View Full Version here: : Typical maximum magnification
11-05-2007, 10:09 AM
This thread was inspired by questions posed by Dazzler regarding which expensive eyepiece to purchase. I observe from my backyard before midnight and am typically limited to less than 100x magnification, with only rare occasions where I can go higher. At my previous residence, which was only 2 blocks away, it seemed that I could regularly go higher and sometimes up to around 180x.
What magnifications can others use? Might be a good one for a poll but I don't know how to set that up.
11-05-2007, 10:56 AM
Good idea Tony. I've pushed my 12" Dob up to 334x so far just out of curiosity. But the full moon spoilt the view anyway. But i'm lucky i live in a small town, probably about 1000pop. So skies up here are pretty dark. Mind you i've only got the stock eyepieces that came with the scope and a 2x Bintel barlow. Better eyepieces would help for sure.
11-05-2007, 11:16 AM
From my Melburne surburban backyard, last night, during twilight, with a neighbour's bright outside floodlights lighting up everywhere, I was enjoying Saturn with the 9mm Plossl that came with my 8" f6 scope, using a Bintel 2x barlow. I calculate that to be around 267x. The image swam a bit, but the Cassini division was easily seen as was planet's shadow across the rings. Venus, much lower and in hazy cloud (that soon enveloped Saturn) was much worse.
According to the light pollution maps mentioned elsewhere on the Forum, my backyard is smack bang in the "orange" and closer to the "red" (worst) than the "green"!
I was happy with that performance!
11-05-2007, 12:11 PM
I think I'm going to be feeling very enviuos with people posting about 200x and up.
Duncan, I'd swap my premium eyepieces for premium observing conditions any day. Basic plossls do a fine job.
11-05-2007, 08:41 PM
I would expect to go up to around 200 - 250x for planetary observing.
Anything else, 120 - 150x is plenty (e.g. bright globulars).
Remember that higher magnification darkens the background sky if you're trying to find faint objects and the sky isn't as dark as you'd like.
In the UK a big problem in observing from suburban areas, particularly in winter, is the heat rising from houses causing poor seeing. I'm not sure how much that is an issue here since few people have central heating. But in any urban/suburban location you potentially have sources of heat that may be degrading the seeing in a very localised way, but usually exactly in the direction you want to look!
Returning to eyepiece quality, I found that the GSO eps that came with my scope were pretty poor above around 100x, so I guess it depends whether the issue is quality of location and/or quality of equipment.
11-05-2007, 11:13 PM
I used to live in a relatively dark sky suburb until a few months ago about 32kms from centre of Perth. When I lived there I only had SkyWatcher 10 and 25mm Super Plossl's, a Meade 26mm Series 4000 and a ( cheap ) Celestron 4mm Plossl. My scope was a SkyWatcher 200mm F5 Newtonian and my views of DSO's were great ( due to dark sky ), planets not too bad at 100x. Now I live about 2-3kms from the City centre ( lots of skyglow ) but have recently purchased Vixen LV 4mm and 20mm eyepieces. DSO visual nebulosity is very faint here ( a bit better with Baader 1.25" UHCs filter ) but with the Vixen eyepieces I have never seen such detail on Saturn and Jupiter before. I have also bought a SW 254mm F4.7 Newt ( 1200mm focal length ) so with that scope I have had great views of the planets and moon at 300x with the Vixen LV 4mm. The LV 20mm gives crystal clear, sharp images when combined with my SW 2x Barlow ( 120x ) and also on it's own ( 60x ).
When you get down to it ...... ideal setup ...... DARK SKIES and GOOD QUALITY EYEPIECES.
p.s. I have not experienced that combo yet.
12-05-2007, 11:32 AM
Guys, for maximum magnification on planets and doubles, light pollution has very little, if any, bearing...
More important is the presence (or lack of) other houses, with heating.. and thermal turbulences that go with them.
I was able to go up to 360 (4mm ortho) with mu 10" f5.6 mirror, I tried even 2x barlow with that on Moon once, but the results were questionable and acceptable only during very brief moments of turbulences calming down.
I envy people living in small towns for their dark skies...
and when I go out (to my friend's farm in Dalesford) I am using only low magnifications with my dobson, but most times binoculars are enough :-)
13-05-2007, 03:59 PM
I wont tell you some of the insane hights I have tried...
But Bojan is right sky movement is the thing...
I live 30 ks South of a one horse town, no neighbours, no street lights, looking over the State forest toward the closest "big" town (Grafton) 70 ks away.
So no light but high magnification lets you know the sky is moving.
If I look over just my shack.. doors wide open..pretty stabalised you would think..but no its... amazing the heat coming off the roof.
I once used 3x barlow 12mm ep thru 12inch on Eta Carina and I was surprised how decent a view...and that must be close to 400x I dont go high mag ..
I find the lower the magnification the better for me.
I like a wide view generally even galaxies seem better a little smaller than a little larger.
13-05-2007, 04:07 PM
Speaking of magnification, what mag do you suggest for looking at galaxies (visual) through the 12" Dob? I'm guessing between 40x-100x would probably be best. Looks like we might get a break in the clouds tonight. Hopefully i can find one to look at.
13-05-2007, 05:07 PM
The clouds may part but it will still not be dry maybe..
Just use your largest F/L ep , have a good look on the object you target..take time not to go as high as you can when you arrive..go higher and get a feel for the differences... Sorry I am thinking only deep sky.. planets and Moon go as high as possible.back off when it wobbles...
but I am usually at about 50 times I worked out... thats a surprize did not think it was that low...so there you go
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