vlaiv

I'm aware of that - I was just pointing out that human eye has quite dynamic range. It can see 0mag star and 13mag star in the same scope without much difficulty. This means that if something is very bright - and we attenuate it by ND5 type filter - it will still be visible to human eye under right conditions. So to address original question It is ND type filter so it blocks all wavelengths and under right circumstances you will be able to see laser spot thru this filter. When I say right circumstances - that depends on how strong reflected laser light is and how bright ambient is. You might need to pull on the shades to create darker ambient to get enough contrast for laser beam / spot to be seen good.

From what I've seen - it is very very good camera. I don't have first hand experience with camera itself, but I had access to data it produced and I liked very much what I saw. @Ken82 has first hand experience and should be able to provide more info on data size and processing requirements as well as general impressions of the camera.

You don't need to do green channel. In fact, you can choose which one you don't want to do if you are doing luminance as missing channel can be made by L - sum_of_other_two. If you are going to go for this approach - I advocate you skip blue as it is channel with arguably worst SNR on most targets, so it's best if you make that one instead of green. Green is rather strong on most targets and you want that so you can have a good SNR in given amount of time.

Not easy one to do from the top of the head. Let's try some reasoning. Baader solar film is ND5 which means it attenuates 10^5 times. That is 10 magnitudes (stellar) of difference. Using telescope one can easily see 10 mags of difference - Vega and mag 10 star and Vega, while bright is not unbearable to look at (I'm comparing 8" views from memory here). If your laser spot is anywhere as bright as Vega in a telescope - you should be able to see it thru ND5 filter.

I donćt think you'll see much difference, but that really depends on how, where and what you image. Main thing about cooled cameras is set point cooling - not the temperature itself. With set point cooling you have chance of proper calibration because you control temperature. We can sort of see what impact -10C vs -20C for ASI1600 can have if we examine dark current vs temperature graph posted above. At -20C dark current is 0.0062e/s/px while at -10C dark current is about twice that so let's go with 0.012e/s/px. Usually doubling temperature is about 6C but if we look at a graph - in this semi log plot - in -20C to -10C line has smaller gradient then after, so 10C as doubling temperature is not far off. Now let's examine single 300s exposure (that is long enough for CMOS). At -20C dark current build up will be about 1.86e while at -10C it will be twice that, so 3.72e., Associated noise components will be ~1.364e and ~1.93e. Both very similar to read noise of 1.7e. In 300s I guess one would accumulate enough of Sky signal to swamp both read noise and dark current noise. If that is the case - there won't be any difference in images in terms of SNR. If you can't do -20C due to climate - don't worry, odds are that differences are minimal to -15C or -10C, because dark current is low to start with and we don't do very long exposures with CMOS sensors.

I think it is very good effort! Don't think that Mak127 is not suitable just because it is "slow". Just be aware of it's limitations - and that is narrow field of view - which by the way works very nicely with targets like this. I'm almost certain that above image contains more data and with careful processing, one could pull out a bit more. Processing is also a skill that one can improve on. Not an expert on DSLRs, but I think that ISO6400 is unnecessarily high. Something like ISO800/ISO1600 would be a sweet spot - depending on camera model (I'm sure someone else will offer correct advice on your camera model). Would like to encourage you to do a bit more subs - 19x30 is just shy of 10 minutes of total exposure. You can't expect much in that short amount of time. A way to combat long focal length is to bin your data. That improves SNR, but makes smaller image (same FOV, but less pixels in height and width).

Yes it is. Large secondary, isn't it?

Provided that star was right in the center of the field - I would say your collimation is off. Scope needs collimation. Here is my scope (larger defocus) for reference:

As far as I can tell - only skywatcher smaller models that come with new mounts don't have collimation screws on the back - all other models do. In fact, so far, there has been couple of models of 130mm scopes by skywatcher 130/130M (old model F/7 said to have spherical mirror), SW 130P - one with parabolic mirror - F/5 scope - same as Heritage dob, SW 130PDS - that is photographic model with 2" focuser and 10:1 microfocusing and latest 130PS. Out of all of those - only 130PS seems not to have collimation screws. Same goes for smaller newtonian and Skymax 102 (maksutov). I recently purchased Skymax 102 for myself but did not want to go for bundled model because of that - I purchased scope and AzGTI mount separately and got regular scope that can be collimated. It was a bit more expensive than bundled option I wanted to suggest that as an option for you, but it seems that 130P is not sold as OTA (optical tube assembly only) and Az-Eq pronto is not sold separately in UK. You can get that mount from TS in Germany but it would probably be better to purchase locally where you can get good customer service.

