rl

An absolutely stonking set of images. I think I will blow the dust off my 12"...

Taken 2200 UT approx 15 may 2020 8" Newtonian, 900mm focal length, 7 *60 sec lights, 4*60 sec darks, QHY183C camera, Orion skyglow imaging filter, centre crop. Galaxy is about 6 arcmin diameter. Supernova is the 2nd star up of the 4 in a vertical line just to the left of the galaxy

Welcome to SGL!

These used to be sold as a set...50, 42, 30, 26mm some years ago. I bought the set having just completed a 14" f/6 Newtonian, had no budget left and wanted some cheap 2" eyepieces.. I was very disappointed...the Paracorr followed shortly afterwards but made very little difference. I found the off-axis astigmatism a serious problem, the moreso because trading up introduced me to the green-and-black widefield crack cocaine of the eyepiece world to which I have been addicted ever since... They work fine with a 6" f/10 refractor

I think Andrew S's comment says it all. And spending the change on a chunkier mount with proven pedigree has to be a step up providing you're not planning to carry it around. . On the other hand, playing devil's advocate, you have looked at the final results. Doubtless as objectively as possible. But has the ease with which those images have been obtained been considered? A lot of the scopes on that list are multi-use by design..both visual and AP. You seem to be concentrating on the AP side of things. Would a dedicated astrograph be better, like a FSQ85/106? No flattener spacing to worry about, and a bit faster shortening exposure times? No back focus issues getting filter wheels in the chain et cetera...You can have a lot of frustration getting the scope/ flattener combo working properly if you're pixel peeping for perfection in the corners. The astrograph is a one-trick-pony but they do that trick exceedingly well. Some of this is a numbers game (apart from cost). Every premium scope will be checked over very thoroughly before leaving the factory and 99.9% will be perfect. The other 0.1% got dropped on the way. As for the ED120, I've never heard a bad word about them.....but I doubt if the QA is quite as good. But if you buy from a good dealer you can always change it if it's not up to snuff on arrival. I've never owned a premium refractor, and just having tried to argue the case for one...in truth I'm not convincing myself!

I've tried both AG12 and CT12 Newtonians (both 12" F/4 carbon fibre) on a AZ-EQ6 mount and both were too much weight even with an extra counterweight. And that's before adding the filter wheel, camera et cetera. Scopes this size really deserve something in the EQ8 class. Given really good mirrors in the first place, I've not found the large secondary obstruction to be much of a showstopper but there will be a slight loss of contrast. It's never going to be the ultimate planetery scope but the large aperture makes up for a lot if the atmosphere plays ball. And yes, on lower magnifications for certain, coma will be an issue without a corrector. As will off-axis aberrations in budget eyepieces..

Better can be the enemy of good sometimes. The way I see it from the above posts: You have an extremely capable mount and the enthusiasm to carry it as a portable. It is probably the thing you're most likely to keep. I've done the same with an AZ-EQ6. You are prepared to guide. The widefield element in the equation is only there because people say it's easier. That much is true..tracking errors are less important at shorter focal lengths. But a guider takes that issue away provided everything else is mechanically sound. . You have a good camera with biggish pixels. It's an excellent camera for weddings and holidays...I'm not sure how long you will be satisfied with it as an astro camera. Most people end up making the jump to something more specialised. But it will always be useful for those widefield shots where you need a 35mm sensor. And it's certainly a great start. For deep sky work the (painful) software learning curve is the same pretty much regardless of scope. You still need to learn PHD2, Autostakkert, APT, Photoshop or their alternatives. Most prime focus setups are undersampled. If you're obsessing too much over this, you're looking at high-res lunar or planetry imaging with high frame rates. Seeing and tracking errors make matching the scope resolution to the pixel size a bit pointless for long exposures. Personally I think the Redcat is a bit limiting. It's small, light and optically fast, compact and bijou, but it's only like a better camera lens. I'd love one for holidays... The rite of passage for many people with good reason is the Skywatcher ED80. At 600mm native it's a step up in focal length..the flattener brings that down a bit. And they're always good as a second scope. But you could go longer on that mount budget permitting..the mount would take an ED100 plus flattener if that were to suit yout target choice. That is still a portable option given you're driving. Have a good look at the targets you wish to image. It's worthwhile doing the maths to see how they would look for various OTAs. There is only one M31 and M42... Paralysis of analysis!

What do you mean by wide-field in this context? Do you have a set list of targets you're going to try? The EQ6R will carry virtually any scope you can pick up with one hand. Is there any mileage in looking for a scope with a built-in flattener? Looking ahead, this preserves all of your back focus for incidentals like filter wheels, flip mirrors et cetera, and this sort of scope is usually designed to cover a 44mm diameter imaging circle.. I've always likes my TS65Q for this reason. It's obsolete now but it has a 70mm successor. It's a chunky little beast but no problem for an EQ6. Of scopes affordable to most people, it is the best engineered of the ones I've seen with regard to astrophotography. The very early ones had issues with pinched optics in the cold, but that was very quickly fixed. https://www.teleskop-express.de/shop/index.php/cat/c224_Flatfield-APO-Refractor-Teleskope.html RL

It will doubtless do a very good job as a guidescope but yes, it is overkill in terms of optical quality. A lot of people make do with a cheap achro 80mm for 50 quid secondhand. Whatever you choose does need to have a sturdy focuser and attachment to the main scope. Some people reckon a slightly soft focus can be an advantage in making the centroid of the star image easier for PHD to calculate It's not quite as overkill as my Pentax 75 SDHF which was used solely as a guidescope for years by its previous owner... A 72ED would double up as an excellent travel scope.

