Louis D

44 minutes ago, JTEC said:

Interesting debate 🙂.  Is the outcome the measure of an observation or is it the entirety of the observing experience? For a decade or so I imaged, lugging equipment to remote places with beautiful skies slogging away in gaps of cloud in the UK and teaching others to image as well. I remember the excitement of the early results.  But more than that I think back to being out under the stars, being there,  being part of the night and its silent progress and, as the mount ticked away, scanning the sky with binos or just looking up. Now, I’m a visual observer and haven’t imaged for years and I’m not tempted back.  I had enough of jiggling with field-flatteners, trouble-shooting autoguiders, tripping over wires, staring at screens, trialling software, pixel peeping for the technical edge, processing and reprocessing … all of which took far more time than I spent under the sky.  But I’m glad I did the imaging.  The good thing is we have both, each has its own power, each complements and neither excludes the other. 

You make some very good points.  When I've only got an hour to get outside after work and before bedtime to get up rested enough to go to work the next day, I simply don't have the time, desire, or patience to mess around with setting up and fine-tuning an imaging rig.  If I lived in the mountains of New Mexico and had a permanent observatory imaging setup, I might feel completely different about imaging versus observing.  I could actually do both at the same time using preprogrammed imaging runs.  However, unless I was imaging something no one else had imaged in the same way, I'd have a hard time justifying doing it at all.  I took a lot of snap-shot images through the eyepiece of bright objects starting out in amateur astronomy years ago and lost interest in it within a couple of years.  Nowadays, I just enjoy communing with nature and the celestial sphere from the quiet of my backyard.

Any SAEP (kidney-beaning) issues when used on such a bright object?  Any finickiness holding the entire field of view at once?  I've read that SAEP is the main issue with the entire SSW line.

Just like camera lenses, high end prime lenses (eyepieces) generally stomp on entry level prime lenses (eyepieces).  High end zooms generally stomp on entry level zooms.  High end teleconverters (Barlows/Telecentrics) generally stomp on entry level teleconverters (Barlows).  A high end zoom might stomp on a series of entry level prime lenses/eyepieces.  It's a matter of comparing apples to apples rather than apples to oranges, just as in photography.

Specific to your question on the Barlowed 25mm Starguider, it might perform similarly to the 12mm.  It definitely would have much longer eye relief.  By itself, the 25mm Starguider is a poor performer in the outer field in sub-f/8 scopes.  The 12mm is quite good in comparison.  Rather than degrade eyepiece performance, high quality Barlows generally improve the performance of marginal eyepieces by slowing down the light cone to within the design range of the eyepiece.  Unlike photography, it is necessary to consider appropriately matching eyepieces to scopes based on the f-ratio of the scope and the design f-ratio of the eyepiece.  Unfortunately, most eyepieces don't list their design f-ratio.  Thus, you need to read up on eyepiece reviews in scopes of varying f-ratios to get an idea of how it might perform in your own scope(s).

I have a GSO version of your scope; and at f/5, it is fairly demanding on eyepieces.  If you move into wide apparent field of view eyepieces someday, you'll want to invest in a coma corrector for it as well to get the most out of your eyepieces.

That's a TS-Optics 90mm FPL-53 Triplet APO I bought a few years back.  I've read it may be a Sharpstar scope.

To me, the Hercules/Antlia 1.25" wedge looks like a 1.25" version of the 2" Meade, Starfield Optics, and Altair Astro wedges:

Coincidence?  I think not.

27 minutes ago, ollypenrice said:

The same applies to the gap between my 26mm Nagler and my (imaginary) 40mm Pentax.

For the 14" SCT, I'd get the 40mm Lacerta ED.  At f/6, it's nearly as good as the 40mm Pentax XW-R, with a bit less eye relief, but 3/4 the weight.  At f/10, it should be nearly indistinguishable.

Here's my comparison image at f/12 from my 127 Mak:

As I've said in other related threads, keeping my older eyepieces works well for my budding amateur astronomer daughter.  I've already loaned her my eyepiece sets I bought just to compare them (Paradigms/Starguiders and HD-60s) along with lower end retired eyepieces such as the 30mm 80° Widescan III clone and 40mm Meade 5000 Plossl.  As she progresses, I'll eventually loan her my retired 27mm Panoptic and 12mm/17mm Nagler T4s.  She may also end up with the 40mm Lacerta ED or 40mm Pentax XW-R at some point.

Yes, I've dropped over $600 on step-up eyepiece sets just to see how good or bad they are, and then report back here on them for your collective edification.  You're welcome. 😄

On 27/12/2022 at 02:14, Giles_B said:

Having been advised by FLO that the Lunt Herschel Wedge will come to focus with simple eyepieces with this scope, I'm now looking out for a Lunt (wanted ad posted!).

