Orion Binocular Viewer
Is Quoting Yourself Plagarism? Chewing on Your Own Words Lighting Up Both Hemispheres A Three Scope Sampler Cold & Clear Hanging Twain with Selene Pushing the Magnification Limit Moon & M35 Astro.Geekjoy Deepsky Atlas
Is Quoting Yourself Plagarism?
"For many decades folks were very happy with the fact that both of their ears could hear music - even if it meant that the sound they heard was exactly the same (that is lacking stereophonic sound modulation).
BUT eventually the requirement for "High Fidelity" sound demanded that the sonic experience of the listener duplicate that of being in the concert hall. As such, depth of audio perception became an important attribute of the listening experience.
Such a "stereo" experience however, is not to be expected in amateur astronomy. For as we know, to see even the nearest stars shift against the background of space requires that optical signals from two scopes located on opposite sides of the Earth's orbit around the Sun (sum 186 million miles) be presented to the eyes simultaneously.
But, even a monaural listening experience allows both ears and more importantly both halves of the human brain to participate.
Of course this is not true in amateur astronomy. We observers are only able to admit light into one eye - and by extension only one half the brain's ability to process optically encoded stimulation is engaged.
In this way we have exposed one potentially serious deficiency related to our observing experience. AND that deficiency is a strike against most astronomical equipment now generally in use.
CONCLUSION ONE: SOMEDAY THE USE OF BINOVIEWERS WILL BE THE NORM AMONGST AMATEURS - NOT AS NOW - THE EXCEPTION." - http://astro.geekjoy.com/astrospeak/startesting_backgrounder.html#3.
For me, someday is today. Will life with a binoviewer live up to my expectations?
Chewing on Your Own Words
I have three scope buds. Not a single scope has enough infocus travel to incorporate the four extra inches required to bring a star at infinity to focus on an eyepiece mounted in a binoviewer. FACT: Today's telescopes are largely incompatible with today's binoviewers. FIX: Install a barlow lens. RESULT: Double, even triple the effective focal length of your telescope. GAIN: Large magnifications with even short focal length instruments. LOSS: Field of view.
CONCLUSION: Binoviewers using many of today's telescopes is a "Good news, bad news" punchline...
Yesterday (Wednesday, September 13, 2006), I took possession of Orion's Binocular Viewer. The unit came in a well-constructed aluminum case. Although the carrying case lacked a handle, there was enough interior room in its foam-fitted interior for both the binoviewer and a barlow lens. The unit itself included individual knurled focusing for each eyepiece and smoothly varying inter-optical spacing that wraps comfortably around the bridge of the nose. For the money (less than 200USD plus tax) the unit is a true bargain.
Spent a couple hours that same afternoon at home puzzling through the best way to adapt the viewer to the F5 80mm (Pup), F12 150mm Intes MCT (Argo) and F9.8 102mm C102HD achromat (Vicki). After a great deal of experimentation with three barlows (an older 2 element Shorty, a newer 3 element apochromatic shorty, and an older 3 element apochromatic Ultrascopic "Longy", I only succeeded in bringing the viewer to focus using the "Longy" on all three scopes. Then a stroke of insight: The older model shorty uses a extended rather than internal lens. Pleasantly, I was able to cannibalize the lens, and thread it onto the end of the viewer. Happily, the resulting configuration worked on Argo in association with my old 1.25 inch diagonal. Unhappily, using the pair of 25mm Ultrascopics with the two element barlow lens threaded on (not in) the viewer barrel, the scope was throwing up 210x views of a distant cell phone tower i typically use for daylight optical testing.
What I really wanted was those 70x views Argo normally gets with a 25mm eyepiece. So I took the plunge and repositioned the primary and secondary mirrors to increase focal length as much as possible. In the end, I only succeeded in completely throwing off Argo's collimation without getting anywhere near using the viewer sans 2 element barlow. I spent the evening re-collimating Argo using Polaris.
