Cosmic Geoff

I actually have an 8"SCT with focal reducer, but I only use it occasionally in the EEVA role, for EEVA of small objects. And it has an alt-az mount. Surprisingly enough you can use an alt-az mount for EEVA, as the live-stacking largely takes care of the field rotation. If you have a recent model Synscan handset, you can plug a USB cable into it and control the mount that way for plate-solving etc.

I suggest that you as far as possible put together a EAA rig with what you have to hand, and see how that goes. You however appear to lack a widefield scope, which could prove an expensive acquisition. My current preferred arrangement is: 102mm f5 achromat, ASI224MC, helical non-rotating focuser, EQ-5 Synscan mount, Sharpcap 4. (essentially stuff I had already) A total integration time of 30 mins seems ambitious, unless you go somewhere really dark. I usually do 150 secs or so from an urban area.

I don't think that modular construction, or new drives for old mounts, is ever going to be cheap. But it occurs to me that with the advances in technology available today the fitting of new drives to old mounts could be facilitated by using laser-scanning to design brackets and couplings and then printing them so that a new modular drive can be attached. (If this sounds like science fiction, I should point out that this is how up-to-date private dentists produce tooth crowns in one visit - search for CEREC.) I note than none of the 'alternative' GoTo drives for the EQ-5 seem to include a full GoTo handset - worth around £140 these days - relying instead on a computer connection.

Sharpcap works well for image acquisition, and the successive versions have become increasingly sophisticated, offering polar alignment, focus aids, etc. It allows you to 'live stack' of you are interested in EAA. (Rival capture programs are available). I checked out APT but found it complicated and never put it to real use. My advice is to try Sharpcap, and if you feel you are outgrowing what it has to offer, try NINA or APT. Whether you intend to use an astro camera or a DSLR also has a bearing on which software you will want to use.

Amazon have the buying power to lean on suppliers for a lower wholesale price. They allegedly underpay and overwork their workers and pay little British business tax. If you have a problem, do you think Amazon will deal with it effectively? And do you think they will continue to sell astro kit at those low prices once they have put FLO, Tring Astro, etc out of business?

You don't need to buy one. Few people are bothered by the L-R reversal.

It looks like the correct one for your scope, but why not support a proper astronomy dealer who needs your money much more than Jeff Bezos does?

Looks like it, but why not buy via a proper astronomy site rather than via Amazon?

A scope of 50 to 80mm aperture will not perform well for planetary imaging. For that you need something like an 8" SCT (on your mount.) AFAIK any of the telescopes you list should work fine with an astro camera.

Back focus is irrelevant if you are imaging planets (or other small objects) or live-viewing them on a screen. It becomes an issue if you are using a large-chip camera and want the image to be sharp right to the corners. As it happens, the standard Celestron diagonal is about the right length to give the correct amount of back focus (it does not have to be accurate to .001 inch). Yes, it will reverse the image L-R but you can undo that in software. There are all sorts of other ways of providing some extension. For instance, if you buy a SCT to T-thread adaptor, you can then use T-adapter tubes to connect the adapter to your camera, which should have a T-thread on its front end. SVbony do a kit of T-extension tubes which you can play with to get various extensions. If you have not done so already, consider buying the Celestron f6.3 focal reducer, which will do a number of useful things for you: convert your scope to a f6.3 (faster for imaging and live-viewing), give a wider actual field of view, and IIRC provide some field flattening. Note that I was obliged to use a diagonal along with my f6.3 reducer, otherwise the imaging train hit the base of the mount when trying to aim at high objects!

Bear in mind that the C6 has a f10 focal ratio, which renders a Barlow less than necessary for visual use and also of doubtful use for planetary imaging. If you use a camera with a pixel size of 2.9 um rather than the 3.75um of the ASI224MC, the scope will deliver an adequate image scale without a Barlow. In practice I rarely used a Barlow for planetary imaging with a C8 as I found it delivered little or no benefit and made the outfit harder to use.

I got the Sharpcap 4.1 comet tracking feature to work tonight (9th Feb). I don't know what I did that I didn't try before, other than waiting for an exposure to complete giving the display time to update.

The second telescope is best used for widefield viewing, not looking at planets. The aperture is rather small for viewing galaxies and other 'faint fuzzy objects'. With a budget of $185 you are in danger of getting a telescope that is disappointing and discourages you from pursuing astronomy further.

I bought a license and tried again last night (6th) but could not get the comet-tracking feature to work before cloud rolled in.

