Louis D

1. Try removing the four screws holding the rack against the pinion.  That should allow you to remove the pinion and then slide the focuser tube out.
2. You may want to remove the focuser from the tube for the next step as well via the three screws attaching it.
3. Clean out all the gunk out with carburetor degreaser spray or similar on both the focuser body and focuser tube.
4. Relube it with white lithium grease.
5. Reassemble everything in reverse order and adjust the four pinion screws to achieve the focuser tension you like.
6. You may also need to verify that your focuser is aligned with the optical axis.  A laser collimator in the focuser tube is pretty effective for this.  You just need to ensure the laser beam exits the dead center of the objective.  There are other methods, obviously, but I'm not familiar with them.  You just loosen the three screws slightly and gently adjust the focuser's aim.  Tighten them when you're satisfied you're realigned.

2 hours ago, faulksy said:

mine is in the garage

Has the wife ever noticed it in there?  I know I can obscure new items in my garage pretty easily because it's rather cluttered.

Then post images of what you've got and we can all take a swing at trying to figure it out.  Often times, the barrel and retaining rings dictate the order.  Double convex lenses can be troublesome when they're almost, but not quite, symmetric and can fit in either direction.  Sometimes, the negative field lens can be flipped as well as everything still fits.

1 hour ago, amaury said:

Hi people, 

just out of curiosity, Is the Orion E series 7-21mm Zoom a rebranded Svbony SV135?

At least on paper they seem to be exactly the same Zoom.

https://www.svbony.com/SV135-1-25inch-Zoom-Eyepiece-/

https://uk.telescope.com/Telescopes/Orion-E-Series-7-21mm-Zoom-Telescope-Eyepiece/rc/1306/p/132442.uts

 

More than likely by the looks of it.  At least Orion didn't double the price like they usually do with their rebrandings.

15 hours ago, faulksy said:

try and hide a 20" dob then

Get a used Tectron Dob that collapses into a single, closed cube shape and can be used as an end table.

I bought another branding of that scope for $24 shipped last March off of ebay.  I've converted it into a 70mm superfinder with a 2" visual back for widest field views (9 degrees with a 40mm Pentax XW at 7.5x).

It uses 0.965" eyepieces, not 1.25" eyepieces.  Check the insertion barrel diameter of the supplied eyepieces on yours.

I has a ~35mm aperture stop just behind the 70mm objective, probably to improve image quality on such a fast objective.  I removed both the focuser and objective cell (three screws hold each in place) and used a small block of wood to push the stop out of the front of the tube.  It's just held in place by friction.  I then reblackened the interior because it got all scratched up by the plate being pushed out.

The focuser tube itself has another 50% by diameter aperture baffle that can't be easily removed, so buying wider field eyepieces may be of little use because they'll just vignette.

All that said, it makes a decent, low power spotting scope as delivered.  As I've redesigned it, it makes for an astoundingly good wide field finder.  It came with a pretty decently corrected 70mm f/4.3 achromatic doublet and metal tube that was worth the $24 alone.

The WO 1.25" diagonals have a constriction in the eyepiece receiver that causes vignetting for widest field 1.25" eyepieces.

I have one I use with my binoviewer (22mm clear aperture, so doesn't impact me), so I can confirm this constriction.

I use GSO/Revelation 2" diagonals with my refractors and even my 127 Mak with a 2" visual back.  They allow me to use my extensive collection of 2" eyepieces in them.

I suppose you could use ultra narrowband filters to block most light pollution.  They would allow you to do fairly decent nebula photography.  They don't come cheap, though.

Astrodon - 1.25'' Mounted OIII 3nm Narrowband Filter

Astrodon - 1.25" Mounted Narrowband H-Alpha 3 nm Filter

Astrodon - 1.25" Mounted Narrowband NII 3 nm Filter

Astrodon - 1.25" Mounted Narrowband SII 3 nm Filter

Check the following diagram to see if the shapes match your lenses:

18 hours ago, Zermelo said:

I saw M3 for the first time last week (150mm/Bortle 4/no moon).  I was hoping to resolve a few stars - I have done so with M10, M12 and a few others - but it was just a grey blob. I think M3 is harder.

