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  1. This test chart is for determining your scopes ultimate resolution, the line pair per millimeter criteria, its defined character on lunar and planetary targets. It is independent of aperture. Aperture equals a brightness gain not a concomitant resolution gain. goto normankoren.com for instructions and the test image. OBJECTIVE QUALITY determines its edge spread function, the smoothness of figure, the degree of polish, how closely it adheres to the design when implemented, and is independent of size, increasing size only adds brightness, a potential power increase and eye comfort, a bigger exit pupil. Essentially the point (!!!) is that the eye sees a line much easier than a point. The following is a snipet from an article on sensor size and the eye. Do Sensors “Outresolve” Lenses? by Rubén Osuna and Efraín García The was copied directly from a camera and sensor article by luminous -landscape.com To add data to the assertion of superiour resolution POTENTIAL irregardless of size. <snip> The separation between cones in the fovea is 0.0015 millimeters, which limits the maximum possible visual resolution to 20 arc-seconds. In practical terms, it is known that 30 arc-seconds are barely discernible. Adopting that number as a bound, 60 arc-seconds can be a good practical value for the average absolute visual acuity limit. In effect, a very small isolated spot cannot excite a sufficiently large number of retinal cones, but a line does. We can perceive more detail if it is formed by lines instead of spots, which implies that we can see a line thinner than the diameter of the minimum spot size perceivable. Another factor to be considered is contrast. The eye resolution also depends on the contrast between the bright areas and the dark areas. Even more, it is higher if we look at high contrast bright lines (or spots) on a dark background, and lower if we look at dark lines (or spots) on a bright background. We can also see a thinner line if it is isolated from other adjacent lines. We can see an isolated black line on bright background if the line is at least 0.001 millimeters thick (1 micron), considering an optimum (for resolution) viewing distance of 25 centimeters. This translates to 0.8 arc-seconds. An isolated bright line on a dark background can be seen irrespectively of its size, only depending on the brightness of the line. End snip Cassini division and rilles are examples of separating an edge, a LINE. An obstructed mirror loses tonality intensity so when it tries to seperate a slightly brighter dull grey line from a slightly less grey line, like the Alpine rille at .3arcseconds wide, it can't do it, blurring the finest fine scale contrast data making it essentially invisible. An apo passing purer whites and blacks has better potential resolution of lines than a mirror simply because of TONE loss. My apo has NO PROBLEM with observing it as its contrast function is immensly high. So it Requires Needing Brute Force, to make the same observation, its EXACTLY the SAME phenomena as seeing B33, the HorseHead, with a tiny but potent 70mm for when PROPER IMAGE SCALE is applied, its an EASY target given 'ultra' conditions. So please know that the absolute resolution, the visible CONTRAST of extended objects with linear features used with a superb lense a resolution MUCH much GREATER THAN POINT ONE arcsecond can be realized, any comparison with its specific p.s.f. number is NOT APPLICABLE and a grievous mistake. HOPEFULLY y'all LEARNED something useful that could help you better observe. Lines and points are two different biological KINGDOMS. A modification of our approach to getting the absolute best image is needed; IMO quality instead of aperture. Thus the massive investment in exit pupils for this magical tube, a true Divinity tube delivering a PURE & UNABERRATED wavefront. AND you know, if you had QUESTIONS I would have done my best to answer them but....no. Only lewd comments on CN - jeesh low lifes sure multiply like a nasty virus on fora there..... Is it any wonder that people of principle dont post in CN anymore. BillP dr. d EdZ etc etc much at all if ever anymore! I wonder why that is ??? SGL is going down the same path looks like. Ignorant savages with a computer ready to [removed word] on anyone not measuring up is probably (definitely) the reason why. Clear and steady line skies Clean free and easy educated seeing P.s. is willful ignorance the de fact standard now ?? where any ludicrous and crazy ideas is floated, lies profligating endlessly, so that actual knowledge is swamped out by noise, dismissed outright and is fakeness now the edifice that we wish to build upon?? I have posted a radical insight into observing vis a vis ULTRA-transparency, a followed through post, this is critical new/lost knowledge and nada peep Do you also hear, the crickets chirping while sad music plays in the background ?? I've nearly a THOUSAND helpful posts (without a mcg of vitriol) and I get suspended FOR EDUCATING ????¿¿¿¿ WTF ??? Seems it IS true that a prophet is not valued in his own home. i guess i was mistaken about this place too 2 welcome posts !! So thanks all for massively great welcome here !!! Sooo great If you dont want my wisdom thats cool i will take my fantastic toys home with me me and my EVOSTAR Divinity tube @1/15wavefront Peak to Valley or BETTER, to observe the Lords glory, without rancor and without tiny intellects futzing the view. Beauty eh!! 20mm T2 & 12Naglers 6.5Morph 6Ethos 4.5Delos 4TOE 3.3TOE Eyepieces for an average tube, I think not. If that offends you all I am CERTAINLY NOT apologetic about it. Thanks for all the memories laughing sarcastically emoji Over and....out P.p.s. long live stupidity May it always cause grief to the TRUTH I believe I am done now. Thanks !!!
