Cosmic Geoff

For what it's worth, I bought the Celestron Omni 2x Barlow lens to use for planetary imaging with an 8" SCT and a ASI 224MC camera. I never got results that were better resolved than without the Barlow, or any better than a kit Barlow lens. I think the seeing might have been the main problem. I later switched to an ASI462MC which with its smaller pixels is a better match for the SCT (without Barlow). You definitely need an Atmospheric Dispersion Corrector when the planets are at low altitude, like Saturn at its most recent apparition.

If you want to image small galaxies with the C8 (not a trivial task) you will need a mount like the HEQ5, the EQ6, or maybe the Celestron AVX. Plus an autoguider or off-axis guider (one of those things that attach into the optical path). I am not familiar with this particular kit, but you need a full aperture filter for white light viewing, and take care not to melt the scope or your eyeball. For H-alpha you'd need a dedicated scope like a Lunt, and they are expensive. There may be energy reducing filters and H-alpha filters you can stick on a C8, but again they will be expensive. I did manage to get some planetary images with my C8 SE. Or you could buy a Seestar S50 and see where you want to go from there.

I originally bought the Seestar S50 on the assumption that I would use it about twice a year on hassle-free visits to dark skies sites, and it was worth it just for that. In fact I have had it for six months and used it more than any of my other outfits, and imaged nebulae I never thought I would be able to image. To me, the proposition that one shouldn't buy one because an outfit costing four times as much (+ hours of processing time) will give better results is ridiculous.

The back focus (with the Celestron f6.3 reducer) is not that critical. It's about 10 cm, which you can achieve, for instance, by fitting the camera on the end of the standard 1.25" diagonal. Or, if you have a mount with suitable clearance, fit the camera at the outer end of a flip mirror assembly or straight-thru extension tube.

It seems an insecure means of mounting the OTA. I have never heard of anyone mounting an OTA that way.

I see your problem. 🙁 It would be better to attach the scope directly to the mount via the dovetail. There are various workarounds that might be tried for the finder position problem: See if you can use it as-is. Buy another finder bracket and Araldite it into the desired position. See if a right-angle finder will work - you can arrange it to stick out sideways so you don't have to crane your neck when trying to aim upwards. Remember that you have a GoTo mount, so with luck you will only need to use the finder a couple of times a night (for alignment).

Yes, that's what the adapter on the almost identical Celestron 127 Mak looks like. You just need a 90 degree star diagonal - lots of choice there. I found that the diagonal that came with the scope worked just fine, so no need to spend a lot of money. I had to buy a good quality 10mm eyepiece (£50+) to get the best out of the scope. You definitely don't need a Barlow with a Maksutov of focal length 1500 mm. You will also need a finderscope of some sort. It will mount onto the Synta finder bracket visible in your photo. I wouldn't bother with a 2" adapter and eyepieces. They cost more and the scope does not have a big hole in the rear. Do you have a suitable mount for the Mak?

So does the mount still work properly with its hand controller? If it does, I would leave well alone there. If you appear to have a communications fault between AZ-EQ6 and computer, then investigate the cause. Various things might need resetting e.g. the serial port number, the baud rate, etc. It is not wise to upgrade firmware unless you have read the small print and know for sure that the upgrade is going to have a desirable result, which outweighs the risk of something going wrong. In the worst case, you can be left with a 'bricked' piece of kit and have to buy another.

I recommend you get a multi-test digital meter (available cheaply online) and use it to test the polarity and voltage of any supply BEFORE you plug it into any Vixen device. e.g. Neoteck Multimeter Pocket Digital Multi Tester Voltmeter Ammeter Ohmmeter AC/DC Voltage Current Resistance Diodes Transistor Audible Continuity with Backlight LCD for Factory and other Social Fields: Amazon.co.uk: DIY & Tools

Available from FLO for £21.

I think that you need a clearer plan before buying. It appears that you are interested in imaging rather than visual. Be clear that some telescopes are not well suited to imaging because of the way they are mounted. This includes the Celestron C8 SE and any Dobsonian mounted scope. If you want to image, the possibilities are (in ascending cost) a fixed digital camera (DSLR), a DSLR on a star tracker mount (for widefield shots) a small refracting telescope on GoTo mount, and CMOS astro camera (for EEVA, see other thread in this forum), a small refracting telescope on equatorial GoTo mount, with DSLR or CMOS astro camera, and autoguide, for medium field deep sky imaging, Various larger aperture telescopes, e.g. a SCT with focal reducer, equatorial GoTo mount, autogulde, CMOS camera or DSLR, for imaging small galaxies etc. Lunar and planetary imaging requires a different approach. The bigger the telescope and the more sophisticated the mount, the more satisfying the results are likely to be. You require a dedicated planetary astro camera, and take short videos (see 'lucky imaging' technique). The telescope in this case will be the same as what you would use for visual observing of planets. I almost forgot the Seestar S50. If you buy one of these highly automated devices, it will do the whole imaging thing for you. To get a rig that outperforms it, you would have to spend a lot more money. The only caveat is that with its short focal length it is not much good for planetary imaging.

