Louis D

I'm not sure what you mean by "large in mm", but according to the Tele Vue Eyepiece Specifications page, the 13mm NT6 is 1.6 inches in diameter and the 19mm Panoptic is 1.7 inches in diameter.  I'll leave it to you to convert to millimeters.

1 hour ago, Carbon Brush said:

Then of course March 3rd and October 10th are easily mixed due to some mounts etc. using the date format that only the US seem to use. 

Off topic, but why didn't you phrase it as 3rd of March and 10th of October to be consistent, or were you just baiting us Americans?  Until computers became ubiquitous, American wrote the date (on checks and such) as Mar 3, YYYY or Oct 10, YYYY.  Thus, there was no confusion in the pre-computer days because no one substituted the numeric equivalent for the month.  Americans only reverse the spoken month and day for a very few holidays like the 4th of July and Cinco de Mayo.

Logically, for computers to properly sort dates, the only order I use on file names is YYYYMMDD.  Otherwise, using left to right sorting with DDMMYYYY as in Europe, all dates sort first, then months, then years.  That is not a particularly useful way to sort hand dated documents.

I have my counterbalance weight protruding out away from the tube to offset the weight of heavy 2" eyepieces at higher altitudes on my alt-az mount when using my refractors.  It's also mounted about the same distance forward as the eyepiece is backward relative to the altitude axis.

Let us know how your arrangement works out for you.

Filters simply cut out some wavelengths of light to make others more prominent.

For nebula, a good quality OIII filter can make otherwise invisible nebula like the Veil pop into visibility by blocking all light except around the wavelengths where the nebula emits light.

A UHC filter is good for more types of nebula, but doesn't increase contrast as much because it has a wider passband allowing in more light pollution and sky glow.

For both of the above, stick with Astronomik or Lumicon brands for best results.  I've tried cheap OIII filters, and they are basically blue-green filters that don't even pass the proper wavelengths to be useful.  The cheap UHC filters are reportedly better than the cheap OIII filters, but I've never tried one.

A Moon & Skyglow (M&SG) filter uses Neodymium doped glass to cut out certain middle wavelengths of light to accentuate the blue and red ends of the spectrum producing a slightly purple hue.  They tend to be a jack of all trades and can help somewhat with light pollution and as a decent Jupiter/Mars planetary filter.  Don't waste your money on the expensive brands.  Every spectrographic analysis of cheap brands I've seen shows they are all almost exactly the same.  It's one case where you don't have spend a lot to get decent performance.

Variable polarizing filters can be handy on the moon and during solar observing with the proper solar filtration (full aperture or Herschel wedge) to attenuate the light to a level making detail detection easier.

Various yellow filters can be handy to cut unfocused violet light on achromatic refractors when observing bright objects, improving sharpness by leaving only the wavelengths which are properly focused.  Combined with a light green filter, unfocused red light at the other end of the spectrum can also be attenuated on very bright objects like Venus.  Of course, the object ends up being very green.

Various color filters can help bring out specific planetary details, but are generally not thought of as particularly useful or necessary.

These folks on your side of the pond have some caps.  Agena Astro sells them on our side of the pond.  They also sell some eye guards/cups in case you need them as well.

10 hours ago, LDW1 said:

Every time you want to change eps, which you do almost every time, you still have to unscrew the one half that is attached to the ep and then screw it on to the other ep, with this you just slide the eps in and out, fast and slick.  My 2" wedge ( Altair Astro ) has a built in rotable polarizer. I am sure you knew all of that ?  Cheaper, $16 vs about $40 US ?  Simpler ?

I looked at the Altair wedge and thought it was pretty slick, but I ended up going with the 1.25" Hercules wedge since I never use 2" eyepieces to view the sun.  I also couldn't justify the extra $300 at the time for the Altair for as little solar observing as I do.  I also looked at the Lacerta wedge, but decided that didn't I want to crouch behind my telescope and look up most of the time since the sun peaks at around 83 degrees above the horizon during the summer here.  I was surprised how polarized the light from a 90 degree wedge is with the Hercules wedge.

