Cosmic Geoff

The visual back of my Celestron 127mm Mak has a male T-thread.

I think you need to step back and do some basic research on the construction and use of astronomical telescopes, before you think of making one. Also look at reflecting telescopes (Newtonians). For instance, you mention buying an objective lens of 150mm (6 inch) aperture. I think you should be sitting down when you check the price of this, assuming you can find one to buy. If you have to buy the optical components, it will almost always be cheaper to buy a second-hand telescope than to make one. A modest aperture will suffice to show Saturn with the rings projecting on each side, e.g. a 70mm aperture refractor.

Given the age of the telescope I suspect that the chance of being able to buy a replacement part is nil. A skilled machine shop should be able to straighten it out for you, if you can find one in your area. You might be able to replace the entire focus tube assembly, if you can identify a modern one which is compatible, but that could be expensive. People often upgrade the focusers on modern scopes. As for the focus, telescopes are generally constructed to give them a useful focus range when particular parts are attached. For instance, my Startravel is designed to focus with a diagonal and eyepiece attached, and to attach a DSLR a t-thread extender tube is required. It is quite common to discover that for attaching cameras you need to shorten the tube (Newtonians) or add extension tubes (refractors). I bought a T-thread set of extender tubes which in combination offer various lengths of extension.

Some of these could put you off astronomy for life. You should buy from a specialist astronomy retailer. Astronomy is not a cheap hobby and you should be prepared to spend for something that performs well and is not a pain to use. The 130p dobsonian quoted above would be a good choice to start.

I have the ZWO ADC and it works well. If you are undecided which brand to buy, toss a coin.

The highest power eyepiece I ever used with my 127mm Mak was 8mm. Forget the Barlows and buy a decent 8 or 10mm eyepiece. The higher power eyepieces supplied with these kits are notoriously not much good. When I bought decent eyepieces of 8 and 10mm for my Mak the improvement in performance on double stars was marked and obvious.

Why would you want 12v or 13.8 volt regulators/converters? I have run mounts directly from my LIFEPO4 power tank for years without incident. The actual output voltage versus discharge state of these batteries can be found on data sheets.

I have a Celestron LiFEPO4 power tank which already has USB ports built into it, not to mention handy red and white work-lights. Note that a "12v" LIFEPO4 battery will require a specialist battery charger - mine came with a 16 volt charger.

The quoted loadings exclude counterweights. For visual use, you can load the mount up to the rated load (e.g 9Kg for an Eq-5). I put a 203p Newtonian (which weighed 9Kg+) on an EQ-5 and it worked well enough for visual use. For imaging, one is recommended not to load the mount to its full capacity. I am now using the same mount for EAA with a 102mm Startravel (I had to buy a smaller counterweight), and that works well. The counterweights on an EQ mount do not weigh the same as the scope and accessories (usually less) as you can position the weights anywhere on the counterweight bar as required. The actual weight needed depends on the physics of levers (q.v.)

You do not need large aperture for imaging, unless you want to image small objects at large image scale. Look at the small refractors that some imagers use. Exposure time makes objects brighter.

Is this for visual or imaging use? The manufacturers may quote for visual use, or for both. Suggested loadings for imaging are much lower. An EQ-5 will take about 9Kg for visual use. I put a 200p Newt on an EQ-5 and it wasn't too bad (for visual use). Logically, if you look up the load capacity of an EQ3-2, the load capacity of your proposed combo with be somewhere between that figure and 9Kg (for visual use). If your aim is imaging with the 150PDS, then forget the EQ3-2 and start saving for a proper mount.

When I had that version of EQ5 I bought a 6 volt lead-acid battery and a charger (the latter intended for R/C gear). Given the ubiquity of 12v power sources you might consider a 12v-to-6v stepdown converter.

If you don't have the user manual for the CPC, you can download it. I have a smaller version, and find it particularly suited to planetary imaging, as well as general viewing. I have also used mine for imaging small planetary nebulae. I have fitted it with two finders, a red-dot for coarse aiming, and a 9x50 RACI finder for fine aiming. The Nexstar 'Precise Goto' menu item is very useful for locating smaller fainter objects. If you don't have a dew shield (essential in UK) you can buy or make one. (If you have deep pockets, a dew heater ring and black aluminium dew-shield are available. The metal dew-shield looks very smart - saw one at at astronomy show.) You can hook the mount (actually the handset) via cable to a laptop, which allows you to control the telescope via various programs. I suggest you read up on Celestron SCT material generally - this may uncover some useful topics and tips. Check out nexstarsite.com. Your mount or handset might benefit from a software upgrade, especially if the GPS doesn't work, but remember the engineer's old saw "If it ain't broke, don't try to fix it." 🙂

Depends what is causing the light pollution. Once upon a time, street-lighting used lamps that emitted a few narrow-band wavelengths easily filtered out. With modern white LEDs it's useless, except that a filter that costs more than your scope outfit might offer a slight improvement. If you are observing gaseous nebulae, narrow-band filters e.g 'OIII' will offer a distinct improvement.

