Louis D

18 hours ago, vagk said:

Hi

How do you remove stucked dust particles that do not come off while blowing?

Try soaking them with cleanser from a damp cloth to dissolve them.  You may need to try several different solvents.  You can even put a bit of saliva on the tip of your finger and work it into the spot in case it's organic, like tree sap.  You can even try your fingernail if all else fails to try and pop it off.  Your nail is way too soft to damage either the glass or coatings; however, the adhesion of the spot could take some of the coating with it, so no guarantees.  Dissolving is generally your best bet.

1 hour ago, badhex said:

One minor niggle is that the 1.25" EP adaptor gets a bit stuck sometimes on insertion, and a couple of times I nudged the scope enough to lose my current target.

Yeah, GSO machines their eyepiece holders to a close tolerance.  You also have to watch out for the compression ring trying to ride up and jamming on an eyepiece safety undercut.  It hasn't happened to me yet, but I've never tried forcing an eyepiece up and out to precipitate it happening, either.  If it snags, I loosen the set screw further and jiggle the eyepiece a bit to reseat the compression ring before pulling again.  After it's out, I inspect the ring by running my finger around it to make sure it's fully seated before putting another eyepiece in.

Looks like a low budget sci-fi alien invader's ship descending from the sky. 😜

Magnified, they appear to be overlapping semicircular arcs.  Perhaps there's a dominant reflection from one side only going on somewhere?

I remember looking through an etalon type solar scope once and being shocked at how difficult it is to make out the image visually.  It's in a super dark and far-red color probably due to passing the H-alpha line.  I couldn't make out much detail and was completely underwhelmed.  Maybe my retina is just really insensitive to deep red?

I'm wondering if these line filters like H-Alpha and Calcium H/K are more appropriate for photography than visual.  Perhaps the Hydrogen B, Sodium D and Helium D3 lines might work visually, but seem more rarely sold.

18 hours ago, v4cascade said:

I went with the lazy susan ball bearing ring

Do you ever find it too smooth in that it tends to overshoot and/or not stay put due to a complete lack of "sticktion"?  I could see if the base were not completely level it might contribute to "windmilling" of the upper assembly (seeking the lowest potential energy state).

15 hours ago, badhex said:

Thanks Louis. I guess I'm just trying to find some small improvement wherever I can as most of my observing will be from this location for the foreseeable, but in my heart of hearts I know it might be a fool's errand - obviously the best improvement will always be darker skies. 

Perhaps I'll persevere with the UHC for now and see how I get on. Most people seem to say that Orion see great improvement with a UHC, however I personally found the Oiii to work better in that particular case. 

I could do with a list really of which filter of the two will work best in which targets. 

David Knisely of the Prairie Astronomy Club has written some nice web pages about nebula and LP filters that you might find useful:

Useful Filters For Viewing Deep-Sky Objects

Filter Performance Comparisons For Some Common Nebulae

I think because light pollution filters apply such a light touch, that they're actually more effective at increasing contrast in areas with little light pollution.  Rural skies mostly deal with street and yard lights that are more limited in the spectrum they pollute.

In heavily light polluted skies, light pollution filters don't appreciably increase contrast as compared to the more heavy handed UHC filters in my experience.  I think it's because there's so much light pollution across the entire spectrum in urban skies thanks to myriad light sources.

Simply put, you're unlikely to ever see low surface brightness, face on galaxies in Bortle 8/9 skies with any filtration.  However, they might stand out better in Bortle 3/4 skies with a light pollution filter.

6 hours ago, wookie1965 said:

Only thing is I have a 2" 28mm and no space. 

Get a deeper case and switch to vertical storage.  You'll be able to get so many more eyepieces into the same length by width real estate.  You'll just have to memorize where things are.

10 hours ago, badhex said:

Astronomik seems to do two LP type filters, the CLS and CLS-CCD both shown in this graph - I presume the CCD one is literally designed for CCDs and not human eyes. 

It looks like the CLS-CCD block IR where the CLS does not.  Since CCD can see IR and humans cannot, the CLS should be fine for visual.  Also, it looks like the CLS will pass the C2 lines at 511nm and 514nm where the CLS-CCD might not pass them quite as well.  This is important for comet hunting.

I would also recommend getting a decent 2x Barlow to "slow down" the f/4 light cone so your stock eyepieces will perform better and at a higher power.

The 6mm Expanse is supposedly decent, but suffers from kidney beaning (SAEP) and poor stray light control from what I've read.  I'd probably get the 5mm Starguider instead.  They're also known as the Astro Tech Paradigm and Agena Starguider Dual ED.

