ollypenrice

I wouldn't regard the 8 to 11 as an upgrade so much as a change. It works both ways: the 8 gives a wider FOV. On the other hand the 11, I think, will cover a full frame chip, restoring a lot of FOV. Call it an upgrade if you also change the camera... Olly

What I do have is an image of this region from the Tak. With luck I may have the linear stacks on a hard drive in one observatory, meaning I'll be able to see how they combine. Should be fun. Another trick in the pipleine will be to try a different cable route in front of the RASA's corrector. At present I've got the cables following a circular guide but I'll try a U shaped guide instead. These seem to have caught on. I've never produced my images for pixel peepers and pixel peep myself only in order to get a feel for what's going on. All my processing is directed towards a normal viewing. Where I'm obliged to present at full size (small targets cropped from TEC140 data, usually) I obviously have to work differently. In the case of this image the first thing I did was resample it to half size, at which it was still large enough. It's not intended to be 'zoomable' to very high resolution. If that were the objective then I guess I'd bite the 88 hour bullet! To take this image I really think the RASA is the right instrument. For cropped close-ups, it isn't. Olly

Yes indeed, very modest exposure time. But if we compare the RASA 8 with an 80mm refractor, which might be the alternative at this kind of FL, the RASA has (allowing for the central obstruction) 4.9x the light grasp. So 3 hours equates to 14.7 hours. Six panels later, that comes to an alarming 88 hours, as opposed to 18. On the other hand the stellar image quality, seen at full resolution, is not as good in the RASA as from a good refractor. But then, on the other other hand, the fast F ratio is stunningly good on separating nuances in the dust. I'm really enjoying the RASA. It's brought a fresh approach to imaging for me. Olly

Neither has anybody else, Adam! Sorry, a typo as Dave says, now corrected. Thanks. Olly

Another project with Paul Kummer, whose RASA 8/ASI2600 OSC rides on my Avalon Linear in one of our robotic sheds, the Observatoire Per Frejval. 6 panel mosaic, about 3 hours per panel in 3 minute subs. This was a mosaic that did not play nicely and required three attempts to get to the stage of having a processable 6 panel to start with. Even then there was a lot of manual tweaking needed. The strawberry-like nebula is IC348 and above it is the colourful NGC1333. There's an interesting shaft of Ha light in the upper left as well. Olly

The optics will be fine and easy to collimate when needed and the mount is compact. My only reservation would be reliance on the smartphone. I know that humanity is losing the ability to do anything at all without a smartphone but, in this case, my concern is about the light from the screen. Even though it's small and can be turned down, it's still a light and you're still looking at it when observing. Deep sky observing requires the best night adaptation you can manage and I'm not convinced that any kind of screen is a good idea. I've used red cellophane over a PC screen and it's 'better than nothing' at best. Olly

I think the question may be unanswerable because, if the faster scope is of similar quality, it won't be of similar price. Faster optics are more expensive to make and harder to colour correct, not to mention harder to flatten. It is possible to have a fast, well-corrected scope in this class but it's very expensive. The Tak Baby Q. The 'DSLR' clause in the question is a bit of a curved ball since these cameras do thrive on fast optics. I've no idea how the comparison would play out in this regard. Olly

The speed of the system is very important in this discussion but it is not defined by F ratio in isolation. The system's speed is defined by flux per pixel, so a larger aperture putting more light onto larger pixels is a fast system irrespective of F ratio. (The larger pixels can be binned pixels in this case.) We could see what the numbers say but, where I live, there might not be any numbers to look at! Night time temperature varies between about 23C in summer (making the DSLR very noisy) and -20 in winter, causing DSLRs to drop dead! Olly

Vignette changing per filter could easily be the filterwheel not returning to the same precise spot. This is a very well known problem which manifests itself, above all, with flats. Edit: Also, are you dead sure the focus hasn't moved? It rather looks as if it has. Olly

Bless you and thanks very much indeed for this, Lee. This will point me in the right direction. Colour profiling is on my 'to do' list but will have to wait for the paper. My printer is an ET-1500 rather than an XP like yours. I cannot find an Ecotank version of the XP 15000 , all the ones I found were cartridge with 6 inks. Olly

