Cosmic Geoff

I imaged Venus early one morning. It's bright enough for anything. I don't know what a Wratten #47 filter is without looking it up, so don't know why you'd want one. You'll want a fairly short exposure to avoid burning out the image. I got a half-phase image that was bright on one edge and faded toward the terminator line - interesting effect.

I bought the ZWO IR-cut filter (for correct colour imaging) and the ZWO 850nm IR-pass filter (for IR imaging) with my ASI224MC. The exposure required for IR is about ten times the colour exposure.

Looking at planets visually is often a disappointment, as bad seeing often messes up the image, or the image looks 'too bright'. Some observing experience is needed to get a good view. A single shot camera image is almost guaranteed to be blurred, which is why serious planetary imagers shoot a video and then process it to extract a sharp image. If you want to test your new 'scope, let it cool down outside for an hour or so, aim it at a not-too-bright star near the zenith, and using a high power eyepiece, look for concentric diffraction rings around a central dot.

One can access the CF card contents on the Canon 300D using a Windows XP laptop with the Canon driver installed. One can then import or preview the images on the laptop screen. This is an obsolete OS. With Linux Mint Cinnamon 19, one can access the camera's CF card and import the files using the Pix utility, without needing to find a Canon driver. (I wonder how many people know that? 🙂) The import seemed a bit slow on my old Dell D430 laptop.

I am not familiar with that mount, but can you not swing the OTA past the vertical to the other side, and rotate the star diagonal through 180 degrees, so that the finder is now on the upper side?

Bumping this up - this has been an informative thread. I have now received the video monitor. It is decidedly not HD with a resolution of 719x234 dots, which is enough to read the camera menus but does not show all the detail in the stored images. I'll need to try it in the dark and see how useful it is in practice.

The effective field of view when planetary imaging is quite small, and unless you use a flip mirror diagonal assembly (look it up) or centre the planet accurately in the eyepiece, you will have difficulty getting the planet image seen by the camera. In any case, a DSLR is not the best tool for planetary imaging. You really need a 'planetary camera' which is a specialised video camera, used in place of the eyepiece. An ASI120MC-S would be a useful entry level camera for this. With my planetary cameras I have to switch between the full frame (for target acqusition) and a 320x240 pixel region of interest (for more efficient video capture). The video is later processed into a sharpened image. What is a flip mirror? see: https://www.365astronomy.com/365Astronomy-Imaging-Flip-Mirror-with-Non-Rotating-Helical-Micro-Focuser.html

The 300D is one of the few Canon cameras not supported by Backyard Eos. Canon's own software does not run on recent Windows OS. IIRC, APT does not support the 300D either.

I recently acquired a Canon 300D body to gain some experience of handling a DSLR. I can attach it to at least one of my telescopes, and it was not hard to take pictures in daylight with it attached to a 102mm f5 achromat, or with a Canon zoom lens I bought used for it. In the dark though it's a different story, when I can't see the controls, can't see if it's in focus and can't see if the exposure was right on the small built-in monitor. I got a dawn picture of the Moon + Venus, handheld, using the zoom lens, which has a very grainy sky background. Using the 102mm achromat on a EQ-5 GoTo, I got an image of the Double Cluster, with very grainy background, and M31, also with a very grainy sky background. The exposure was 4 secs IIRC. I have ordered a used 5.6" video monitor to use with the camera which I am hoping wil help, assuming it works and Hermes don't lose it. 😦 Any tips?

M76 was live stacked with 16 frames x 5.04 sec exposure. The Veil was live stacked with 18 frames x 11.5 sec exposure.

I can't see that I would do anything very different, which was to start with an inexpensive visual telescope and gradually work upwards to an imaging setup that would cost nearly 2500 UKP if ordered new today. I certainly would not have ordered that last telescope as my first instrument - it would have seemed far too expensive. Some people are intent on trying deep sky imaging but I have avoided it so far. Beyond that, my advice is no different from what I would put in any other 'What scope' thread: make some basic decisions: do you want to 'keep it simple' or have all the electronic assistance (= GoTo) you can afford? Get something that suits your situation (dark skies or urban murk) and your physical situation (how far to you need to carry it?).

Celestron brand should fit but it does not mean others will not. You can even make your own from cardboard or an exercise mat and it will work as well as a bought one.

Try a plain unheated dew shield. If that is not adequate at your location, then look at heaters. I don't use a dew heater.

Good advice above. The diagonal should not hit the mount if the 'scope points vertically up. The scope should be as far forward (or up) as it will go in the clamp - it is not meant to 'balance'. Starsense alignment is meant to start with the scope pointed in an index direction - I use horizontal due south. I have found that a poor connection at the power inlet on the mount will cause mount misbehavior of the kind you describe. With poor sky conditions in the form of bright sky I have found that the controller can give an alignment successful message despite pointing in completely the wrong direction. It is less aftected by scattered clouds. You should also re-check the dummy stuff such as lat/long location, time zone, etc. Updating the firmware never fixes this kind of issue. But the Starsense should be updated to the latest issue as you have done, to fix more subtle issues (always read the small print).

Since budget does not seem to be a problem I would suggest you get an entirely separate outfit for astro imaging, on the lines of a small APO refractor mounted on an equatorial GoTo mount. That means you can have the C11 on an alt-az mount (eg the CPC1100 package) which will be a lot easier to set up if you don't plan to have it permanently set up in some sort of observatory, and also easier to use. (and cheaper than the CGX-L package). If you are determined to get an equatorial mount for the C11, there is no need to restrict yourself to Celestron mounts (unless you can get them at a particularly good price, of course).

