Cosmic Geoff

I am wondering if the secondaries of recent Celestron SCTs are interchangeable, or are they part of a matched set of optics? Is "Deluxe" the same as "Edge HD"? - as I have read somewhere the suggestion that the Edge HD models work somewhat better as visual scopes because they get special finishing in the USA, while the regular ones don't.

I have to say that this reminds me of when I was selling a used electronic organ. I hauled it round to the buyer's house, and he then refused to accept it because there was a chip out of a wood frame on the back, so I was obliged to refund his money and haul it back. 😦 A star test might set the OP's mind at rest.

The package is new, but the SCT is a 40 year old tried and tested design and large numbers have ben sold packaged with other mounts.

Trying to view galaxies from a large town like Luton will be largely futile. At best you will see the bright cores of a few of the brightest galaxies. From an urban site, I have had better results with electronically assisted astronomy. With a 102mm f5 refractor, a ASI224MC camera and a GoTo mount, and live stacking, I have been able to see parts of the shape and structure of galaxies down to magnitude 11. I have been going through my astro club's oberving list and been able to detect every one of the galaxies on it, as though I was using a larger visual telescope at a dark skies site.

Note that some entry level reflectors now have fixed primary mirrors so that newbies who buy them do not have to worry about collimation. I don't know if this applies to the one under consideration. (And expensive premium quality refractors DO have collimation adjustment, so it's not simply a matter of refractors - good, reflectors- bad). Collimation is akin to servicing your car and checking the tyre pressures - it needs doing, but not something to worry about every time you use the equipment. Given that the 4" refractor does not have a central obstruction and the 5" reflector does, there is unlikely to be a marked difference in performance, and other factors like the different focal ratios, chromatic aberration in the refractor, and choice of eyepieces all enter into the equation.

I suspect that in common with various other lower priced outfits, the included eyepieces are intended as 'starters' and after you have tried out the scope you could think of upgrading them if you feel it is worthwhile. My experience of the 'starter' 10mm eyepieces is that they are a 3 element design and not very good.

Beware the term 'push-to'. Conventionally this means the mount is equipped with encoders which track the motions of the scope and computes and displays where the scope is pointing. This required that the outfit is aligned before use in the same manner as a GoTo mount. The system is popular (in the US) with owners of larg Dobsonians. A push-to system is similar in cost to a GoTo outfit. Starsense refers to two different things - a hardware accessory costing several hundred dollars, and a smartphone app that uses the same plate-solving technology. I have no experience of the latter.

I am 72 and unfit, and I can carry mine. 🙂

GoTo systems absolutely do NOT align them selves automatically. An alignment has to be performed at the start of the session and then the mount can go to objects automatically. The alignment requires some operator action and (usually) some basic knowledge of which bright star is which. The Nexstar+ system has an option (Skyalign) for aligning on three bright objects even if you don't know what they are. To a degree the alignment can be automated by two devices - the Starsense accessory (costing several hundred dollars) takes images of the sky and plate-solves them to figure out the alignment. And you still need to enter the location, time and date by hand. If you add a GPS module this takes care of the location, time and date entry. In theory, a GoTo, Starsense and GPS would do all the work for you, but in practice this is a complex collection of electronics and may not always work as well as hoped. I have Starsense, and find that while it works fine when calibrated, on subsequent nights it has an annoying tendency to consistently place the desired object just outside the field of view. In other words, your Dad may require a favourite-son accessory when using a Goto scope. 😀 However, either Starsense OR GPS for me reduces the alignment effort to below the threshold of annoyance. I would not say the 6SE is 'better' - just a better match for the 6/8 SE mount. And it costs nearly as much as a 8SE, which is probably why most buyers seem to go for the bigger scope. So far as I am aware, the Evolution line is not significantly heavier than the SE line. The OTAs (telescope tubes) are identical and the tripods mostly look the same. The CPC line of fork mounts on the other hand are far heavier and decidedly not portable. (Weights on sales listings are not alveys reliable). 6SE and 127SLT is not a level comparison. The former is more expensive, has a larger aperture and has a more stable mount.

