[Mircea Pteancu]

Altundeva ,unde sunt oameni obisnuiti ,nu oameni mari si oameni mici ca pe ulitele forumului nostru,undeva unde sunt amatori care construiesc sau cumpara cu precadere lunete,acolo asadar predomina parerea ca o montura buna pentru o luneta cu focal de un metru nu este usor de construit;iar pentru o luneta cu focal de peste 1,5 metri este chiar dificil.Dar ma rog,pe langa faptul ca oamenii aceia sunt si nitel mai inapoiati,cum tocmai s-a explicat aici,familiarizati cu Unitron,Towa,Mayflower,Jaeger,Carton,Saers,Zeiss si alte d'astea (numai de pe alte meleaguri,nimic mioritic),dumnealor nici nu beneficiaza de savantii pe care-i avem noi,ca sa nu mai vorbim de oamenii mari cu care suntem binecuvantati noi,pigmeii de pe aici.
Iata mai jos descrierea unor observatii facute de unul din aceia,cu o prapadita de luneta de 63mm.De data aceasta fara diafragmare,am verificat textul ,sa nu mai enervez pe nimeni.In privinta distantei dintre granita noastra si Danemarka ,inca nu am reusit sa fac nimic.Lectura placuta,micutilor!Mircea

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Hi Edwin

I have seen too many objects, that most observers consider "impossible" in a small scope, to remember them all. A few do stand out in my memory, however.

First and foremost must be my observations of G1 (also known as Mayall II), the brightest globular cluster in M31 and the brightest globular in the local galaxy cluster. I have seen it several times in my 63mm Zeiss Telemator. It is roughly mag 13.5, when you include the two mag 14 field stars right next to it, which I couldn't resolve. The cluster alone is mag 13.7. Many people report of having huge difficulties in finding it, even in large scopes, but that is because they don't have an accurate map. The field is easy enough to find a few degrees from M31 and the globular easy in my 5" refractor, where it is clearly visible as a small fuzz, much like NGC 6229 in a 50mm binocular.

Another is Minkowski 1-64, a planetary nebula in Lyra. It is roughly mag 14, though I suspect that to be a photographic magnitude and that it must be at least a magnitude brighter in visual.

Then there's the Draco Triplet, a triplet of galaxies in Draco, one of which is a mag 13.1 edge-on. It was extremely difficult, but I spotted it one superb evening. The other two are mag 11 or so, bright and easy to see.

NGC 4486B is a companion to M87. It is a dwarf spherodial galaxy, just like M32 and roughly of the same physical size and surface brightness, but of course much more distant and thus around mag 13.5. Still, it is possible to see it in my 63mm Zeiss. M87 has four other companions that are a challenge in a 60mm.

Surely, UGC 11465, a mag 11 galaxy a few arcminutes north of 16 Cygni, also belongs on this list. I had to use 84x and place 16 Cygni outside the field, but then I could hold the galaxy a few seconds each time. Yes, you can see UGC galaxies in a 60mm, although only a few!

Then there are the number of PK planetaries I've hunted down with homemade maps, made from Palomar Survey images, as well as the large number of more or less anonymous galaxies. The list goes on and on. Minkowski 1-92 "The Footprint Nebula", IRAS 09371+1212 "Frosty Leo", Markarian 501, Berkeley 10, IC 289, IC 1747, the list goes on and on....

I have probably forgot many.

Clear skies!

Thomas, Denmark

[Forever_Man]

Totusi... cum poate vedea obiecte de magnitudine 13+, cand luneta are teoretic limita de magnitudine in jur de 11 ?

[MariusP]

Poate atinge magnitudine mai mare decat limita teoretica daca cerul pe care se face observatia are magnitudinea limita cu ochiul liber mai mare decat cea luata in calcul de estimarea teoretica...

[Forever_Man]

Poate avea cerul acea magnitudine pentru a putea fi observate obiectele de care se vorbeste ?

[MariusP]

Cred ca da. Din cate stiu eu, limitele teoretice sint calculate pentru o magnitudine limita cu ochiul liber de 5.0 sau 5.5. Un castig de 2 magnitudini ar insemna 7.0 sau 7.5 pentru ochiul liber, deci o valoare 3, respectiv 2 pe scara Bortle.