I went with the Hercules solar wedge.  Being 1.25", it doesn't take up that much back-focus.  It works perfectly well.  I ordered direct from them before China cracked down on retailers not going through approved marketplaces like AliExpress.  It looks like their online store may be back up again.  They're also available under Hercules and no-name versions on AliExpress here, here, here, and here.  They're low cost, but work very well.

1 minute ago, Mr Spock said:

I don't get why people have telescopes and don't look thought them 😜

For me lately, it's been a combination of poor weather, lack of spare time, and sheer exhaustion keeping me from using mine.

For a long stretch in the 2000 to 2012 time frame, I was too overwhelmed with helping to raise three little kids to get out much to observe.  Luckily, I didn't sell my gear, so I was able to get back into observing relatively painlessly once they all became tweens or older.  It was also good for at least one of my kids who took an interest in astronomy.  The other two were too busy playing video games or dancing/teaching dance to be interested in astronomy.  I had maybe 7 or 8 eyepieces, a few Barlows, and three scopes back in 2012.  This has exploded to over 70 eyepieces, 8+ Barlows, and 7 scopes today.

1 hour ago, Franklin said:

Just wait till @Louis D sees this thread, he must have about a million eyepieces!

I've been observing for about 25 years now.  Being a bit of a hoarder, and not being hard up for money or storage space, I tend to collect eyepieces and compare newer ones to older ones as references.  I'm sort of like the musician with 40 or more trumpets or guitars.  Each has its own characteristics to be experienced.

It would have the spherical aberration of an uncorrected f/2.2 spherical primary, which is to say a lot.  I've looked through an f/4 spherical primary Newtonian (Celestron FirstScope 76), and only the central region of a 20mm Plossl was barely usable.  f/2.2 is going to be way worse.  I'm not sure how much the camera corrector lenses would help with the SA.

From my online reading, the RASA does indeed use the standard SCT Schmidt corrector plate which is very nearly plane flat at the macro level.

5 hours ago, JeremyS said:

But it doesn’t show my right hand 😳

So that's why you keep it in your pocket!  We won't tell. 🤫

As I've said in previous, related threads, I love panning about rich star fields at lower powers discovering star clusters that are not at all obvious at higher powers.  It's sort of like going out for a drive on an empty road and just enjoying the scenery instead of heading for a destination.  It's just relaxing to have no particular observing plan which allows me to unwind after a stressful day.

2 hours ago, JeremyS said:

Never worked for me 🤔

You probably didn't have a vintage chemistry set with potassium nitrate in it.  It was included for making a smoke bomb.  Of course, it's also the main ingredient in gunpowder.

I'm thinking they need to sell the Breaking Bad chemistry set to put the fun back into childhood chemistry: 😉

1 hour ago, Paz said:

I use parfocal baader filters when I'm using a filter changer and it works well for me. I admit I don't know if other manufacturers make their filters parfocal.

Especially if, like me, the observer uses filters from multiple manufacturers and even multiple generations from a manufacturer (looking at you, Lumicon).  In that circumstance, there's little hope of parfocality across filters.

I have been known to swing over to a nearby star to achieve best focus and then return to the nebula.  This is best done in one axis if using an alt-az mount to make getting back more repeatable.

16 hours ago, Don Pensack said:

It works OK in really dark skies, but, as a technique, its true value is in planetary use, where you can quickly see what filter you want to use to yield the detail you want to concentrate on.

I can vouch for that.  I have been able to quickly try multiple filters in this manner and home in on the best 2 or 3 for a given planetary object.  Then, with two hands, I can move two filters in and out of the light cone in quick succession, and sometimes even stacked, to tease out details.  If one seems to be working especially well, I'll go ahead and screw it into the eyepiece yielding the best view for that night's conditions.  In this manner, I can rapidly try out multiple combinations of eyepieces and filters, wasting less precious observing time futzing about with equipment.

Now that Santa has officially gifted me this eyepiece at Christmas, I spent an hour+ with the 3-8 Svbony zoom in my 90mm f/6.7 APO last night viewing Jupiter, Luna, Mars, and the Pleiades.  Here are a few impressions that stuck with me:

