Learning to like high power views

[Chipela]

When recently buying my first telescope, my idea was to concentrate on planets and moon and get a lot of (easy) enjoyment with high power visual observing.

Having now observed a few evenings, I'm surprised to have found out how useful and convenient a low power eyepiece really is. And on the contrary, how many questions have raised when using the high power eyepiece (Delos 4.5mm giving 167x on my 150PDS). Some of them below:

First of all, the view through 4.5mm is so empty and dark. I guess the darkness of the background is because of high magnification but I expected the view to be 'a sky full of stars' like with the 28mm. Is it that I have only happened to find emptier places on the sky or is the limiting magnitude of my equipment or non-perfect observing conditions cutting out so much of the background stars?

The second issue is the 'sparkling' of the targets. They are restless and shoot sparks (evenly) to all directions. Is this because of atmospheric conditions? Or heat currents inside the tube? I also suspected collimation but I believe I have done that correctly and everything looks ok with 28mm.

Then there is the need to constantly adjust RA  . But I guess that's life (or a sign to upgrade from EQ5 to HEQ5  )

But all-in-all, I'm very happy with my new hobby and what I have already observed!

[John]

I generally don't employ high power until I have a target object already in the field of view. Using high magnification on random parts of the sky will often generate a fairly empty field of view.

Try it on the Pleiades cluster. At low powers it looks to be a fairly rich star field. At 200x there are plenty of parts of it that will look rather sparse.

Get a globular cluster in the field at low power though, then apply 200x and the effect is quite different. They are comparitively densly populated objects but don't occupy a large patch of sky.

If you prefer observing with low or medium magnifications though then thats fine - do it that way. There are no "rules" on how we should observe the sky

[Charic]

Whilst my Skyliner is cooling to ambient, I'm looking through the 70° afov Panaview, just sweeping around the skies, If I'm in a hurry to view.

When the scope has equalised, I then use the higher powers as and when required.

I observed during the week to test a new Delos. My scope has been in a cupboard for many weeks, Months even, and whilst carrying out a Star test, (Wow!  how good does my collimation look, just perfect) I noted just a couple of whisps of a thermal in my scope, and by tilting back and forth was able to change the direction of the thermals in relation to my angle of view, just for the fun of it ( its alive in there?)  And having a wider field of view also helps even at higher powers.

My Panaview was chosen to look at M31 Andromeda?

From my garden,  M31 is  a miserable faint smudge of grey, cant even really call it light ( although it is) its just a smudge. But from a dark site, even my 70° Panaview is not wide enough? The galaxy is huge and well detailed, very impressive indeed, and quite rightly, as its so large, the light is further afield, and to capture it  at its best, visually, you need low power and wide field. Oh! and a very dark environment away fro street lights.

Its not until you experience it ( as you have )  just how powerful low power really is!

[rockystar]

Thing to remember is that at low power you are narrowing your field of view, so not seeing as much sky.

Stars will drift out of view after a short period of time, as long as you are polar aligned, you'll only need to adjust RA, you can get a single axis motor to track, or use your slow motion controls on the eq5 ( you don't need to upgrade for visual) get some long cable adjusters if you only have the knobs that came with it

[Charic]

Don't you mean high power!

[rockystar]

Don't you mean high power!

Yes of course, thanks. I always have to try and sort it sort it out in my head: shot focal length = high power, low magnitude star = very bright; good job this hobby isn't too confusing

[Mak the Night]

I only really use high power (200x plus) for lunar/planetary observing. Sometimes the Powermate and Barlows are left in the case and a 32mm Plossl is my first low power choice. I do like to up the magnification to over 100x for targets like the Orion Nebula.

[Northern Soul man]

Great thread guys - I find M31 under my light polluted skies a remarkable object - visually under my skies its just a bright "patch" of sky, I was looking just last night at the thing and got round to thinking that just, with a very bright core, how much "star light" power this galaxy has, yes I know that the dust lanes will produce a certain amount of scattered light to us, but just think how much power is needed to produce such a sight in our skies over 2 million light years away!! just breath taking.

Paul.

[Ruud]

I love low power! I always use the lowest power that will show me the detail that I'm after.

[Mak the Night]

I think it's the inverse square law that governs the brightness of an object at a particular magnification. Aperture is also a factor of course, I think a rough guide is to start with approximately 10x per square inch of aperture and then work up the magnification. It's what I tend to do. Usually a 32mm Plossl first (approx 41x on my 4" Mak), then usually my 24mm Panoptic 68° (54x), then the 19mm Pan (68x) if I'm feeling lucky lol. After that, the sky's the limit. Well ... 241x on the Mak!

[Chipela]

Commenting my original post:

After a few successful observation nights I'm starting to get used my high power eyepiece. I bought a one axis motor drive which of course solved the drifting issue. Actually, I think it's a must accessory since I want to share the views with my family members and friends and it's really too big hassle to manually rotate around RA axis all the time.

I've also started to appreciate the dark background of the high power view since with the local light pollution, the views through the low power eyepieces are often so low contrast.

The third issue still remains, the stars are not pinpoint with the high power eyepiece. I strongly suspect it's because of mediocre seeing because the imperfection changes dynamically. It's just a bit unfortunate that I can't e.g. split the Double Double cleanly with my x166 eyepiece (at best the two stars are elongated dots) although many people mention that they are able to split them cleanly with < x150 magnifications.

[John]

Those are interesting observations.

Splitting close double stars is quite a test of optical quality as well as the seeing conditions. Under reasonable conditions a 150mm scope should be able to split Epsilon Lyrae at around 150x. Is the collimation of your scope in reasonably good shape ?

[Chipela]

Those are interesting observations.

Splitting close double stars is quite a test of optical quality as well as the seeing conditions. Under reasonable conditions a 150mm scope should be able to split Epsilon Lyrae at around 150x. Is the collimation of your scope in reasonably good shape ?

Collimation should have been ok because I collimated my OTA after I first failed to split Epsilon Lyrae. The image got better but still not good enough.

The issues I'm suspecting are maybe a less-than-perfect cooling of the OTA and overall seeing conditions. I have to try again when there is the next opportunity.

[John]

The seeing conditions have been very "mixed" to say the least lately. When we have actually any open sky to see, that is