Definitely buy or make a dew shield. The prism diagonal is quite decent so I would not replace that. You only need to use the finder during setup so I would not bother replacing that unless it becomes faulty. A f10 SCT is not demanding of eyepieces, so you may be disappointed on buying new ones, unless your existing eyepieces include 'starter' eyepieces that you got with other scopes. The 25mm Plossl that you probably got with this scope should be a decent one. Some people like to add a 2" eyepiece to these scopes. I have not bothered, as I have a widefield scope, and the expense of adding a 2" visual back, 2" diagonal and 2" eyepiece is significant. And the hole in the back of your scope is a lot less than 2" diameter. A 32mm Plossl eyepiece will give you some extra field, much more cheaply. If you are interested in planetary imaging, the outfit is quite capable of doing this - just add a good planetary video camera and a laptop. Zooms have their uses, but the field of view at minimum magnification (max fl.) is rather small, and the action on mine is so stiff that I cannot change the magnification without taking the zoom eyepiece off the telescope.

The harrison one should be better quality than the cheapie. You will probably need an extension lead unless you have an external power socket close at hand. As for the other one: adaptor jack size: 5.5mm x 2.5mm, compatible with 5.5mm x 2.1mm What?! I don't think so. Personally I use external battery packs or a multifunction car starter as I do not like using trailing 240v leads in the dark.

As I own both of the mooted outfits, the 127mm Mak and the 8SE I feel qualified to comment. Both are sensible choices but: This is a cause for concern. Some people just don't get on with GoTo systems and prefer the more basic manual aim-and-look outfits. However the Celestron Nexstar system is easier to use than Skywatcher's Synscan and we get fewer messages about it here from baffled newbies. A GoTo system does not align itself - the alignment is a operator procedure that can take several minutes (though if you have a Starsense + GPS you will be closer to this ideal provided the thing works properly). The 8SE is definitely a more capable instrument, but the 127mm Mak being smaller and lighter is potentially a more versatile instrument and I have used mine for general viewing, viewing galaxies from a dark skies site, sunspot viewing (with full aperture filter) spotting planets in daylight, and (with a manual AZ-4 mount) as a quickly deployed grab'n go. Both can be used for planetary imaging, but I gather your father will not be interested in that. As commented above, the C8's SE mount is on the limits, but if you keep the legs retracted and have a stool to sit on, and are at a site sheltered from the wind, it is perfectly usable (for visual use). You only need the red dot finder for setting up so no need to replace it right away (on the other hand they seem unreliable so a better quality replacement may be needed at some point). As standard the C8 SE comes with one decent eyepiece, a 25mm Plossl, and a decent prism diagonal. You will need some higher powered eyepieces in addition, but the scope is f10 so no need to buy anything fancy. If budget is not a problem you should consider the more expensive Evolution variant which has a better quality mount (but not necessarily a better quality tripod). Similar remarks apply to the 127 Mak SLT outfit. The higher power (9 or 10mm) eyepiece in the kit needs replacing with something decent to do justice to the Mak's first-rate optics. I found the SLT tripod to be annoyingly wobbly and I no longer use it. It is necessary to extend the slim legs to get the scope to a usable height. After a while I made a permanent garden installation to replace the tripod and 'bowl', or I put the Mak on an AZ-4. I don't use wireless connections, preferring to use the handsets - less to set up, less to go wrong, less to troubleshoot.

I'm not saying I'm right, but I've tried imaging unequal doubles, and given that the AC separation here is about 20x the AB and that overexposed stars tend to bloat, if one tried to image all three Castor elements together, the second image is the kind of thing one might get. I expect the answer may eventually emerge.

According to the virtualcolony deep sky database, Castor has a faint more distant companion: of mag. 9 at 72", same PA. http://virtualcolony.com/sac/star_search.php?con=GEM&sep=2.0&mag1=10.0&mag_diff=9.0&order=ra_hr

What are you intending to view with the telescope? The focal length of this telescope is around 2 metres, so it is not best suited to alt-az point-and-look unless your finder and slow motions are very good. If you intend to use it mainly for looking at planets, a manual equatorial would not be any harder to use (once roughly polar aligned) and would offer the convenience of only needing slow-motion action on one axis. I'm sure somebody can recommend a suitable alt-az head if that's what you want, and also a tripod. The EQ-5 tripod is meant to support a 9KG scope + a similar load of counterweight + the weight of the mount head, and is also available separately with a flat top and 3/8" screw interface. There are Sky-watcher Alt-az/EQ mounts that would mount your scope, but these are GoTo and also quite expensive. If somebody gave me a Stellalyra CC 8", I would probably buy a Celestron AVX mount for it, and see how well it worked if I just aligned on the planet I wanted to observe.