I did find that the binoviewer would come to focus in Argo without the diagonal. However, observing position using my Skyview Deluxe equatorial mount is awkward for anything exceeding 45 degrees in altitude. I do not see myself ever doing more than experimental observing using the straight-through configuration - even if it does mean getting 70x views of the star fields etc.
The next day (Thursday the 14th) I went about the business of installing the 2 element shorty-barlow configured viewer in the 80mm achromat. It was a no go. I was about 3mms shy of focus at infinity. I did notice that the ST80 uses an internally threaded locking collar on the 1.25 plastic adapter between the focuser and the diagonal (or eyepiece). Removing this collar (located against the knurled focuser tube) closed inside focus travel enough to achieve perfect focus with the 1.25 inch diagonal and barlow headed viewer installed.
With this simple modification to the Pup, I now had two scopes that could accommodate the barlow-headed viewer. More importantly, with 1200mms of effective focal length and a pair of 25mm Ultrascopic eyepieces I was throwing true one degree 50x fields into both eyes. The field looked enormous. That's what binoviewing star fields is all about!
Vicki however, was another matter. There was no simple trick I could use to close the 15mms of inside focus gap using the barlow-headed viewer. The only hope would be to have a machine shop remove 15mms from the optical tube itself and remount the visual back. I'll have to give this a lot of thought before proceeding. My main concern would be the potential for off-axis vignetting of the light cone should the barlowed viewer head lie too close to the objective. 15mms however should have no impact on images lying in the middle part of the field.
Like the Pup and Argo, Vicki brings the viewer to focus with the 3-element long tube Ultrascopic barlow installed ahead of the 1.25 inch diagonal. Under such circumstances the weight of the viewer is highly leveraged as several inches of additional focuser travel is needed to place the barlow head where it can achieve focus with some nine inches of negative lens optical divergence.
Lighting Up Both Hemispheres
The human eye is an extraordinarily complex neuro-opto-muscular device. Photosensitive neurons lining the retina can be stimulated by as little as a single photon of visible light. Musculature associated with the iris allows the eye to dilate to about 7mms of entrance pupil (aperture). The eye gathers light over a 70 degree field of view. By day, sensitivity to light is decreased by several mechanisms. This include pupil contraction due to iris extension, reduced neurotransmitter levels, and the evacuation of rhodopsin (visual purple) from the retina. By night, pupils expand to decrease the focal ratio of the eye (introducing aberrations but gathering more light), neurotransmitter levels are increased at axons, and rhodopsin bathes the retina encouraging photosensor depolarization.
The human brain is bilaterally symetrical and functionally organized. Depolarized photoneurons on the retina project tiny voltages along the optic nerve using neurostimulators. These signals feed along the optical chiasm to the more ancient reflexive parts of the brain where even single photons associated with objects in motion can stimulate conscious attention and reflex. On-axis signals from each eye pass ipsilaterally to the associated occipital lobe at the back of the cerebrum where they are organized according to color, brightness, shape, texture, and location. Off-axis signals pass to lateral occipital lobes which do the same kind of contrast analysis for peripheral vsion. All this input is passed into the parietal lobes at the top of the human brain to be synthesized with interpretive information originating from the temporal lobes at the side of the head and colored with perceptual bias originating from conscious attention focalized in the pre-frontal lobes of the brain.
Seeing is a very complex task. It's a wonder to behold...
And a binoviewer - despite any fundamental optical incompatibility with most astronomical equipment - allows more of the brain to get into the act.
For me that act began in earnest on Thursday evening September 14, 2006. Sure I'd observed with binoviewers before - and using much better equipment. Astrobud Dan's Takahashi FS102 apochromat had no trouble bringing his microscope cannibalized binoviewer to focus with and WITHOUT a barlow. That instrument gave astoundingly clear, high-contrast views of star fields, clusters and the two gas giants. I also recall seeing M82 through a 10 inch Takahashi Mewlon set up in cassegraine configuration. It seemed to me that M82 was awefully large in the eyepiece - but the 10 incher had the aperture to light up the eye with structure and contrast despite the half a magnitude loss induced by splitting the signal in twain.