• It is usable with eyeglasses at 8mm, a bit harder at 7mm, borderline at 6mm, and pretty much unusable from 5mm down to 3mm.  This runs contrary to my flashlight projection measurements showing a pretty consistent 8mm or eye relief.  At the long end, I'd say it has about 15mm of usable eye relief.  Zooming in, I can see the AFOV retreating into the distance (actually just narrowing in subtended angle) sort of like that "sunken place" scene in Get Out, forcing me to cram my eyeglasses harder and harder into the eyepiece.  For 5mm and below, I removed my glasses, but the eye relief was still almost too tight to use comfortably.  Based on that, I'd say ER drops from 15mm to 8mm as you zoom from 8mm to 3mm.  It doesn't feel like a linear change, though.  The ER shrinkage from 8mm to 7mm to 6mm seems as relatively small as the extension of the top of the eyepiece in that range.  As the top extends more going to 5mm, 4mm, and especially 3mm, the ER decreases more noticeably.
• It is close to parfocal, but for critical focus on objects like Jupiter's bands, an eighth turn of the fine focus knob was needed going from 8mm to 7mm.  Less was needed for the next few jumps.  End to end refocusing was definitely needed no matter which end was focused first.  However, on star fields like the Pleiades, the defocus was hardly noticeable.
• It seemed like there was a touch of field curvature (focus change) center to edge across the zoom range, but it was barely noticeable.
• There was a bit of light leakage through the field stop indicating it is not a physical ring defining it but rather the combination of several lens edges.
• Field distortion seemed low.  Yes, there was a bit of rolling ball effect going on during panning, but it was pretty minor.
• Star fields like the Pleaides looked great across the zoom range.  I'll have to try it on smaller star clusters on better nights to see if this observation holds up.
• There is some edge astigmatism starting around 5mm which gets progressively worse heading toward 3mm.  I think there is some from 8mm to 6mm as well, but it was vanishingly small.
• I was seeing yellow/purple fringing at higher powers across the field on Jupiter and Luna.  I don't think it was seeing or the scope, but since I didn't have time to pull out lots of eyepieces or other scopes for comparisons, I'll hold off making any more comments on my chromatic aberration impressions until I can verify them through comparative analysis.  It might just be an artifact of the FPL-53 triplet or the seeing.  I did remove the TSFLAT2 field flattener from the diagonal and my eyeglasses from my face, but the chromatic aberration remained.  Also, the center didn't seem to sharpen up all that much with the flattener removed.  It is known to impart a bit of spherical aberration there.
• On the whole It seems like an 8mm-4mm design stretched to 3mm.  Correction is excellent from 8mm down to 6mm across the field.  At 5mm, it is getting just a bit worse at the edges.  Things start to degrade a bit more rapidly going to 4mm, mostly at the edges but also some in the center.  Pushed to 3mm, and things seem to go south.  The central area is still passable, but the edges were not that great.  As such, it seems like a very good 5mm-8mm zoom as far as correction and eye relief goes.  The 4mm to 3mm range seems like it's mostly there for exceptional nights and strictly on-axis use.
• Ironically, the view of Jupiter was best at 8mm.  Zooming in didn't reveal any more band details last night.  Mars showed some albedo features, but I couldn't discern much else.  A washed out front was moving through causing a light breeze, so that may have contributed to less than perfect seeing conditions.
• The ~60° AFOV is very nice.  However the jump to even 70° with another eyepiece I had at hand did feel massively wider in comparison.
• Zooming action was smooth with just the right amount of dampening, and click stops were easy to move between.  I'd say they got the mechanical action just about right.
• The insertion barrel is so long that it noticeably protrudes below the 2" to 1.25" adapter of my GSO dielectric diagonal, but not long enough to strike the mirror.  This might prevent it from inserting all the way into some 1.25" diagonals.  I suppose I'll have to check it with my 1.25" WO diagonal that I mostly use for binoviewing. (Edit: I measured it to be about 2mm short of fully seating in the diagonal.)
• (Late addition I just remembered) I specifically looked for light scatter around bright objects, but I didn't see any obvious issues at any focal length.

This is certainly not a perfect eyepiece, but it would be absurd to expect it to be so given the relatively affordable price.  Overall, I'm happy with Santa's "gift".

Also, it's easier to nail down good field performance over a 50° AFOV than over a 70° AFOV.  So, for a 70° AFOV eyepiece to do it better than a 50° AFOV eyepiece is quite an achievement.

2 hours ago, Don Pensack said:

S&T uses a pivoting magnifier similar to a theodolite that can measure apparent field to <0.1°

Unless the pivot point is exactly at the exit pupil, which itself can be poorly defined due to SAEP (see 26mm Meade MWA), rotating the measurement device can make the AFOV appear larger than it appears from the exit pupil point with eyepieces that either lack a field stop or have it misplaced relative to the eyepiece focal plane.  I see this with Rini eyepieces all the time.  I can "look under" the edge if I back away from the exit pupil and roll my gaze over to the opposite side above the eyepiece.  With flashlight projection, the projected circle has a gradient field stop instead of a sharp field stop, again making it difficult to determine the AFOV.  Below is a composite showing three Rini eyepieces, none of which have a physical field stop.  Note how fuzzy they get near the edge even photographically making it difficult to judge what the AFOV is:

My point is, some eyepieces can defy even the best measurement efforts.

