What is the Maximum magnification you use (in UK)

[Hairy Gazer]

I read a comment made on here the other day about the maximum magnification you can realistically use in UK skies (250x apparently). Therefore I was wondering what everyone else thinks this is, especially for you guys with 16" plus, apertures.

I'm still fairly new to this game (only being observing for about 7 months), and only have a 5" Newt at the moment (but am about to replace with a 10" Dob) so I don't get any higher than 159x (6.3 mm).

 

[Moonshane]

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.

[M110]

Definitely depends on the target at Moonshane says above, however the maximum I have so far used with my limted aperture of 102mm is 200x. This was using my 6mm EP on the moon and double stars.

[Space Hopper]

My binoviewers max out at 185x

I know if the seeing supports that sort of power, i'm doing very well.

With Mars, Jupiter and Saturn being poorly placed 125x is more the norm.

Lunar for me, much the same.

Solar i'm using around 40 to 50x which i find is plenty.

 

With the Dob, mostly i'm working at 50 - 100x

For me Low power, wide angle and rich field is best, with a binoviewer if i can.

 

 

 

[Mr niall]

I’ve had good views of saturn at 250x, But 150 is normally the max, same for Jupiter.  I often go up to 200x for splitting double stars but honestly do at least 75% of my cruising around at 50x and rarely feel the need to go higher.

[ronin]

Around the 150x mark. Little use for anything more, that covers Saturn and Mars when it appears next year will required values that realistically mine would find difficult, the scope collection tends  to be on the smaller size. Will say I want a good image, a 300x blur is of no interest to me.

However as Mars interests me little also (seems a bit odd) then I am content at around the 150x area and that covers just about everything other then Mars.

[Hairy Gazer]

The bit I'm missing is if most people use a low magnification, then why bother buying powerful scopes, if your only going to use the same magnification as that of a smaller scopes. 

I know you get a lot more light through, but at low magnification, does the extra light really make that much difference? 

Edited November 14, 2017 by Hairy Gazer

[swamp thing]

35 minutes ago, Hairy Gazer said:

I read a comment made on here the other day about the maximum magnification you can realistically use in UK skies (250x apparently). Therefore I was wondering what everyone else thinks this is, especially for you guys with 16" plus, apertures.

 

Regularly go way over 250x (20" Dob) 

.......Oh! and it rules doing so  

[Mr Spock]

Depends on the target for me too. In the C9.25 I generally have: x235 on Jupiter, x294 on the moon and Mars, x392 on doubles.

Since I've had this scope Saturn has never been high enough to get more than x107 

[chiltonstar]

With a 180 Mak, up to x250 for Saturn, Uranus and Neptune, x200 about optimum for Jupiter, and up to x540 for doubles (above x400 mainly empty magnification, but it does allow the disk diameter and separation to be measured).

Chris

[Ben the Ignorant]

2 hours ago, Hairy Gazer said:

The bit I'm missing is if most people use a low magnification, then why bother buying powerful scopes, if your only going to use the same magnification as that of a smaller scopes. 

I know you get a lot more light through, but at low magnification, does the extra light really make that much difference? 

A bigger scope is like a better computer screen: smaller and brighter pixels, you see more even if the image has the same size. And when the core image can stand enlargement, you can do it without losing sharpness.

[Mr niall]

Magnification is largely irrelevant when It comes to telescopes. In theory any telescope can magnify any amount.

You have to remember the  main idea of a telescope is to amplify the limited light coming from the night sky, not to make things bigger.  Your pupil has an aperture of about 6mm give or take in the dark, so a telescopes job is to turn that 6mm aperture into 70 or 100 or 200mm depending on your scope. Magnification is just the icing on the cake - it adds detail to what you are seeing, Binoculars are a prime example, I have a pair of 15x70 binoculars - that’s just 15x magnification but because of the 70mm aperture I can see a lot more than if I were using 15x50s say. And so it goes.

 

[Hairy Gazer]

Thanks everyone, that makes a lot of sense, I was a bit worried i was wasting mny time buying a 10" dob.

 Mr niall, are you able the view with the 15 x 70 binoculars by hand? I was thinking of getting the same pair but was worried i'd need a tripod because of the wobble.

 

[Mr niall]

9 minutes ago, Hairy Gazer said:

Thanks everyone, that makes a lot of sense, I was a bit worried i was wasting mny time buying a 10" dob.

 Mr niall, are you able the view with the 15 x 70 binoculars by hand? I was thinking of getting the same pair but was worried i'd need a tripod because of the wobble.

 

Sort of - really helps if you are in a chair, I struggle after more than 5 mins without some sort of support but find the views through them spectacular so don’t mind. My particular bins are viewed a bit like marmite on here - they are not regarded as amazing bins but in terms of value for money I reckon they’re a no brainier. Many on here prefer 10x50s for the comfort and easier to hold aspects, which is true. But I love my bins!