[Forever_Man]

Cu formula simpla x+5logD, pt x=7 (magnitudinea locului de observatie), luneta de 63mm va vedea pana la 11. Deci cum a vazut obiecte de mag peste 11 ?

[Doru Dragan]

Romanii mai mint, americanii nu mint niciodata Ce treaba ai tu "cum a vazut obiecte de mag peste 11"? A vazut si gata! Care-i problema
Cica erau niste naufragiati pe o insula. Toti barbati. Aveau de toate pe insula aia, apa, mancare, soare, plaja, mare dar ... totusi le cam lipsea ceva La mica departare era o insula pe care naufragiasera numai femei. Frumoase. Baietii mai tineri de pe insula cu barbati se tot gandeau cum ar face sa ajunga pe insula cealalta. Privelistea era minunata dar ... intre cele doua insule innotau o gramada de rechini. La un moment dat unul din baietii tineri il intreaba pe unul mai in varsta de ce nu se straduie si el sa ajunga la insula cealalta. "Care-i problema?" zise cel in varsta "Se vede foarte bine si de aici"

[zoth]

[MariusP]

[Mircea Pteancu]

Thomas a facut o remarca ,o citez mai jos:

''mag 14, though I suspect that to be a photographic magnitude and that it must be at least a magnitude brighter in visual. '' Mircea

[Ionut Dohotariu]

Cred ca e bine sa mai condimentam si cu ceva mai amuzant! !!!

[Mircea Pteancu]

Ca sa continui off-topicul...
Thomas afirma intr-un alt mesaj ca locatia sa are un cer foarte intunecat.Pe de alta parte a mai spus ca locatia sa are un singur dezavantaj major ,in privinta caruia nu poate face nimic,latitudinea geografica.La el multe obiecte interesante sunt mult mai apropiate de orizont.
In tineretea mea,am citit mai multe rapoarte greu de acceptat pentru observatorii -posesori de instrumente mediocre si aflati sub un cer spalacit de poluarea luminoasa.Acele rapoarte ale unor posesori de telescoape Questar ,aflati sub un cer de calitate,descriau observatii de obiecte aflate la 14mv si au fost publicate in ''Sky&Telescope''.
In ciuda atitudinii super-mercantile asumate de mult timp de aceasta revista si a atitudinii anti-ATM,totusi nu cred ca redactorii de la aceasta revista sunt ''botanisti'' -asta la mine inseamna ca ''nu pun botul''.
Revenind la montura mea,daca-i voie sa mai vorbesc despre ea...
Erwin ,sau altcineva,ar putea va rog sa-mi spuna excat ce inseamna a slefui filetul unei monturi din teava de instalatii.
Mircea

[KosmynC64]

D-le Pteancu
Aşa arată o montură cu trepied pentru o lunetă Meade de 60 mm.
Este de vânzare şi dacă sunteţi interesat vă rog să răspundeţi pe PM.
Vă mulţumesc cu respect.
Cosmin

[Mircea Pteancu]

zoth
mai demult ti-ai exprimat dorinta de a afla noutati de la Thomas Jensen.Iata ca in aceste zile a facut o comparatie intre doua lunete Zeiss de 60mm (+) si o luneta Vixen diafragmata la 60mm (individu' asta e culmea,cum incalca ''legislatia'' romana).Cel mai scurt instrument este la F/13 iar cel mai lung la F/20.
Rezultatele sunt interesante si pline de invataminte.De notat
- ocularele folosite au fost ,cu o singura exceptie,orthoscopice japoneze Kokusai Kohki

-paradoxul campului vizual mai mare al ocularului de 7mm

-paradoxul Vixen

Lectura placuta,Mircea
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Hi friends

A few days ago, after some discussion about a 60mm f/20 over on CN, I decided to take some of my 60mm's out to play. I wanted to compare them to one another and see what I would find. I found both some things I had expected, as well as something totally unexpected. More about that later. First, we must meet the competitors:

1: My Zeiss Telemator, a 63/840mm cemented achromat of high quality from 1989. Fully coated with Zeiss coatings. Diagonal a standard 1.25" Vixen diagonal, coated. Telescope equatorially mounted, but motor not turned on.

