It should be noted that these old clasic big refractors are all constructed at the optimal f15 focal length. I think this is where the difference between modern refractors and newtonians becomes muddled, most are made to be less cumbersome by reducing tube length and therefore f ratio. 30 years ago long tube f15 refractors were the norm, and 8", 10" and 12" newtonians were standard at f6 and f7. You have to get scopes with these longer focal lengths custom made these days.
The observer is looking through the AP 7"/f9. The orange one on top is a Celestron Comet Catcher. Not the best picture for showing off the refractor but you can just make out the tube assembly.
I worked there for many years many moons ago well before the fire in 2010 which destroyed the observatory & planetarium. I haven't kept in touch and am not really sure if any of the telescopes were saved.
Thanks for the photo. It sure looks substantial.
Regards,
Renato
Are you suggesting that their FOV may be a bit narrow?
I think that with achromats and newtonians image quality improves with focal length. Visually this is not as obvious, but photographically the difference is very noticable. The increase in CA is easily seen between my f7 and f5 achromatic refractors and although the image is much brighter in my 10" f4.5 dob than my 8"f6 newtonian the coma in the 10" is really noticable.
As an owner of one of the worlds finest commercial 6" APO's - an AP Starfire 152EDF which I have done some good observing time with under dark skies before relegating it to it's true calling (astroimaging) and having spent many hours at Wiruna at several SPSP's with high quality 12", 16", 20" and 24" dobs I can happily say the overall viewing experience through all the dobs left the views through the Starfire for dead - end of story
Of course as an astrograph the Starfire rocks and as mentioned gives text book perfect crisp stars and great contrast
As an owner of one of the worlds finest commercial 6" APO's - an AP Starfire 152EDF which I have done some good observing time with under dark skies before relegating it to it's true calling (astroimaging) and having spent many hours at Wiruna at several SPSP's with high quality 12", 16", 20" and 24" dobs I can happily say the overall viewing experience through all the dobs left the views through the Starfire for dead - end of story
Of course as an astrograph the Starfire rocks and as mentioned gives text book perfect crisp stars and great contrast
Mike
I couldn't agree more and I'm glad you used the term 'High Quality' as this is important both for planets and deep sky as a good mirror will perform better on all objects.
Took the 28" f4.2 out last night. Peter Read had sprinkled his magic fairy dust on it a few days earlier. Magnificent viewing of Mars and Saturn about 1 hour east of Perth, best views of those planets ever. Air was cold and still with some dewing. Mars was like looking at Gorbachovs head, the dark areas looked like continents on a pink ocean, ice cap had a black eye. Saturn was awesome, the crepe ring was ash grey I swear I could see the planet through it, best encke ever. I'm ruined, all nights from now on will compare this one. Also split Antares for kicks Antares B a lovely green. I wish I had witnesses.
Took the 28" f4.2 out last night. Peter Read had sprinkled his magic fairy dust on it a few days earlier. Magnificent viewing of Mars and Saturn about 1 hour east of Perth, best views of those planets ever. Air was cold and still with some dewing. Mars was like looking at Gorbachovs head, the dark areas looked like continents on a pink ocean, ice cap had a black eye. Saturn was awesome, the crepe ring was ash grey I swear I could see the planet through it, best encke ever. I'm ruined, all nights from now on will compare this one. Also split Antares for kicks Antares B a lovely green. I wish I had witnesses.
Yeah...sounds exactly like a night with the 6" Starfire (not)
I wonder why modern professional scopes are all mirrors?
Not all are reflectors but certainly the vast majority are. Simply put it is much easier with large optics to make a mirror that is supported underneath than a lense that is only supported at the edge. The largest refractor is the Yerkes 40" in the US. Any larger than that and the lense sags under it's own weight and is not useable.
My Gawd! you large reflector owners are too much .
Go ahead and keep patting your selves on your backs ( like a winning politician ).
Its like my sweet 5inch f8 istar refractor TRUMPS ! my 50mm finder ,, you know I think its the 5x the aperture that gives it the advantage , like Barry's 28 incher will do to my refractor that's what 5x plus aperture will do and yes mate I will be a witness to your report , I look forward to that Barry .