What is your level of experience? What do you expect stars to look like? A star should look like a point of light, irrespective of the telescope's field of view, or the magnification. Anything else is scatter or diffraction in the optics. Maybe if you look for double stars or globular clusters or planetary nebulae you will find those of greater interest. The 10mm kit eyepieces are generally acknowledged not to be much good, and deserving of an upgrade of the same focal length.

You need an EOS to T2 adapter, and a T2 to scope adapter. It seems you already have the latter for the SCT. Some refractors have a T2 thread at the focuser. Seems your Swift has this, so you just need the aforementioned EOS to T2 adapter, and possibly a T2 spacer to get focus.

A 120mm APO and a HEQ5 + accessories would be a good setup. Assuming that this is the kind of scope you actually want. What are you going to do with it? Another thing to consider - keep a cool head and add up the new retail prices of all these items - it does not have to be exact. Another Sky watcher ED 120mm comes in at about £1400, and the HEQ5 is about £1000. If you think this offer is a bit too good to be true, don't part with any money till you have checked this out from all angles, and if possible gone to see the items yourself. As a guide, astro kit on good clean & working condition typically sells used for about 66% of the new price.

I don't have a freedom Find mount but I have a Sky-watcher EQ-5 Synscan and three Celestron Nexstar mounts. I've always preferred the Celestron software - it's a little easier to use and has one or two features that the Synscan doesn't. I have not felt the need of Freedom Find, as though it can take a while for the mount to slew round, I often have little idea where it's going to end up pointing.

I'd say the mount/tripod is inadequate. It might do for visual use but for deep sky imaging it is clearly inadequate. Some imagers use a smaller Newt than that, e.g. a 130PDS, on a much heavier mount (Heq5 or EQ6). By the way, one night I forgot to position the counterweight on my EEVA imaging rig and the EQ5 Synscan was apparently not affected at all.

The most practical solution would be to order a replacement 4/5 SE motherboard, which hopefully you can obtain from Celestron or their distributors. OTOH, if the "chips" are generic resistors, capacitors or diodes, you might be able to source suitable replacements on ebay. This assumes you have the capability of identifying and desoldering/soldering them yourself. If not, you would be better advised to buy the motherboard.

What is your budget? Is weight or bulk a constraint? You could add a Newtonian to that list. Why have you ruled out a Schmidt-Cassegrain? For planetary observing, the bigger the aperture, the better (seeing permitting).

Rather than rushing to buy anything you should take a step back and do two things: 1) Buy the books "Making Every Photon Count" by Steve Richards (a book on deep-sky imaging available from FLO) and "Guide to High Resolution Lunar & Planet Imaging" by Dave Eagle FRAS (see his website www.star-gazing.co.uk for distribution.) Depending on how much you understand of the contents, certain conclusions can be drawn... The investment of £20 +£10 here might save you much more money further down the line. 2) I understand that you already have a camera, and a small telescope. As others have suggested, put the camera on some sort of mount and try imaging the night sky with it. Then attach the camera to the telescope and try imaging something with the combination. Download some free software with which to process the results. After this experience you should have a better idea of what practical astrophotography is like. You will then have a much better idea what to buy in order to progress with the hobby than if you buy expensive kit blindly. The Advanced GT isn't a bad mount. It's obsolete, but similar to the current model AVX. "Scope" I assume refers to the C6, which is a handy scope to have but not a first choice if you want to image anything. The focal length is much too long for widefield and it's on the small side for planetary imaging. Note that you can generally download the user manual for any mount or mount/telescope retail bundle from the Internet. If you are not familiar with GoTo mounts, it would not hurt to download a manual and read it. The instruction manual for my EQ-5 Synscan mount runs to about 50 pages.

You probably need to read up on the techniques for planetary imaging. 🙂 The normal method is to take a short video, but a DSLR may not be well suited for this - serious planetary imagers use a large telescope with long focal length and a planetary camera that can take high-speed video and crop the region of interest.

If you want to image these in particular you should pay close attention to what telescope, camera, filters, mount etc and in what sky conditions the imagers you want to emulate operated. I have tried imaging both these objects from my Bortle 6 location with the gear mentioned above and the results were very poor.

To give you a pointer, for EAA I use a 102mm f5 achromat telescope, an ASI224MC camera and a EQ5 Synscan mount. (Partly because I had all this gear anyway) It works really well for quick images of anything that will fit in a 0.5 deg field, e.g smaller galaxies and various planetary nebulae. It is not much good for imaging planets (too small & focal length too short) or for really wide field images (all of M31), or for taking long exposure award winning images. If you all up the prices you will see this is over £1000 worth of kit, excluding the laptop. You do not need a large aperture for imaging - a bit of exposure time brightens things up marvellously - unless you want to image very small things at a high resolution. If you want to image anything you need a decent mount - you can always change the scope or the camera. You mention dso imaging with a large Newtonian in your initial post - that is not beginner stuff, and generally requires autoguiding. And check the prices of large chip cameras.