My Rambling Thoughts

A set of very nice eyepieces

I had my eyes on Explore Scientific eyepieces after reading numerous reviews. They are supposed to offer Tele Vue-like (i.e. excellent) performance at a budget price, but "budget" is relative — they are still pretty expensive. Then I discovered they are priced quite decently on TaoBao (in the ballpark of their old US$99 price point), so I ended up with the following :sweat::

F LenDegWtEye reliefPriceMag*True field*Exit pupil*
Explore Scientific 68° 24mm24mm68°329g18.4mmUS$14062.5x1.09°2.03mm
Explore Scientific 82° 11mm11mm82°279g15.6mmUS$160136.4x0.60°0.93mm
Explore Scientific 82° 8.8mm8.8mm82°255g15.6mmUS$160170.5x0.48°0.75mm
Explore Scientific 82° 6.7mm6.7mm82°228g15.7mmUS$160223.9x0.37°0.57mm

*On a 127mm f/11.8 scope.

Also, a Explore Scientific 1.25" 2x Focal Extender, 255g, US$120. With it, I am well covered from 11mm to 5.5mm (near the max for my scope), or even 4.4mm if I were to push it.

F LenDegMag*T field*E pupil*

The next step, 3.35mm, pushes it too far. The image is fuzzy, dim and very shaky. The scope can magnify up to 250x (2 x aperture in mm), anything above is mere simple enlargement at considerable expense of brightness.

At first, I only intended to buy the 11mm, 24mm and the 2x barlow, but the 24mm eyepiece was temporarily OOS (and the 11mm eyepiece was stuck in the same order!), so I accelerated my plan to fill in the gap between 11mm and 5.5mm.

There is a huge gap from 24mm to 11mm. One reason is that the ES 14mm 82° eyepiece is described as worst of the lot with significant field curvature, though I wonder if it shows up on a slow scope. The ES 16mm eyepiece is 68° FOV only — with just 11.9mm eye relief! The other reason is that there is simply no need to fill in the gap. Low-power (~50x) is used to observe star field, high-power (>150x) for planets, in-between is not meaningful*.

* Unless they cover 1 – 2° true field (nice magnification for star field) or give 1 – 2mm exit pupil (optimal eye resolving power). For my long focal length scope, these are covered in its low-power (really medium-power) mode already.


When I was buying the ES 6.7 and 8.8mm eyepieces, I was debating if I need 82° FOV. They are heavier, more bulky and expensive. At high-power, you are focusing on the object, typically a planet or double star. Even with such wide FOV, the surrounding is typically void black due to high magnification.

It turns out that I can only see around 60° when I wear my glasses (requires ~20mm eye relief), so the extra FOV is "wasted". However, I expect to get better with more viewing. :lol:

The extra FOV is useful in the initial positioning, though. I'm sometimes able to get the target planet in the view immediately using the RDF (Red Dot Finder) without having to switch to a low-power eyepiece and centering it. That's pretty convenient.

Even though the ES 8.8mm and 24mm eyepieces replace the bundled 9mm and 25mm Kellner eyepieces, I suspect I may still use them sometimes — but it is the opposite from what you expect!

The ES 24mm eyepiece is very bulky! It is described as a "hand grenade", which is an apt description given its shape. Despite so, I foresee using it for its wide field. The bundled 25mm EP, although said to be decent, has too narrow a true field to be useful for anything other than viewing the Moon.

The ES 8.8mm eyepiece is okay in terms of physical size, but after viewing through it, I realized the puny 9mm EP works well enough too. It is often ridiculed for its poor image quality, but I don't see it. Maybe I'll be able to tell them apart with more viewing. :lol: The planets show up sharp and detailed. It has a much smaller FOV, but it is just enough to show Jupiter with its four main moons — I got to press my eye against the eyepiece to see the outermost moon.

One too many?

A minimal set is two eyepieces, barlow is optional. Usually people recommend getting just three eyepieces for a start (for low, medium and high power). I got four with a barlow!