  2. Hi all, So to put my welcome post to bed; What is ultra-transparency and how the heck with all the myriad transparency issues could you EVER get ULTRA levels of it ??? Its really simple actually, but first what IS Light Pollution ?? Then, how do you minimize it. Mother Nature does that by rain, winds, and other complex weather systems interplay and how their various interactions act out for each unique location but essentially, when it rains and blows, it CLEANS all, scrubs the local area of all foreign particles, of all types, pollen, dust smoke and suspended water droplets WHY, and when static, a stagnant entrenched weather pattern, causes the ever increasing amount of that distressing possibly horrendous (and hideous) LP by the continuous added foreign particulates multiplying nefariously. Eg. Exhaust gases, industry. BACK SCATTER is the CAUSE of why LP is. Rain cleans it all up and the amount of derived transparency is directly tied to the amount and extent of its duration. If a system occurs which gives steady rains, heavy and extended periods of it, thats IDEAL potential conditions for ultra-transparency. IF after several days of heavy rain know that is really just Mother shining up the windows, for a CRYSTAL CLEAR view out. Let me tell you a true story of my only successful observation of B33, the HorseHead nebula and IC 434 the background part and NGC 2024 the Flame nebula with Alnitak centred in a TeleVue 70mm F/6.8 Pronto & T2 12mm Nagler. This is 40X @1.75mm exit pupil and 2°true field. I lived in Vancouver British Columbia for most my life so really blessed to have tremendoously good seeing AND plenty of rain; with at that time growing up(1980s) good darkness while discovering my love for astronomy (tiny Tasco & Huygens 20mm observing Pleiades nebulosity) I'd guess B6-7 back then before Bortle, the steady decline in conditions till the present B9+ predicament but the good seeing remains however bad the LP is. { I imagine that with the same combo today I'd see EXACTLY the same view given the same conditions but I'm ahead of myself. } In '94 I purchased my dream refractor and used it ever so briefly, this unit had excellent optics with next to zero SA, of course it showed some colour error but its smoothness of figure was beautiful, so I am impatiently waiting out a deluge of epic proportions, hey Van is known for wet but this was BAD, so 5 days later when it finally pooped itself out and was replaced with majestic seeing I decided what the heck and pointed it at Orions left belt [from close near the CENTER (Burnaby)] and was STUNNED when in focus their were two (2) clouds ??!! I was sure it was clear out so I looked away from the Pronto to peer up and no it was clear so really perplexed looked again into the Nagler and was floored, ASTONISHED actually, to see a little tiny dark hook precisely where B33 be. The combination of my good eyesight, a good scope, PERFECT IMAGE SCALE plus a PURECLEAN atmosphere combined to shatter the notion of this being a difficult object WHATSOEVER. I used 70millimeters remember. I think its very hard to see because of three main things, too much applied power, poor atmosphere or poor optics or all three and include possible acuity issues and..... The REAL secret lies in getting the initial view, the small scale contrast information condensed enough to make it more luminous THEN ADD POWER, increasing the image scale THEN, to get further enhancements to the observed target. Its a very red object also, so if peoples acuity in the longer wavelengths is compromised REDUCE your power more. It is PERFECTLY counter intuitive to ever try to observe a PERCEIVED Extremely Difficult Object in the middle of a big city and I also would be blissfully unaware of how EASY it really is but for an impatience