10 replies to this topic

[RobSter]

What would be the best magnifications for DSOs with a 200mm F/5 scope, and what's the lowest magnification you would use?

[jfaaz]

33x (30mm), 41x (24mm), 50x (20mm), 76x (13mm) & everything in between. To top it off, a 2.5x Powermate for observing the DSOs when you find them.

Jon

[Lucifigus]

I would suggest a low power Ep to give the maximum true field of view. This is for cruising and finding objects and viewing large objects. DSOs will take a fair amount of power so an EP to give you about 125x will be good for globular clusters and some galaxies. Occasionally you may wish to go higher, to somewhere around 160x.

Gary Weber

[Tom L]

You need somethng at 175x for the best viewing on a consistent basis. At 1000fl, that would be about a 6mm ortho or EP of your choice.

[rboe]

And that is if seeing will allow it. Some areas have more good seeing nights than others which should drive your desire to get the shorter focal lengths. If you are not sure, a barlow or powermate to take your other eye pieces to the desired power will give you an idea if you should look at expanding your collection.

It's a matter of personal taste but I'm a wide field low power kind guy. Many times forced into that position due to *bleep* seeing.

[David Knisely]

What would be the best magnifications for DSOs with a 200mm F/5 scope, and what's the lowest magnification you would use?

Well, probably the lowest magnification would be something around 29x or maybe a bit more, used mainly for finding things. This would yield an exit pupil of around 6.9mm which is close to the maximum for the dark adapted eye. This would allow the wider fields needed for locating many deep-sky objects. For a maximum, you could go as high as 400x, but much of the time, you would be observing at less than a third of this level, especially for deep-sky objects. If you want to know what levels are useful for which objects, read the article "Useful Magnification Ranges for Visual Observing in Astronomical Telescopes" on our very own Cloudynights site:
http://www.cloudynig...gnification.htm
I would probably get one eyepiece in the low range, and use a Barlow to get it into the medium range, then get a high power range eyepiece and use the Barlow to get into the *very* high power range. Clear skies to you.

[lighttrap]

With my 200mm f/5 scope, I use a 2" 32mm ep for 31.25x as the lowest mag. It's good for showing wide swaths of the sky but with low contrast. For better contrast, I use a 1.25" 26mm ep for 38.5x. Perhaps most of all, I use either a 1.25" 15mm for 67x or 12mm ep for 83x. That seems to be a good general all around useful mag. range after I've found what I'm looking for. Believe it or not, I find that I do most of my observing between about 50x-150x and that holds true for several scopes. People talk about max power, and super high magnifications, but here in the NC cloud belt, and atmospheric transition zone, conditions hardly ever support going over about 250x.

[jmoore]

This is the same size scope I have, too.
My most used mags are:
- 40x for finding (w/ wide-field EP)
- a couple pieces in the 50x-80x range for most open clusters
100-125x for most faint fuzzies
160x-270x most common useable range with this scope (in my experience) for planets, or for cranking up on planetary nebula or globulars.

[erik]

you may be able to get away with using a 2" 40mm ep, as it would be exactly 8x the focal length, which is supposedly the maximum amount before darkening from the central obstruction becomes a problem. i use that ep in my f/6 scope, which gives me 30x. in your f/5 scope it would give you 25x in your scope, a nice power for scanning. depending on where you live, your highest useful magnification will vary. for planetary viewing, 200x is a good power to shoot for, many nights you may not be able to use that much, and some nights you'll be able to use more...unless you live at 7000 feet elevation and where the air is still.

[RobSter]

You've cleared that up, now i have a nice amount of information to refer to.

[F.Meiresonne]

Mostly the max power i use is 250x with my 10 inch for DSO that can take it such Globals.However there is one exception,the Moon. Seeing permitting, i can go sometimes to 300x and rarely even to 380x, but really thats is only on the moon.