Seek and Magnify

[25585]

What magnifications and fields of view do people here use for seeking objects?

Once found, what magnification stages do you run through to try for the image size and detail you want?

[NGC 1502]

 

Most of the time with my 10” Dob I starhop at 44x and a 1.5 degree field of view. With objects like the double cluster, Veil nebula, M81/82 etc, that’s where I mostly stay. Maybe add my Ultrablock filter, if appropriate. For naked eye planets or double stars, I can start much higher, 92x,  just centre the Telrad on it. Occasionally I may go higher on something like M82 to  tease out the diagonal dark lane in that galaxy. Globular clusters or tiny planetary nebs take high power well.

For deep sky, quite often I then may go in larger steps, 170x, 250x. For planets I find smaller steps more appropriate. Jupiter often looks sharper at 133x than 170x, if the seeing is not great.

HTH, Ed.

[LukeSkywatcher]

With my 8Se, focal length=2032mm. I scan the skies with my 25mm Vixen NPL which gives me a magnification of 81x.

I then move down to about 15mm which gives me 135x. 

Depending on the size of object, I'll ramp up the magnification or go down. 

For planets, I'll typically use an 8mm which gives me 254x.

I agree with Ed. Jupiter looks great at about 13?x. It's small but the details are very sharp. 

 

[cloudsweeper]

8SE - 42mm/x48/1.34deg, or 36mm/x56/1.28deg.  These give a decent wide view for checking where you are, and exit pupils respectively 4.2 and 3.6mm.

I then go up in sometimes close steps, depending on the target, until seeing degrades the view.  And as Paul says (above), lowish mag (x80 to x120) often gives the clearest and most pleasing view.

With the frac, I start at 36 or 30mm, enjoying over 4deg of field, but the exit pupil is high and contrast poor, so I rapidly move through the EPs perhaps down to 3mm (x200).

Doug.

[LukeSkywatcher]

One thing I hinted at but didn't say is:

Don't get too hung up about image size. Jupiter is no bigger in an 8" scope than it is in a 4" scope (all else being the same). The more aperture you have, the more light gets to your eye. More light = better details.

The more you observe objects, you will start to pick out finer details. 

What's that website which shows you roughly what to expect to see with any scope and EP. I can't think of it. It's very useful and I've found it to be quite accurate. 

Here's a different site. Same thing

https://astronomy.tools/calculators/field_of_view/

 

 

 

 

 

 

[MarsG76]

Seek low power and than try various magnifications and filters until I get the best combo...

 

[LukeSkywatcher]

49 minutes ago, MarsG76 said:

Seek low power and than try various magnifications and filters until I get the best combo...

 

Exactly. Don't forget to refocus every time you change the EP. 

[MarsG76]

34 minutes ago, LukeSkywatcher said:

Exactly. Don't forget to refocus every time you change the EP. 

Unless they're par-focal.

 

[MarsG76]

1 hour ago, LukeSkywatcher said:

Exactly. Don't forget to refocus every time you change the EP. 

I guess you can slightly de focus on a star field if you want to see lots of ring nebulae ? HAHA

[Mr niall]

With my Mak 127 a 30mm Plossl gave 50x, with my Opticstar ar90 f8.8 its around 30x.

my favourite is definitely around the 80x mark seems to generally be a good balance between contrast and widefield - and you can see the details on most of the planets. If that isn’t enough about 120-125x is my next stop but I rarely go higher.

[NGC 1502]

13 hours ago, MarsG76 said:

Unless they're par-focal.

 

Good advice mostly, but even so-called parfocal EPs can need a tweek for the sharpest view. For instance, my 10mm TV Radian needs more than a tweek when changing from other TV parfocal Radians. Others are spot on parfocal.

Ed.

My predictive spell checker needs throttling........I SAID TWEEK NOT TWEET.........OK, GOT THAT ?   rant over.....?

[25585]

4 hours ago, NGC 1502 said:

Good advice mostly, but even so-called parfocal EPs can need a tweek for the sharpest view. For instance, my 10mm TV Radian needs more than a tweek when changing from other TV parfocal Radians. Others are spot on parfocal.

Ed.

My predictive spell checker needs throttling........I SAID TWEEK NOT TWEET.........OK, GOT THAT ?   rant over.....?

Tweak?