But tonight I was on my own. And because I wanted star fields I dropped the shorty configured binoviewer into the 80mm Pup with the only pair of eyepieces i have (two 25mm Ultrascopics).
Where'd I stop first - Polaris! At 50x and through 4.5 ULM skies in the San Jose lightdome north of Backyard Boulder Creek, no definitive sign of Polaris-B. On to Vega - excellent color just a slight delta between intra and extrafocal diffraction ring frontiers. On to the Double Double. Through 4.8 ULM overhead skies barely managed to hold the 10.5 magnitude come sharing the field with the slightly distended Epsilon 1 and Epsilon 2 pairings. M57? Smallish and ill-defined at 50x. 10.6 magnitude test star just held direct in the "Challice of the Ring". M13? No resolution here, but well contrasted against a satisfyingly dark background sky. Albireo? Splendid at 50x with fine warm yellow / aqua blue coloration.
Then it was off wandering the rich star fields of the summer Milky Way. I randomly slewed from Cygnus to Lacerta without any particular study in mind. Stars everywhere - but not always as profuse, some occasional near voids, and at least one obvious, but unidentified brightly scattered open cluster.
50x. 52 apparent degree ULtrascopic field stop. One degree fields. Large enough to let you see the lay of the sky. Magnification enough to resolve open clusters. Light enough to bring out contrast. This sort of thing could be contagious.
Of course, I was kind of wondering how much light I was loosing to that BAK 4 prism splitting all them photons. As it turned out and on a night such as this the Pup without binoviewer would hold stars down to magnitude 11.1 at 50x. With it, 10.6. Basically, the binoviewer stunted the Pup's already limited stature down to a mere 65mm in aperture.
Is it worth the loss of illumination? Is it worth the additional ungainly weight added to the OTA? Is it worth the need to keep those eyepieces as vertical as possible whenever repositioning the view to another part of the sky? Is it worth the hassle of having to dupe up on your eyepieces while pretty much getting stuck with only higher than generally useful magnifications? Is it worth having another accesory to tote around with you and keep track of while observing?
Is it worth it?
The answer comes down to this: Will the experience of lighting up both halves of my brain lure me out under the Night Sky with any frequency? Or will the thing end up collecting more dust than starlight? Will I ever really bother to play "one-eyed jeff" again?
A Three Scope Sampler
On Saturday, September 16, 2006 the Moon entered the fourth quarter. Such a day of the week and phase of the moon lends itself nicely to partying - star partying. Being the social creature I can be (sometimes), I headed out to Bonny Doon Airport for the twice moonthly Santa Cruz Astronomy Club (SCAC) sponsored 'Scopes Night Out'.
I brought along the Pup plus binoviewer, loaded with 25mm Ultrascopics and the nominally 3x barlow lens attachment. During the course of the evening, I tried the unit on three scopes: A C9.25 SCT, 115mm TMB fast apochromat, and a 70mm ETX-70AT achromat. I might as well have just left the binoviewer at home in terms of the ETX.
Like the 80mm Pup, the ETX would not achieve focus - even with the barlow lens cannibalized and attached to the binoviewer. Interestingly, in regards to the C9.25 and the 115mm TMB I could have just as easily left the barlow attachment at home. Both instruments achieved focus through their respective diagonal's with, or without, the need for optical assistence on the part of the barlow.
Unlike the Pup and ETX, the TMB APO came with a manually extensible drawtube. Without the barlow lens, the drawtube on the TMB still had another 3 inches (or so) travel before the binoviewer would have been "minned out". Of note is the fact that such a drawtube (along with the dew shield) is typically collapsed so the instrument can be carried in the smallest possible travel case. Despite this, there was no sign of vignetting in the off-axis light associated with the views through the TMB. One reason may be that the owner uses a two inch diagonal allowing the maximum amount of light ingress. The scope also has a very large diameter visual back. Some refractors, it would appear, come well designed for straight binoviewer (no barlow) use. Most however, do not. Caveat Emptor!