Look at these photo's , I was set up looking at the moon and Venus in under 10 miniutes , the 20 and 22 inchers were ready about 30 miniutes after this photo was taken ,,, if lucky .
Note the 2 man lift in the background in the 1st photo ? not much fun at 3am after a 9 hour session , but I stayed and helped these mates strip down .
Yes these 2 monsters perform , but at a price and in Darwin its very hot and humid at 3am , horrible .
Aperture rules ,,, sometimes ..... .
I like Laurie just like the way a refractor shows stars , the planets and moon , at the 200-250x , and that's about the atmosphere will allow 90% of the time .
I did have my (sold) Tak M210 at 806x on Saturn one night and will never forget it ,, but it was driven , I can only imagine what 1025x on a DOB was like ,, 4 seconds between nudges ? .
Look at these photo's , I was set up looking at the moon and Venus in under 10 miniutes , the 20 and 22 inchers were ready about 30 miniutes after this photo was taken ,,, if lucky ..
If that was the case those telescopes are a very poor design, or your friends are painfully slow at setting their scopes up.
Here is a link to Alan Dyer's image of the observing field after the scopes were set up at last weeks Ozsky event at Coonabarabran.
It took us less than 70 minutes to set up those 7 telescopes, which included pegging down tarps under my 2 scopes.
Andrew Murrell arrived a bit later and it took Andrew just over 30 minutes to set up his 25"/F5 Obsession and his 18"/F4.5 Obsession.
Your friends obviously mixed a lot of talking in with the setting up.
Quote:
Originally Posted by brian nordstrom
I did have my (sold) Tak M210 at 806x on Saturn one night and will never forget it ,, but it was driven , I can only imagine what 1025x on a DOB was like ,, 4 seconds between nudges ? .
Brian.
My dobs all track very nicely at high powers. They all have GOTO and Servocat Tracking. 1050X in the 18" Obsession is a walk in the park.
Most amateur "dobs" would be lucky to be used once a week due to the hassle of setting them up.
Hi Matt,
That's not necessarily always the case. My 10" and 14" SDM's are left fully assembled in the garage all the time. It takes me less than 3 minutes to wheel a scope outside, set it down, drop the wheelbarrow handles out and connect the power supply. Another minute to fine tune the collimation and I am observing in less than 5 minutes from the time I open the garage roller door. Similarly, it takes me less than 5 minutes to pack the scope away at the end of the night. The biggest chore of the setup and pull down is carrying the eyepiece case in and out of the house.
Its funny you should say that - but I have related on this forum before of the night at ASNSW 's Wiruna property when Clives 7" Starfire stood unused with a crowd of people viewing Jupiter through an older stock 10" F6 Dob circa 1980's that stood next to it . There were a load more features visible as there was now colour differentiation between festoons in the bands. The planet disc in the 7" was sharp but all the bands were gray in fact all the detail was fairly black and white compared to the Newt. It was just plainly a more satifying view in the 10"
That 7" Starfire was a masterpiece but so long as the optics are good quality aperture simply rules - no free lunches there...
Bravo - Thanks for proving my point - although the crowd was looking at the dob I suspect "Clive" wasn't going to be parting with his AP despite what may have occurred on this one anecdotal experience
That's not necessarily always the case. My 10" and 14" SDM's are left fully assembled in the garage all the time. It takes me less than 3 minutes to wheel a scope outside, set it down, drop the wheelbarrow handles out and connect the power supply. Another minute to fine tune the collimation and I am observing in less than 5 minutes from the time I open the garage roller door. Similarly, it takes me less than 5 minutes to pack the scope away at the end of the night. The biggest chore of the setup and pull down is carrying the eyepiece case in and out of the house.
Cheers
John B
Yep me too, I leave them set up ready to go at the drop of a hat. I've got the 16 and 18 loitering behind me and the 28 is out in the yard right now tracking the moon waiting for Mars and Saturn later on. I have modified the back door and can wheel in/out the 28 fully assembled. Its not that hard to set up, wheel out the mirror box on wheelbarrow handles, attach truss poles, attach truss ring, attach uta, hook up cables, collimate, go. Piece of piss.
(not)
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