I can't resolve the smaller/farther away GCs either in an 8" Dob.

17 hours ago, StuartT said:

I actually cut all the way through. For any eyepieces shorter that the full depth of the foam, I simply cut the cylinder of waste foam and then poked it back down the hole to plug part of the depth. (I was quite pleased with that idea 😊)

 

I also do that with pick&pluck foam to prop up shorter eyepieces.  I just shove some plucked pieces into the bottom of the hole.

1 hour ago, Astro_Dad said:

If coma becomes a concern in the future, would you recommend a coma corrector and if so what would be a reasonable entry level one to test (if at all possible - the Paracorr looks to be the “standard” but is expensive relative to the cost of the scope).

I use a GSO/TPO/Revelation coma corrector with a 25mm spacer ring between the eyepiece holder and the optics section.  As long as your eyepieces focus within 5mm of their shoulder in that configuration, at least 90% of the coma will be corrected along with flattening the field slightly.  It appears to be currently unavailable in the UK in any branding.

Back in 1998 when I bought my 8" Dob, it came with no eyepieces.  I bought a 2" 38mm Rini MPL from the seller as a "finder" eyepiece, a 14mm Pentax XL for mid-range power, a 9mm Vixen LV for a bit more power, and a 5.2mm Pentax XL for highest power.  With my strong astigmatism, I had to buy long eye relief eyepieces, and the only options back then were the XL, LV, and LVW lines.  The XLs were $240 back in '98, which is about $390 apiece today.

I can easily resolve M13 and M22 in my 8" Dob at 200x or higher, but not in my 72mm or 90mm fracs.  They just run out of resolving power it seems.

On 13/03/2021 at 15:31, discardedastro said:

Here's hoping it makes it through the UK border/customs/logistics handling. Took me 7 weeks to get an item from a warehouse in Essex to Oxfordshire as it got stuck in an endless loop of paperwork!

Ironically, after week 5 I gave up and asked for a refund and parcel recall, bought the same thing from a UK supplier (fortunately the other parcel with the hard-to-get bits had arrived by then) and 2 weeks later the thing turned up. 3 weeks later and I'm still trying to get it back to them for a refund. Of course we've now dropped out of all the EU consumer protection stuff - so things like refunds within 15 days of asking, statutory protections on returns are somewhat more jumbled and confused now. Worth being aware of and thinking about!

Now maybe y'all will understand why private American sellers won't ship out of the US.  There's too high of a probability of items being stuck in customs for an interminable length of time and the buyer requests a refund.  That, and some countries have a high probability of fraudsters buying items, and then defrauding the seller in multiple ways without any seller protections.

7 hours ago, Ouroboros said:

I can see how you can make vertical cuts into the foam. But how do you cut underneath the plug of foam you have made? Or are you cutting all the way through? 

I would assume so since most foam sheets for smaller cases don't exceed 2" in thickness.  To get more thickness, more sheets of foam are stacked together.

4 hours ago, StuartT said:

Thanks everyone! I actually ended up using one of these and it worked a treat. So I now have a safe and comfy home for all my bits and pieces 😊

Nice find.  I didn't come across those in my searches.

6 hours ago, Marc1964 said:

LIke you, not thrtilled by experience and Aliexpress not helpful.

As much as I suspected.  I've been in no hurry to switch from ebay and Amazon for Chinese sourced items.  Both will support the buyer in every case of fraud.

I use my 2" GSO ED 2x Barlow with the TV Panoptic Barlow Interface more than any of my 1.25" Barlows because I enjoy being able to use my large array of 2"-only eyepieces at double the power.  As I said above, I just stick the combo in the focuser and leave it for an entire viewing session just to change things up.