Unlike MCT Argo, most catadioptic telescopes use primary mirror shift to achieve focus. This type mechanism has a tremendous amount of focal range and achieve prodigious near focus. However, there is no guarantee that such a range continues well beyond infinity - as is needed to provide the four additional inches of focal travel needed to support an un-barlowed binoviewer. Again, if you are serious about seeing the Universe two-eyed, be sure to purchase your chosen binoviewer before shopping for a scope. Then make sure the model you are interested can accommodate the binoviewer without a barlow when focused on infinity.
In terms of pure observing enjoyment be prepared to change your nocturnal lifestyle once you begin actually binoviewing the heavens. For one, you'll find yourself seeing maybe one-quarter of the normal number of studies viewed over the course of the evening.
In terms of star parties, plan to spend far less time behind the eyepieces...
I made a few checks through the scopes used. We had a 5.5 ULM sky with 6/10 seeing overhead. The 115mm APO could just hold a 12.3 magnitude star near the Ring at 100x with the slightest aversion. At the same magnification, the 9.25 inch SCT required the same slightest aversion to reveal the 13.0 star neighboring the Ring itself. The calculated effective aperture of the 115mm APO is 97mm. That of the 235mm C9.25, was reduced to 180mm. The APO lost roughly 15% effective aperture. The C9.25, 25%. Given that I am only estimating the effective magnifications above, it's pretty clear that binoviewer use reduces effective aperture by roughly 20%. (The value for the Pup was also 20%.)
We ran a check on Double Double resolution (Epsilon Lyrae) comparing the view of a single quality 8mm eyepiece with that of the binoviewer using the 25mm Ultrascopics and barlow lens thread-on using the 115. There was no visible difference apparent between the views in terms of resolution. In making a similar comparison with the Ring Nebula (M57) it was agreed that the binoviewer view - despite being appreciably more engaging - was visible dimmer. Contrast was comparable however, since the binoviewer also darkens the background sky to the same degree (0.5 magnitudes).
Is a binoviewer the ultimate accessory?
It is, if you want your recessive observing eye, and all those associated neurons, to get in on the act!
Cold & Clear
Last night was January 15, 2007. Despite global warming (quite possibly because of it!) temperatures on the Bonny Doon ridge were in the low 20's. Braving the low oscillatory rate of ambient infrared radiation, El Marko, Dylan and I managed to to pull together an observing session. The fact that the air was relatively still was a real boon to our evening out. I have no doubt that had there been wind, even observing stalwart El Marko would have found something necessary to do indoors...
Although all my scope buddies remained at home, I wouldn't be without at least one observing companion - "Binny" (the binowiewer) stocked with twin 25mm Ultrascopic eyepieces. To be accurate, I really didn't even need to bring along Binny. (I'd left the binoviewer plus eyepieces and barlow head with El Marko while I was away visiting friends in Washington state.) This would be a reunion, of sorts. One that would lead to me retrieving Binny for use on Vicki, Argo & the Pup on warmer nights to come.
Dylan had his Orion 4.5 inch dob setup first. Orion, though still in ascent, was well placed southwest. We turned the scope at 90x toward the Great Neb. Caught occasionaly glimpses of the Trap E. Nothing definitive however. I thought the sky dark enough (5.5 ZULM) to have a look at the Flame Neb near Alnitak. Sure enough the little dob revealed a large welling up of nebulosity at 35x. We went on to have views of the Crab, M35, M78, & 79. Dylan, in his early teens, has had the dob for more than a year now and has become a fine astrogator. (Dylan also has remarkable visual acuity, in fact he had no trouble picking out NGC 206 in the Andromeda Galaxy through the binoviewer mounted in El Marko's TMB 115 APO.)
