What is the Maximum magnification you use (in UK)

[Charic]

On 14/11/2017 at 21:37, Hairy Gazer said:

........maximum magnification you can realistically use in UK skies........

I like Moonshanes answer, it just depends really? and there are so many variables to overcome!.

For me, 200x is my practical limit based on the size of my aperture,  and focal ratio, although theoretically, twice that is possible, but not regular.
To achieve 200x I'll use the equivalent of a 6mm eyepiece.
I have viewed the Moon at 375x which was mighty impressive, though I doubt anything else up there would look as good.
 

[N3ptune]

Over 3 years of observation in Canada (sorry wrong country ), 212x was my most used power on the moon with 8" aperture, my Newtonian can take it easily. I can go up to 286x (35.75x per inches) occasionally (moon) too but it's never has good has 212x and the image is much darker too. 

For stars and DSO it's variable, powers are usually in this range, 29x, 40, 55x, 80x, 143x. The longest time passed at the eyepiece would be at 212x sketching the moon 26.5x per inches of aperture. For the planets, they are very low this year so 212x is not very optimal.. I bet it's going to be 143x, 166x (or less) in 2018 for the Mars opposition this summer.

I am not very tempted to invest in more power then around 200x.. but my telescope could probably handle a bit more on the moon.. (220x, 230x ?) It's not a very good instrument for the double stars so the range between 250x and 400x is not really useful for me.

[mikeDnight]

It depends on the target! My most used high mag is between X176 and X200 or there abouts. For an object like Mars, which needs high power to obtain a reasonable image scale while its still only 5 arc seconds, I use X269 to X296. If I tried using those powers on Jupiter it would cripple the view. My scope is only 100mm aperture, which I think gives it some advantage, in that it seems to be less affected by atmospheric turbulance than some larger scopes, making the use of high powers practicle at times. The highest power I've used with effect on my 100mm is X474 while looking at the Moon and Venus, but it was an exceptional night!

[Paz]

I agree it varies a lot. I usually don't go over 100x with the ST120 in practice but it can go a lot higher. I remember winning views in my ST80 at 160x on one occasion. The maksutov is usually used up to 190x at night and up to 127x for solar white light, but can go higher. The vx14 can do 230x pretty much any time and 307x most of the time. I've got the facility to go to 525x but that is very rarely used.

The brighter and more contrasty the target and the higher it is in the sky make a big difference to what is possible. I also do the same as others have referred to where you deliberately up the magnification past the ideal aesthetic viewing magnification level as some details can be more easily unpicked or star separations more accurately measured. I've never heard of a word to describe this but I think of it as technical observing if that makes any sense.

Edited January 22, 2018 by Paz

[wesdon1]

I'm new to astronomy, but i kid you not, i was viewing the moon this morning (Mon, 22/04/19 around 5am BST, Liverpool, UK) at 500x mag with my 130mm/900mm Newtonian and although there was a bit of image wobble, i could see really well! I'm expecting almost everyone to laugh at me or call me a liar but i swear it's true! I put a 3.6mm plossl on the 2x Barlow, effectively making the plossl a 1.8mm, just to see how bad the image would be, but was shocked when i actually managed to get a sharp focus ?? It's opened my eyes, literally, to what's possible when seeing, optics and collimation etc all come together perfectly! I'm assuming it would never happen with anything else as the Moon is very unique in that it's relatively huge, very very bright, and obvs silly close to earth, in astronomical terms.

[ollypenrice]

When trying to split doubles the observer is not looking for an attractive view of the stars but simply for evidence of separation so a very high power may do that. When looking at the moon and planets the objectives are different since we are looking for fine details accurately rendered.

Unless I've missed it the thread has not mentioned a highly critical number which does not derive uniquely from aperture or magnification and that's exit pupil. Certain targets, and most famously the Horsehead, are dependent on exit pupil. (Exit Pupil in mm = EP's FL in mm divided by its F ratio.)

Olly

Edited because I originally said 'scope's FL' in a senior moment!  Thanks to Steve (Trikeflyer) for pointing this out.

 

 

Edited April 23, 2019 by ollypenrice

[Stu]

3 hours ago, wesdon1 said:

I'm new to astronomy, but i kid you not, i was viewing the moon this morning (Mon, 22/04/19 around 5am BST, Liverpool, UK) at 500x mag with my 130mm/900mm Newtonian and although there was a bit of image wobble, i could see really well! I'm expecting almost everyone to laugh at me or call me a liar but i swear it's true! I put a 3.6mm plossl on the 2x Barlow, effectively making the plossl a 1.8mm, just to see how bad the image would be, but was shocked when i actually managed to get a sharp focus ?? It's opened my eyes, literally, to what's possible when seeing, optics and collimation etc all come together perfectly! I'm assuming it would never happen with anything else as the Moon is very unique in that it's relatively huge, very very bright, and obvs silly close to earth, in astronomical terms.

When you get a spell of stable seeing it is amazing the power that can be used, particularly on the moon. No one will think you are lying about that . Thing is not to assume you will be able to do it very often, just make the most of it when it happens.

[wesdon1]

On 22/04/2019 at 09:53, Stu said:

When you get a spell of stable seeing it is amazing the power that can be used, particularly on the moon. No one will think you are lying about that . Thing is not to assume you will be able to do it very often, just make the most of it when it happens.