I also like my method for eyepieces plagued by SAEP like the aforementioned Meade MWA 26mm.  I back off the camera to where SAEP is not much of an issue and take an image and go from there to figure out the "easy to view" AFOV.  I suppose it's the same point as the top of the cylinder of uncertainly for its exit pupil.  If the rotating device could pivot there, it should be able to get an accurate AFOV, plus or minus the effect of a field stop defined by SAEP rather than a physical ring.

On 23/12/2022 at 08:57, Don Pensack said:

Well, not quite dead on:

XW:

40  68°

30  68°

20  70°

14  69.4°

10  68.4°

7  69.3°

5  69.3°

3.5  68.5°

XL

40  63.3°

21  61°

 

The point is that without some serious pincushion distortion (not Pentax' general rule), a 28mm is more likely to be ~52° in a 1.25" barrel.

Well, my AFOV measurements via flashlight method and photographic method are below:

3.5XW : 70° and 70.2°

5.2XL : 66° and 64.8°

7XW : 70° and 70.0°

12XF : 60° and 61.1°

14XL : 64° and 64.9°

40XW-R : 70° and 69.7°

What methods did you use to measure your values?

Photographically, the more accurate and precise method, these are all range between 0° and 1.1° off, with 0.3° being the average including the XF and 0.16° excluding it.  I'm sticking with Pentax providing bang-on values for XL and XW eyepieces to within 0.24% error using 68° for the denominator.  That would make the 55° claim for the 28XL to be somewhere between 54.9° and 55.1°.

Let us know how that goes as far as viewing comfort to take in the entire FOV.  I've measured the 27mm Pan to have 14mm of usable eye relief.  I have to push in so hard with eyeglasses to see the entire FOV that in the past I've scratched my eyeglass lens on the exposed eye lens retaining ring.  I was furious.  I retired mine in favor of the 30mm APM UFF.  The Pan might have a bit tighter star images on axis, but that's its only advantage over the UFF that I've found.  Back when I bought the Pan in the late 90s, I was actually shopping for a long eye relief 30mm SWA eyepiece with excellent correction, so it just took about another 20 years for a viable alternative to show up.

6 hours ago, Viktiste said:

As others have said, it depends on the thieves. Drug addicts or kids looking for some quick cash will be in and out quickly and only steal stuff that is easily fenced, and will probably flee if spooked by lights and sirens. But if it is as gang of pro thieves - then maybe not. And they might be more likely tho steal the expensive stuff (imaging setup) in addition to the cheap stuff (pc).

After this incident I never leave my gear unattended for long periods, and sadly it kind of ruined the hobby for me.

Wow, what part of Norway did that theft occur in?  I picture a mostly empty country filled with fishing villages, fjords, and snow capped mountains.  Norwegian cities are typically portrayed as utopian paradises on travel shows here in the US.

As far as the BCOs, it might come down to if you need astigmatism correction for your eyesight at lower powers and thus larger exit pupils.  The 18mm would be too tight for eyeglasses, but the 32mm might work, depending on eye lens recession.  BTW, I couldn't find a 32mm BCO, only a 32mm Baader Classic Plossl.  If that's the case, I doubt if you could extrapolate anything from the BCOs to it.  I'd probably look for a pair of vintage 30mm Ultrascopics/Eudiascopics instead.  They're known to be of exceptional visual quality.

Find out what they've been stealing.  Generally around here, they've been smashing car windows to steal laptops, phones or guns left in cars parked outside.  They don't generally bother with backyards or sheds because there's generally nothing of small and high value there unless they know it's the home of a contractor with lots of high dollar tools stored outside.  Generally, though, these are in a trailer, and they'll cut the hitch lock, hook it up to their own pickup, and tow the whole thing away.  They don't generally break into houses given the high gun ownership rate in Texas, and the court proven Castle Doctrine to shoot to kill to protect one's abode.

I'm thinking they might steal an open case of eyepieces thinking they're camera lenses, and perhaps a cased small refractor thinking it's a professional camera lens used for sports photography.  I doubt they would take the time or effort to grab an entire imaging rig setup outside just due to its ungainliness.  They might steal a laptop nearby yanking it free of any attached cables and cords.  Think like a criminal.  They want to be in and out in under 30 seconds, and they want stuff that can be easily fenced.

9 hours ago, Don Pensack said:

That's true.  Distortion can make a difference.  But are you sure the XL28 was really 55°?

Based on my measurements of my Pentax XL, XW, and XF eyepieces (6 in total), Pentax has always been dead on accurate with their quoted AFOV numbers.  Thus, I have no reason to doubt their number for the 28mm XL.