making me BREAK THE RULES, reading everyone problems you'd think you have to strain and use massive aperture when nothing could be further from the TRUTH. Literally two clouds, can you imagine that??!! REDUCE BACK SCATTER ENOUGH and its like being in outerspace SO if any LONDONERS or other large population centre astronomers out there WITH good seeing thats also hit with lots of rain type climate, you have a narrow window of PERFECT opportunity arrive when conditions of ultra-transparency materializes briefly, after heavy rains. I was never able to accomplish the feat again as some lowlife stole it soon after. Ultra-transparency; When hard objects DO make themselves known. No back scatter No problems with LP Simple as that !! Clear steady and clean skies Y'all
  3. Hi, Without reading the previous 25pages; My most useful powers and Exit Pupils (EP) is 45X @2.2mm EP And 135X @.74mm EP BUT thats using a 4" F/9 apo. YMWillVary depending upon your systems focal length and ratio. Build around those, with the next critical pupil you might purchase dependent upon the quality of your sky, its darkness, steadiness and transparency and WHAT you really enjoy observing most! The other critical factors are your eyes acuity and quality of your scopes figure. I always recommend a quality zoom as the first upgrade as it communicates so much relevant and vital data. It shows the level of atmosphere stillness, your average seeing frequency. The powers you enjoy most, and is critically useful as a lunar explorer, mated with 2X Barlow in my case. Clear and steady skies Clear and steady skies
  4. That is a really lovely image Laurie. I have enjoyed your images while I lurked and now I'm a member I can finally say job well done !! Clear and steady skies
  5. I also vote for a value zoom to start. Dont get the best zoom just a nice value one and play around with it and eventually you will find powers you enjoy best and that will help you to narrow choices to a select few eyepieces. That was my first upgrade path. To find the power most useful to you is the minimum power which shows the most detail the most often. For me at 53.5°N that meant a minimum planetary power of 135X (and that is just sufficient with my 4" scope) but with 10 inches aperture brightness will be an issue for you. No exp. with ES. Clear and steady skies
  6. The oscar for immersiveness and freeing oneself from earth, the ultimate spacewalker, is TeleVues Type2 20mm Nagler an unparalled experience of 82° visual excellence, dam the weight !! The Versatility oscar goes to the Baader Mark IV zoom. The lunar eyepiece of a lifetime is in my considered opinion the 6mm Ethos @150X and 2/3degree true field. Highest and acutest data retrieval eyepiece oscar is/are two, TOE 4mm & 3.3mm. Clear and steady skies
  7. Hi Giles_B! The quality of your scopes figure is critical to deciphering its details and your lack of seeing Cassini is worrying, its really critical to have your optics clean, collimated and good stability of the sky before doing intensive Mars study. The Mars 2020 closest approach on Oct. 20/21 I witnessed with 2X Barlow and 6.5 Morph (270X) using my 4" F/9 and gifted with a long moment of zero blur it looked completely etched with green/grey Syrtis Major and a luminius orange eye of Hellas staring back but it was the blazing, purest of whites, ice cold icicle dagger of the south polar caps intensity, stabbing my eye repeatedly, which really impressed !! I purchased 4mm and 3.3mm TOEs because of that image. If you can eventually see Cassini div. and given good steadiness and at a high culmination Mars should provide some nice views but it takes dedicated effort and a higher power than either Saturn or Jupiter does. My chosen powers for it are the two TOEs at 225X and 272X Good luck Giles !!