[S.A.M]

Magnification is not everything with astronomy, so many times I see shops selling telescopes with magnification as a main theme.  I use a Meade 8 inch (203 mm to younger members) and rarely go above 143X yet the scope is capable to go up to 400X ish?

Peter

[25585]

2 minutes ago, S.A.M said:

Magnification is not everything with astronomy, so many times I see shops selling telescopes with magnification as a main theme.  I use a Meade 8 inch (203 mm to younger members) and rarely go above 143X yet the scope is capable to go up to 400X ish?

Peter

About 125x is roughly my max, using hand guidesd alt az only. But I do like to know how much larger than naked eye, an image I am looking at is.

[rwilkey]

I use 32 - 35mm (PanaView or Panoptic) as 'finders' and then go down to about 100x, which is the optimum in my 100ED which I use most of the time, a 9mm Nagler (though I am quite partial to the ES82 8.8mm which gives me 102x) gets me this magnification.  On planets I usually go up to 150x with a 6mm William Optics SPL.

[25585]

On my 900mm scopes I use a 9mm Baader Morpheus which is 76 deg AFOV. Its a good optic for such a short focal length, a worthy & less expensive rival to the Pentax XW 10mm.

They are all quite close for TFOV:

 

[John]

I find that I'm using higher magnifications more over the past 18 months or so than I have in my previous years in the hobby. I'm finding particularly that high magnifications (ie: 300x plus) do actually help pull out fainter planetary moons (eg: Triton at Neptune, Titania and Oberon at Uranus), the central stars of planetary nebulae and supernovae in small dim galaxies and also the finest lunar detail, conditions allowing.

With some light pollution to contend with I find that going longer than a 25mm eyepiece is not really too productive in terms of observing faint objects unless they are very large in which case I do employ the lowest power / widest field that I can get (31mm Nagler) while retaining a reasonably sized exit pupil. 

I try and have my finder scopes as accurately aligned with my main scopes view as possible so that I can be sure that whatever is central in the finder is also in the centre of a high power field of view in the scope. I do also sometimes use the above lowest / widest eyepiece as a finder as well.

The key thing I think is to be adaptable and flexible and to do this a good range of eyepieces are helpful. Currently I think I have 15 or so ranging from 2mm to 31mm in focal length, all of which seem to "earn their keep" at sometime or other

 

[25585]

1 hour ago, John said:

I find that I'm using higher magnifications more over the past 18 months or so than I have in my previous years in the hobby. I'm finding particularly that high magnifications (ie: 300x plus) do actually help pull out fainter planetary moons (eg: Triton at Neptune, Titania and Oberon at Uranus), the central stars of planetary nebulae and supernovae in small dim galaxies and also the finest lunar detail, conditions allowing.

With some light pollution to contend with I find that going longer than a 25mm eyepiece is not really too productive in terms of observing faint objects unless they are very large in which case I do employ the lowest power / widest field that I can get (31mm Nagler) while retaining a reasonably sized exit pupil. 

I try and have my finder scopes as accurately aligned with my main scopes view as possible so that I can be sure that whatever is central in the finder is also in the centre of a high power field of view in the scope. I do also sometimes use the above lowest / widest eyepiece as a finder as well.

The key thing I think is to be adaptable and flexible and to do this a good range of eyepieces are helpful. Currently I think I have 15 or so ranging from 2mm to 31mm in focal length, all of which seem to "earn their keep" at sometime or other

 

Wish I could find, or at least differenciate Uranus & Neptune from stars, let alone their moons! (Forget about Pluto or Mercury). Hoping to see Saturn's moon & Mars too someday. I have on one exceptional night seen a couple of fainter moons of Jupiter - new scope, shiny well collimated mirror probably helped.

Knowing which galaxy is what from a cluster. Globulars, OCs & planetaries, other nebula are easy by comparison. All made more difficult by FOVs being spun & twisted depending on the optics of any scope without a RACI view.

But hand guiding, switching from a high mag ep with narrow TFOV, to an even higher/smaller one must require the deft sleight of hand skill of a croupier in a casino! I can understand the attraction of small FL zooms.

But when something good is found, what a buzz!

[John]

11 minutes ago, 25585 said:

Wish I could find, or at least differenciate Uranus & Neptune from stars, let alone their moons! (Forget about Pluto or Mercury). Hoping to see Saturn's moon & Mars too someday. I have on one exceptional night seen a couple of fainter moons of Jupiter - new scope, shiny well collimated mirror probably helped....