I downloaded the SharpCap 4.1 beta and tried it out last night on three comets. To my disappointment, I could not try the comet-tracking feature as it insisted a Pro license was required, despite some text indicating that one could try out NEW Pro features without a license. I suppose I ought to buy one just to support the software creators. 4.1 also made a pig's ear of saving the comet image files in the right folders. Yes, it is a beta, but I will stick with 4.0

After accidentally unscrewing the wrong bit of my ASI224MC in the dark, I found that exposing the sensor is a bad idea. It is quite difficult to get rid of spots and smears that show up subsequently when imaging, and difficult to determine whether they are on the sensor or on the clear window. It is possible to clean the window disc by the usual methods. As for the sensor, it seems safe to dust it off with a fine-bristled art brush. Be careful of blowing on it, as a aerosol may deposit unwanted stuff. Vacuuming might work. IIRC there are materials and techniques for cleaning DSLR sensors. Replacement window discs may be available from ZWO.

Apparently the observatory section has low sides but a fixed gable end. I would be inclined to make a modification there, and make the top half of the gable end hinge down. Nevertheless it is an improvement on the high-sided roll-off-roof designs I have seen pictured elsewhere.

I have the same experience with mine. I could not adjust out the vertical backlash with the settings, and the scope once slipped downwards while in use. I tightened a large nut but it was not very slack anyway. The 'slipping downwards' has not recurred. Your videos show a lot of play, but I do not recognise that part so cannot comment. My advice is to just live with it unless it is making the outfit unusable for visual use.

A similar message from a Celestron mount often means that the mount firmware needs to be refreshed/reprogrammed. But maybe it's time to bin the Gem5 and buy a mount that works.

There are a number of issues here that we need to tease out. Firstly, telescope mounts are a relatively low-volume business, produced in thousands at best. Compare that with cars, produced in millions, or smartphones - tens of millions. Re modular parts for new mounts: I don't see the benefit for the manufacturer. For the more expensive mounts, the demand from users is mostly for GoTo mounts, to the point where there is little point (commercially) in providing anything other than the GoTo version, engineered for production. As for modular parts for old mounts, we already have this situation with the EQ-5, which I assume was originally a manual mount. One can buy it as a manual, as a motorised, and as a GoTo, and buy kits from Sky-watcher and (apparently) from various third-party suppliers to upgrade it to GoTo. But are all the old & new EQ-5 and their clones all mechanically the same? There's the problem. If they are not, there is no guarantee that the kits will fit. It is unfortunate when the electronics on an old mount fails, but there is little incentive for the manufacturers to keep supporting the same mechanical design for decades so that spare electronics for new mounts will fit it. It would be good if, as iantaylor suggests, the mounts had a standard interface between mount, motors and electronics, but engineering this would probably increase costs. As some of you may have noticed, Skywatcher and others have yet to fit a proper USB port to their mounts rather than a lashup involving a serial chip, which suggests a lack of resources for serious development. I have looked inside one or two GoTo mounts and been surprised at how little stuff is in there in some of them - a circuit board and a couple of cheap-looking motor/gearboxes. And is a Synscan upgrade worth the £350 or so they charge for it? They can charge that because there is no off-the shelf ready to fit alternative and they are made and sold in low volumes. I suspect there already are people who can take old and failing drive systems and upgrade them, but this bespoke service is unlikely to be cheap.

Any GEM GoTo mount of adequate capacity would do the job, e.g. HEQ5 or AVX. An EQ5 GoTo will not be of adequate capacity IMHO. As for budget, I'm still laughing. 🙂

Colours will come out wrong if you don't use an IR cut filter.

I wouldn't buy either, especially not the reflector. The 80mm f5 refractor will be best suited to low-power wide views. An 80mm f10 refractor (suitably mounted) would be a better buy. If your budget is very low, your money might be better spent on a pair of 10x50 binoculars.

If he has to make up the observatory-shed to your order, rather than supplying from stock, it is reasonable to ask for a deposit. Likewise if delivery is involved. On the other hand, it is wise to make due diligence checks. Reviews? Answers the phone? Discloses a street address? Has a website? Company House listing? Why does the supplier not accept credit or debit cards? 99% of traders do, even street traders and 'Big Issue' sellers. Also check that the site where the shed is to go is what the supplier is expecting. Concrete base?

Yes, they are, but a mini-Dobsonian of similar aperture (130 or 150mm) might also fill the bill and could be cheaper and equally portable.