If you're imaging with a monochrome camera all the same theory still applies; light at only one wavelength will be in precise focus. If you focus in the green, the red and blue light will still be slightly off focus. With a B/W image this will look look a slight loss of sharpness. One way around this is to use a colour filter, typically green, or sometimes red to help with seeing. But this costs light, pushing up the exposure time. Not a problem on the sun, moon or brighter planets but a big problem with most else. The problem is most apparent in short focus achromats..and it is not the only issue. Some of these scopes have a lot of uncorrected spherical aberration for which a coloured filter won't help. I'm afraid there is little substitute for a triplet or apochromatic doublet if you want good results! Excepting of course the excellent Newtonian in your avatar....(cue heated replies...)

What is the mount (and therefore the weight limit?) If it's a star adventurer you're stuck with a 5kg all-up limit. Is this going to be unguided? I've owned the ZS61+flattener on a SA mount and it was very good over an APS-C sensor with 60sec subs. sometimes 120s. Can't usefully comment on the rest.

I'm impressed with that image given that you're using a small guide scope with a long focus OTA. I've never tried a separate guidescope at that sort of focal length...the advice is always to use an OAG. Well done.

I've used both CF and Aluminium Newtonians all by OO. The metal ones are much cheaper but less rigid, and rigidity is important if you're hanging a couple of kilos of kit off the focuser. I've found the CF ones better for this reason alone. But the CF material is a dew magnet, and it's easily scratched which is a real bummer on an expensive scope. Metal is easily touched up with spray paint should you have an accident in the dark. I can't comment from experience on steel.

I've been looking at Izar myself for a few nights in various scopes over the last week: 75mm Pentax SDHF refractor: marginal split at *125 because the fainter component is close to the 1st diffraction ring 80mm GT81 refractor; marginal split at *120 slightly clearer than the Pentax. 200mm f/4.5 Newtonian; easy at *150. Very clean split 20 April I could regularly split this star with my old 5" achro, and I've done it in a ST120. Your long focus achro should split it comfortably.

Brilliant stuff. A good example of what the LowSpec can achieve. And well presented. I'm inspired to dust off my own spectrometer...

Newtonians at F/4 have two main plusses; They are compact for the aperture. a 12" F/4 is a reasonable portable proposition for anyone fit and healthy with a car. They are very fast photographically. The minuses; The central obstruction tends to be bigger. This need not be a dealbreaker but if the scope is for photography then the secondary will be oversize to fully illuminate the whole of a 2" circle. If the mirrors are really accurate this does not have to be a dealbreaker for visual use. Collimation needs to be good. You need good eyepieces; only expensive ones work well at F/4. I've owned several F/4 newts and been very happy with them. My current scopes are a 8" F/4.5 and a 12" f/4. What made you choose F/4? Slower ones are much easier for the inexperienced...

I'm running an Orion Optics CT8 which is f/4.5, with a carbon fibre tube. Also a Skywatcher aplanatic coma corrector. Mount is an AZ-EQ6. I can recommend all 3 items; the OTA might be expensive but it holds collimation well and the CF tube is light and rigid (but scratches fairly easily). With a DSLR and the coma corrector, big finder the weight is about 12kg which is a perfect match for the AZ-EQ6. The CT8 is an expensive route to a 8" Newtonian but it's also a stonking visual scope; it's my "keeper" scope. But the Skywatcher / Orion options won't be far behind and you don't need the last degree of optical perfection for prime focus photography. The skywatcher Aplanatic is a bit expensive compared to the simpler CCs but it does what it says on the tin...coma is indeed corrected all the way to the corners of a APS-C sensor and the focal plane is indeed flat. It also works down to f/4. You need the special 58mm adapter which is a nasty little sting. In retrospect I wish I'd bought the EQ6R since I've never used the Alt-Az facility but the Az-Eq6 does a brilliant job. The whole setup can be moved outside and set up in 15 mins by a 60-year old so it's not too onerous. I prefer it for visual over my grab-and-go 80mm ..the extra aperture is worth the setup time.

Always a cracking target. Well done. Nitpicking over small defects somehow misses the point...

I would very much doubt if so many capacitors have spontaneously failed. In fact I'd be surprised to see one. There would have to be a very good reason (like gross overvoltage) and the silicon bits would probably pop first. How did you get into this situation?

It has been my fortunate privilige some 25 years ago to visit some of the world's best sites at Las Campanas Chile, Sutherland in South Africa and others. You certainly can see to mag 7. Not just that, the number of Messier objects usually reserved for binoculars which are easily seen by the naked eye is astounding. M33 is easy if low towards the north, ditto M92 and many others. I always found it harder to spot well-known constellations because the first and second magnitude stars get lost in the myriad of smaller ones. And then there is the Milky Way which starts to look like a photograph, and Venus casts a shadow on to paper. Aperture may be king but site is the ace..

It should be absolutely be fine if the collimation is ok. You will need to wait for the scope to cool down before trying any close doubles (closer than 2-3 arcsec) and need steady seeing. Wide doubles, any scope will do The weapon of choice for close doubles is generally considered to be a long focus refractor, for reason of their contrasty diffraction patterns, but I've used all sorts successfully over the years, including short focus Nertonians. The main thing is that the optical quality needs to be good, and the seeing good enough to allow full use of the scope's resolution. Refractors really come into their own on doubles that are very unequal but your scope should not be too far behind.

An excellent result...I'd quit while you're ahead! More seriously, like a lot of things in astronomy, a law of diminishing returns sets in looking at the improvement you get for extra time, cost and effort. And your standards go up with more experience which only adds to the sense of frustration...

If you want tickets for the lectures then book now....they're always sold out on the day. You can still get in to the exhibition.