I disagree on the camera-optics priority and think that the gain per pound with optics is tiny compared with the gain of going from a DSLR to a cooled camera. The 130P performs out of its skin when well fettled, as shown in its dedicated thread. A bit big for an EQ3, perhaps? I don't know. There are limits, though. The Skywatcher ST series, for instance, are non starters for imaging, in my book. With expensive optics, what do you gain? Usually it's - larger corrected imaging circle/flatter field so use a small-chip camera and it doesn't matter at all. - faster F ratio in refractors nice but not essential. - better colour correction in refractors Important, though not needed for narrowband imaging. - better focuser Important. - improved resolution A bit of a myth for imaging, though not for visual. The difference is tiny. I've used 'good affordable' optics from WO, Meade, Skywatcher and Altair Astro and premium optics from Takahashi and TEC. In terms of resolution the difference is scarcely discernible. I agree that the older generation, small chip CCDs are great value and I'd rather do DS imaging with an old Atik 314L than with a new unmodded 5DMk1V. The good news, here, is that the excellent old CCDs are both excellent and cheap. Olly

I decided to branch out into printing my own photos and, perhaps, those of our guests. If you're interested, this is the story so far. (If you're an expert on this I'd really love to hear from you because my poor brain is already addled!) The cost of ink cartridges made me go for an ink-tank printer. I don't want to have to agonize over whether to run off a print or not. I went for an Epson 15000 despite its limited 4 ink spec because more colours in a tank printer would have been way over budget. It can print up to A3 and longer, up to a metre, if given custom cut paper. Setting it up was easy. Canon ended up excluding themselves by being unavailable and when I saw that Canon France themselves were out of stock of some ink colours I thought, 'No thanks.' I bought a Datacolour SpiderX to calibrate my screen. It can't have been far out but I now know it's done. First prints: very pleased but not there yet! Resolution is fine and the colours are fine, but colours don't have anything like the saturation on paper that they have on screen. Accordingly I've been boosting the vibrance and saturation in Ps and Lightroom before giving them to the printer. Other things to watch out for are the contrast (gamma I guess) and the white point. A modest boost in contrast and a slight reduction in exposure at the bright end give a better result. I think the prints run out of dynamic range at the top. I'm going to switch to Epson premium photo paper to remove one variable, but it hasn't arrived yet so I'm on supermarket glossy for now. Experiences and advice would be most welcome. Olly

What strikes me is that the dust shadows on the flat don't align convincingly with those on the light. The circular shadow at lower right on the flat has a shadow equivalent on the light but the overlapping shadows just above half way up have no equivalent on the light. A very faint pair of overlapping shadows at upper left on the flat have a dubious but more emphatic equivalent on the light. It would be instructive to place the flat over the light in a layers program to test the shadows' alignment precisely. Interestingly, though, the vignetting has been fixed by the flat. This leads to two contradictory conclusions: - The flat is brightening the light in the corners. - The flat is darkening the light where there are dark patches on the flat. These dark patches may or may not be properly aligned but if they were misaligned they would produce bright patches on the light - and they don't. I'm going to assume that nothing at all probable is going to produce small circular bright patches on the flat (which would produce equivalent dark patches on the light) so we are left with the puzzling thought that these flats are both brightening and darkening the light in different places. I can't explain that but I do think it risky to take flats after moving the setup. Dust moves. Also, these dust shadows are certainly not caused by contaminants on the sensor. They are far too large and out of focus. There's a formula somewhere for calculating the distance from the chip of a particle of dust based on the size of its shadow in the image. However, your shadows are caused by something at a distance from the sensor, for sure. Olly

I'm not sure about the 6SE but, on the larger SCTs, the field is ultimately limited by the baffle tube - which means that a 2 inch back and widefield EP can reach that limit without the reducer. Like Mark above, I have one but never use it. Olly