El Marko setup the TMB 115mm APO on an altazimuth mount. Because the mount includes digital setting circles, he took a few moments to do a three-star alignment. The DSC stayed on task throughout the evening. We of course, didn't use it early on since we were largely interested in bright, expansive studies that would give the most engaging views through Binny. (Later that evening we put the DSC in "sky tour" mode and challenged ourselves to identify faint open clusters in the region of Perseus and Orion.)
The TMB is meant to be a compact travel scope. It features an extensible drawtube. The drawtube means that Binny can be used natively (sans barlow lens attachment). Through Binny, the Ultrascopics were throwing up 2 degree fields at roughly 25x. We were able to frame M42, 43, NGC 1973/75/77 plus part of open cluster NGC 1981 in Orion's sword. At that magnification, all four trap stars were resolvable but due to the low power and loss of magnitudinal reach, no sign of Trap E was seen.
Of course, not seeing more than the Trapezium was no disappointment! The Great Neb was spectacular through Binny. The 4.5 inch APO revealed massive quantities of nebulosity throughout the region. The oft-dubious NGC 1973 series was obvious to all of us. Contrast was so superb, I even considered making a run at the Horsehead south of Alnitak. (El Marko forbade it!)
Stars were highly condensed (with only occasional atmospheric flaring). This made views of open clusters especially enticing. The Perseus Double Cluster was on everyone's short list. As usual, time spent at the eyepiece was more protracted than when observing monoptically. Since we were in the region, we also pulled up a view of the Little Dumbell planetary - an easy catch even at 25x with a clear sense of duplicity. Now that's a double double! Two clusters and two planetaries each feeding photons to two eyes and two halves of the brain.
We concluded the evening with a view of Saturn. The ring system is now visibly undisclosed. Because of this, Cassini was a bit of a challenge and visible only near ring ansae. The anterior ring cuts a nice swath across the planet's northern hemisphere. The south polar region appeared shot through with lovely blue-gray mottling effects. All this was seen through Binny at about 200x using what is billed as a 2.8x barlow (pumped up with 4 inches of image divergence).
Perhaps the most striking thought that kept recurring to me throughout the evening was this: Aperture really didn't seem to matter, as long as there are enough large, bright studies in the night sky. Why even prosaic star fields held there own charm...
Hanging Twain with Selene
You've probably read or heard it somewhere: Binoviewing the Moon is like hanggliding over the desert. Well, the night of Monday, January 22nd saw me out with Vicki hanging two - eyepieces that is.
I started early, not very long after sunset. There she was, a vague silvery crescent against the grey sheen I've come to recognize as clear skies in the early dusk. After re-orienting Binny to keep him perpendicular to the back deck, I had to center Selene in the finder with my eye several inches behind the finderscope. No problem though, it wasn't like having to track down NGC 6543!
The first look through Binny wasn't exactly breathtaking, more like "so???". But contrast was low, and the moon, though sharply etched at times, wavered in thermals rising above my neighbors peaked roof. No criticism here, it's 40 degrees out!
Always being the optophile, I wondered how much magnification the shorty barlow was adding to the binoviewer. Surprisingly, the erstwhile 1.9x shorty negative lens was only adding 1.7x through Binny. Could I be wrong? No, sure enough the moon only lost about a third of its girth outside the 52 degree apparent fields thrown up by the twin 25mm Ultrascopics. That meant 70x. At 1000cm focal length, the 25mms would easily encompass the entire moon natively at 40x. So yah, 1.7x gain using the shorty barlow lens threaded into Binny's nosepiece. No wonder Saturn looked so diminutive the other night. (You're Right, I've made no mention of sneaking a peek at the Ringed Wonder through one of my own scopes in this article yet have I?)
So what about hanggliding?
