Getting New Astro-Stuff
A Solution Without a Problem Spending Money Wisely? Wisely Spending Money Nailing Down the Eyepiece Question If at first you don't succeed, buy and buy again...
A Solution Without a Problem
Say you have 200 dollars quickly gaining mass in your pocket and you just got to spend it on something astronomical. You already have two scopes (a 150mm F12 MCT and an 80mm ST80). And a set of decent Orion Ultrascopic eyepieces (35/25/15&10mm fl) plus two barlows (a 3x Ultrascopic and 2x shorty). Add to this one set of filters (including Ultrablock nebula filter). Put all this on a Skyview Deluxe equatorial mount (no right ascension drive - it takes up a needed manual slow motion position), and you're ready to go...
To go where and get what?
Well, first I know the 80mm "Pup" achromat needs a decent star diagonal. (The old one displays considerable astigmatism.) Now might be a good time to pick up a 2 inch diagonal for Argo and pass the 1.25 on to the Pup.
But Argo may not bring all eyepieces to focus with a 1.25 inch adapter...
Then why not a high quality dielectric coated 99% transmissivity 1.25 diagonal. That should push Argo up into the 80% transmissive region, right? But would it truly make much of a diff? Probably not.
Meanwhile, you dig those nice super-wide field views using Panoptics etc. But they are off the financial radar. And only the more expensive Nagler's give truly sharp stars across the entire field.
So OK, how about that mystical 1mm exit pupil eh? Remember how fine M13 looked at 150x through Argo? Something in the 12mm range would be perfect. BUT, how much more perfect than the 120x-15mm, or 180x-10mm?
So forget a single eyepiece - for now.
What about a zoom? Sure, a zoom would be nice - especially on those grab and view nights with the Pup. 50 to 150x with Ultrascopic barlow on the Pup or 75 - 225x without barlow using 150mm F12 Argo. Intriguing! But will image quality stand up? And how about that 40 degree low power field of view - just where you need a wide field most!
And OK, how about just getting a new scope? Something with some serious photon collecting potential. An 8 inch fast newt would be great - especially on galaxies - a place where Argo strains to go. Could probably pick one up used at $200 - already have a mount.
The fact is, I'm clutching vainly at finding a problem to solve.
Argo is a fine scope and on really dark nights reveals M51's spiral arms and the Sombreros bisecting lane. Sure, the Pup needs a decent diagonal. And if I can make a 2 incher work on Argo (without excessive re-positioning of the secondary) - all the better.
But beyond these two "necessities" there really is no rationale for spending good money poorly.
Might be a good time to start saving up for that Nagler...
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Spending Money Wisely?
Earlier today, I dropped by Dan's to borrow his Nikon Zoom. Then on to Watsonville, CA and the main Orion B&T outlet located there. Brought Argo along with mount and a couple eps. Tried out a 2 inch diagonal. Sighted on the most distant target I could find and wow. Both the 35mm and the 10mm Ultrascopics eyepieces came to focus. Diagonal even came with its own 1,25 adapter. Not bad!
So picked up a $75 two inch diagonal and a couple of $50 eyepieces. What eyepieces? Well heck I'd just bought a 2 inch diagonal gotta(!) have a two inch eyepiece too. So the 42mm Deep View was just the ticket. And cool Orion sells a 66 degree aparrent field of view 20mm inch and a quarter eyepiece these days. "The Expanse". So expensed the Expanse and the DeepView and the diagonal. $200 spent - good riddance!
Returned home to Boulder Creek and set up the diagonal again. And, of course, it turned out that the "distant" target I used at Orion was not. So had to make a critical decision about the diagonal in a knowledge vacuum. Should I adjust Argo's secondary to achieve focus or not? Did a bit of an experiment first. Basically, I centered Argo on a distant cell phone tower and rotated the diagonal through some 180 degrees. Well, the image stayed pretty much at center at 180x. Even better than the 1.25 diagonal. Made sense. Larger mirror is easier to install "square" than a smaller one. I was sold. Made the commitment and altered Argo's secondary position to compensate for the deeper 2 inch diagonal / 1.25 inch adapter combo.