The title of the thread was, Is the advice "The HEQ5 is the entry point to AP" just plain wrong? Quite honestly I can't recall many threads which have remained as firmly on topic as this one! You cannot have a rational and objective discussion about any mount without including pixel size. A setup's resolution is determined by just two numbers, one of which is pixel size and the other focal length. A mount's fitness for purpose is defined by it's ability to support this resolution. That is precisely the point of the discussion, which is why I think it has remained on topic. As for what should take priority when setting up a rig, I'd have thought this was also implicit in the original post? I hope you don't find anything acrimonious in anything I've said along the way. No acrimony has ever been felt or intended. If the latest EQ3 is an alternative proposition to the oft-cited HEQ5 then that's great news and those with experience of the mount are free to express their satisfaction. Your figure of 1.02 arcsecs is very persuasive evidence in the mount's favour. (We're having a bit of a fight with our Avalon Linear at the moment and for some reason that's about where we are with it. It should be better but isn't, or not consistently.) Olly

Surely you're preaching to the choir, here, though? Precisely this advice is given almost as often to beginners as the advice to regard the HEQ5 as a minimum. I've no idea how many dozens of times I've said it myself over the last decade or more. Yes, I've been more a widefield junkie than a galaxy or PN specialist over the years and have made or collaborated in a number of 30+ panel mega-mosaics, but I wouldn't be without the high res stuff I've done as well. https://www.astrobin.com/347486/B/ https://www.astrobin.com/full/393219/0/ Another thing I've enjoyed is adding high res data to widefields for the 'areas of interest.' https://www.astrobin.com/full/335042/0/ I would never advise anyone to start with high res, though, because it is less forgiving, much more expensive and needs stable seeing as well as transparency. Anyway, when are we going to hear chapter and verse on the guiding RMS of the EQ3 Pro? It's time for an infusion of facts into this conversation!! 😁 I've no idea what this mount can deliver since I don't even recall seeing one in the flesh, but if it's good enough to run at half the pixel scale of its imaging rig (or thereabouts) I'll gladly doff my hat to it. Olly

I've done a great deal of imaging at over a metre. Six years or so with a 14 inch ODK but, more recently and with small pixel cameras, I've done similar targets with a metre of FL and a TEC140. On balance I prefer the TEC but the 14 inch would have been more productive had our camera been willing to work binned 2x2. Unfortunately it refused to so so. Sometimes they won't. I do wonder if the more-than-a-metre FL has had its day unless you have a site of exceptional seeing. Olly

I'd probably go for the cooled CMOS camera because I've never really been a fan of the DSLR for AP. However, the EQ3 choice would not offer future proofing much beyond the Samyang in my view. I've asked a few times on this thread about what EQ3 owners achieve in RMS under guiding. Anybody? Olly

I can, Peter. I was a reluctant imager with a visual background, but I'd taken the huge risk of throwing my all into emigrating to offer astronomy at a reliable dark site. I soon discovered that the visual observers were not going to be my salvation! Most of my bookings were from imagers bringing their own gear, so I realized I was going to have to become an imager. Fortunately I soon found that I loved it. I had an LX200 10 inch for which I bought a wedge, buying into Meade's twaddle about this being a deep sky imaging dream. It was, of course, a nightmare. Around the same time I contacted that most excellent man, Ian King, to seek his advice. He said, 'EQ6, monochrome CCD with filters, autoguided, short FL refractor.' This is what I bought, initially using my TeleVue Genesis (Mk1 Pearl River F5) which was not colour corrected for imaging but got me going. I then went for a Tak Baby Q and a succession of further upgrades but Ian's advice was the best I ever received and I tend to repeat it all these years later. Give me an autoguided HEQ5, an APSc CMOS camera and a Samyang 135 lens and I could die a happy man. Olly

I don't want to see the thread locked but I do think it's going round in circles. Precisely tracked deep sky imaging at between, say, 1"PP and 4"PP is one thing and 'other astrophotography' is another. Is it worth fighting over a question which is easily resolved by making a distinction between the two? Olly

That's downright lovely and more proof, if any were needed, that the Samyang 135 is the most remarkable optic in years. Olly

Quality all the way. Olly

I hope you get it sorted and I'm sure an optical engineer could do so. It's interesting that oil-spaced lenses are often regarded with suspicion but there are three here living permanently in observatories and none has had any problem, perhaps because the lens elements are necessarily sealed? Olly

Lovely dusty shot. Beautiful. Personally I see a giant underwater shuttlecock being investigated by a small porpoise. (Good whisky, this. ) Olly

Have you done a full review on here? I'd be interested to read more, as would others, I'm sure. Olly