you not say? I think that images in 1000x600 range are good match for computer observing? With larger sensor - there is more "room" to put enough "large" pixels. Larger sensors are faster sensors (when properly paired with optics and binned). ASI183 is not bad choice in this regard. It is small sensor but has enough pixels. Even if one bins 4x4 (and they will likely do so because pixels are small at 2.4µm) they still have 1374 x 918 image size (originally 5496 x 3672). However, ASI183 is not far away in price to ASI294 - £780 vs £980 with area increase of 113% (more than double) versus only 25% increase in price. For someone on limited budget - it does make sense to go with smaller sensor, but if budget allows - I'd say go with larger sensor.

You might like to consider something like iOptron 70 maybe. You want mount that can handle about 20Kg of equipment with ease. EQ6-R has 20Kg max payload - and that is for visual. 8" Scope is going to be around 10Kg mark - add another one and all the gear and you'll easily hit 18-20Kg of gear It was rather simple - I went by your requirements. You wanted to look at both small and large DSOs. From camera and pixel size - this means about 800mm of focal length. I just picked telescope with largest aperture at that focal length. Here is comparison of two scopes: EdgeHD 8" can't properly frame even Orion's nebula with smaller sensor. You either need to spend money on large sensor or compromise on telescope design. In this case - it is fast F/4 optics. As for planetary - I was going by the budget. Realistically, in 6" size - 6" F/8 newtonian is one of the best planetary scopes - and in fact the best if you are not willing to spend £2000-£2500 on the scope alone and get 6" APO / ED doublet (Even SW 150ED is £1800 for OTA). You can get 6" CC - but it will have 34% central obstruction versus 25% CO of this newtonian.

It would be good to know your approximate budget - you mention few thousand, so that is quite sensible starting point (anything over £2500-£3000 is probably too much). Another important thing would be the mount - what sort of mount do you have at the moment and do you consider an upgrade to it? I too often focus on the detail so what would be best for you - if I explain the details and select the best for you, or just select the best without going too much into detail? Here is setup that will give you good performance: https://www.firstlightoptics.com/zwo-cameras/zwo-asi-294mc-pro-usb-30-cooled-colour-camera.html + https://www.firstlightoptics.com/reflectors/skywatcher-quattro-f4-imaging-newtonian.html and matching coma corrector: https://www.firstlightoptics.com/coma-correctors/skywatcher-f4-aplanatic-coma-corrector.html Totaling ~ £1800 To keep in mind that you'll need quite a few additional gadgets if you think of operating this remotely - like motor focuser and such. Cheapest planetary option would be to go with: https://www.firstlightoptics.com/reflectors/skywatcher-explorer-150pl-ota.html + https://www.firstlightoptics.com/zwo-cameras/zwo-asi224mc-usb-3-colour-camera.html For additional ~£450 or so without accessories (you'll need 2x barlow and motor focuser again).

Rather different requirements. I'm not sure that EEVA style planetary is even feasible in the sense we think of planetary imaging. Planetary imaging is based on very short exposures that freeze the seeing and optimum sampling rate that will capture everything scope is capable of delivering. It involves heavy processing with rejection of majority of frames and keeping only the best ones - and afterwards strong sharpening. None of which is possible in EEVA style planetary. For this reason, I would put planetary requirements in second place - as any camera capable of 30fps will deliver live feed of planet similar to that of observing at the eyepiece. As far as DSO EEVA is concerned - you want to focus on 4 things: 1. read noise - you want that to be minimal (this is beneficial for planetary imaging as well - but not important for planetary EEVA) 2. QE of sensor - you want that as high as possible 3. Aperture 4. Sampling rate / resolution In fact - points 3 and 4 combine to give you "aperture at resolution" - which is equal to speed. Best EEVA setups are large scopes with large sensors. These tend to be the most expensive ones as well. Mono is better than OSC. Planetary views are not going to be as interesting with Mono as with OSC. For example - imagine that you have 4" scope and you sample at 2"/px. Using 8" scope and sampling at 2"/px will make your setup ~ x4 faster as you will be using x4 more photon collecting area for same sampling resolution. If you can afford it ASI 2600 either color or mono would be very good choice. Combine that with 10" or 12" F/5 newtonian and you are going to have very fast EEVA setup. At 1500mm FL with 3.76µm pixel size if you bin x4, you'll get ~2"/px resolution. That is x9 faster than 4" scope at 2"/px. In fact - depending on your funds and mount - you could be able to piggy back 6-8" Cassegrain with ASI224 for planetary?

