Ricochet

If you're only able to get one Starguider then get the 12mm. In my experience there were no DSOs that the 8 was better on so it is purely a lunar/planetary eyepiece in an 8" dob. Barlowing to an effective 4mm is ok for lunar and Uranus/Neptune, maybe Mars. 

The 12mm would be your workhorse DSO eyepiece and barlow to a 6mm that you can use for lunar/planetary more often than the 4mm. 

The doughnut should be in the centre of the mirror. Unless it is some strange reflection it is nowhere near the centre and needs to be recentred. To do this you will have to remove the primary mirror cell from the bottom of the OTA, carefully remove the doughnut from its current position without scratching the mirror, accurately replace the doughnut, reattach the mirror cell and finally collimate the telescope. Given that this is a new telescope you will probably want to contact your supplier and get them to fix or replace the telescope. 

I guess that the only way to find out for sure is to contact Meade and see if they can tell you what chemical the warning refers to. I think it can even refer to chemicals used during manufacture, that aren't really present by the time you receive the product. 

8 hours ago, banjaxed said:

Are you sure the wire is broken as it looks like it is just the insulation to me.

If it is the insulation then pvc tape will be fine to stop any moisture from getting in.

This is incorrect. The black sheath is not insulation, but mechanical protection for the conductors and their insulation. It looks to have been pulled out of both the cord grip and the moulded section that prevents the cable from being bent at too tight a radius. Insulating tape will not provide the necessary strain relief if the cable is tugged while the plug is in the socket. As the existing plug is moulded it cannot be opened up to refix the sheath in the chord grip. The only options are to cut the existing plug off and wire the cable into a rewireable plug where the chord grip can be accessed, or to buy a whole new cable. 

8 hours ago, Fabiolus said:

I am thinking of cutting near the female adapter and soldering it back to the entire length of wire that came from the laptop adapter even though the gauge is bigger

You cannot do this. The cable is flexible (and likely to be flexed in use) and a solder joint is very inflexible. Without adequate strain relief (heat shrink and insulating tape are not strain relief), the cable will break at the point where the joint is made. This could result in electric shock, fire and/or the electronics in your mount being damaged.

If you want to join two cables then you need to do so inside a suitable jointing enclosure. It is easier to make one connection in a new plug. However, the cost of the plug and the cost of a new cable will be similar enough that you would be better off buying the cable with moulded plugs.

7 hours ago, JamesF said:

I believe there are other SGL users who have the Skywatcher 72ED on the Star Adventurer.  I don't know if they guide or not.

I think the tripod should be ok.  Mine looks a lot like a cheap clone of that one, though it does have a handy little hook on the bottom of the main stem that allows you to add some weight to further stabilise it.  Perhaps the Manfrotto does too, but it doesn't show up in the photos.

James

I suspect that the Manfrotto is from the same factory as our tripods and that the quality is about the same. The ballhead is identical to that supplied with the other brands, including the quick release plate, which is not a normal Manfrotto one. The element series are also not listed as made in Italy, like the rest of the Manfrotto options. The usual hook is visible in the images on the official Manfrotto site. However, the Manfrotto linked above is one with 4 locks/5 leg sections, by going with another brand you can get 3 locks/4 sections which should be more stable when extended.

I would think a 7-8mm would give the best planetary performance but that you might want to push to 6-7mm to get a bit more image scale. The 6mm Baader Classic Ortho and 8mm BST Starguider are all good choices at around the £50 mark. 

If you just want to spend a small amount of money on eyepieces that are optically superior (but no higher magnification) to the ones supplied with your scope then the 10 and 23mm Aspheric eyepieces available on eBay direct from China fit the bill. You can also look at the barlow sold by FLO as "Astro Essentials" which is nice optically without breaking the bank, although paired with a 10mm eyepiece you might find your telescope cannot handle the magnification. 

We will need a lot more information than that. Do you have an exact model number or can you tell us what type of telescope it is, the aperture and focal length? What eyepiece or other accessories have you placed in the focuser? Are you trying to use it on astronomical or terrestrial targets? 

Perhaps photos of the set up exactly as you are trying to use it will help. 

Which particular 8" dob do you have? The Skywatcher dob, for example, has separate 1.25" and 2" eyepiece clamps/extensions that you use one at a time, but that are stacked together when you receive the telescope. This catches out many, many new users who then can't achieve focus. This also makes sense with you being able to focus on terrestrial objects. Closer objects require the focuser to be extended further. If you have an extra extension in place then it makes sense that you can focus on things that should be too close for your telescope to focus on but not on things far away that it is designed for. Posting a photo of your focuser will allow us to see whether anything looks amiss in this department.

 Anher thing that sometimes confuses new users is what the focuser does.  Some people turn the focuser to make stars bigger, thinking that it will zoom in, but this doesn't work. All the focuser does is focus the image at the given magnification that your telescope-eyepiece combination provides. At all magnifications that you can use, stars will always be point sources. This means that you should always turn the focuser to make them look smaller. When you are way out of focus all you will see is one big doughnut of light. As you turn the focuser, this should become smaller and you will see a small doughnut for each star in the field of view. Keep going and they will become points (or as close to as your telescope/the atmosphere will allow). If the stars start becoming larger then you have gone past the point of best focus. If you reach the end of focuser travel without coming to focus then you know that you have the wrong number of extensions in the focuser. If you're winding it into make things smaller then you have too many, if you're winding it out you don't have enough.