On 19/03/2021 at 06:10, wulfrun said:

Easily solved, although re-aligning the secondary wasn't my idea of fun.

Aligning a massively off secondary with a laser is the only thing they excel at.  You just have to be careful not to lase your own eye(s) when looking down the front of the tube to get the beam centered on the primary because the return beam can be no where close to the secondary.  I wave my hand over the front to figure out where the return beam is before looking down the tube.

Done right with the secondary collimation screws quite loose, it's very intuitive to figure out which way the mirror needs to move to getting it pointing straight at the primary's center.  You then just carefully tighten up everything and move on to collimating the primary.

At least here in the US, the only recent arrests have generally been of rednecks stupid enough to lase a police helicopter.  Hello, they have night vision cameras on them that can easily pinpoint your location.

I have green laser sights permanently mounted to each of my scopes or alt-az mounts or permanently attached to a Synta/Vixen finder foot.  They have built in alignment screws and come with a momentary switch on a coiled cord as well as a push button toggle switch.  They also come with either a 1 inch diameter barrel mount or a Picatinny rail mount.  For permanent mounting, I affix a short Picatinny rail to the scope (think Dobsonian).

Here's the sight I've been using.  They're pretty cheap from ebay China if you're willing to wait a few weeks.  You'll also need to order the proper rechargeable lithium ion batteries and charger.  I prefer the longer battery version (18650) of these sights because the battery lasts longer on cold nights than the shorter 16340 version.  The longer version only became available in the last couple of years.  The sight is longer, but I think it's worth it.

Just buy a regular green laser pointer separately for outreach.  You don't want to be faffing about trying to realign the laser sight each time you dismount/remount it.  They hold alignment really well once set.

1 hour ago, Paulgra said:

Thanks again I will look into getting a bst starguider eyepiece should I go for say a 5mm one or the 8mm/ 12mm as suggested would it be also worth getting a Barlow

Thanks

The 12mm will yield 63x, the 8mm 94x, and the 5mm 150x.  Ideally, I'd like to see 75x and 125x which would be 10mm and 6mm for day to day usage.  Splitting the difference, the 8mm at 94x seems like a good bet for a first eyepiece.  If you find yourself wanting a bit lower power most of the time, get the 12mm.  If you think a bit more power is needed, the 5mm would be logical.  Personally, I'd lean toward the 8mm and 12mm combo under UK skies despite my initial 5mm/12mm recommendation.

FLO has a 10% discount if you buy two at once, and they sponsor this site.

7 hours ago, MrFreeze said:

I think this might work - https://www.aliexpress.com/item/33000127040.html . IF it really is a 43mm thread. It doesn't specify whether it is 42x0.75 or 42x1 at the other end either, and the threaded section isn't that long, so won't take too much weight.

David

Almost assuredly M43x0.75 and M42x1 since it's meant to reverse mount lenses onto a Universal lens mount (M42x1) rather than a T2 (M42x0.75) mount.  The 43mm thread is almost certainly 0.75 pitch which is the standard for filters.

That means the thread pitches are backward relative the Baader adapter (M43x1 and M42x0.75) despite the diameters being the same.

Most 2.5x Barlows measure closer to 2.1x to 2.2x from what I've read.  Regardless, the 6.5mm should provide decent high power views.

I would probably recommend getting a 5mm BST Starguider instead for even higher power (150x) along with a 12mm BST Starguider for a decent mid range eyepiece (63x) to replace the so-so 10mm kit eyepiece.

To get to a very wide field of view, you could get a 35mm Aero ED 2" eyepiece sometime in the future.  Yes, the exit pupil will be 7mm, and it will struggle at bit a f/5, but the wide true field of view for locating and centering objects makes it totally worthwhile.

I've got multiple Barlows and rarely use them.  They're clumsy to add and remove.  When I do use one, I tend to put it in the focuser and leave it, doubling the power of every eyepiece, for a given observing session.