Louis D

1 hour ago, dark knight said:

I think it was Space X Star Link satellites

Probably.  SpaceX just launched 60 more on Sunday, so they have probably yet to attain their final orbits and are closely following each other for now.

According to this chart from Ohara, FPL-55 is much closer to FPL-53 than it is to FPL-51:

If it is easier to work with and cheaper than FPL-53, then it probably is a win-win all around.

Hmmm.  This scope seems to have replaced the TS-Optics Photoline 90mm f/6,5 Triplet FPL-53 APO.  Searches for it redirect to this new scope.

vs.

The new one is about 50 Euros more, slightly faster, no removable segments, has a flimsier looking focus knob, comes with a carrying handle, appears to use collets instead of compression rings, and substitutes FPL-55 for FPL-53 glass.  It would be interesting to compare test reports and actual images taken with both.

I have the older version.  It's quite nice, though I don't know where they get the 6kg load capacity of the focuser from.  When I load up mine with a 2" GSO dielectric diagonal and 17mm ES-92 (not even 3kg combined) and point it near zenith, it wants to unwind.  I have to tighten up the two focus tensioners (one on the pinion, one on the tube).  Perhaps they're referring to deflection?

I still don't know why focuser manufacturers they don't use a system similar to the Manfrotto geared central column.  The crank axle comes in nearly perpendicular to the rack and is completely impervious to having thrust driven backward through it:

I'm guessing they use a worm gear arrangement.  Perhaps there would be too much slop for a fine focuser?  I don't know about others, but I almost always approach best focus from only one side (that being the lifting side) anyway.  If I overshoot, I tend to come back to the other side and creep up more carefully.

Once you're at the right height with the tripod crank, you just snug down the column lock which pushes the two flat sides of the column against two bearing pads to prevent any play in the system.  Something similar would appear to be applicable to focusers.

3 hours ago, Don Pensack said:

At f/5.3, the size of the field that hides the coma inside the Airy disc (i.e. does not reduce the Strehl of the scope below 0.80) is 2.65mm wide.

Think about the field stop diameters on your eyepieces.  I would bet none of them has a field stop that small.

So some, if not most, of the field in an f/5.3 scope will suffer from coma to the point the image is degraded.

And in a low power eyepiece like Magnus' 35mm Panoptic (38.7mm field stop), the difference is huge!

Because the Paracorr essentially makes the coma in the scope the equivalent of an f/13.3 scope, so a 40mm field has zero coma

(I think it's a lot larger than that, but that's as far as the charts go).

Field sizes without coma larger than the Airy Disc:

f/4--1.14mm

f/5--2.22mm

f/6--3.84mm

f/7--6.10mm

f/8--9.1mm

f/9--13mm

So, assuming your low power eyepiece will have a field stop somewhere in the 38-46mm range, it really looks like if you want a coma free low power field, it kind of doesn't matter what the f/ratio of the scope is--

you need a coma corrector.  I tend to view a newtonian as a catadioptric scope: 2 mirrors and a coma-correcting lens system.  My scope is f/5 and I view it as essential.

 

So, would putting a 3x Barlow in that f/4 system make the coma appear no worse than in an f/12 scope?  That is, do Barlows (telecentric or not) have any effect on coma?

I ask because my higher powered eyepieces with strong negative sections (10mm Delos, 9mm Morpheus, 7mm XW, 5.2mm XL, 3.5mm XW) tend to look roughly the same with or without a CC in my f/6 Newt.  The same can't be said of my longer focal length premium eyepieces, even accounting for the stronger field curvature without a CC.

I specifically went off and bought used sets of both the Meade HD-60s and AstroTech Paradigms (Starguiders) just to see how good or bad they are and compared them in this thread:

If you're used to paying $300 to $500 for a single eyepiece, it's pretty neat to get two whole sets for under $600.

I compared them again to other eyepieces in my collection in this thread:

If you need to wear eyeglasses due to astigmatism, the HD-60s are the clear winners.  If you're price sensitive, the Paradigms (Starguiders) are the clear winners.

Did it require any additional in-focus relative to the eyepiece alone?  My GSO CC requires 11mm of in-focus.  As a result, neither my 25mm Paradigm (Starguider) or S-W 5-8mm zoom will come to focus with it (I have a very low profile focuser optimized for an undersized secondary).  I've read it is anywhere from 10mm to 19mm.