Everything came to focus. - Everything BUT the 35mm. Oh well, I had that 42mm 2 incher anyway. Of course, can't use the 3x Ultrascopic barlow anymore with Argo. But it's great for the Pup - along with Argo's old 1.25 diag.
Did some daylight tests on the cell tower and neighboring "snow-fenced" alpine meadow. What snow fence? Torn down now - either by man, beast, or natural elements.
Compared the 15mm Ultrascopic to the Nikon Zoom at about 120x on the cell tower. The Ultra gave a slightly crisper and brighter view. A wee bit suprised as the Nikon is regarded favorably as a zoom ep. Hmmmm.
Did a daylight comparo of the 1.25 20mm Expanse unit versus the 25mm and 15mm Ultrascopics. Through Argo the 25mm Ultra was sharper at the edge. But the Expanse was as fine through the Pup. Keep in mind that the Expanse has that 66 degree AFOV while the Ultra is at 52. Field flatness was very good - at half the cost. On axis performance with the Ultra's slightly superior in both scopes. The Expanse has the more pleasing field of view and seems to map well against the achromat in terms of field flatness...
Sky around here has been pretty good - for early February. So I had a chance to "Night Test" the new setup as well.
The 42mm is pretty poor for field flatness. Frankly, its on-axis performance is equally underwhelming. Finally both eyepieces have poorer coatings than the Ultras. Did extensive comparos between the 15 & 25mm Ultras and 20mm Expanse. The usual effects of exit pupil were apparent on M42. And poor seeing made definitive tests of optical virtuosity impossible. (All eps had trouble holding the dimmest trap member.) The only real problem with the Expanse is a lack of good coatings. I was finding the Flame nebula everywhere near Alnitak! Meanwhile, not only did the 25mm turn it up but even revealed its two major divisions!
Seems to me the main problem with the coatings was light reflected off the observers own eye or entering from from extraneous light sources. Street lights, lamps etc. around the scope beams off the eyelens back into the field of view. Meanwhile, there also appears to be slightly more of the usual light scatter and subtly reduced transmissivity associated with light passing through the ep itself.
The Expanse would be a satisfactory ep however - if I didn't already have the Ultras... One thing I am learning through all this: There really are differences between eyepieces. Clarity, transparency, flatness, eye relief, freedom from internal and external reflections, off-axis light infringement - even physical things like weight and shape plus that special "aesthetic" or attractiveness to eye and hand. The Ultras have all of it. The Expanse well, what do you expect for 50 bucks!
Just had to make some kind of comparo between the 35mm Ultra and the DeepView 42mm. So I went through the trouble of extending Argo's focal length again - but under the less favorable conditions of the nightime sky. What a mess. Fortunately, there was enough travel in all the secondary components (pivot and adjustment screws). But I must have added another 5mm's to Argo's focal length to compensate for the 1.25 adapter (and the one I have is trimmed down!)
The 35mm ended up showing much better on and off-axis stars. Like the 25mm, it revealed the Flame - which the 42 did not due to all that extraneous light.
So what to do? Well hey, all the Ultras come to focus now. Might as well return both eps to Orion and pick up something useful. Zoom?
Nah, fields too narrow and even Dan's fine Nikon isn't quite (but almost) as sharp as the Ultras.
As I said, I had some reservations about the weight of the 2 inch diagonal. Without the 2 inch eyepiece this is far less a problem - but observing position gets wierd when the diagonal is rotated anywhere near Argo's finderscope.
The Pup likes Argo's old 1.25 just fine. Much better than el cheapo I'd been using - and far less coma / astigmatism apparent.
Too bad the sky was so unsteady - would have been neat to see how well both scopes and the Expanse would do on the Gas Giants.
Thought I'd include some observing details from the evening:
Only the 35mm Ultra did a good job of revealing the dimmest member of the Theta Orionis Four (the Trap). And this was through Argo. Higher magnifications (Expanse 90, Ultra's 120, 180x) just didn't seem to cut it - although I don't recall if the 25mm gave a good view. Seeing stability was just too poor for higher magnifications.