Dark skies are amazing - as the others say above. Not easily compared with an urban area. With an 8" SCT, looking for galaxies from home was unrewarding, but at my sister's place in Devon one year I was using a galaxy list in the GoTo and logging fainter and fainter ones till I ran out of energy. However, I imaged one particular galaxy field from home with my 4" f5 refractor, that I'd seen in Devon with the 8" SCT, and I imaged all the same faint galaxies.

Indeed. I suggest you look up the recommendations for lifting heavy objects, and see how that fits with the weights of the above-mentioned objects and whether you will be lifting them from the ground or just from e.g. a bench to the tripod. Personally I take great care to avoid lifting my CPC800 (20KG) off the ground and endeavor to keep my back straight when lifting it. If I have to hold something up at arm's length, then 10 Kg (the weight of an 8" Newt) is plenty. I move the CPC800 OTA/fork assy around on a trolley. One can buy special trolleys that take a tripod and associated kit.

If a part is missing, the likelihood of finding a replacement is probably nil, unless you can acquire another scrap C6. Or have a part made, e,g by 3d printing.

These might be worth a significant amount of money, and inexpert attempts to dismantle or clean them is likely to reduce their value.

It occurs to me that Apple's new Vision Pro smart glasses (see PC Pro magazine, April 2024 issue 355) would do what you want. You'd just need to produce your own software, as before. They cost $3499 though. If you want to produce your own telescope-like device, you would need a LCD screen (120mm in diameter???) and an achromatic lens of about a quarter of the focal length of the ST120 objective (ie about 150mm) to project an image of the screen into the eyepiece plane. Or to simplify things, just have an eyepiece that focuses directly onto a smartphone screen. Note that a lot of eyepieces won't do this so you might have to make or modify one. Also there are commercially available digital setting circles which will give a readout of where in the sky the attached telescope is pointing - see Nexus DSC.

I think you should have a good look at what a 12" scope looks like when mounted on your preferred mount. I had a 8" f5 Newtonian on an EQ-5 and was not pleased to find that with the tripod legs fully extended the eyepiece was about 7 feet off the ground with the scope aimed near the zenith.

Don't back the film with plexiglass, glass or clear acrylic. This is not necessary, and unless the material is of optical quality, it will degrade the image. It won't do any harm to paint the opaque part of the cap, but I doubt this is necessary.

Not necessarily an inherent feature of SCT scopes. The manufacturing quality seems to have been variable in the past. I have found them sensitive to slight mis-collimation. Some people claim the EDGE HD models perform better visually. Also ED vs SCT is not a level comparison, as (unless you can afford an 11" ED or APO) the ED scopes will have a smaller aperture and hence less vulnerable to atmospheric churn. In theory, (asides from the effect of any central obstruction) you might get the same effect by stopping down the larger scope.

I don't see why you would need two from this list. Just buy one of them. I would need some convincing that the 120ED would be much of an advance on the 127mm Mak.

I would have thought that the GPS does not need to be set up. I have GPS built into one of my Celestron mounts and it just works if one turns the mount on, selects an alignment mode and waits a bit.

Cone error is an error pertaining to German equatorial mounts. If you are not using a German equatorial, this suggests you have a problem with the software. In any case I do not see what this has to do with the GPS dongle.

Your options for a Alt-Az GoTo fall into two groups, those barely adequate for your 4.1Kg scope (and don't forget the added weight of finder and eyepiece) and those like the Az-EQ5 with a much greater capacity and a much higher price tag. One of our astro club menbers had the ST120 on an Ioptron alt-az GoTo, IIRC.

The plug connection between cable and mount is a common source of trouble. Touching it can cause the connection to momentarily break, causing the GoTo setting to fail. You can fettle the split center pin or use a cable tie etc to stabilise the cable. There is no 'best battery' - any power source that supplies a clean 12 to 14 volts and adequate current will suffice.

A decent field of view for what? Potential deep-space imaging targets vary hugely in size, from the Orion ring (very large) to planetary nebulae (often very small). Any given rig will only cover a limited range of targets to advantage. A telescope like the one you cite will cover a range of targets but you may struggle with the very large, or the very small. With the Seestar S50, for instance, some nebulae fit nicely, but some are too big for it, and all but the nearest and brightest galaxies come out looking rather small. I would suggest that both your quoted mounts are totally inadequate for the intended purpose. I suggest you look at the EQ-5 Synscan as a minimum. A lot of imagers who presumably know what they are doing use an Eq-6. For long exposure runs you would want an equatorial mount to avoid field rotation.