 

Uranus and Neptune show clear disks at 100x and upwards. Quite different from stars. Mercury looks like a small version of Venus with a scope - small but the disk and phases are not difficult to see telescopically.  I've seen up to 6 of Saturns moons but not Phobos or Deimos at Mars, as yet. Beyond the bright 4 Galilean moons, the next brightest Jovian moon is magnitude 14.1 (Amalthea) and then 14.8 (Himalia) so should be in reach of a really large aperture amateur scope but very challenging I suspect.

 

[swamp thing]

On 29/05/2018 at 09:17, LukeSkywatcher said:

 

Don't get too hung up about image size. Jupiter is no bigger in an 8" scope than it is in a 4" scope (all else being the same). The more aperture you have, the more light gets to your eye. More light = better details.

 

 

As the principle purpose of a telescope is to magnify, your comment "don't get too hung up about image size" did not fill me with much confidence.

.......To add that "jupiter is no bigger in an 8" scope (all else being the same)" is somewhat confusing.....and misleading.

In what way would "all else being the same" apply here????

I ask because if we are talking of two scopes with the same eyepieces in them that could well produce very different magnifications. 

eg
8" f/6 with 20mm eyepiece = 60x magnification 
4" f/6 with 20mm eyepiece = 30x magnification.  Note that these two scopes have the same focal ratio therefore the same exit pupil (quite a lot of the same's here!!! ) Yet the magnification is completely different.

Not only is it not the same but the 8" scope is at twice the magnification (therefore the object being viewed covers 4x the area) and the surface brightness is the same in each scope.

I hate to be pedantic but we must strive to be accurate when encouraging others.  

 

 

 

[GavStar]

41 minutes ago, 25585 said:

 I have on one exceptional night seen a couple of fainter moons of Jupiter - new scope, shiny well collimated mirror probably helped.

 

Do you mean the very small moons that John refers to in post (ie beyond the main 4)? If so what size scope did you see these in? I’ve read that you need something like a 20 inch scope to see the smaller moons in part because of the brightness of Jupiter nearby...

Amalthea was discovered with a 36 inch refractor!

[Stu]

17 hours ago, NGC 1502 said:

Good advice mostly, but even so-called parfocal EPs can need a tweek for the sharpest view. For instance, my 10mm TV Radian needs more than a tweek when changing from other TV parfocal Radians. Others are spot on parfocal.

Ed.

My predictive spell checker needs throttling........I SAID TWEEK NOT TWEET.........OK, GOT THAT ?   rant over.....?

Ed, we’ve all seen your tweets every time you have to refocus....  

[25585]

30 minutes ago, GavStar said:

Do you mean the very small moons that John refers to in post (ie beyond the main 4)? If so what size scope did you see these in? I’ve read that you need something like a 20 inch scope to see the smaller moons in part because of the brightness of Jupiter nearby...

Amalthea was discovered with a 36 inch refractor!

It was my original 12 inch Dob. At the time I had better, darker, clearer sky than I do or have had for years now. A road with no street lighting or neighbours living close & so brightly lit.

I had a Nagler 13mm type 1 smoothie at the time, also new.

[Stu]

2 minutes ago, 25585 said:

It was my original 12 inch Dob. At the time I had better, darker, clearer sky than I do or have had for years now. A road with no street lighting or neighbours living close & so brightly lit.

 

I’m sorry to say but I suspect that these were background stars. A mag 14.1 object close to a bright planet would be extremely challenging

[barkis]

9 hours ago, S.A.M said:

Magnification is not everything with astronomy, so many times I see shops selling telescopes with magnification as a main theme.  I use a Meade 8 inch (203 mm to younger members) and rarely go above 143X yet the scope is capable to go up to 400X ish?

Peter

Agreed, sometimes too much emphasis is on Magnification, yet some still rack it up, and become disappointed 
when the image actually degrades. Other factors can impinge on the results one gets, atmospheric disturbances, Humidity, fog, although a slight 
case indicates a quiet sky, and can usually be a good time for planet observing. Lack of scope cooling time is another no no.
  Ramping up the  Mag. is fine, but stop before the image degrades. 
I think most observers are aware of this anyway, but some newcomers to visual  Astronomy may need reminding.