Cosmic Geoff

A GoTo Dob is a lot more expensive than a basic manual Dob. You should question whether you would not prefer a SCT on a GoTo mount (affordable if used, and much more compact), or a Newtonian on a GoTo mount (more potential for forays into basic imaging, or mounting alternative scopes.)  A suitable Eq GoTo mount for an 8" Newtonian is likely to cost you more than I paid for my C8 SE outfit (used).

BTW, I had a Newtonian on a manual equatorial mount, and I thought the combination was horrible and user-unfriendly.

While doing some solar observing just now, it occurred to me that unless your mirror is smashed into tiny bits like an auto windscreen, you should be able to use the biggest piece to determine the focal length.  Set it up so that it focuses an image of the Sun back onto a piece of white card, and measure the mirror-to-image distance.  This will give you the focal length with a reasonable degree of accuracy.

Armed with the diameter and focal length, you can then get quotes for a mirror from amateur telescope makers and other optical specialists. Once you have an agreement in principle, you can give the maker the bits to play with, so that he can confirm the focal length and figure (spherical or ???).

Given that a MN 190, smaller than your scope, costs around £1000, this approach may prove cost-effective.

What about the screen and keyboard? I use a Windows 7 Dell Vostro laptop (look it up) at the telescope for planetary imaging and some processing, which suggests the requirements are not too demanding.

IIRC the Powerseeker is not highly regarded, but the Celestron Nexstar 6SE is a decent piece of kit.  It has the same mount as the C8 SE. 

1 hour ago, shropshire lad said:

Haven't got round to using this mount as a eq.

We should have asked before (or you could have told us) - what model of mount is it?

2 minutes ago, shropshire lad said:

I was just trying to determine if polar alignment is good enough with polaris or does it need aligning to true north?

Thanks for your inputs.

With the latest version, Synscan gives you a slightly cryptic readout of how accurate your polar alignment was, which you can fine-tune or ignore.  If you mechanically polar aligned on Polaris, it will therefore indicate a small error. If you try using it to GoTo objects, you will find out how good the polar alignment is in practice. I suspect that any polar alignment will prove good enough for visual use. (Remember that alt-azimuth GoTos work just fine and they are not polar aligned at all.)

A very precise polar alignment is only required for long exposure astrophotography.

Did you mean 'Synscan software'?

If you did, the latest versions offer you the option of fine-tuning the polar alignment after a successful 2-star or 3-star align.  The exact details are too complicated to quickly explain here.  Try it and study the manual.

The original concept of the Dobsonian was that you could build your own using junk parts rather than buying a factory made scope and mount at a fancy price.  Alternatively, it should be possible to source a ready-made base if you search around, but your budget is low.

Making a base shoud be a straightforward DIY project - the Skywatcher ones are made of chipboard, I believe. Also budget for a finder scope (various options) and eyepieces at around $50 each.

I'll note in passing that in theory you could fit the tube with tube rings and dovetail bar and mount it on a german eqiatorial mount, but this would be rather expensive.

Today I dug out a couple of dew heater bands (large and small) from my spares box and measured their resistances. Together they would consume 1.75 amps at 12 volts.  That would flatten a 17AH battery pack in about 9 hours.

The older Canon DSLRs are fine for day use but not user-friendly for astro use compared with newer models which have liveview etc.  Try focusing through the viewfinder on a bright star and cross your fingers.

See the beginners telescope section on forum sponsors FLO website. That shows what beginner scopes they could sell you (if they had stock).

Also check out the Celestron 127mm Mak SLT - mine still gets regular use.

6 minutes ago, stargamed said:

I have been able to put the camera into my refractor scope and get a close up image of a leaf from about 100 yards away with color too.

That is significant, as to focus on objects that close you would need to move the camera further out than for infinity focus.  A Barlow lens may enable you to get a proper focus at infinity, but your field of view will already be on the small side.

6 hours ago, Pryce said:

Would probably be hard to get my hands on a suitable mains converter anytime soon though. Would a standard 230v-12v converter work or do I need somerhing more specific? 

What do you mean by a 230v-12v converter, exactly? To power your kit from the mains, you will need a unit that converts mains power to regulated +12v DC.  There are hundreds of such things, ranging from power bricks to large bench supplies with screw terminal outputs.

If you can use mains power, that is likely to be the cheapest and most reliable method.  For powering a visual mount (and no dew heaters) I use a battery pack. It's quicker and safer than running an extension cable and the charge lasts for several sessions.

So your 17AH power tank went flat after about 4 hours? Without knowing the total load, I could not possibly comment on whether this is bad or normal.  What was powering the laptop? Laptops are a power hog.

4 minutes ago, Paul M said:

My recommendation would be good second hand NEQ5

That would be good if you need a heavy mount for something else but overkill for a Mak that weighs about 4Kg. 

Most of the wobble in a SLT mount is down to the tripod so upgrading that rather than the whole GoTo mount is a sensible upgrade.