2: My Zeiss "Reisefernrohr" (travelling telescope) with 60/850mm airspaced E-objective, all from 1910. Not coated, of course, and I used a Zeiss diagonal from the same era, which is also uncoated. Altaz mount.

3: My Vixen 80/1200 stopped to a 60/1200mm f/20. Objective fully coated with standard MgFl coatings. Diagonal, a 36.4mm Vixen thread-on, is also coated. Mounted on GP equatorial. No motor.

I have enough eyepieces that I could get the scopes close to each other in magnification. This was very important to get a reasonably reliable result. I could use the following magnifications and eyepieces:

Telemator: 12.5mm 1.25" KK ortho: 67.2x
9mm 1.25" KK ortho: 93.3x
7mm 1.25" KK ortho: 120x
5mm 1.25" KK ortho: 168x
4mm 1.25" KK ortho: 210x

Zeiss Travel: 12.5mm 0.965" KK ortho: 68x
9mm 0.965" KK ortho: 94.4x
7mm 0.965" KK ortho: 121.4x
5mm 0.965" KK ortho: 170x
4mm 0.965" KK ortho: 212.5x

Vixen: 18mm 1.25" KK ortho: 66.7x
12.5mm 1.25" KK ortho: 96x
10mm 0.965" Zeiss ortho: 120x
7mm 1.25" KK ortho: 171.4x
6mm 1.25" KK ortho: 200x.

The images at high power were especially revealing, and most of the comparison was done at around 170x, in which case all the eyepieces used were KK orthos (Kokusai Kohki).

So what did I expect to see?

1: Telemator: Brightest image, with the most pronounced chromatic abberation, but still very high contrast.

2: Zeiss traveller E60: Dimmest image, with second-best color correction and very good contrast.

3: Vixen: Close to no chromatic abberation and extremely sharp images. A little brighter than the Zeiss E60, but dimmer than the Telemator.

And what did I see?

I found all of the above to be true, but there was also some unexpected surprises, as I have already mentioned. Test object was the Moon, two days past full, in so-so seeing with good moments. A little wind and no clouds. Warm, but with surprisingly little dew.

The Telemator was brightest by far, but had a noticeable (when you looked for it) blue halo beyond the edge of the Moon and upon close scrutiny, the Moon had a very pale yellow-green hue, but the images were still very close to a neutral grey. The hue was extremely pale, and when you just sat down and looked, you never noticed it. All as expected. Star test shows lots of chromatic abberation and some spherical abberation. This scope will show astigmatism during cooling, since the internal focuser tube works like a thermos bottle, so it takes a while to cool.

The Zeiss E60 was quite dim at the high power of 170x, but didn't loose contrast or sharpness at that power. The image was almost yellow-brown, but there was almost no hint of chromatic abberation and the limb of the Moon was pure and crisp. The performance of this old scope is really something special. Essentially perfect star test with exceptionally crisp fresnel rings. Has trace amounts of astigmatism in-focus. Cools very fast.

The Vixen, however, gave a startlingly clear and sharp image, even better than the Zeiss E60. There was basically not a hint of any false color and the image was extremely pleasing. It was slightly yellow in tone, but I am not sure why, since there was no chromatic abberation visible, but perhaps it was just the somewhat dim image that did it. It was a bit brighter than the Zeiss E60, but fainter than in the Telemator. Again, all as suspected. Perfect star test when stopped to 60mm f/20. Period. Cools very quickly, like the E60.

Now for the unexpected!

The image in the Telemator, to my great surprise, appeared somewhat "grainy" at 168x and 210x and this was also visible to a lesser degree in the E60. I am at a loss to explain it, since it had the brightest images, and it is very hard to describe. Especially since it never showed up in the Vixen, even at 200x! This is not to say that the E60 wasn't sharp, for it held its own against the Vixen and showed the same, difficult details. In the latter, however, the Moon appeared like in the Apollo shots - really - with softly rolling hills and with a smooth, realistic impression. It was distinctly different than the others, which gave a "harsher" view, especially the Telemator.

Also, I couldn't find anything in either scope the others couldn't show, but there were differences here as well. The Telemator showed a lot because the images were so much brighter than the other two, that the eye had a much easier time seeing it, while the other two had superior contrast and ever so *slightly* crisper images, which in turn helped them show difficult detail. And every difficult detail showed up easier in the Vixen than in the other two. And once I realized that, I noticed something about the Vixen, that I hadn't before: It was much easier to look through and the images were much steadier.