If you can get your power up to around 75x to 90x, you should be able to easily see the moons and major bands of Jupiter, their shadow transits, the rings of Saturn, and perhaps some of its brighter moons.  Thus, a 5mm to 6mm eyepiece, or its equivalent with a Barlow would do.

A Barlowed zoom might also be a good choice to allow you to seek out the highest usable power without spending a fortune on individual eyepieces.

5 hours ago, Paul_Sussex said:

The BST Starguiders seem to be popular - pity they don't do a 30mm/32mm as well.

You wouldn't be able to have a 60 degree apparent field of view with a 30mm to 32mm 1.25" eyepiece like the BST Starguiders.  Around 50 to 52 degrees is about the limit in that range, depending on distortion, so you might as well go with a Plossl of some sort.  At f/12, they perform quite excellently.

I have a 32mm GSO Plossl which has noticeably better contrast than my vintage 32mm Orion Sirius Plossl thanks to better coatings.  I don't know how much of an improvement you'd get moving up to an NPL or Baader Classic Plossl, let alone a Tele Vue Plossl.  I'd probably put that money toward upgrading my visual back and diagonal to 2" so I could use wider 30mm eyepieces, even if they vignette a bit.

Too bad you're not in the US.  Lots of options for large vehicles here.  I transport my 15" Dob in the back of my 2003 Chevy Astro Van with the rear seat removed.  We use a two person dead lift to get it into the back.  I can still haul 5 people and plenty of  gear in that configuration.  Of course, it gets 12mpg city and 17mpg highway and would never meet ULEZ emission standards.

On 05/05/2022 at 03:43, chiltonstar said:

My cat has to work for a living. She sits on my feet on a cold night when I'm observing (Chief Foot Warming Executive) then sprints off to zap anything small and furry to protect me from attack (Chief Rodent Control Officer).

Chris

Lucky you.  My neighbor has 5 outdoor cats that think our yard is theirs as well, and yet I still have to trap our ubiquitous Texas field/attic rats.  How did you train yours to do their job?

It seems like if you're going down this route, why not start with the 60mm version?  I can see a massive improvement in number of stars visible using a 60mm finder over a 50mm finder.  However, the weight of these custom finders relegates them to positions on the scope where they won't throw off balance in my experience.

10 hours ago, jetstream said:

This works.

 

I've used it before for DIY projects.  While it's better than nothing, it's doesn't really have any light trap effect at grazing angles.

Wouldn't one of the imaging forums be a much better place for your question?  Unless you're doing manual guiding with an eyepiece in the OAG, I don't see how eyepieces even figure into this. 

7 hours ago, Zermelo said:

I bought the 23mm in that range recently, to avoid paying postage on another item to the River Organization. At £13.99 it was a speculative punt - it has only three elements, and one of those appeared to be plastic - but I had read some positive reviews elsewhere.

I've used it a couple of times and it's actually not that bad. I didn't check its claim of 62° AFOV, but it seemed about right. And the sharpness was good across about 90%.

I put together some existing images I have to show how a couple of budget 20mm/23mm eyepieces compare.  The 20mm is the SVBONY UWA with a 67° AFOV and the 23mm (closer to 23.5mm) is the Aspheric with a 63° to 64° AFOV.  Neither is great at f/6, but both improve dramatically at f/12.  When shopping for eyepieces to use in a slow scope, budget eyepieces become a much more viable option.  Both also work great at f/18 in my binoviewers with a 3x (effective) Barlow element to reach focus.

Adding a baffle ring at the bottom of an eyepiece with an inner diameter no smaller than the field lens can greatly reduce some forms of stray light.  The Vixen HR eyepieces did this:

They even extolled their careful attention to stray light control:

I've also read of folks disassembling their eyepieces to blacken lens edges and spacer rings as well as to add flocking to reduce stray light.

4 hours ago, Paul_Sussex said:

May be getting a Telrad from someone in my local club, but think I will still need a 90 degree RACI.

When you start finding objects with the goto, make sure to look up to the sky using whatever unit power finder you settle on.  This way, you'll quickly learn the sky and eventually you'll find you don't need the goto anymore for the showpiece objects.  I love going to public star parties and putting a floundering newbie's scope on a DSO using dead reckoning on the sky and sighting along the scope.  It never fails to astound them.  Sometimes, I shoot from the hip and don't even sight along the tube and just go by judging alt-az angles looking at the tube orientation.  You too can get there with practice.

Personally, I would recommend the Rigel QuikFinder over the Telrad for the 127 Mak due to size.  Even a cheap RDF can work well enough starting out.

A 50mm RACI would be money well spent just for the wide angle views to put objects into context on the sky.