I assumed that you were doing solar observing if you were using a variable polarizer.  I suppose you could use it for full moon lunar observing as well, but I just use binoviewers in that case.

I rarely swap eyepieces once I find the magnification I want to solar observe at.  At that point, I don't feel too bad about the inflexibility of my system.

I did put a 2" polarizer in my 2" to 1.25" adapter's M48 filter threads and a 1.25" polarizer on an eyepiece for variable solar dimming on my Dob when using a Baader solar filter.  Since I only have 20mm of in-focus available on it with the CC in place, the Meade solution is a non-starter.

Let us know how well the Meade solution works for you.

Indeed, minus the 6.5mm and 12mm focal lengths.  However, minus VAT, they equate to 104 USD each which is a bit on the high side.  That would be over $600 for a complete set if they were all available.  Just a few years ago, they were only $400 for a complete set including custom case (before tax).

Wouldn't it be vastly cheaper and simpler to just thread a single polarizer on the eyepiece and a single polarizer on the front of the diagonal?  Then, just rotate the eyepiece in the holder to vary the darkening effect?  This would require no additional in-focus as an additional benefit.

I do something similar with my Herschel wedge.  I set the variable polarizer to the maximum brightness I want for the session by trial and error inserting and removing it a few times, rotating the two component filters wrt each other.  Once set, I leave the eyepiece in the wedge and rotate the eyepiece to further vary the brightness based on what I'm observing on the sun, taking advantage of the partial polarization of the light from the wedge's prism interacting with at least one of the variable polarizer's filters.

This Gosky variable polarizer can be separated into two filters and costs only $16 shipped from China.

If those Meade's were the original 5 element smoothies for a decent price, I'd grab them because they'd be an easy resale if you didn't like them.

The Meade HD-60s are discontinued and only available used.  I wrote up the following thread comparing them to the Starguiders.

3 hours ago, Daf said:

Thanks all. It is the 2" Stella Lyra (I guess GSO?) ED 2x Barlow, I already have.

Marked Taiwan with the recessed 1.25" adapter, it's GSO.

Vintage long Barlows simply won't come to focus in many refractors because they don't have enough focuser in-travel if used after the diagonal.  This isn't an issue with Newtonians.  When used before the diagonal, they will produce more magnification than what they're marked for because the optical path length is longer.  Focus should be achievable in this mode, though.

Shorty Barlows will work well in either, but cheap ones tend to degrade the image somewhat.  Shorty Barlows also tend to increase magnification faster with longer path length because they have a shorter focal length (there's an inverse relationship between them).

If you have a GSO/Revelation 2" ED 2x Barlow, the nosepiece is M48 threaded and can be screwed onto the nosepiece of a 2" diagonal like a filter.  In that mode, the optical path length will be somewhat longer than when used after the diagonal with the original tube and eyepiece holder, but not a lot longer.  As such, you might get 3x at most, so it might be a good option for slightly more magnification.  I'll have to try it sometime with mine to see what the resultant magnification and focuser travel requirements are.

7 hours ago, clafann1 said:

There's also something curious I found out on high power eyepieces: it seems that on a 4mm eyepiece you can see exactly the same "viewing area" as the 25mm eyepiece, still, since the hole of the eyepiece is so tiny, you can only see the center, the remaining image can only be viewed by "peeking" at an angle. that totally surprised me lol

Perhaps with short eye relief 4mm eyepieces this is the case; however, long eye relief eyepieces like Pentax XW, TV Delos, and Baader Morpheus don't have these issues at any focal length.

Welcome Chris.  I grew up across the Mississippi River in Iowa.  I actually toured Bradley University in Peoria when I was considering which college to attend nearly 40 years ago.  It seemed like a nice college and Peoria seemed like a nice town.

Of course, all I can think of is the phrase "Will it play in Peoria?".  I don't know if the majority on here would know that phrase being UK based in large part.

Don't be shy about asking astronomy questions.

They look like tree sap spots to me.  Do you observe near any trees?  Either way, they're completely innocuous.  Cleaning them off won't improve the view through the objective at all.