I believe it is a good scope - it is well regarded. If one is aiming for the scope for the children or something with aperture yet portable - it is very good solution. I personally don't like open design in dob telescope (collapsible truss type) and it only accepts 1.25" eyepieces and it has helical focuser (I'm not sure if I would like that) - but that is just me.

That one will certainly have main mirror cell capable of collimation. It is bigger and better scope - 2" focuser capable of accepting both 1.25" and 2" eyepieces. Thin spider, more aperture ... In my view, only drawback to that scope is that EQ3-2 is EQ mount - and if you watched above video for EQ-AZ avant models - you've seen the need to rotate OTA. Larger scope is harder to rotate in its rings (not impossible, but harder than lighter smaller scope).

My view on that particular bundle is that it is very nice combination. I started with something similar and had a lot of fun. I really like that little mount as it can operate as EQ mount and AltAZ mount. It is however a lightweight mount so we can't expect it to be rock solid. There is motor option available for that mount so it can be easily converted into a tracking mount (not goto, just regular tracking) - which is excellent for planetary observation. I would recommend AltAz mode for general observing and EQ mode for high power planetary / double star work (with perhaps tracking motor upgrade). My only concern about this bundle (and other bundled scopes) is the fact that scopes can't be collimated. Whether this was done to save the weight (which is a good thing on such a small mount - it is always better to put lighter scope on a given mount then heavier one) or was it done to reduce costs, or perhaps that goes with modern "consumer" practice - use item until it works and then purchase another one instead of fixing the first one - I have no idea. On one hand - removing collimation is very beneficial for novice astronomers as many dread the idea of adjusting the optics, but can manufacturer guarantee that scope will arrive in perfect working order (even if it was in perfect order at factory - there is transportation that can easily knock mirror out of collimation) and that it won't get out of collimation during use?

There is many things wrong with that scope for astrophotography applications. First is telescope design - which is ok in general but in this particular model - poorly executed. Then there is mount which is very light and wobbly and tracking is nowhere near precise for use of telescope for photography. Even using simple camera and lens on that mount would produce questionable quality of images. Then there is issue with focuser - being plastic and flimsy ... Why do you need serious kit to properly do astrophotography? I suspect that you know a few things about regular photography, so I'll use analogy. You know how you really need a steady hand when you use longer focal length lens and shoot something like 1/60th exposure? Image is much sharper on tripod than from hand? Also - the longer exposure, worse the blur and also longer focal length - worse the blur. Now imagine you have a moving target (earth rotates constantly - so stars move), you use at least x10 longer focal length than regular lens and you use at least x100-1000 longer exposures and you want to end up with sharp images. Kit that you are using must be really precise and really sturdy in order to give you chance of doing that.

It might be, but not on a budget that you have. Here is quintessential starter setup in astrophotography: https://www.firstlightoptics.com/pro-series/skywatcher-evostar-80ed-pro-heq5-pro.html Just add suitable field flattener (I wonder why one was not included in this bundle).

No you can't. In some circumstances you can do it via tilting secondary only but in general case, even with spherical primary - you would need to move secondary or tilt focuser to get proper alignment.

In fact, come to think of it - you don't need anything but your camera, lens and a nice tripod to start doing astrophotography and learning stacking and processing images. Your exposures will be limited in length to avoid excessive star trailing. Star tracker that I mentioned above will help you do longer exposures and still have nice round stars.

Hi and welcome to SGL. Best that you can do on that budget is to get a decent star tracker and use your camera with regular lens to take images of the night sky. This will let you have some fun with astrophotography and you will learn the processing and calibration of images. With above you will be able to do - wide field astrophotography - nice images of star fields and constellations. Some large nebulae and couple of largest galaxies. Setups that can do "closer up" astrophotography start at about x4-x5 your budget new (could be had for x2-3 second hand).

Not being able to collimate the scope can only become issue in two cases: - either you receive the scope that is out of alignment when you purchase it or - scope goes out of the alignment due to use. If neither of the two ever happens - I don't see inability of collimating the scope being an issue at all. Both of above have happened to me and I'm pretty sure everyone else doing astronomy with reflector scopes.