[Stu]

A 10" scope is a very worthwhile investment and will keep you happy for a long time, possibly for as long as you observe!

It is worth remembering that a bigger scope does not necessarily make objects brighter. It is a hard concept to get your head around, but no scope will make the surface brightness of an object brighter than you see with the naked eye. The main function of a larger scope is to be able to make faint galaxies and nebulae much bigger whilst maintaining that surface brightness; your eye can perceive larger objects more easily than smaller ones.

The guys with big dobs go chasing small, faint galaxies which need dark skies and mid to high power to see, that's what the big mirrors do for them.

As others have said though, high power is not the main objective, and much observing can be done at low and mid powers. It totally depends upon the object you are observing.

[alanjgreen]

18 hours ago, Hairy Gazer said:

The bit I'm missing is if most people use a low magnification, then why bother buying powerful scopes, if your only going to use the same magnification as that of a smaller scopes. 

I know you get a lot more light through, but at low magnification, does the extra light really make that much difference? 

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

Edited November 15, 2017 by alanjgreen

[chiltonstar]

4 hours ago, alanjgreen said:

 

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

I am not sure I would completely agree with this statement - look at some of the refractor posts where 50x per inch is easily achievable, and very desirable for certain planetary targets!

Chris

[Timebandit]

 

35 minutes ago, chiltonstar said:

I am not sure I would completely agree with this statement - look at some of the refractor posts where 50x per inch is easily achievable, and very desirable for certain planetary targets!

Chris

 

Yes 50x per inch is very achievable in a quality refractor in good seeing conditions. I do not class magnification as a disadvantage for planetary at all. In fact I see magnification as a positive on planetary, that is as long as the image remains razor sharp. Magnification is useless IMO as soon as the image starts to blur.

Aperture is important, but just as important is the quality of optical glass or mirror. As better quality optics at a certain aperture in one scope can out do the same aperture in a different scope at the same magnification, under good seeing conditions. A telescope is only as good as the weakest link in the optical chain?

[25585]

Larger diameters, theoretically anyway, make splitting double stars easier.

Can anyone advise on significant magnification & aperture increments for increasing arc & resolution etc?

[laowhoo]

On 11/14/2017 at 16:37, Hairy Gazer said:

I read a comment made on here the other day about the maximum magnification you can realistically use in UK skies (250x apparently). Therefore I was wondering what everyone else thinks this is, especially for you guys with 16" plus, apertures.

I'm still fairly new to this game (only being observing for about 7 months), and only have a 5" Newt at the moment (but am about to replace with a 10" Dob) so I don't get any higher than 159x (6.3 mm).

 

Here's something for your encouragement

Visual Detection at the Eyepiece

http://www.bbastrodesigns.com/visual.html

and his other articles that also address this, or observing generally, make a nice bit of kit for your consideration

Is Aperture King?

http://www.bbastrodesigns.com/Is Aperture King.html

Why I see More and What it Means

http://www.bbastrodesigns.com/The New Sub-F3 Richest Field Telescopes.html

Telescope Magnification is Key

http://www.bbastrodesigns.com/Telescope Magnification.html

Fear not. And if we ever build another scope, it'll be a 10"

[Danny83uk]

Max i go for is 200x for uk skies. I was advised of a good rule (regarding Newton telescopes) and that was to max your magnification to the aperture size, allowing that 200x was your upper limit. So on my SW 130 i use an 8mm (wasnt a 6 EP on the market in my price range) for my SW200 i use a 5mm giving me 200x.

[Piero]

The way I see this, the maximum magnification depends on: 1) seeing quality, 2) optical quality, 3) optics collimation, temperature etc, 4) user interests, and 5) mount. 

I believe in neither "empty magnification" nor "the 50x / inch of aperture rule". 

I fully understand and accept that some (most?) people prefer to magnify up to a level in which the image is still crisp and sharp. To me though, this is down to one's taste rather than reaching "empty magnification". Assuming (1-3), there are still many features one can spot on high contrast targets even when the image is not completely sharp and this because it is easier to see details in a larger image than in a smaller one. Personally, I like crisp images from an aesthetic standpoint, but I'm also intrigued in spotting new tiny features that would pass unnoticed at lower magnifications otherwise. Studying these limit details plays a significant role in this hobby for me. Examples: tiny craters and faint soil irregularities on the Moon; different cell shapes in solar granulation observed in white light. These features start being more visible at >300-400x, and I would not certainly label them as insignificant. Surely the seeing needs to cooperate though. 