Hi Stu/Super Nova, thanks for the comments. I was really shocked and pleasantly surprised. I won't get my hopes up for it happening very often, because as you say it's rare to get seeing that good, i'm quickly learning! lol. I actually almost got rid of my 3.6mm plassl almost the same night i first used it because due to me being a newbie, and not having collimated my 'scope, when i first tried it on a few stars the view was so dark and blurry. So i assumed i had a dud eye piece! even though i had bought it brand new from FLO lol! i've since learned about collimation, seeing etc. so i know better. For your information, i am on my second scope, my first was a SW 1145p ( 114/500 ), now i have a SW 130 eq2. ( 130/900 ). I'm 5 mon ths in to my new hobby. It's beyond amazing and i only wish i had got into it years ago!

[Trikeflyer]

On ‎22‎/‎04‎/‎2019 at 08:41, ollypenrice said:

When trying to split doubles the observer is not looking for an attractive view of the stars but simply for evidence of separation so a very high power may do that. When looking at the moon and planets the objectives are different since we are looking for fine details accurately rendered.

Unless I've missed it the thread has not mentioned a highly critical number which does not derive uniquely from aperture or magnification and that's exit pupil. Certain targets, and most famously the Horsehead, are dependent on exit pupil. (Exit Pupil in mm = scope's FL in mm divided by its F ratio.)

Olly

 

 

I thought that exit pupil eyepiece (not scope's) FL in mm divided by scope F ratio? Is that what you meant Olly? Or have I got it wrong?

Steve

[Stu]

9 minutes ago, Trikeflyer said:

I thought that exit pupil eyepiece (not scope's) FL in mm divided by scope F ratio? Is that what you meant Olly? Or have I got it wrong?

Steve

That's right, eyepiece focal length divided by scope focal ratio.

[ollypenrice]

50 minutes ago, Trikeflyer said:

I thought that exit pupil eyepiece (not scope's) FL in mm divided by scope F ratio? Is that what you meant Olly? Or have I got it wrong?

Steve

Sorry, yes, typo. I'll correct it above.

Olly

[Peter Drew]

The magnification per inch of aperture for given seeing conditions reduces as the aperture increases. On a night when 300x is the seeing limit that represents 100x per inch for a 3" and only 10x per inch for a 30".    ?            

[wesdon1]

On 14/11/2017 at 21:49, Moonshane said:

Depends on the target. Lunar and doubles in good seeing allows up to 500x (honestly). Planets maybe 300x max and other objects depends on the size. Solar  between 50-150x.

I have scopes from 102mm  to 400mm. My most common magnification is hard to say but it's the one that frames the subject and maintains sharpness given conditions. Usually 100-200x but it's irrelevant really as there are so many variables. 

Maximum is not equal to regularly used of course.

I got 500x Mag on the Moon a while back. I was using a 130mm/900mm Newtonin, with a Super Plossl 3.6mm EP, in a 2x Barlow. The veiw was obviousely a bit wobbly with atmosphere at high mag, but no more affected than when veiwing Moon at 150x ish. I only tried it to get an idea how awful the veiw would be! haha what a lovely surprise i got when it worked so well! (on that particulare night/conditions etc)

[wesdon1]

On 24/04/2019 at 13:18, Peter Drew said:

The magnification per inch of aperture for given seeing conditions reduces as the aperture increases. On a night when 300x is the seeing limit that represents 100x per inch for a 3" and only 10x per inch for a 30".    ?            

I'm like Johnny 5 from that 80's film with the lovable Robot! INPUT! INPUT!!! ahahahaha 

[wesdon1]

On 15/11/2017 at 16:32, alanjgreen said:

Hi Hairy Gazer,

I like the sound of "powerful scopes"!

The key you are missing, is APERTURE

Imagine your pupil at a size of 1-5mm looking up at the night sky, you see X stars

Now imagine your pupil at 130mm (like a 130mm aperture scope) looking up at the night sky, you see 10X stars

Now imagine your pupil at 500mm (like my 20" dobsonian scope) looking up at the night sky, you see 100X stars

The "power" of the scope is in the amount of light that it can capture coming from those far away light sources. A 20" scope at x150 magnification will produce a much brighter image than a smaller scope at x150 magnification. That brighter image should reveal details not seen in the smaller scope.

 

Magnification is the enemy of the observer believe it or not! If you consider the total light from my examples above produces an image of BRIGHTNESS Y at the eyepiece then every time you increase the magnification you reduce the brightness of the image (Y/2, Y/4 etc)

Therefore a big aperture scope and mid/low magnification should produce a highly detailed bright image...

Then we have to throw in the factor of the earths mushy atmosphere that impacts that view, the bigger the scope the more susceptible to the atmosphere it becomes as the big scope can "see" the atmosphere and this impacts the view, another reason to keep the magnification low.

Its a complicated equation and magnification is just a factor within it. Seems obvious that all I need is x1000 magnification to see "the Apollo mission leftover equipment on the moon surface", but all you will see at that magnification is a "mushy fuzzy image thats impossible to bring to focus" at the eyepiece.

This is why we need many eyepieces at our disposal so we can play to the strenghts of (1) the scope (2) the conditions (3) the target.

You should look to get x50, x100, x150, x200 & x250 magnifications covered for your scope

Manufacturers like to quote the "aperture rule" which says the maximum magnification for your scope if x50 per inch (25mm) of aperture - this is never achievable (nor desirable) in real life.

HTH,

Alan

This is one of the best, most easy to understand explanations for this highly complicated and DEBATED issue in our beloved Hobby I have ever seen! Thank You! 

 

Wes, Liverpool, Bortle 8-9.

[Pixies]

On 22/04/2019 at 06:36, wesdon1 said:

, i was viewing the moon this morning (Mon, 22/04/19 around 5am BST

I find the viewing is often better at that tine of the night/morning. Perhaps because houses, etc. have had time to cool down overnight and before the central heating kicks in!