None of the eps used with the Pup gave a steady view of the faintest Trap member. All required some aversion to hold - depending on just how bad seeing stability was at the moment (5-/10). Both the 25mm Ultra and the Expanse could show the "Darkness Cliff" opposite the Trap from the Eagle's Beak (some call this the "fish mouth ugh!). But each required a bit of aversion. Interestingly, the Ultra (at 48x) and the Expanse (at 60x) captured just about the same actual field of the M42 region. The difference? Image scale of course.
Using the Pup (at 48 & 60x) on Saturn, the Expanse had a little more extraneous glow. This made Titan a little harder to hold direct than through the Ultra. But exit pupil could be a factor here. I thought the Nikon Zoom also had a bit more glow as well.
In terms of field flatness the 42mm, 35mm, 25mm and 20mm all showed edge astigmatism. Some of this is my eye. However, the 42mm appeared comatic even on axis. The others went through the usual focus at center, coma at 1/3rd field out, astigmatism at 2/3rds field out pattern. The view of the Pleiades was unacceptable through the 42mm. At 35mm, it was decent - even showing the Merope nebulosity. (Fine transparency 5.5+ZULM). So unlike the Expanse, DeepView elements probably not well matched or collimated to one another...
I took a look at the Crab Nebula through the 35mm. Very nice. Excellent contrast. Good dark sky. Pinpoint stars all the way to the edge - as long as they were dimmer than say, 6th magnitude. I should add that the 2 inch diag does not cause the 35mm eyepiece to rise above the lip. So it appears that installing a filter now does not effect focus as it did with the 1.25 diag.
Cassini was not visible this evening. Nor were either of Jupes belts. That's how bad it was...
It would be good to hold onto the Expanse for further testing, but really - it and the 42mm must go back. I like the widefield of the expanse but the coatings are not worthy of the optics...
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Wisely Spending Money
I started laying out my next trip by looking over Orion's on-line catalog. Experiences with the DeepView and Expanse eyepieces renewed my respect for the four Ultrascopic's in Argo's observing kit. I also have that large 2 inch diagonal, filters, and barlow to protect. So an accessory case made sense.
Meanwhile, several months ago my original observing stool finally had it with me wiggling around on it. The aluminum legs collapsed and since then I have shown far less enthusiasm for observing.
Picked up the observing chair and accessory case at the Watsonville outlet. After last nights testing, felt the eyepieces deserved the case. And of course, its always nice to have something soft (and at least potentially) warm to settle onto while contemplating the eyepiece view at the butt-end of a telescope. So along with protecting my assets, it was time to support my ass.
Along with the accessories, I went ahead and grabbed a 6mm Expanse. This allows Argo to hit 50x per inch aperture without using the shorty barlow. Meanwhile the Pup will be able to achieve 200x - 60x per inch through the 3x Ultrascopic.
I knew the accessories were a good choice, but doubts lingered about the eyepiece?
After taking care of a few chores, setup Argo with the 6mm and made a comparo. Now to be honest, I thought I had purchsed a 7.5mm eyepiece and was a bit putoff by how dark the cell tower field was compared to the 240x view offered by the 15mm / Shorty barlow combo. But once I realized that I had returned with a 300x 6mm things made more sense. (NOTE: There is no 7.5mm Expanse available.)
At 240x, the cell phone tower was visibly smaller than the 300x field but due to their apparent fields of view this was less than obvious...
Like the previous day using the 20mm, daylight testing was inconclusive. And of course this is not unexpected. The 20mm Expanse suffered from problems associated with coatings - not optics. Would the 6mm have similar problems by night time sky?
The first test was using Pup on the Moon. And here it was where the coatings and generally poorer baffling in the Expanse revealed itself. As the moon drifted out of the field, a very unpleasant amount of spurious light was broadcast into the field. But other than this, both chromatically and optically the Expanse did a fair job in stacking up against the 15mm and 10mm Ultras using the Shorty Barlow.
Saturn too was well up and the sky had darkened. I used the Expanse first and got a very fine view of Cassini (sharpened pencil), the SEB, ring shadowing, etc. BUT there was that annoying glow around the planet. I followed this with the 10mm shorty barlow combo (220x). This had less glow but otherwise the view was comparable.
So do I really want to make a nother run to Watsonville?
