Cosmic Geoff

Early morning session with CPC800, ASI462MC, filter wheel, ADC, visual pass, UV and methane filters. Jupiter & Saturn: 5000 frame video, processed with Autostakkert & Registax, Moon 500 frame video (infrared), methane single shot of 556ms. The Saturn image is similar to that from 20 July, while the Jupiter image is my best for this season. The Jupiter image taken with the CH4 (methane) filter is interesting. It shows the GRS, a bright belt and two moons.

Only if your expectations are low. A good scope for planetary viewing (or imaging) bears little resemblance to a good scope for beginner DSO imaging. You could try DSO imaging with the 114/500 if you put it on a serious mount. If you are limiting yourself to one scope, then you should decide what sort of thing you want to image (ultrawide, e.g. the Orion ring), wide field (M31 and companions), narrowfield (small distant galaxies or planetary nebulae), or planetary, and buy accordingly. Trying to make one scope or camera do everything is unlikely to end well. There are tools that can show you what field you get with a particular scope and camera.

The C925 will not be balanced once you move it away from the horizontal, unless there is a balance weight not visible in the photos. Also note that the Celestron OTA is designed to be mounted via a dovetail bar on the side. My 8" Celestron SCT is mounted that way.

What objects do you want to see? Faint extended objects will be invisible or very hard to see in Bortle 7, while planets and double stars will be observable. EAA would help to some extent.

I'd need convincing that it is worth trying to upgrade the mount, given that it is already GoTo and has plain bearings. If its existing performance does not match your ambitions and the APO scope, I'd say you need to invest in a better mount. I use an EQ-5 Synscan for EEVA imaging with a 102mm achro. The mount has a bigger weight capacity than the EQ-3-2 and has roller bearings. Ambitious imagers recommend an EQ-6.

SCTs with their typical f10 focal ratio, are not demanding of eyepieces, so no desperate need to buy exotic eyepieces. I use Plossls for the lower powers. An 8mm eyepiece is the highest power you are likely to need. I have a 5mm Celestron X-cel LX I acquired as part of a bundle, but have only used it once or twice in my SCT.

Have you looked on FLO or other sites, to see what kind of mount is bundled with Celestron's C925 when sold with a mount? You will see that they are all GoTo mounts. Celestron don't offer a non-GoTo or manual alternative. See also the CPC925 which is integrated with a fork mount. I have the same tripod that's used for the CPC925. It's quite a heavy item and very rigid. I fitted a second dovetail bar on the OTA of my C8 SCT to mount accessories and to give something to hold on to while mounting the scope.

A case where a camera will reveal far more than the eye. From my Bortle 6 location I have secured many images with a 4" refractor that show spiral arms in galaxies.

It's an adequate planetary camera. But there are later models with smaller pixels that match better with typical planetary scopes, e.g. no Barlow needed with a SCT or Mak. With a ASI224MC and a f5 scope you'd want to use a Barlow lens of around x3.

Check out AWR: AWR Technology (Astronomy - Electronics, Motors, GOTO drives, Sidereal Clocks, Display Units) who may be able to do something for you.

Revelations of driver trouble here: New ASI120MM Mini Drivers Not Working - Beginning Deep Sky Imaging - Cloudy Nights

Premium batteries should work, but I have found that the cheap "8 for £1" batteries are useless. Try a proper power supply if you can. I have not encountered a case where refreshing the firmware restored an apparently dead handset to life. I assume you are plugging the handset into the socket marked "Hand Control". But if you want to try it (which entails buying cable, adaptor and downloading various bits of software) you might at least get an idea of how dead the unit is. Does anything happen if you press the R/L/up/down buttons in the middle of the handset? You could also dismantle the mount base to see if anything is unplugged in there.

The problem could be anything from bad connections to a faulty handset. Since you got it from an estate sale, there is no guarantee that someone hasn't opened it before you and fiddled with the insides. Are you using an adequate +12v PSU? You can buy replacement handsets, but i suspect this could cost more than you paid for the whole thing.

