Saturn Opposition @ Tiong Bahru Park with Giant Dobs

[rlow]

haha...there is only one 12.5" Portaball in this region, if I am not mistaken....

[Airconvent]

But we have the next best thing, an 18" Zambuto ! Probably the biggest scope in Singapore... Have not seen it in a while though...Missing owner!

[Canopus Lim]

Nice report!

"IMHO, the excellent OMI mirror perhaps held up against the Zambuto quality-wise, but the comparison showed that once again aperture wins as I could readily see more details in the features of Mars through the 15" dob. And the colour saturation was better too."

Regarding this statement, I agree that larger aperture, assuming all things taken care, will definitely give a better image; Better as brighter, better contrast and resolution and better colour saturation. On the internet, it seems a lot of people think that it is all about resolution when using telescope, but the actual fact is when looking at extended objects: moon, galaixes, nebulae, planets, aperture is king. At the same magnification, a larger aperture telescope will yield a larger exit pupil. Take it that the exit pupil of the telescope is the entrance pupil to the eye. Since the focal length of our eyes are constant and at night, the limitation of the light is the exit pupil size. Since f/# is related to focal length/ aperture (exit pupil of the telescope), a larger telescope will have a smaller system f/# (system as in telescope+eye).

By optics, a smaller f/# will translate as the above results. Brighter image, better colour saturation, higher resolution and higher contrast of fine details (because Modulation Transfer Function is better).

Our biggest advantage in Singapore is that large aperture telescopes can perform it's best because there is almost zero temperature difference between indoor and outdoor and our climate has very little temperature drop and thus neglible acclimitization of the optics to the outdoor temperature. The other huge advantage as stated is that the planet can rise very high, close to zenith. Based on experience, it can mean a difference from 300x to 400x or from 400x to 600x if the planet is low vs one that is high position. Although Singapore is poor for DSO, it excells well in double star, lunar and planetary. Aperture rules here.

[starfinder]

But we have the next best thing, an 18" Zambuto ! Probably the biggest scope in Singapore... Have not seen it in a while though...Missing owner!

Yes, missing 18" scope owner... could you be so kind as to put it to good use this weekend?? Jupiter, Mars and Saturn all in one evening, hurry whilst stocks last! We can help you carry it out...

Btw, as it's an Obsession 18" UC, the mirror would be an OMI or Galaxy.

Btw no. 2: List of Dobs in Singapore.
I believe there are now at least 4 Obsessions in Singapore: 18" UC, 15" Classic, and two 12.5" Classics. Plus another 12.5" Classic possibly on the way, making it 5. Then there is one 12.5" Portaball and at least one 8" Portaball. Plus cloud cover's 14" dob, a 12" Sumerian dob, Bornfree's 10" dob (Reise 250D), and Gary's 10" dob. And RLow's Zambuto-powered home made 15" classic dob, probably the largest ATM scope in Singapore or the region. Hope I've not left out any dob from the list.

[Edit: added a reference above to the Reise dob.]

Yes, the 18" UC remains the largest aperture in Singapore, as far as I'm aware too.

Our biggest advantage in Singapore is that large aperture telescopes can perform it's best because there is almost zero temperature difference between indoor and outdoor and our climate has very little temperature drop and thus neglible acclimitization of the optics to the outdoor temperature.
... Although Singapore is poor for DSO, it excells well in double star, lunar and planetary. Aperture rules here.

How about getting a 22" UC?!
http://www.obsessiontelescopes.com/tele ... /index.php
'Only' US$9,995. Maybe joint ownership amongst a half dozen of us, and stored at a self-storage facility? Would need to store a mini-ladder too. The owners could keep track of usage with a WhatsApp chat group.
Let's start dreaming.

[rlow]

my 15" dob is not the largest ATM scope in the region...there is a 16.1" dob lurking somewhere...

People here have mentioned getting a bigger dob, so far it has not materialise yet....

[Airconvent]

my 15" dob is not the largest ATM scope in the region...there is a 16.1" dob lurking somewhere...

People here have mentioned getting a bigger dob, so far it has not materialise yet....

Richard,
Let's be ambitious and aim for a 22" for your next project! That would make it the biggest without a doubt!
But also have to upgrade your trusty stool to a full ladder!

[rlow]

Richard,
Let's be ambitious and aim for a 22" for your next project! That would make it the biggest without a doubt!
But also have to upgrade your trusty stool to a full ladder!

wow! how on earth did you read my thoughts?

I was just discussing with Gavin about his UC 22" obsession...

[rlow]

Nice report!

"IMHO, the excellent OMI mirror perhaps held up against the Zambuto quality-wise, but the comparison showed that once again aperture wins as I could readily see more details in the features of Mars through the 15" dob. And the colour saturation was better too."

Regarding this statement, I agree that larger aperture, assuming all things taken care, will definitely give a better image; Better as brighter, better contrast and resolution and better colour saturation. On the internet, it seems a lot of people think that it is all about resolution when using telescope, but the actual fact is when looking at extended objects: moon, galaixes, nebulae, planets, aperture is king. At the same magnification, a larger aperture telescope will yield a larger exit pupil. Take it that the exit pupil of the telescope is the entrance pupil to the eye. Since the focal length of our eyes are constant and at night, the limitation of the light is the exit pupil size. Since f/# is related to focal length/ aperture (exit pupil of the telescope), a larger telescope will have a smaller system f/# (system as in telescope+eye).

By optics, a smaller f/# will translate as the above results. Brighter image, better colour saturation, higher resolution and higher contrast of fine details (because Modulation Transfer Function is better).

Our biggest advantage in Singapore is that large aperture telescopes can perform it's best because there is almost zero temperature difference between indoor and outdoor and our climate has very little temperature drop and thus neglible acclimitization of the optics to the outdoor temperature. The other huge advantage as stated is that the planet can rise very high, close to zenith. Based on experience, it can mean a difference from 300x to 400x or from 400x to 600x if the planet is low vs one that is high position. Although Singapore is poor for DSO, it excells well in double star, lunar and planetary. Aperture rules here.

Yang Beng brought up some good points!

But it is not just aperture that matters. Quality in optics is equally important. If you compare two mirrors of the same large aperture, an excellent quality mirror will beat a standard quality mirror in terms of sharpness, contrast, being able to push magnification, seeing more fine or faint details etc. And excellence in mirror quality is not measured just by PV, RMS or Strehl Ratio.

[Canopus Lim]

Yeah no disagreeing with you.. I am using a ZOC mirror too..