On 14 Sept I tried EEVA imaging a number of planetary nebulae and other objects, with 102mm f5 achromat and ASI224MC camera on alt-az SLT mount & wood tripod. Among the most interesting were M76 and part of the Veil nebula. The Veil is just visible in the image. Skies are Bortle 6 here.

Some suggestions: Concentrate on observing stuff that punches through the murk, eg the Sun, the Moon, the planets, and double stars. To observe the planets you will need a good view (low horizon) to the south. It seems that deep space astrophotography will be a tough ask from your location. Or you can subscribe to services that give you time on a remote telescope.

Depends what exactly you want to do with it. The C9.25 and C11 would be great for visual observations regardless of what mount you get. For planetary imaging you should get a better mount - for the C9.25 that would be at minimum the Evolution mount and the heavy duty tripod. Or the CPC925 veriant - but be warned that this is very heavy. The C11 could be used vith various mounts including the CPC1100 setup, which would be good for planetary imaging, but the CPC1100 ota/fork assy is alarmingly heavy. You could put either scope on an EQ6 mount, but what for? A SCT is not suited for beginner's deep space astrophotography. If you are not going to attempt deep space astrophotography, you can do everything with an alt-az Goto mount which will be much easier to manage. It is rumoured that the reason SCTs are relatively cheap secondhand is that people buy them for astrophotography and after trying it they sell the scope on. You could get the Edge HD version, but note that the extra correction optics are mainly intended for imaging, and won't do much on a planet in the centre of the field. On the other hand, some claim that these models perform better visually, and it is rumoured that the Edge HD models are hand-finished in the USA rather than machine finished in China. That may be an Internet rumour though. The Starsence is a handy time-saving accessory that can be bought separately, but note that I have found that having GPS built into the mount leaves little incentive to fit a Starsense, as the setup work is reduced to aligning on a couple of stars, which is quick and easy with a Nexstar alt-az mount. I mostly prefer to use handsets rather than the extra complication of cabled computers or wifi tablets.

I think for planetary imaging you could ignore the balancing so long as the outfit is roughly in balance. My experience is with alt-azimuth GoTo mounts which are not balanced in the first place. I star align with an eyepiece and then fit the imaging accessories. It would be nearly impossible to do a star alignment using the planetary camera - the field of view is far too small.

Great choice of telescope. The C8 is not demanding of eyepieces: with mine I use the 25mm that came with it, a 15mm Plossl and a 8-24 zoom or an 8mm eyepiece. Don't buy an eyepiece/filter set.

I am not sure what the problem here is. The tripod should not deflect visibly when loaded with the scope and counterweight. Also, for visual use, any slight change in the levelling will not be critical. How are you measuring the levelling? With a bubble built into the mount head? That is not an accurate device, but sufficient for visual setup. In fact, this mount and tripod, being part of an entry level kit, will be on the wobbly side, and if you feel it is inadequate the only solution is to buy a more substantial mount and tripod.

Which mount did you get with the Celestron Nexstar 8 (and is this the C8 SCT?) The popular entry level SE mount is not suited for astrophotography, wedge or no wedge - there is too much wobble and backlash. A lot of people buy a SCT and wedge with the intention of doing astrophotography, find out the hard way that this was a bad idea and either sell up the whole outfit or buy a german equatorial mount. Indeed I have seen it written that this is the reason that SCTs are often surprisingly cheap second hand.... One issue quoted is that polar alignment is such a pain that you would only willingly want to do it once and leave the outfit permanently set up.

You could use the scope as-is with its star diagonal for terrestrial targets if you don't mind the left-right reversal. Otherwise look for a suitable erecting prism diagonal - maybe ask retailers to avoid being caught out by vague descriptions. Remote viewing from indoors is not as easy as you imagine. I have the Starsense, and while it is a time saver it is not (in my experience) any more accurate than a two-star align so it is not guaranteed to drop objects into the eyepiece FOV. Then you need a camera. Unless you spend a great deal of money the chip size will be small, giving a FOV similar to a 6mm eyepiece, making it difficult to get an object centred on the chip even if you stand by the telescope, let alone remotely. A DSLR will have a much larger chip but may introduce other problems. Then you have to focus. If you have to adjust this remotely, this means an electric focuser. I suggest your first step should be to attach a camera to the scope and see just how difficult it is to get an image on a screen, before you think of trying it remotely.

If you want to attach a DSLR you need the PDS variant, otherwise you may find you can't get focus with the camera. Some imagers use the 150 PDS with an EQ-6 GoTo mount, which seems to show how far the mounts you are looking at are off the mark. With your budget you could get a tracking mount on which to mount the camera directly for widefield imaging, or a telescope on a light mount suited for visual only, which you could try experimenting with for imaging or EVAA. I found I could do interesting EVAA with a 102mm f5 refractor, SLT alt-azimuth GoTo mount, and ASI224MC camera but the camera alone would use up most of your budget. And I used a more rigid home-made wood tripod.

You mean change the whole outfit? That opens up a wider set of possibilities (depending on your budget). The 150/750 would be less of a 'wind sail' as well as being lighter. You would definitely need a barlow lens with it for planetary imaging. And it might require more exotic eyepieces for general observing. If working in a windy environment you should think of using a heavier mount, e.g. EQ-5. A wind shield would only be partially effective and could itself be a hazard in the event of really high winds.