Be careful to distinguish between this Orion, (which may be the US-based company) and Orion Optics UK, who offer premium services.

I think this needs some qualification. Overall their quality matches that of the other popular brands and the quality of the main optical parts (main mirrors and objectives) is generally good. But there is plenty one could point to as being less than perfect. From personal experience: The equatorial mounts have a latitude adjustment system (paddle + latitude bolts) whih has given many users trouble with bent bolts. The Synscan GoTo system baffles many users, especially novices. The starter eyepieces supplied are of poor quality and generally need to be replaced. The basic Red Dot finders are unreliable and start to malfunction or fail to turn on after a few months use. Others have complained about the too-basic focusers on some of their cheaper telescopes. In fairness other brands may use almost identical sub-standard parts. This underlines my previous point about astronomy not being a cheap hobby. Some of these issues can be overcome by spending more money on accessories. Or by buying a premium product that costs a lot more.

A number of brands, Skywatcher, Celestron, Meade, Bresser, Omegron, etc offer competitive prices - all these are in fact manufactured in China, sometimes in the same factories, and some of these brands have common ownership. Then there are premium brands like Takahashi. What constitutes 'value for money' is a matter of opinion, as the popular brands often include annoying cut-price features in their products. Astronomy is not a cheap hobby, so if you select a telescope solely on the basis of low price, the result is likely to be disappointment.

I have set up the equivalent arrangement with Nexstar+. With that you don't have to set a baud rate anywhere, and you have to set the COM port you are using in the app you are trying to connect to the mount. If you are seeing the device in Device Manager without any fault symbols or 'driver problem' notices then it ought to work.

I append an actual camera settings file for a ASI224MC shooting the moon through a f10 8" SCT. Note that the gain is about 358 and I have reduced the area to 800x600 to speed up the frame rate. [ZWO ASI224MC] Debayer Preview=On Pan=332 Tilt=248 Output Format=SER file (*.ser) Binning=1 Capture Area=640x480 Colour Space=RAW8 Temperature=15.2 Hardware Binning=Off High Speed Mode=Off Turbo USB=80(Auto) Flip=None Frame Rate Limit=Maximum Gain=358 Exposure=0.008653 Timestamp Frames=Off White Bal (B)=95 White Bal (R)=52 Brightness=0 Auto Exp Max Gain=300 Auto Exp Max Exp M S=30000 Auto Exp Target Brightness=100 Mono Bin=Off Apply Flat=None Subtract Dark=None #Black Point Display Black Point=0 #MidTone Point Display MidTone Point=0.5 #White Point Display White Point=1 TimeStamp=2020-10-26T21:35:17.0822658Z SharpCapVersion=3.1.5049.0

I note that you are using a f10 refractor. Some experts advise using a f/ratio of up to f20 (including Barlow) for planetary imaging. However I have tried planetary imaging a lot with a f10 SCT and found that while images at f10 were often successful, images with a Barlow were often worse than at f10 and I could rarely figure out why. I suspect that the seeing at my site does not support imaging at long focal ratios.

I used to own an EQ-2 clone, and I thought it was rather wobbly for visual use, let alone astrophotography.

I recommend the ASI224MC camera for planetary imaging. Most astronomy software runs on Windows. If you have only one laptop, it might be a good idea to get a used Windows laptop for imaging rather than take the Mac outside (especially if it has all your holiday snaps and all your emails on it).

I had the same thing happen with the tripod of my C8 SE (bought used.) This is possibly the same tripod. I deduced that since the parts are plastic the root cause was over-tightening. Rather than buy a new leg (!!) I found a metal tube the right size that would slide over the broken part as reinforcement and stuck the whole thing back together with Araldite. Yes the Messier objects do look like faint fuzzy blobs, especially in light-polluted skies. We keep telling newbies this... Yes the basic red dot finders are not reliable. I have been replacing them with other devices. Latest purchase was a Bresser model that seems better made. Have you tried looking at double stars? If you find them interesting, there are enough of them viewable with a 6" SCT to keep you occupied for ages. If you do sell your outfit, you should get a good price and ready sale with the current supply shortage.

I don't know the technicalities but basically it adds the exposures and discards shots that cannot be synchronised (not enough stars, etc) It will compensate for field rotation. I use Sharpcap and then increase the contrast in Adobe Photoshop Elements.