49 minutes ago, johninderby said:

Gnome - Gardening naturally on mother earth.

Yes that is where the name gnome comes from.

More totaly useless info for you. 😁😁😁

🤔

From the Online Etymology Dictionary:

gnome (n.1)

"dwarf-like earth-dwelling spirit," 1712, from French gnome (16c.), from Medieval Latin gnomus, used 16c. in a treatise by Paracelsus, who gave the name pigmaei or gnomi to elemental earth beings, possibly from Greek *genomos "earth-dweller" (compare thalassonomos "inhabitant of the sea"). A less-likely suggestion is that Paracelsus based it on the homonym that means "intelligence" (see gnome (n.2)).

Popularized in England in children's literature from early 19c. as a name for red-capped German and Swiss folklore dwarfs. Garden figurines of them were first imported to England late 1860s from Germany; garden-gnome attested from 1933. Gnomes of Zurich for "international financiers" is from 1964.

I assume you're having a bit of fun with us with your backronym for gnome.

5 hours ago, Stu1smartcookie said:

But , does it stop "rotation" if you use the wedge when taking photos ?

Yes, it stops field rotation.  But to quote you above:

18 hours ago, Stu1smartcookie said:

I want visual astronomy , and the chance to take a few pics of planets (mainly) .

Neither of these use cases requires the suppression of field rotation in an SCT.  For planets, you takes tens of thousands of very short exposures and use software to select the best images, derotate them, and then align them.  Since there are no diffraction spikes from spider vanes, you don't have to worry about rotating diffraction spikes between frames as there would be with an alt-az Newtonian.  For big Dobs and planetary imaging, folks generally use an equatorial platform to control diffraction spike rotation across frames, at least within one, one hour tracking pass of the platform.

Here's an image of the NexStar 5SE with the equatorial wedge raised:

That doesn't look stable at all.  I've got to think there's lots of flex and opportunities for vibrations to keep ringing through the system.  Any sort of breeze could set it to vibrating like a mechanical clock work.  It certainly would be useless visually in that mode.  Anytime you touched the focuser or bumped the eyepiece, it would take forever to settle again.

Compare it to this older C5+ equatorial wedge:

That thing looks a whole lot more stable with 3/8" metal plates everywhere.  I'd also wager that fork arm is metal rather than plastic.

Being equatorially mounted wasn't an afterthought back then.

Are you talking about the NexStar 5SE?  If so, it's already fully goto in alt-az, so tipping it with a wedge adds nothing for visual observing except additional vibrations.  In pre-computerized goto days, the equatorial wedge was the only way to track with a fork mount.  That's no longer true.

28mm RKE in a field flattened AT72ED at f/6 compared to some others in my collection:

So, basically, pick some ancient European tribal name name such as Thuringia, Ostrogoth, Visigoth, Alemanni, Pict, Suevi, etc. and slap it on a telescope sold in Europe?  By this reasoning, we'd be getting Koroa, Mohegan, Powhatan, Takelma, Wyandot, etc. branded telescopes here in North America.  I guess I better get started trademarking them.

I bought a 127 Mak on an alt-az mount for my daughter to use on camping trips.  It's fairly compact.

52 minutes ago, Kyle Allen said:

They claim to be ‘night vision’ but just gave a yellow tint to everything!

But can you see anything at night (moon, a street light, etc)?  If so, "night vision". 😉

There are several advantages to using longer focal length eyepieces with a Barlow/GPC/OCA/OCS:

1. The light cone is slowed down allowing lower cost eyepieces to perform well.

2. The eye relief is better in longer focal length eyepieces which makes viewing more comfortable.

3. Longer focal length eyepieces are less likely to magnify collimation imperfections in the binoviewer.

Makes me glad I'm a bit of an eyepiece hoarder.  I can just go to my collection to try something different.  My grown daughter can also borrow from it like a library.

2 hours ago, Soloula said:

We got a movie projector for the garden a few months back and have a managed to set up our Bose speakers for decent sound. Were out for my youngest’s 5th birthday last month and I checked with neighbour if it was too loud. Won’t be doing that again. I’m so [removed word] off today at all the times I’ve gone out my way to be considerate - not listening to music in the garden when the suns out and they’re out, not letting the kids make too much noise in the garden past 6.30 when their wee ones go down, holding off lighting the bbq until they bring their washing in. I feel like such a mug going out of my way to be decent and then I get treated like this. Lesson learned.