I have never used heaters with my SCT. You can make your own dew shield out of foam mat or cardboard if you want. I'd rate a dew shield as an essential #1 accessory. If you have plenty cash, the new aluminium dewshield looks very good and is compatible with the Celestron heater ring. Planets can be a disappointment if viewed visually, looking small and over-bright. It's best to use a lot of magnification, which makes them look bigger and dimmer. They may look blurry at high magnification, but at least you can see some detail. I tried 5 and 7mm eyepieces on Mars once or twice when the seeing was good, but that's an extreme. Generally a 8 or 10mm eyepiece would give enough power for your scope. You could get a zoom eyepiece, which will either suit you or indicate which fixed eyepieces you need to buy. Also check the collimation of your scope - if it is not spot on, performance will suffer. It should be OK on a new scope but you never know...

I dragged myself out of bed on the morning of the 20th, for what the forecast claimed would be a clear night. There was cloud around, which gradually got worse, but I secured my first Jupiter and Saturn images of the season. CPC800, ASI462MC, ZWO filter wheel with UV/IR cut filter, ZWO ADC, videos of 5000 frames, gain 350.

I've seen an observatory mounted 16" LX200, which had a non-adjustable wedge, probably the norm for this class of instrument.

I have taken a large number of DSO pictures with an ASI224MC, basically because I had one already and did not want to spend loadsamoney on a more suitable DSO camera.

The reason for such guides is to match the pixel size to the resolution of that aperture of scope. The focal ratio here includes the effect of any Barlow lens etc. For example, a 2.9um pixel size used with a f7 scope and x2 barlow would be about right. For planetary use the FOV will normally be restricted to keep the resultant video to a manageable size. A large sensor is not entirely wasted as it is useful for finding the planet and centering it. It will also be advantageous if you also want to use the camera for deep-space imaging.

The GoTo is more to keep the planet in the FOV when you have narrowed the region-of-interest for taking a video. It drifts off quicker with solar system align than with 2-star align, which suggests that tracking with a poorly aligned equatorial or a manual mount will not be much fun. Also useful for finding Neptune. 🙂

If starting from zero, you need a GoTo mount, a telescope of medium to large aperture, and a planetary camera. My last purchase was a ASI462 with 2.9um pixels. This camera is already superseded. If you already own an ASI120MC or a ASI224MC, that will work. Note that the smaller pixel cameras do not require such extreme effective focal ratios as recommended for larger pixel cameras. Most serious planetary imagers use a SCT of 8" or larger, or a Newtonian of similar aperture.

With the similar GoTo mounts from Celestron, a common cause of failure was that the mount firmware got corrupted and needed to be re-programmed via the handset connection. I have no idea how you'd reprogram a Supatrak mount. Good luck with that. ☹️

Buying fancy diagonals will give a marginal, perhaps un-noticeable gain in performance over stock types. If you pay more, the gain is mainly in better construction, longer coating life etc. If you want more performance for visual astronomy on a budget of £500, the obvious answer is to buy a 8" or 10" Dobsonian.

The Moon images look over-exposed and the focus is not good. I suggest some research on the advanced controls for your smartphone's camera. Can you manually control the focus or exposure? Can you lock it at focus on infinity? Note that the size of the Moon is about 1800 arcseconds and the size of Venus (at present) is 41 arcseconds.

You have still not told us what camera you are using. If you are taking a photo through the eyepiece and the image is visually in focus, then the camera image should be roughly in focus. But if you are using a smartphone it may be trying to use its own autofocus & auto-exposure, and for all we know it's trying to image the insides of your telescope. A true image of Venus taken through this scope with a 20mm eyepiece will probably be on the small side.

I made the observations (images) on 7 July above at around 4pm with Venus at its highest. I could try yesterday's experiment again with the Sun near the meridian. I suspect that OSC camera response divided by corrector plate attenuation results in a major loss of UV signal. I am thinking of trying a Blue filter next time I get the chance.