If you do feel an OCD need to clean them off, and alcohol based cleaners like BWF don't cut it, Roland Christian of AP telescopes has recommended in the past using a bit of saliva on the end of a clean fingertip.  The enzymes in the saliva will dissolve the tree sap and your fingerprints act like a harmless scrub pad.  After that, clean as normal.

I've never had issues with dew spots because dew is basically distilled water.  If it is carrying dissolved air pollution, that's a different matter.  Luckily, we don't have much air pollution in the part of Texas I live in, so no issues with dew leaving a residue.

I've been messing around with some cheap Chinese color filters I picked up off of ebay for cheap (the 6 filter set), and combining their light green (similar to a #56) with a GSO #12 deep yellow should block all of the blue (the yellow does this) and red light (the green does this) while transmitting 76% of the green and much of the yellow and some of the orange wavelengths.  The Meade green interference filter passes about 94% of the green and most yellow while blocking most orange and red wavelengths and allowing a bit of blue.  Adding the #12 yellow should block the last of the blue, but it might be superfluous for achromat refractor usage.  I could not distinguish any significant difference in hue while holding the #56+#12 combo to one eye and the Meade green to the other eye.  I'll have to try out the two filter variations on bright targets at night in the ST80 sometime as a verification step.

BTW, that cheap filter set comes with an excellent magenta filter that equally passes about 78% of the blue and red wavelengths while passing only 44% of the green.  I'll be trying it out as a Mars filter at the next opposition.  It's way cheaper than the Brandon Magenta filter.

Once the exit pupil gets small enough, weak astigmatism in your observing eye may become unobtrusive without correction.  Here's Tele Vue's chart for their Dioptrx line:

You can calculate the exit pupil by simply dividing the eyepiece focal length by the scope's f-ratio.  For instance, your 6.3mm Plossl in your f/5.9 scope yields a 6.3mm/5.9=1.1mm exit pupil.  According to the chart, you might to want use astigmatism correction if your cylinder prescription is 2.0 diopters or more.  I have 2.0 diopters of cylinder correction and can verify I can see sharpness improvement at a 1mm exit pupil when wearing eyeglasses.

For a low power eyepiece, I would probably recommend the 30mm APM UFF or its other brandings ( Meade UHD, Celestron Ultima Edge, Altair Ultra Flat Field, Tecnosky Ultra Flat, and Orion (US) Ultra Flat).  It is perfectly corrected edge to edge at f/6 and has plenty of eye relief for eyeglass wearers.  With a 5.1mm exit pupil in your scope, you would need well less than 0.5 diopter of cylinder correction to avoid wearing eyeglasses, so this eyepiece is a good choice if you have more than that amount of correction.  There are plenty of lower cost eyepieces with decent eye relief and wide field at or near this focal length, but they don't perform nearly as well at f/6 as this eyepiece.

For high power, if your astigmatism is low (1.0 diopter or less), you could get away with not wearing eyeglasses and use eyepieces with less eye relief.  Personally, I use a mix of Pentax XL and XW eyepieces with long eye relief at high powers because it's more comfortable, relaxing, and I almost never need to clean the eye lens of these eyepieces because my eyeglasses form a barrier to prevent eyelash gunk from getting on them.  The Morpheus line might also be a good choice at a somewhat lower price point.

23 minutes ago, F15Rules said:

Potential issues:

- Insufficient eye relief for eyeglass wearers.

I can just barely see the entire field of the original 30mm ES-82 mushroom top (same JOC made eyepieces as the Celestron Axiom LX and the original Meade 5000 UWA) wearing eyeglasses.  Being a scaled design, the 23mm would put the FOV just out of reach.

At least for the 30mm version, it has strong ring of fire and some very minor edge astigmatism in the last 10% of the FOV at f/6.  Stars are also not as pinpoint in the central 50% as the 27mm Panoptic or even the 30mm APM UFF.  Stars remain a bit bloated in comparison at best focus.  It's why I keep all of them.  Each has its strengths.  Have you compared the 23mm to a 24mm Panoptic or similar for central sharpness?

It does have a perfectly flat field even to my presbyoptic eyes.  I assume the 23mm is the same way.