Anytime they're having a backyard get together, pop over the fence top and say "Hi!".  I did that with a neighbor who got so mad he threatened to beat me if I did it again.  I asked him to repeat his threat while I recorded it with my phone.  He backed down realizing that was assault, plain and simple, under US laws.  As long as I'm on my side of the fence, there's nothing he can do to stop me from interrupting his get-togethers with a friendly "Howdy neighbor!".

I got my neighbor to back down on his lights by going out nightly with a Cree LED tactical flashlight and shining it in his family room windows, zig-zagging it all over the place.  When he came out in a huff, I pointed out I was trying to astro observe, and was trying to figure out why his security lights came on every time I came out my backdoor or moved around my own back yard as if it was a criminal act to do so.  I told him I was trying to figure out if they were light or motion sensitive sensors.  He rearranged them and turned down the intensity and motion sensitivity.  They didn't seem to like having the tables turned on them with regards to nuisance lighting.

Just now, Peter Drew said:

Apologies for multiple posts, don't know what went wrong there?    🙂

You can ask a moderator to delete the extra posts.

I've had it happen when my internet connection was flaky, and I hit return multiple times before it actually posted thinking the first time didn't work.  They all got queued up until my connection returned.

2 hours ago, Puffafish said:

I have wondered about getting a zoom lens, but always thought you compromised on quality to get the zoom action.

You compromise relative to the best corrected eyepieces out there, but not relative to these crappy MA eyepieces supplied with the scope.  Most 8-24mm zooms have 7 elements and tend to work pretty well by most accounts.  The 7.2-21.5mm ones are also well thought of.  In fact, you can see how two zooms compare in an f/6 ED refractor at 12mm in the comparison image I posted just above.  Both are clearly better than that 12mm Meade MA which is comparable to your stock 10mm eyepiece.

6 hours ago, merlin100 said:

I was curious about the supplied SW EP's back in March this year, when I bought my 200P Dobsonian...

https://stargazerslounge.com/topic/349974-sky-watcher-skyliner-200p-eps/

Thanks.  It's too bad they're so crappy.  Below you can see the 9mm and 12.5mm generic Kellners I got with my ST80 20 years ago relative to much more expensive eyepieces.  They're not bad except for eye relief and vignetting:

Edit: I just noticed I do have an MA, the 12mm Meade Astrometric MA that I picked up for cheap used.  I remember using it and thinking, this is bad.  Especially so since it is sold for astrometric usage.  Now I'm wondering how an MA differs from a properly executed Kellner.  I found this CN post by Martin Pond which indicates the field lens is acrylic in a 25mm Meade MA with a slightly curved instead of flat outward facing first surface.  Using Acrylic instead of glass for one element could certainly account for the poor image quality.

What exactly is this stock 10mm eyepiece that everyone pans?  Is it a Ramsden or Huygens?  Kellners are generally not as bad as the descriptions of this 10mm.

1. Are you using the same coma corrector in both?  I have certain eyepieces that exhibit a fuzzy field stop without a CC, and a sharp one with one.  I've never noticed SAEP becoming more or less pronounced with or without a CC.
2. Is this the only scope that causes the Nikons to kidney bean?  It is very odd indeed.  I've not heard of this issue before.
3. Do any other eyepieces in your collection kidney bean under the same conditions?
4. Do the Nikons kidney bean with or without the EiCs installed?

6 hours ago, bomberbaz said:

That becomes a 4x barlow in my mak with binoviewers

I use a Meade 140 nose piece screwed onto the front of my binoviewers, and I get right about 3x with the combination.  The 140 Barlow is 2.4x by itself.  I think being a medium length Barlow helps limit the power growth when used with the longer binoviewer path.

2 hours ago, bomberbaz said:

I agree with this as I found out recently. My binoviewers add quite a bit to the focal length to my 127 mak, can't remember the exact detail but think it took it from F12 to F13.8 with the added focal train distance. 

However, it's far less of an increase than using a 2x Barlow nose piece to reach focus.

You'll probably want to remove the focuser from the tube as you suggest.  Next, see if there is a way to remove the plate holding the pinion against the rack.  Once the pinion is removed, the focuser tube should slide out.  Do all this over a cookie sheet or other lipped pan to catch loose parts.  Once the focuser tube is out, you can inspect everything for damage.  Hopefully, nothing is permanently damaged.