Finally, you need to make sure that your finderscope is properly aligned with the telescope. During the day, point the telescope on the furthest object you can find, a distant treetop, church spire or TV ariel. Once you have found it in the main telescope, adjust the knobs on the finderscope so that it also points exactly at the object. At night you can then fine tune it on the moon, or a bright star (when you can find one).

18 minutes ago, pregulla said:

SW is closer to 30nm and there are some reports of it being roughly same performance as Ultrablock.

Do you have a source for that measurement? 30nm is pretty tight for a UHC filter so I would be pretty surprised if that proves to be the case, particularly given that, as far as I know, there is no such thing as a SW UHC, only a generic filter erroneously sold as "Skywatcher" in the UK because it is imported by the same distributor who imports all the SW equipment.

If you're happy with the 16mm then you don't need a 14mm, 12mm is as high a focal length as you'd want in my opinion. I used to use 12 and 16mm quite happily in my 8" dob, until I tried a 14XW and sold the rest to fund a 10.

40 minutes ago, Trikeflyer said:

You see the black rectangles in the picture of the mirror, they all need to be the same size

I think you'll find the large one is the focuser. 

To the OP, follow the astro baby guide. It will show you how to block the reflection of the primary so that you can start by getting your secondary centred under the focuser and appearing circular. 

6 minutes ago, Lockie said:

6" f/8 Newt on a EQ mount should be very good for Lunar and Planetary. 

I think she wanted to know value on the second hand market. If the mirror is decent, and the bearings on the mount, I'm thinking around the £200 mark. Any thoughts? 

 

I'd guess 150-200, depending on the buyer(s). Competing with a new Skyliner 150p might push the price down. 

4 minutes ago, Lockie said:

I think all manufacturers should do that!

Yeah, they've not kept it up with the new ones as far as I remember. 

Look at that, it even gives the year of manufacture. 

2 hours ago, Lockie said:

lol I was trying to make that branding out, cheers. You've got better eyes than me

I've got an advantage because that logo stares me in the face every time I sit at my dob 😉

14 minutes ago, Lockie said:

Any thoughts beyond this? It could  even be an old Bresser?

Given the fairly large Bresser Messier branding stamped on the bottom of the tube I'd say that's a pretty good guess. If your friend can get a close up of the silver data plate under the focuser that will give all the necessary details. The mount looks like the standard Bresser one (Exos 2?). 

Looks good Alan. Let us know how you find it in practice, and the mount that was supplied with it. 

I'll guess an ES Firstlight Mak, 100 or 127mm. 

On 27/05/2019 at 22:25, ginandtonic said:

Great picture from 2 nights ago on the beach 20 mins north of Essaouira (Moulay Bouzerktoun) - 30 seconds exposure, no processing at all... The dark sky in Morocco is really nice for astronomy.....

Really great image. I hope you don't mind but I've nicked it for use as my desktop wallpaper.

However, I'm still at a loss as to whether an 80mm ED would get much use alongside my dob. 🤣

On the SW Newtonians the standard 2" and 1.25" eyepiece clamps are also extension tubes. It is the expected behaviour that if you choose to use a 2"-1.25" reducer instead of the 1.25" eyepiece clamp/extension you must leave the 2" eyepiece clamp/extension fixed to the focuser for all eyepieces. 

However, if you use 2" eyepieces you will soon also want a 2" Clicklock. In this case you should take careful measurements to determine which parts(s) you will need to buy so that the focuser tube is the correct length in order to achieve focus.

55 minutes ago, Jazzo111 said:

Does a vt8 telescope have a slightly offset secondary mirror?

It will have the offset away from the focuser built into the secondary stalk. So long as the secondary looks centred when you look through a cheshire/sight tube it will be fine. 

To get your mirror back in the right place put one hand into the telescope and take hold of the secondary mirror stalk (not the mirror) and turn it so that it faces the focuser. While still holding the stalk, tighten up the centre screw. 

Sky safari for a planetarium. Clear outside and a weather app with radar data for the weather. 

5 minutes ago, Nerf_Caching said:

If I expose my SCT to sunlight, I have to be careful not to cause internal heat buildup due to the folded light path

You don't need to point the telescope directly at the sun. Pointing at the sky, somewhere east of where the sun is when you set up, will do. 

I think the first thing to do is to try the eyepieces that you have and see if you enjoy using the refractor visually. 

Given your skies, star clusters and fields will probably be the main DSO targets and I would think that you will want to use eyepieces <18mm to keep the background sky relatively dark. However, a 24mm 68° eyepiece will still be useful as a finder with the maximum field a 1.25" eyepiece can show. 

There will be a retaining ring on the underside of the filter, just tighten it up.