The Sky-watcher 3.8" tripod (listed by FLO) will not do what you asked for in your original post, but it looks like it might be easy to make an adaptor plate for a SLT mount head if you have metalworking tools.

13 minutes ago, NenoVento said:

Yesterday I also noticed that the DC socket is a bit loose (which was the cause for some connecting issues that were driving me crazy!).

That is a problem with many mounts that use the same connector style. (e.g. SE series).  I have cable ties stuck on next to the sockets to restrain the cable. In the case of the CPC800, it helps if you pass the cable through the loop of the adjacent carry handle. You can also splay the centre pin with a sharp craft knife.

No such tripod exists. You will have to make an adaptor. If you search around you may be able to find a suitable design.

I bought a spare 'bowl head' from astroboot and made wooden legs for it. (It was rather laborious.)

We had a couple of Meade achromats with GoTo mount at our local astro society. They were not well regarded, and Meade do not have a good reputation for customer support.

The Powerseeker - see the comments above.

The 152-750 looks like a reasonable scope but the mount might prove to be on the wobbly side.  Also the mount is descibed as alt-az but looks like an equatorial in the picture, which does not give one much confidence in the seller.

Where are you? The last link was for Egypt. If that's where you live, you may have limited choice in what you can order, particularly with the Covid-19 epidemic causing supply problems.  As noted above, depending on what you want to look at and your capabilities with tech, you might find the equatorial mount more of a nuisance than a help.

Note that some reputable astro dealers like FLO can ship internationally.

I have a CPC800 and had trouble with the azimuth bearing, which caused problems with tracking and a notable resistance when spinning the mount with the clutch released.

I followed the procedure you mention but fortunately found that all I needed to do was slacken off a large adjustment nut.

I have not read much positive about these mounts mounted on a wedge, and my own experience is that a C8 is not the best tool for deep space astrophotography.  All the deep space images I took with a C8 looked awful, giving me no incentive to persist, while those I took with a 102mm f5 refractor were often pleasing.

I'd just add that should you manage to rebuild the focuser and eyepiece attachment, you should also acquire a 2" to 1.25" adapter, which would allow you to use 1.25" eyepieces, which for the shorter focal lengths (e.g. 15mm) are cheaper and more practical than 2" barrel eyepieces.

I would agree that if too many item-specific and hard to source parts are missing it could be better to just buy another scope outfit.

As a rough guide, a complete focuser assembly could cost £100, and eyepieces £30 to 50 each, and a replacement GoTo mount and tripod for a refractor that size, £550.

Also as a guide, a similar outfit, a Sky-watcher 120mm Evostar on a EQ-5 Synscsn Goto mount, costs about £839, so if you can fix yours it is worth having, or re-selling if you can't fix it.

Observing faint and extended deep sky objects like galaxies from a light polluted area does not work well. You ideally need to be at a dark skies site.  What is the Bortle value where you live?  You will see more galaxies with your existing scope at a dark skies site than you would see with a 12" from a town.

On 29/11/2020 at 07:36, stargamed said:

Popping the camera into the reflector or the refractor telescope yields nothing.

Typically, the camera needs to be further in toward the objective lens than an eyepiece would be.  The position needs to be exact, otherwise the image is so out of focus that nothing can be seen.  This can mean that focus cannot be achieved, particularly in the case of a typical Newtonian reflector, or a refractor with limited focuser travel.

As for your trouble with the drivers, this is not impressive. Maybe you should just ask for your money back.  I had no trouble at all getting two ASI cameras and a Celestron camera to work with Sharpcap, or getting the Celestron camera to work with the software supplied. 

13 hours ago, aeneas said:

I think it does make sense to learn everything first doing well with a minimal setup and visual only and then adding one item at a time. The only item I am tempted to start with asap is the ASIAIR - not for AP, but even just using a guidescope with the ZWO174MM mini camera for the system to give me a more precise polar alignment and control of the mount for browsing the skies via the ASI iPad app... I guess I'll need to figure it out. 

I assume this is a GoTo mount... You do not need to do any of that for visual observing. Just get the mount polar aligned as best you can (mechanically) and then do a star align (electronic) and you should find that you can GoTo objects and track them just fine.  You don't need any apps either - just use the mount's handset.  Even the alt-azimuth Celestron GoTo mounts find and track just fine and they are not polar aligned at all...

A closer polar align may be needed for astrophotography, but you can worry about that later.

As for the Grand Conjunction, it looked good on the 19th and 20th, so don't despair of seeing something...

You could get an ASI120MC-S for £150.

I should point out that the field of view you get will be similar to that of a 5mm eyepiece - maybe not what you were expecting. 

If you own a DSLR with a large operating screen and LiveView you could try attaching that.

You need an actual field of view of about half a degree, so whatever gives you that will work.

I used an ASI224MC on a 102mm f5 achro yesterday.