orly_andico wrote:add on to Weixing's post...
Now a C11 has a focal length of 2800mm, for a per-pixel resolution of 0.3 arc-seconds! so the mount error will completely swamp any resolution you get from the C11.
Also consider that urban seeing causes disruptions in the order of +/- 5 arc-seconds (it's much, much worse in the day.. so forget any ideas of reading street signs in Batam.. with my C9.25 during the day I can see heat shimmering over <1 km distance at the eyepiece).
Orly, thank you for all tech info. Though I can just digest it on the surface but I can grasp it (i was into amateur photography + used to telephoto nature shooting).
Agree with the unstable atmos disturbance during the day. I'm just trying to find some other uses for it as well, the equipment's not cheap. As you can see, I like to "look". LOL!
My experience with terrestrial observations during the day esp hot days is that it could be better if you are elevated high up (that's my case) and if you are observing objects over water, not so much heat waves rising. I did look through a simple 30X50mm scope before on top of another building (about 140m height) and it was not that bad, shimmering is evident but its usable. I guess at 300-600 power that's another ball game altogether. Just now I just woke up and took a peek through my 10x50 binos at 4AM, Batam lights looked pretty stable just a wee bit of shimmering. Nearby ships within like 10km are v stable actually over the Southern seas. But over Mount Faber there is some heat source that make things look bad, I guess if you are looking over some major landmass it mucks things up. Good thing is that a large expanse here is unaffected by that, plus my elevation up here. "Not too bad", I guess. 1-2km objects would mean I am "looking down" and from what I saw yesterday/last night and now its great.
Actually I can see Pulau Semakau from here, and I use it to gauge the air quality. Sometimes its quite bad and I can't see the HPS street lights there, sometimes I can see but with lots of twinkling due to unstability, sometimes its SOLID.
Its quite the acid test/indicator, as the street lamps are all spaced out, its quite far from here, hence not too bright unlike other masses of street lamps.
Another question I'd like to ask is if my location is decent. Its definitely no Tuas/Changi, I thought I saw a post here indicating interest here at P@D, but others saying that its a bad location due to proximity to the CBD - its no go with LP and wind etc. But I wonder if its similar to Marina Barrage. Actually the wind is ok, there are some "dead spots" which are shielded by the huge 3 storey tall roof structures housing water tanks etc). But generally its pretty windy esp during NE monsoon, I recorded gusts of up to 30+ kph on my portable weather station and its pretty cold, like 21-22 deg C. So there might be some v minor thermal considerations of the equipment/mirrors cooling down for 10 mins to stabilise. But nothing too serious I hope, compared to temperate countries of coz. heh heh... The sky expanse is great here, there are 3 major spots so you can move around to avoid the monsoon wind (actually I don't think its sea breeze, just some people's convenient reason why there is wind). The wind dir can get variable but not very often. Local lights are shielded, but only spot is that directly above the CBD is not usable. If you are observing upwards like 30 deg from zenith its great as the skybridge shields you from the lights which are below you.
The good thing is that this is in my own backyard as I have 2 sky gardens here, hence I can be on standby 365 days and nearly 24/7. Any chance comes I grab, something is better than nothing - when the skies clear I can grab every chance to go ob, hence increasing the learning curve even if its just 1-2 hrs. If you plan something, drive.....then that day comes and you are tired due to work etc. Argh. I have had that with birding on Sundays couple of years ago, could not wake up at 5AM in order to reach the site by first light. LOL! And the trek with the equipment is a killer. In fact I think my home is also usable as it peeks into the majority of the Southern skies after discounting Jurong/P Bukum area, no so much LP. If its Orchard/JB facing then I dare not say.