This intrigued me, since all three had lots of time to cool (hours) and all three were set up not a meter from each other, looking through the same air, yet the difference was very obvious. I jumped from scope to scope, but the result was always the same. Each time I got back to the Vixen, my eyes and brain sighed in relief and difficult detail I had strained to see through the others started to pop right out, though it never showed something the others couldn't. Also, the apparent field of the eyepiece appeared larger than in the others, and I was using the same eyepiece design in all of them! I did a comparison, by holding both the 7mm and 5mm KK orthos up to my eyes simultaneously, and the apparent fields were identical, but the 7mm just seemed somewhat larger, perhaps because the eye relief was 40% larger.

But most interestingly, the seeing also appeared to be worse in the two Zeiss scopes than in the Vixen! Apparently, there must indeed be something about long focus telescopes giving steadier images. When a wave of turbulence rolled across the Moon, I could still see the detail rather well in the Vixen, but it was completely washed out in the two Zeiss scopes. The Vixen was also much easier to focus and had a focus spot several millimeters long, where I could fine-focus with my eyes without any trouble at all. I actually had to be careful to let my eyes rest at their most comfortable focus and not let them begin to focus on the image before I had found the best spot with the focuser. Once I had found the best spot, I could relax and spend many minutes just looking and there was never any eyestrain. It was very comfortable and completely different from observing with the two other scopes. It goes without saying, that I tried to obtain the same effect from the other two, by fine-tuning the focus, but I never succeeded. The focus on the two Zeiss scopes was more critical, but still rather easy to find, of course, since these are still f/13 and f/14 instruments, long by modern standards. Yet f/20 seems to be really loose and comfortable by comparison, as well as being *very* easy on the eyepieces.

All in all, the shootout confirmed a lot of things, as well as revealing startling surprises. I would never have expected the f/20 to be so much easier on the eyes in actual use, compared to the others, though I have suspected it for some time. It is much harder to tell, if you haven't got the two scopes right next to one another. And I had not expected the difference in sensitivity to seeing to be so clearly visible. It was a highly interesting night, and I fully expect to do this experiment again, sometime this autumn, perhaps on more targets as well.

Meanwhile,

Clear skies!

Thomas, Denmark

[zoth]

Multumesc pentru amanunte, chiar sunt din belsug in experimentul lui Thomas.
Eu vad trei aspecte esentiale legate de aceste teste:
Primul ar fi ca foloseste oculare ortoscopice kk si focale din belsug, lucruri care mi se par foarte potrivite.
Aceste oculare sunt si preferatele mele in astfel de situatii.
Ortoscopicele kk, acorda un confort aparte in timpul observatiilor prin forma capsulei lor, sunt lipsite de distorsiuni geometrice (relevand in imagine doar ce apartine obiectivului) si au un raspuns cromatic de invidiat, nu am vazut pana acum sa adauge altceva pe imagine decat ce primesc la intrare.
Cand le folosesc, mie imi creaza senzatia ca ma transpun la locul observatiei, totul pare atat de natural...
Al doilea aspect ar fi grosismentul cam mare la care a dus lunetele.
As explica acest lucru prin dorinta de a releva mai usor diferentele dintre instrumente in conditii apropiate de limita.
In locul lui as fi incercat o diagnosticare pe undeva pe la 120-130x, nu mai mult.
Si in fine al treilea aspect, derivat din precedentul ar fi ca duce si ochiul observatorului in conditii de limita, lucru asupra caruia am ceva rezerve.
Sub o pupila de iesire de 0.5mm ochiul incepe sa devina capricios, raspunsul lui spectral cat si puterea de a distinge detalii sunt mai sensibile functie de nivelul de iluminare, de cromatica imaginii si de alti parametri.
Este si motivul (cred eu) pentru care au aparut unele fenomene ce par a nu avea explicatie.
Una peste alta, acest experiment mi se pare interesant
Ii multumesc lui Thomas pentru desrierea in amanunt a experimentului si tie care l-ai transpus aici.
Spor tuturor!