Things improved as the sky darkened. With increased contrast, features began to pop out (seeing stability 7/10) I spent a good deal of time surveying the terminator looking for something spectacular. Ultimately with crater Hercules largely undisclosed, I settled on Atlas to Hercules west. One rich crater!
Then I noticed Endymion and how featureless its lava-filled interior is. So, again I indulged my interest in "on the edge" detail. Sure enough, I caught the occasional, ill-defined brightenings that mark its two main depressions. Two depressions, two eyes, two eyepieces, one Binny, one Jeff, one Vicki, one sleek Selene. A nice first lunar experience. I'll be back...
NOTE: If you remain as puzzled as I about why the gain on my screw-in barlow lens was so low, it's because I wasn't thinking straight. If the moon is 30 arc minutes in apparent size, and it takes a full 52 apparent degrees to squeeze in just 2/3rds of it (20 arc minutes), then the actually magnification is 52*60/20 or 156x. So, my thread-on nosepiece shorty barlow lens has a gain of 156/40 or 3.9. Now that's more like what I expected! - Unfortunately...
Meawnhile, tests with my later model 3-element apochromatic Shorty barlow showed that slightly more than two lunar diameters (one degree) of sky is seen through the 52 degree apparent field Ultrascopics. This basically means that the actual field is only 14 arc minutes for a barlow gain of 5.6 when placing the nosepiece within a true barlow for a magnification of 222x. Yikes! No wonder I canabalized the older shorty's lens!
Pushing the Magnification Limit
So if you can't beat 'em, you might as well join 'em.
Lacking the graces of a drawtube or mirror shift, you're pretty much stuck with an excess of magnification when using a binoviewer (at least until you can afford a correcting lense). So this evening (Tuesday, January 23, 2007), I decided to just go with it and the night sky, and good lunar positioning was ever so accomodating.
The view of the moon at 150x (using the shorty thread-in) was promising. So out with the old shorty and on with the new - 220x. Tweaked the focus on the left eyepiece a tad and wow, was that ever one sharp view of Posidonius! Posidonius A very nice - along with its coterie of mountain peaks well-resolved sweeping from the north to the west.
Then I 'glided' south along the terminator to catch Theophilus' central peak tight and bright surrounded by the abysmal depths of darkness swamping the crater's deep interior. To the east, the interior was bordered by a brilliant arc of luminosity marking sunrise along the impact crater's eastern ramparts. Hanging right along the terminator, Theophilus looked just like the ancient symbol for the Sun - a dot, surrounded by a circle.
Covered up the lenses and left Vicki out to await Saturn. If the seeing holds, and I am willing to stay up late enough, should be one fine view...
At 9:30, with Saturn still outside the middle third of the sky, had a decent -- but not jaw dropping -- view of the Ringed Wonder at 220x. One thing noticed was how the planet seemed to float above the background sky. (I suspect this is why many observers ascribe an almost 3-dimensional aspect to seeing it through a binoviewer.) Due to low sky position and poor ring presentation, had difficulty resolving Cassini -- even at ring ansae. The south equatorial belt was visible however, along with the slight difference in albedo between the anterior ring system and northern hemisphere of the planet. Blue gray mottling in the south polar region was less obvious than through El Marko's TMB 114 APO last week.
Moon & M35
Tonight (Wednesday January 24, 2007) Maurolycus central peak stood in luminous bas relief above the crater's darkened interior. And like Theophilus the night before gave a similar impression of the symbol of the Sun. Meanwhile, just north of the lunar equator the fine rille system of Ariadaeus Cleft projected sharply away from the terminator in the direction of Mare Tranquillitatis. In observing the Moon with Binny, I noticed that there's very little limb chromaticism visible through the F10 achromat (a faint, inobstrusive violet is detectable when looked for). However, the Moon does take on a warm slightly yellow cast - as opposed to the bone white normally seen through Argo. Meanwhile, the background sky appears nearly jet black while the Moon itself has yet to be overpowering to the eye. (No neutral density filtering required.)