4 hours ago, Paul_Sussex said:

Some weight in the accessory tray to reduce vibration.

Try putting vibration suppression pads under the tripod feet.  I bought a pair of new old stock, 1990s pure Sorbothane insoles off of ebay and cut them into squares to put under each tripod foot.  Problem solved.  Vibration dampening went from 3 seconds to 1/2 second.  You can also purchase new Sorbothane pads off ebay.  This won't solve your instability problems if you're on spongy turf, though.  Weight is indeed your best option then to compress the turf.  You could also work each foot down through the turf to help somewhat.

Here's what the full Sorbothane insoles used to look like:

I don't think they're sold like that anymore due to cost.  Now, Sorbothane is used in just the heel and ball parts of the insole.

I've never tried the commercially available vibration suppression pads, but if they're using urethane, they won't be as effective as Sorbothane.  When I tap the telescope, vibrations just go "thud", so to speak.  It's really quite amazing.

You're right, I can't recall seeing poor light control documented pictorially anywhere for eyepieces.  I guess it's one of those "I know it when I see it" sorts of things.

Ghosting: Pretty obvious with planets.  If you move the planet around the field of view and a dimmer image, generally on the opposite side of the FOV, dances with it, that's ghosting.  Only on axis will the two images merge.  If the alignment isn't perfect, contrast is greatly diminished and you're better off moving the image off-axis.

Light scatter: An overall term applied to light not going where it's supposed to go.  It can be narrow angle or wider angle.

Glare: Generally seen as a glow or spiking around bright objects on-axis obscuring fine details or close, dim companions.  Professional telescopes resort to using an occluding disk of some sort along with precise baffles.  Amateur scopes and eyepieces rely on fine glass polish, smooth reflective surfaces, and smooth coatings to minimize light scatter.  I believe this form of stray light is referred to as narrow angle light scatter.

Flare: Generally associated with bright objects off axis or even outside the FOV introducing stray light into the FOV.  Again, moving a bright object in and out of the FOV and around the FOV will show light streamers pointing back to the source.  It can be handy for recentering a bright object once it strays outside the field of view.  Telescope and eyepiece design minimize this effect with light baffles, light traps, flocking, blackening, etc.

Internal reflections: Yes, these often lead to flare and can contribute to glare.  If your scope and/or eyepiece are poorly baffled and mechanical/optical bits are not properly blackened, you will see an overall glare or even flare in the worst cases in the FOV.

There is also stray light in systems such as catadioptrics where unfocused light from the front aperture bypasses the mirrors and goes straight into the eyepiece due to poor baffle tube design leading to glare and/or flare.

Sorry I can't help with any photographs.   When I take cell phone camera FOV images indoors, I have to have all lights turned off near the telescope, and I have to shield the top of the eyepiece from reflecting even dim stray light into the camera lens with my free hand, so I have dealt with photographic stray light extensively doing this.

Sounds like a project for you to document photographically. 😉

43 minutes ago, cajen2 said:

Kind of you to research this, but not at that price. The few that FLO stocks, for example, are £188. I've tried other shops but few of them note whether an item is in stock, so numerous emails have led me nowhere.

It's not surprising why Tele Vue is so popular here when the other options are so expensive.

11 hours ago, Alien 13 said:

Nice, have thought about getting some of that paint for the focus tube of my Mak.

I'm thinking of using some Protostar flocking material to line the rear baffle tube of my 127 Mak.  I just haven't had the time to work on that project.

3 hours ago, cajen2 said:

I want to replace my BT Starguider 8mm and Svbony UWA 6mm with a Baader Morpheus 6.5mil. Don't get me wrong, both are fine EPs but I love the wide, clear views that the Morph provides. The trouble is I can't find one in stock anywhere...😥

Have you tried the US?  They're in stock at Agena Astro, Eyepieces Etc, and High Point Scientific to name a few reputable dealers.  They are $299 before VAT here, so figure $359 with VAT but before import tariffs and shipping, so figure about 290 GBP minimum imported.  How badly do you want one?

3 hours ago, russ said:

So this year I have bought a Nagler. A 12mm T4. Only the second time I have owned one.

I much prefer the APM Hi-FW 12.5mm to the 12mm NT4.  It has much less SAEP exit pupil finickiness, much less EOFB (which extends to the center of the NT4), better eye relief, and it's sharper to the edge at f/6.  Of course, I prefer the 12mm ES-92 to either, but it's much bigger and 2"-only.  Some folks prefer the 12.5mm Morpheus to either the APM or NT4, but I've never looked through one to comment on it.  Then there's the Docter/Noblex 12.5mm that's supposed to be terrific except for price and the presence of AMD.