 

Regarding the 50x / inch of aperture rule (or 0.5mm exit pupil), to me this is down to (1-3). Some manufacturers of high quality telescopes also seem to ignore this rule. Examples:

1. The highly praised TeleVue company (http://www.televue.com/engine/TV3b_page.asp?ID=202)

    - advised max mag for TV-60 f/6 is 150x => 0.4mm exit pupil or 63.5x / inch aperture

    - advised max mag for TV-76 f/6.3 is 200x =>  0.38mm exit pupil or 66.6x / inch aperture

    - advised max mag for TV-85 f/7 is 225x =>  0.37mm exit pupil or 67.25x / inch aperture

2. Astro-Physics (http://www.astro-physics.com/index.htm?products/products)

    - advised max mag for 130mm f/6.3 Starfire GTX is 500x =>  0.26mm exit pupil or 97.84x / inch aperture

 

My TV-60 showed some very fine views of Jupiter at 150x (0.4mm exit pupil, 63x /inch aperture; Vixen HR 2.4mm). On the Moon, the image was still rather crisp at 225x (0.26mm exit pupil, 95.25x / inch aperture; Vixen HR 2.4mm + VIP barlow 1.5x). I pushed up to 300x (Vixen HR 2.4mm + Zeiss barlow 2x) but the image lost too much quality. 

The optics of my Tak-100 are a bit better and can easily go beyond 100x / inch aperture under steady seeing. I have so far tested this on Lunar and White Light Solar features. The image remained reasonably accurate and interesting to my eye at 616.67x (0.16mm exit pupil, 156.63x / inch aperture; Vixen HR 2.4mm + Zeiss barlow 2x). 

I find that to really push the magnification the whole optical train needs to be selected. I used to have a Nagler T6 3.5mm which was used with my TV-60. For more than 1 year of observations on Jupiter, I never managed to spot the GRS and under the very best nights I managed to spot the north temperate belt and a faint south polar region. This was at 103x. With the Vixen HR 2.4mm (150x) and other eyepiece combinations up to 120x, I managed to see more Jovian features more regularly: 2-3 festoons on the same night, irregularities on the equatorial belts, North/South temperate belt, North/South polar regions, white lane separating the GRS from the belt.

 

My only advise is to try several magnifications to understand your tastes. Apart from that, the sky (and then the optics) are the limits. 

A quick game: 

- is 10a "F" or "T"?

- is 11a "F" or "P"? 

- is 11g "F" or "T"?

- are 11b and 11c the same? 

- a solar granule can be like 11d.. is this a dot or a circle..?

 

A further comment.

The formula for maximum telescope resolution was conceived for double stars. Planetary features are not double stars. Colour, levels of contrast, and pattern recognition also play a role here. 

Edited January 7, 2018 by Piero

[recceranger]

I reckon it’s no more than x 30 per inch of aperture.  I never take my MAK 150 above x200 on Jupiter or Saturn and on lunar you don’t need to

[laowhoo]

On 12/17/2017 at 15:49, 25585 said:

Larger diameters, theoretically anyway, make splitting double stars easier.

Can anyone advise on significant magnification & aperture increments for increasing arc & resolution etc?

This work was by Roger Clark done with the help of Mel Bartels and Nils Olof Carlin, and is based on the earlier work of Blackwell for the military

http://clarkvision.com/visastro/omva1/

Personally, I'm pushing mag all the time, accepting the limits of my aperture and conditions. I'm also always fiddling/collimating. Realistically, conditions here limit ideal viewing to about 250x generally, but there are always things to try to sneak up on, and sometimes if you wait 30 minutes, seeing will "break" for a few seconds. There really isn't an either/or proposition here, and unless you're trying things just beyond your grasp, well...isn't that what we're doing anyway?

(LOL I just realized what I'm doing--I'm probably trying to get a hint of what the imagers are getting. So be it!)

Edited January 17, 2018 by laowhoo

[niallk]

For viewing planets, I keep an eye on the jetstream forecast.  If it looks promising, I let my 15" dob cool for 2-3hrs, and of course collimate.  I am finding that I usually use 250x in good conditions, going to 330x in very good seeing on Jupiter, Saturn, Mars, Uranus + moons.  The moon takes 330x or more usually.  I have been surprised over the last year than I have gotten my best views ever of Saturn at low altitudes like ~16° at 330x, looking south over the sea. I thought I would be wasting my time even trying.

If the seeing is not so good, I don't target planets!  And sometimes it is absolutely pure mush.   However, checking the jetstream forecast seems to be helping me to shoot for the better nights, reducing disappointment

On an exceptional night, I've observed Jupiter at 560x trying to discern detail within the GRS, with the image holding up sharp (37x / inch), but I found backing off to 420x was an overall better tradeoff for time between nudges on my dob (100° afov ep).  I should have used my eq platform that night!

Seeing and cooling are king, and trying not to look over roof tops with escaping heat plumes etc (I've seen these intermittently destroy seeing when in my back garden).

For DSOs, I use my 6mm for 330x often on planetary nebulae, sometimes more.

I definitely find that I am using higher mags with my 15" than with my 10".

Edited January 20, 2018 by niallk