With Selene rapidly transmogrifying into that dreaded Luna, and far too much in the way of magnification at my disposal, I didn't expect to take much pleasure in deepsky observing. As a warmup, I had a look at the Castor double. With 5.0 skies and 7/10 seeing, got an easy clean split at 130x. (That's right, a more careful inspection of a fuller Moon showed that the 52 degree apparent size Ultras covered slightly less than one and a quarter moon widths - some 24 arc minutes stuffed into the 52 degree apparent field.)
Despite a considerable amount of time hanging with Selene, the real show stopper was the M35 open cluster in Gemini. Despite overflowing the 24 arc minute field, and loss of a half magnitude in reach, cluster stars displayed a great deal of depth. In fact, by assuming that brighter stars were nearer and fainter ones were further away, had no trouble imagining all kinds of 3-dimensional shapes, loops and swirls throughout the cluster.
Fascinating, and abnormally time consuming!
Astro.Geekjoy Deepsky Atlas Observing
This will be my last binoviewer-specific post. But not my last post involving the use of a binoviewer. For it's off to rediscover the Night Sky following a trail well-laid through number crunching and some five hundred hand-entries on public domain star charts. What am I referring to?
Why, the optimal-aperture-based Astro.Geekjoy Deep Sky Atlas.
How does it work?
Aside from pleasure taken in observing the Night Sky, I have another interest (writing software code). Some of that code is embedded right here on Astro.Geekjoy.Com. Other code is associated with my personal website. Many programs have to do with amateur astronomy. Some have been well received by the amateur community. Other's have yet to gain traction. One in particular, Deepsky Susceptibility Calculator has spawned several children. Among them is the Deepsky Studies by Optimal Aperture List which later resulted in Northern Hemisphere Star Charts.
And now?
I don't even have to print out charts on my printer... Nor do I have to keep a separate log of all my Night Sky studies. For you see, everything's been printed - charts, logs, templates, background information, instructions, observing templates - into a single, full color 80 page spiral bound Astro.Geekjoy Deep Sky Atlas.
And I've received my first copy and already put it to use...
For, according to the log embedded in my copy of the Atlas, I was out and about on Friday, February 23rd on or around 7:30 pm PST tracking down a number of deepsky wonders largely culminating to the south through the 80mm Pup augmented with 3x barlowed 25mm Ultrscopic eyepieces / binoviewer combination. On that occasion, my first view was of one "M42" a 5cm (50mm / 2") optimal aperture study and, despite the fact that 4.5 skies predominated in its general locale, I had one lovely 50x view.
As I recall, despite the fine view of M42, neighboring, 10cm optimal, M43 showed only a wispy circular nebulosity fading rapidly to an indistinct frontier when held direct. At the time, the faintest member of the Trapezium (variable star Trap B of approximately the 8th magnitude) could just be held without aversion against the brightest region of the Great Nebula.
And, as expected, 8cm optimal extended nebulosity NGC 1973/5/7, like M43, gave a less than satisfying view (largely due to the overrated cumulative magnitude of the group, but also due to the addition of a binoviewer which effectively reduces the Pup's aperture to 65mm and the 4.5 transparency of the sky).
However, 5cm optimally-apertured NGC1981 was an easily seen open cluster despite its widely scattered population of 7th magnitude stars and large sprawl.
Of course, since I was heading north anyway, I wanted to see if the 20cm optimal Flame Nebula was possible near Alnitek. (At best NGC 2024 was suspected but not confirmed.). Then it was south again. 15cm optimal Globular cluster M79, was easily found and showed a starry nucleus with rapidly dissipating mantle. A quick leap to M78, determined that better-positioned 12 cm M78 proved brighter and larger, although its frontier also lost its edge.
Is the observing world ready for an optimal aperture-based atlas of deep sky studies?
Maybe not. But I am.