Sonmalul

I always feared that if I say here I want to buy a very specific brand and type of scope I would be ridiculed over the roof. But truth ne told, we keep pur scopes mostly indoors and they become part of our furniture in some way. I enjoy looking at things even when they are not used for their intended purpose, just to admire the craftmanship.

That would make it a Bugatti Mowron :)

Big Red is a thing of beauty and mounted on that wooden tripod it looks like it is going to last a lifetime...and your children's lifetime also :)

I like to play tricks on my eyes with binoculars to see if my eyes can reach focus when the instrument in marginaly out of focus. They struggle a bit, it feels like havy lifting done by my eye's lens but I was amazed how off can the focus be and the eye still be able to adapt, albeit after a bit of "flex". This range of natural focus (for me at least) is quite large and i do my focusing by choosing the mechanical middle between the in/out of focus points where my eyes cannot compensate at all. So back-forth back-forth...something like divide et impera for the focuser tube 😋 Differences in depth of field have not been too striking to my eyes through telescopes as they are in an f2 photo lens for example. I feel like we have two focusing systems: our hands on the focuser knobs and our eyes which do the fine tuning for us. So focus in focus :)

This is indeed the only reason I could think of as a reason to manufacturing many lengths of the same aperture frac. Other than that, magnification and exit pupil are just complementary mathematical relations. Like horsepower, torque and rpm.

Then why do they still produce scopes in the f10+ range alongside their identical aperture and mechanics, faster brothers? what's the catch? Seems to me that progress in the refractor world look like going from something lile this https://upload.wikimedia.org/wikipedia/commons/9/9a/Houghton_Typ_620.73.451_-_Johannes_Hevelius%2C_Machinae_coelestis%2C_1673.jpg to stuff like this https://cdn2.skiesunlimited.com/images/D/09947_Orion_alt04.jpg 😜

There is something that makes me think practicality. We can all agree that a long focal length scope is better suited for planetary use than its short length brother which would be best suited for dso viewing or guiding/photo. We can take those two (refractors) as an example: 90/900 and his brother, a 90/500 (and we will be using Plossl EPs) Exit pupil is an important factor in viewing comfort. Exit pupils are dependent on the scope's focal length, the EP's fl and the main lens diameter. For example, to acheive 100x in the 90/500 we will need a 5mm eyepiece and to acheive the same mag in the 90/900 we will need a 9mm eyepiece. The exit pupils of both scopes in those configurations will be 90/100=0.9mm The theoretical magnification limit for both scopes lies at about 180x. It is true that to reach this 180x you will need a 5mm EP in the 90/900 and a "2.8"mm EP in the 90/500 and those will probably make for an eyelash brushing eye relief... But looking at exit pupils up to 100x, those scopes do not seem to complement one another, but rather replace each other. So, ignoring abberations, and not taking into account eye relief so much, wouldn't the faster scope be almost as practical and easy on the eyes for high-ish magnifications as the slower, heavier, harder to mount in the wind scope? just my evening neurons buzzing...

Wow. That would have been a nice piece. Too bad I am so far away and..it's been sold allready. what eyepiece(s) should I get? I used this to simulate the views: https://www.stelvision.com/en/telescope-simulator/visu.php?D=80&F=640&FD=8&type_choix=manu&f_1=26&f_2=15&f_3=10&f_4=6.5&f_5=5&champ_nom=52&champ_alt=&cibles=lune&simu_personnalisee=Simulate I also have a cheap H20 and a SR4 EP. Please don't laugh at me... 🤓

Thank you very much for your time and answer. That is why I have in the first place chosen the f8 over the f5.5 But you see, here is where firsthand(eye) experience comes in handy. I was leaning towards the 90mm because they say it has multi coated lens vs only MgF2 on the 80mm and I thought it would make a night and day difference...hopefully. I will follow your advice and buy (Again) the 80/640 if you say the coatings are not that important for my usage....hoping it will be better.

After much searching online and dozens of phonecalls, it seems the fates are against me. The Bresser 90/900 will be available only from the 1st of of september in my country. The 102/600's situation is the same. I am now left with 80/640 and the 90/500 to choose from. Both are available at once. The 80 is MgFl coated and the 90 is "multi coated". Please help me choose something so I can enjoy a bit of this, (warm period) this year. I would also choose some 15 and 6 mm Plossls for those scopes... I must confess I feel guilty. I haven't contributed with anything to this forum and all i do is ask questions. But I really want to be able to look at something this year...so thank you very much for your kind words everyone.

Judging a mount by its carryweight is somewhat a false advertisment. There can be heavy things put on a mount that create a small windsail/lever and light things (90/1200) that create a lot of pull on the mount with only a little nudge from either ends of the tube. I have used the AZ nano. The mount/tripod I can assure you it can hold 6-8-10kg with no problem, Vertical load!! I rested part on my weight on it for this exact purpose. Twist it and there is your wobble. The problem lies in the joints. Te nano has some flex points: the plastic fork style mounts between the legs and the flathead, the retaining lockrings for extending the legs, the legs rotating a bit... The mount head on its own is very solid. It's all metal with some plastic clading. I wrote in a previous post that if it fits a Bosch surveyor tripod, that will be the ideal mount for me. Bosch Bt160 https://rthde.files.wordpress.com/2013/06/bosch-bt160_.jpg?w=630 Also, the 90/900, as well as the 80/640 and 90/1200 comes with a plastic elastic clamshell mount. This clamshell does not only flex but the only locking nut can be slid of the clamshell with relative ease even when tightened down. Make it too tight and the clamshell flexes and it popa out on its own :/

SpaceCadet, indeed my mind is set on the 90/900. Seems you can read minds I am also a bit put off by one consultant at a major online astronomy shop who said it IS good for my wants and needs but if my area has winds (at it does a lot) and if I can afford the 102/600, get that. I like it, amd I am willing to slend the extra money for peace of mind that it would not wobble. Of what use is a nice tube if it wobbbbbles? My only concern is if it will be able to provide enough magnifications...to use on Venus, for example... I plan on using 26, 12.5 and 7.3 mm Skywatcher "shuper" Plossls.

The choices for me, have boiled down to those: 80/640 again (although i am quite cautious about buying it again from this (only) dealer because mine had a problem and they had another one "resealed" in stock) Maybe they got a lemon lot. 165 Eur 90/900 long fl and I think a good overall package for the money. Fear of it dancing with the winds. 230 Eur 102/600 scared of the short fl not (only) because of CA. Highest price but nice tube rings and focuser. 350 Eur All are on AZ nano. Please help me and spend my money so I can blame you

To continue the princess talk: neah...I need a longer one! That's what she said anyways :P :))) Jokes apart it is indeed a beautiful scope, but I really want a frac (it will be used only sporadicaly) and I really want it in white...and you know...well... a Takahashi is a Bit above my paygrade :P

Helium thank you for your opinion and experience. Much appreciated! I am also expecting Some CA in the 600 but I hope I don't get the "light tails" I got in the 80/640. Any idea what those might have been?(my first red photo) Also, by any chance, do you have any experience with 102/600? CA, I can live with it as long as is does not degrade the sharpness of the focused image too much. But what other optical annoyances can one expect from a 102/600 and not from a 90/900? Thank you!