They are a good option when you already have some accessories and tripods - but not ideal as first scope.

I don't think you want to do that to yourself. In theory, such tripod will hold the scope but it will be disaster to use. It will be barely able to hold the scope and there is simply no mention of smooth motion - you won't be able to track the sky properly with such combination. If you want to put decent tripod + head yourself - it will cost you 150-200euro to do that. You'll get much better platform then these starter mounts that come bundled with scopes. For example you can use something like this: https://www.teleskop-express.de/shop/product_info.php/info/p9334_TS-Optics-Tilting-Head-and-Altazimuth-Mount-for-photo-tripods.html On a good tripod that can carry say 6-8Kg. But I think it is besides the point to talk about this since your budget will not allow for such thing. Just keep in mind - astronomy mount needs to be stable and needs to enable you to track your target as earth rotates and targets in the night sky shift. Cheap photo tripod that is meant to hold camera relatively stable is not going to provide this for you. Closest that you'll get to usable astronomy mount is decent video fluid head - but even those are not designed to handle telescopes - how often do you point your camera straight up? Telescope? Well - most of the time.

I think that it is very good value for the money - but not available at the moment. Are you considering OTA scopes? Do understand that you'll need decent mount to mount them on. Above 90/500 weighs about 2Kg. You need very good photo tripod + alt az head to hold such scope. Combination that can easily surpass your budget alone with OTA scope.

https://www.astroshop.eu/telescopes/skywatcher-telescope-ac-70-700-mercury-az-2/p,5000 with UPS standard shipping to Latvia - it is <160euro. With that kind of budget - you are really looking at very basic telescope and 70mm F/10 is not a bad choice. It will show you the moon and planets - although those will be small. 70mm of aperture is not much but you should be able to see bright messier objects with that. Most of these scopes are made in China and objective lens of the telescope is rather fine. You should value the package by accessories. I don't know much about K9 and K25 eyepieces that come with Levenhuk scope - but they don't really inspire confidence. Neither does x3 barlow nor 4x20 finder scope (who needs finer on 80 F/5 scope anyway?). SW 10mm and 25mm "super" eyepieces are well known - and while 10mm is not the best - 25mm is really OK eyepiece. In fact - both are good enough to keep you going for quite some time until you have budget for upgrade (and most people upgrade 10mm). I'm not happy with 6x24mm finder - you'd be better served with red dot finder instead. 2x barlow is also not something to write home about - but that is what you get in that sort of budget. Many people will actually say - get a pair of binoculars instead to get to know the skies, but 70 F/10 scope is good enough I feel to get you started. Another alternative would be this: https://www.astroshop.eu/telescopes/skywatcher-n-100-400-heritage-dob-telescope/p,45308#tab_bar_0_select However - that is not going to be in stock for some time ... Maybe if you are patient some more - that will give you time to save a bit more and maybe even for prices to come down back to normal (due to C19 - prices are on the rise at the moment). I think that you can get quite a bit more for not a lot more money really. One that I linked already or something like this: https://www.astroshop.eu/telescopes/bresser-telescope-ac-90-500-messier-nano-az/p,64990#tab_bar_1_select

Your budget is really limited with current prices. If you can stretch it, here is very interesting scope that will serve you well - although some people have complained about the mount (these cheap mounts are not very good): https://www.skyhunters.lv/teleskopi/?product_id=23778

No, I did not look at that one - but yes, it does have what it takes and I like the idea it has "fine" adjustment in all axis - using screws for fine positioning.

That is an option too - but rotating everything 180° does not change framing at all - it is just simple vertical flip afterwards to get exactly the same framing.

Yes, with addition that you should use super pixel mode for debayering OSC data so that you end up with 10.5 effective pixel size. In ideal lens, MTF10 would be somewhere at about twice the resolution of MTF50, however, camera lens are not ideal and don't have close to strait MTF curve. Also at MTF10 - image will look soft and you would need to sharpen it up a bit - but that depends on effective SNR. Going with higher sampling rate lowers SNR that you can achieve in set amount of imaging time. There fore it's a balancing act - closer you are to critical sampling rate - more you can sharpen things up - but less SNR you have to sharpen it. If you don't plan to sharpen things up - stay at about MTF50