  8. The '51 glass will require a longer Focal ratio to give an equivalence to the superiour glass holding aperture the same. My F/9 4" coupled with '53 glass (and the long time they have fabricated the tube) has revealed an absolutely astonishing figure, (in the seeing necessary to determine that) with nary one or ANY other perceptible aberrations visible but it took multiple, excessively multiple times, of witnessing truly euphoric images that I now call 'etched fluidity' finally acknowledging what the scope was saying to me all along and know the loudest tell of all is the 'snap-to' when focusing. When SA & CA are very near zero the snap can almost be heard !! Finally one night in deep lunar exploration at near 300X, in magnificent conditions, examining the Alpine Valley rille in minutest detail for about one glorious hour I succumbed and finally really LISTENED to it. It was a Simply Insane LRO type lateral burn obervation, slewing at 2X siderial, up and down its entire length, in such mind blowing detail that this single observation cemented a new ocular plan, sinking the minimallist one, the cheap one, for a MUCH MORE impressive and (VERY) costly set of nine (9) instead of two (2) eyepieces costing a few $ into a new one (@3.3K$!!!), that this pensioner could not really afford, but when you are PRESENTED with a CLEAN wavefront you MUST modify your approach to buying eyepieces as every scope will have a unique function, from ~1/4 -1/20 wave and all points between, it takes a lot of TIME to properly assess an apo telescope unless you have much better conditions than I. I eventually went with consensus opinion when I finally bought and am very gratified by my choice of a Evostar 4incher F/9 (purchased in 2019.) Its a glorious tube and worthy of a deep investment in all aspects, H-a especially, (eventually), but the initial plan was just Barlow, widest t.f.o.v. and zoom. I'm sure you'll make good choices bosun21 just research till your sick then go with your gut instinct. * An F/11 and '51 glass would be AMAZING !!! Clear and steady skies
  9. Hello to all the glimmering illuminati in the sanctuary of sanity, from North central Canada, Edmonton. Recent escapee (PERMANENTLY) from the Crazy Contrary and Confrontational nites place. (Puking now emoji) What a gong show (dating myself) there THEY BLOCKED ME TWICE for attempted educational efforts (i think???). Seems the powers that be there, running that slow mo accident, happen to take offense at ANY attempts of mine to instill new knowledge or more precisely expand upon the parameters of detail, of resolution potentiality that is'nt fully comprehended IMO. Essentially the idea is that lines are MUCH easier to differentiate than a point source. Net effect MUCH better rez than P.S.F. criteria will suggest. Two object types, extended and point, thus two parameters of measurement either arcseconds or line pairs per millimeter. One cannot br interposed for the other.(at my present knowledge level that is !) I will post the complete assertion in an appropriate forum soon. THANK THE QUEEN (what a woman !!) & the good LORD ABOVE for the British high decorum I've seen throughout SGL!! Love love love it !!! I have a barrel of wisdom to share which I will very gladly do plus add some bin reviews and some observational insights I have accumulated over decades of observing so I think I could be a real asset to the forum or thats my hope !! I think the first important idea to share involves back scatter and LP issues and the right conditions which are required to make B33 (very) EASY TO SEE in the rainy U.K. Can you guess already with the provided hint ? Ultra-transparency will be the thread title. My handle is the name of my favourite authors best book IME. Google it and you will know who I otherwise am/was at the constipation nites site. Clear and steady skies y'all
  10. Hi all! I'm at 53.5°N Canada and I've observed night lit clouds since I arrived here 20 odd years ago, from the very wet coast of Vancouver to chilly Edmonton. The last few times out recently and observing them a lot, I see what others have captured, thicker cirrus like filiments stretched over considerable stretches of sky, when previously, they were much smaller and thiner 'clouds' of iridescence and no where near as obvious as they are now. Coincidently (?) Much More Moisture has plagued us here over the last few years especially the last two and this year almost a record amt of precip. Sunshine is not as often as the first 16plus years I was here, and clouds were MUCH less then as now, it will be clear and then suddenly get cloudy when evening arrives, and I am wondering/praying that this is not the new normal now. A bit scary TTTT and I pray its only an anomaly or maybe its only a longer term cycle emerging ?! IDK I will keep observing whatever the trend is though !! BTW: First post!! Glad to be here !!! Clear and steady skies
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