I'm guessing it's a Bird-Jones/Jones-Bird telescope based on the fact that the main tube does not look to be a meter long as the 1000mm focal length would imply and is a relatively fat tube for an f/8.8 scope.  As such, make sure there's an optical element toward the bottom of the focuser.  It would look like a glass lens.  It acts like a permanently attached 2x Barlow element to help correct the spherical aberration of the primary mirror.

9 hours ago, cajen2 said:

@Louis D , would you expect any significant improvement in EOF aberrations for the Nirvana in an F/6 scope?

That's a loaded question.  Over the same ~60° field of view, I would expect the Nirvana to be better since that's still within the 75% inner area of Nirvana.  Over the entire field of view, I would expect the X-Cel LX to be better since 60° is easier to correct than 80° while on a budget.

There's a lot more at play here, though.  At 60° and a lower power, you'll be more easily able to appreciate the view in one glance.  The eye relief will be much longer, making the view more relaxing.  However, the background sky will be brighter making nebula and globular clusters less contrasty.  At 80° and higher power, you'll have to move your gaze around the field to take it all in in more detail.  This will be made harder by the shorter eye relief as you have to move your head to maintain exit/entrance pupil alignment.  On the plus side, the background sky will be darker, improving contrast on fuzzy objects.

I would get the XCel LX if it's available for a good price at the current time.  Just ask about black flecks in the field of view.  There have been multiple reports of blackening paint flaking off onto interior lenses, messing up the view of the moon and the sun (observed with a proper solar filter, of course).

Time to go down the 2" eyepiece rabbit hole. 😁

If the 25mm X-Cel LX is the same as the 25mm Meade HD-60 which I do have, it should be a decent eyepiece.  It's better corrected at f/6 than the 25mm BST Starguider, but it has a slightly smaller true field of view.

1 hour ago, cajen2 said:

(....and no, I didn't break it!) 😆

Sure you didn't.  We believe you. 😉

6 hours ago, Dominic said:

Glasses/contact wearer new to Astronomy

How many diopters of astigmatism do you have in your observing eye?  If it is low, you can probably get away with not wearing eyeglasses at mid to high powers.  I have 2.0 diopters of astigmatism, so I can see an improvement wearing them at all but the very highest powers.  The relationship actually revolves around exit pupil size rather than magnification, but the two are in inverse proportion to each other.

In your situation, I would probably get a 32mm Plossl for 20x, a 12mm BST Starguider for 55x, and an 8mm BST Starguider for 83x.  Since your scope is an achromat at f7.3, it's going to show a lot of false color even with the 8mm eyepiece.  All of these eyepieces will have enough eye relief to be usable with eyeglasses.

I don't find myself using in-between powers very often.  I generally go for lowest/widest power, move up to mid-power for most observing, and then jump to highest power if conditions and the object warrant it.  Technically, both the 8mm and 12mm yield mid to mid-low powers, but your scope isn't really suited to reaching for high powers above 100x due to aperture and false color.  If you mask off false violet/blue and orange/red colors with a light green filter, you could push your power up to 130x with a 5mm BST Starguider on bright objects like the planets and luna and get a rewardingly sharp image.

Even in my 8" Dob, I generally observe planets at around 100x to 125x on most nights because I get the best contrast on planetary details in that range.  The moon and globular clusters are where I push to 200x or more.  Your scope simply doesn't have enough aperture to ever resolve globulars, so they will always look like fuzzy blobs.  That said, open clusters and bright planetary nebula should make for interesting observing in your scope.

D=Diameter of the primary mirror, the big one at the bottom of the main tube.

FL=Focal Length: If you were to measure the distance from the primary mirror to the secondary mirror and the distance from the secondary mirror to the top of the focuser, it would be about 1200mm.

Having bright streetlights can be counterproductive when people forget to turn on their headlights because the roads are so bright.  Sure, they can see the road just fine, but other drivers can't see that car nearly as easily as if their headlights and taillights were on.  I'll flash my high beams at them when I pass them, but they always remain oblivious.  Following them, I notice that they only turn them on once they enter an area without streetlighting.

This doesn't apply to GM and other cars that have sensors to automatically turn on the car's lights at twilight and during wiper usage.  It surprises me this feature hasn't been mandated for all cars by now.