Let's see how the thing does on Jupe first...
After a couple hours Jupiter approximated the skys middle third. Before this I dismounted the Pup and installed Argo. At 300x, sky conditions undid the 6mm. The planet could be seen to distort at the field edges and there was that excess of glow. Despite offering an almost acceptable planetary image, the 6mm just had to go due to its excess of magnification. Saturn however took the 300x well, but then I could just have easily used the 360x provided by the 10mm Ultrascopic plus Shorty barlow combination. No good reason to hold on to the 6mm then.
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Nailing Down the Eyepiece Question
Made my final trip to Watsonville today. Resolved to pick up the 12.3mm EPIC ED2. This would be my last stab at purchasing an eyepiece. So far, despite passable optics (on the Expanse), poor coatings and internal reflections were their undoings. The Expanse series, in my estimation, would be quite satisfactory for deepsky use but are currently incompetent for lunar-planetary applications. Should Orion upgrade the coatings and improve the internal baffling they would make very decent general performers - supporting both casual lunar-planetary and deepsky use.
Returning with the 12.3mm Epic (remember that 1mm exit pupil, through Argo), I did the usual daylight test. Very decent. But what about those coatings? Visually, the eye lens reflected a good deal of extraneous light. Hmmmm.
That evening compared views on the Moon. Splendid! Nice dark background sky. Sharp limb edge. No off-axis illumination. Comparable to the 15 and 10mm Ultras in clarity. So OK, a satisfactory lunar performer.
What about them Gas Giants?
Through 7-/10 skies, and abetted by the Shorty barlow for 300x, Saturn's SEB resolved both frontiers, polar darkening, and blue gray mottling. Ring shadow on planet. Planet shadow on ring, Encke Minima, and ocasionally ribbon-like Cassini division. Five satellites. This is the view I expect to see through Argo on better nights.
On a much lower Jupiter, 300x was excessive. At 150x, easily detected the two main belts along with edge irregularities, barges, and "Great Not-So-Red Spot". Image scale just a wee bit low.
Couple of things I only noticed on Jupiter. One good, the other not so. Argo's 52mm central obstruction creates a "donut shaped" afocal pattern that somehow manages to project right through the eyepiece and surround the planet when centered in the field. Of course the "CO torus" can also be seen opposite the planet as it progresses across the field. This is very strange, I have never seen the torus "resolved" before by any other eyepiece. Usually it simply appears a "darkening" effect in the center of the field. In Jupiter's case, it comprised a "brightening" that contributed to the glow always present around the planet due to atmospheric and optical scattering...
The good thing? For some reason the sky appears darker in the 12.3 mm than it does in either the 10 or 15mm Ultras. It gives that "still ppol" effect I have seen when using the 3x configured 1.25 inch Ultrascopic barlow / 25mm eyepiece combination.
So I wondered if I was loosing magnitudinal reach through the Epic - compared to say the 15mm?
To test the magnitudinal reach question, the next night I turned the 15mm and 12.3mm's on Iota Cassiopeia. Found the Epic did a slightly better job of holding the 12.2 magnitude field star than the 15mm. The test was done under a fifty percent Moon and 6/10 seeing stability - so conditions were not the best for this sort of thing. Allowing for the slight difference in exit pupil, it's clear that the EPIC presents no problem in this regard.
So its a keeper.
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If at first you don't succeed, buy and buy again...
How exactly did I scratch my astro-acquisitive itch then?
Thanks to the generous return policy at Orion B&T, I now have a nice stool to settle on while viewing the night sky. All eyepieces, Shorty barlow, filters and 2 inch diagonal are protected by an easily transported aluminum case. And I have that magical 1mm exit pupil view for use as a "detailer" when viewing deepsky denizens. Plus now, of course, I also have that killer 150x star party magnification for viewing Jupiter, Saturn, Selene, and globular clusters. Add to this the Shorty barlow and I have a near 300x "image scaler" which works fine on Saturn most decent nights and Jupiter under especially good seeing. Finally, the Pup now has a solid diagonal for permanent use plus that satisfying 1.25 inch 3x configured Ultrascopic barlow.
Did I spend money wisely?
Sure! But it took three trips...