@steppenwolf I just carefully read your capture details and saw that you used no G approach to capturing. I wonder why you decided to go without G instead on other color - like B for example? I presume that you used simple math to calculate missing color component prior to color calibration G = L - (R+B). In these kind of images G carries a lot of signal so G channel gets good SNR. Usually due to sensor response and atmospheric scattering, B is the weakest of the three - so it needs quite a bit more exposure to reach same SNR. Maybe B would be better candidate to calculate rather than G because of that?

Very interesting. I have not noticed anything similar on my mount. I wonder what sort of error could we be talking here? You say that pulse happens every 0.5-0.6 seconds? Let's see what that corresponds to. If I'm not mistaken, Heq5 has 64 micro steps per step, and one micro step is 0.143617 arc seconds. Sidereal rate is 15.041, right? This means that every second, we have 15.041 / 0.143617 = ~104.73 micro steps. Interestingly enough - in 0.6s we have about ~62.83 micro steps. I bet that this period is actually 64 micro steps and that you see what happens on a full step. Next thing that I would be interested in is how much absolute error there could be from such a motion. Since we have seen that it is indeed about 0.6s period - in that time frame, mount moves 9 arc seconds. From what I can see on the first video you posted - it looks like mount is going faster in one cycle than it ought to and then slows down in last 10-20%. Maybe it is doing what your oscilloscope is showing - in one "step cycle" maybe it is following sort of sine curve? I'm not sure how we could model this without precise measurement - like having a timed video against millimeter paper or something. In any case, let's go with some very simple error model. Let's say that speed of mount is 20% larger than it should be and then it slows down. It is larger for 80% of time. In 0.48s it is moving at 18"/s instead of 15"/s. What sort of error could we expect? 0.48s * (18"/s - 15"/s) = 1.44 That is very large error and that should be easily noticed as oscillation by people guiding at 1s. Have you tried measuring actual error from DEC drift experiment and pixel scale?

Like tooth_dr mentioned, flat darks don't care much about focus (but do take them regardless of the fact that they are short). I'm afraid that flats are probably going to be useless. You know when you focus - star first is a circle then collapses into a single dot? Dust particles cast shadow that looks like this defocused star - this is because dust particles are some distance in front of the focus plane - they are "defocused" so they cast defocused shadow. Problem is of course that they are on optical element, like flattener or filter or whatever in optical train at a fixed distance to camera. When you bring sensor to focal plane - dust particles are at some exact distance from focal plane and cast shadows of certain diameters. If you change dust particle defocus - you make these shadows larger or smaller. This makes an issue - larger shadows in flats (if flats were taken with focuser all the way in - dust the furthest from focal plane) can't properly calibrate out smaller shadows in lights.

Nope ... Zwo website:

That one also does not have very good correction of CA. It is very good travel scope / small visual instrument, but SW 72ED is going to be much better for imaging. There is TS photoline 72mm model that uses FPL53 and lanthanum glass that has much better color correction and is well suited for AP purposes (as the name of line suggests): https://www.teleskop-express.de/shop/product_info.php/info/p8866_TS-Optics-Doublet-SD-APO-70mm-f-6---FPL-53---Lanthan-Objektiv.html Btw, while I fully support the notion that ST80 is not imaging instrument, has a loads of CA and poor focuser - I have to say that with some careful application it can be used for imaging: This image was taken with ST102 - bigger brother of ST80, and purple fringing was not removed in post processing. It was done with color camera (although small planetary cmos type - ASI185) and only tricks used were aperture stop and wratten #8 yellow filter stacked with UV/IR block filter.

I'm somewhat reserved about that 130PS and in general - SW scopes of latest series that come bundled with new mounts (like pronto, az5, AzGti). It looks like they have been trying to cut down weight of these scopes to make them more stable, and for some inexplicable reason, they decided that collimation systems take too much weight, so these new scopes can't be collimated. Take a look at back sides of some of them: Here is quote from one unboxing post here on SGL: I'm not sure I would like a scope that can't be adjusted if it goes out of collimation.

I was thinking along the same lines, but Skytee with tripod is already over budget. Unfortunately, I don't think any of smaller alt az mounts like Az4 or Az5 would hold such ota without issues (both size and fact that it would hit tripod close to zenith?).