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I would like to share with you an article written by me on high-resolution solar imaging in different wavelengths. Glad that the European Physics Journal (EPJ) Web of Conferences published it. You can read it at:
You can see the different layers of the Sun in high-resolution images using different setups.
I’ve been starting to think about my next scope, and knowing that order lead times are quite long at the moment, I’ve been spurred into writing by the pre-midnight appearance of Jupiter and Saturn.
I’m hoping for some wise input to break me out of analysis paralysis. Here are my thoughts so far. Please feel free to rebut/add anything at all (but you might want to note my PS). Thanks in advance.
Context: I’ve had a "budget" (but quite decent) 70mm F/10 refractor on a GEM for a while now, and recently have started to take observing more seriously, learned my way around a bit, and started to run up against aperture limits. My partner is also interested, but not so keen on spending long hours in the cold watching me failing to find stuff. We already have Telrad, barlow and a few extra EPs.
Location: most observation is likely to be from the back garden, which ClearOutside declares to be Bortle 4 (I would say slightly generous, some nearby lighting) but we have darker skies within a 15 minute drive that we would like to take advantage of with the next scope.
Likely Targets: equally interested in solar system, DSOs and doubles, so not much help on the decision there I'm afraid. Might be interested in spectroscopy at some point, but not a deal breaker. Not really keen on solar.
Imaging: we are both interested to get into this “at some point” but I have taken on board the message that visual and imaging often send you down different paths, and we have agreed that we will prioritize visual for a few seasons, and consider buying further kit later if we do decide to do imaging. It might be a bit nuanced now with decisions like mounts, but ideally we would prefer to spend only what we need for visual work now, rather than going for a higher spec that would also support photography at some unknown point in the future.
Budget: not particularly constrained, but ideally looking to spend no more than £600.
Aperture: I know some have said good things about some 130mm scopes elsewhere, but I feel anything less than 150mm doesn’t seem enough of a step up from the current scope (and also possibly because Patrick Moore always said six inches was the minimum size for a beginner! ). I even considered a 200mm but decided against on portability (and on the heights of some of the prospective observers! ).
OTA: looking to a Newt for bang/buck. There is so much choice that I’ve only been looking at Skywatcher models so far – not because I’ve already decided they’re best, but they seem to be a decent quality/price point for us and then I’ll have something to compare with if people suggest alternative ranges. So in the 150mm arena I've been looking at the Explorer 150P (F/5) and 150PL (F/8). Obviously if we were going to do imaging we’d opt for the shorter model, but for visual the F/8 is quite appealing to me with its 1200mm focal length – better contrast and magnification, more forgiving in various respects (eyepiece design, collimation, …) We’re probably not looking to spend more than £50ish per eyepiece, and may need two or three more yet, so that favours the PL. On the con side, we are obviously sacrificing some TFOV compared with the F/5, and it’s physically longer. I'm thinking a wide-field 32mm will span most DSOs with the PL. The 150P comes with a 2” Crayford focuser, the PL has a rack-and-pinion, I’ve read pros and cons for both? We’re unlikely to make use of 2” ultra-wide field EPs. Both scopes have parabolic mirrors, which I like, and I've read good things about the durability of the coatings. The PL seems to have attracted some good feedback in these pages.
Mount: Getting tricky now. But GoTo (or at least PushTo) is an absolute must, because there will be one or more observers who will be wanting fast location (and even I will probably lose the will to live if I have to star hop too much). I have seen good things written about the Skywatcher AZ GTi (and it’s a keen price), but I’m advised that it’s not too stable with anything larger than a 130mm instrument. So if I went for the F/8 150 Newt, then in the Skywatcher range we’re looking at, minimum an EQ3 pro, possibly an EQ5 pro (I’m quite comfortable with equatorials). Is it worth the extra £160 for the EQ5? Would we only see any benefit in the future for imaging, or will a 1200mm tube behave better now on an EQ5 anyway? One other factor: noise. Small back garden, so motors must be quiet, and need to be able to slip and slew by hand without the GoTo losing its fix.
So, where I am at the moment: For the sake of convenience, I’m still framing this in terms of the Skywatcher range (in the absence of some revelation of a better value offering elsewhere).
I seem to have convinced myself of the following:
- GoTo (probably on an EQ mount )
- Skywatcher are a brand to beat
But still undecided on the focal length. I’ve found one or two “150P vs 150PL” discussions on these forums that are interesting but haven’t been conclusive for me, mainly because I have no preference on planetary vs DSO. I think more of a factor for me on the longer focal length is just the effect on stability, and the impact of that on the mount decision. We could live with the PL on an EQ3 if it were steady enough for regular visual, even knowing that we wouldn't use the mount subsequently for photography, or even for upgrading to a 200mm for visual only. Is it just a question of living with a bit longer wait for the image to settle after focusing, for example? That wouldn't be a problem. But if an EQ3 is only marginally capable handling the 150PL, that would push us into considering either the 150P on EQ3 or 150PL on EQ5.
So as I said, a bit deadlocked at the moment. If anyone can chip in with any thoughts that sway it one way or another (or unpick it and take it in some other direction), I’d be very grateful!
(PS Yes, I know I’ve not mentioned Dobs. Yes, I have considered them, but as I mentioned, it’s important to me that we have a scope that finds and tracks objects. While I’m sure you can make a Dob do that, I don’t think that’s its raison d’être. Please don’t be offended, Dob lovers).
I'm not experienced with LRGB imaging, so thought i'd give it a go on M81. However, when i combine the 4 individually processed integrations i end up with horrible colour hues across the image - they're all aligned and wotnot. Am i running into the issues of light pollution (inside the M25), which i can only remove with aggressive DBE application? Individual files attached.
So on Tuesday night I spent the evening imaging the moon with my Celestron 9.25 SCT and DSLR as shown below and am happy with the images I collated (I only took images as I did intend to take capture video but I got carried away and time was getting on).
I have approx 350 jpeg (and the equivalent in raw) images and have used the Microsoft image composite editor to stitch the frames together without editing them first etc but I wonder if I'm going the images an injustice?
I'm not ready to pay for editing software as I know there is a lot of very good free downloads out there and I'm asking for recommendations. Should I be processing the frames before/after stitching and what software would you recommend? Please offer any advice you have.
I will post the resulting image once I'm happy with the outcome 😁
Thanks in advance,
I recently upgraded to a purpose made astro-camera (Atik Horizon Color). The learning curve has definitely been noticeable, but I cant figure a couple things out. For some reason the pictures are grey scale when using N.I.N.A. I have tried different binning and formats, but the image is always black and white.
If I use the ATIK software (Infinity,Dusk) there is an option for 'Color Binning', and that seems to have fixed it for those programs, but N.I.N.A doesn't seem to have that option (you can not select anything for binning, or select 1x1, 2x2 ect.). But what makes it weirder is that the preview is always color using N.I.N.A. I used a pinhole lens cover to take pictures of my computer screen and it always shows up as color images. However, if I take that exact image file that previews in color and move it to pixinsight, it is grey-scale.
Is this a binning thing, file format problem? At this point I am just confused, if the preview of the image is color shouldn't the image data be color as well?
So far all the problems I have had with this camera have just been simple things that were new to me, but this one is really throwing me for a loop. Thanks for any help.
I've attached a couple images. The first you can see the NINA preview is color, as well with the couple other I took in the bottom right. And the other in a photo of trying to color saturate the stretched image in Pixinsight, and it says that it cannot saturate a grey-scale image. I have tried this with Tif, Fits, and various binning types.