In hindsight, a better selection would be 8.8mm and 24mm — basically replacing the bundled EPs! I chose 11mm over 8.8mm to avoid that and because I thought the 9mm was close to the limit of the scope — but it was not so. The 11mm eyepiece is neither here-nor-there. It is still a good eyepiece, though. :lol:

What's next?

My eyepiece set is complete for this scope. I only need new eyepieces for a new scope or binoviewer. ;-)

Who am I kidding? :-D I'm on the outlook for a 16 – 20mm eyepiece, probably 70° FOV will do. This range is problematic, even the high-end eyepieces have compromises — field curvature or tight eye relief. This range is more for binoviewer, so I'm not in any hurry. (Binoviewer is one big can of worms. :-O)

I may also get a cheap set of wide-field (60 – 70°) eyepieces. The difference in price is staggering. A low-end 60° eyepiece is just S$20. A well-designed 65° eyepiece is S$100! :-O

Astronomy talk, choosing telescope

"Which Telescope Is Best For Me?", 2nd March.


Given the huge variety of telescopes readily available in the market — ranging from toy telescopes to advance or semi-professional telescopes — this talk attempts to make sense of all these by looking at the advantages and disadvantages of the different types of telescopes and telescope mounts. This will provide a useful guide in helping the novice amateur astronomers to answer their question of "Which Telescope is best for me?"

I attended this talk two weeks ago with a small roomful of would-be enthusiasts. The speaker sort-of delivered as far as the subject matter was concerned, although it was a bit dry. He covered mainly the telescope designs and not enough on the mounts and the starter telescope kits.

But I sensed a disconnect between the speaker and the audience, due to lack of local context. The question at the back of my mind were,

  • What can I observe?
  • When are the planets visible?
  • Looking for good observing sites (e.g. unblocked by high-rise buildings)

Also, expectations. First, Singapore is one of the most light polluted places in the world. Expect to see only the brightest Celestial objects (Moon, planets and a handful of bright stars). Second, it depends on the weather. Singapore is frequently cloudly. Cloud = no observation. Third, timing. Not all Celestial objects can be conveniently observed from 8 – 11 pm. Sometimes you got to wake up at 4 – 5 am. Also, they are seasonal. Miss it this year? Wait for next year. Fourth, you need a view of a reasonably-large patch of the sky within 5-minute walking distance of your home — carrying the telescope, mount and accessories! This is the convenience factor. Fifth, it will never look as good as photos. Planets appear pretty small even at 300x magnification. Nebulas are colorless.

The speaker ends his talk with the cliche saying, "the best telescope is the one you use most often." This is true, but it does not help me choose one.

In the end, I would say I find the talk informative for a lay person, but not sufficiently useful, because I still do not know how to choose a starter telescope and what I can see with it.

The Maze Runner films

I finally watched the first two films last month. TL;DR: they are better than the books. :lol:

The Maze Runner is a close-enough adaptation. It tells a cohesive story in 113 mins. But most of the cast get very little screen time. And some plot points are 'blink-and-you-miss-it' type. Many people prefer the book, but I like the changes the film makes. They improve the story — mostly. I've always dislike the psychic link between Thomas and Teresa. Not there in the film.

One thing I dislike is the transition between scenes. Often, the current scene ends on a "cliffhanger" note because something interrupts it and we go to the next scene, and Thomas and/or the audience is kept in the dark. This is done way too many times.

Another thing I dislike is the camera work when the Grievers show up. Very short disjointed takes that was fashionable then. You cannot follow the action at all. It is supposed to be frightening and suspenseful. I can't tell what is going on at all.

The Scorch Trials differs quite a bit from the second book, but I think that makes it better! It certainly makes more sense, has less reliance on deus ex machina and no super-natural powers. There is actually a cure and it has to be harvested from the Immunes. I like that.

My biggest issue is the ease Thomas and his gang escaped from the facility. Escape, sure, but to go so far on foot and remain at-large in the open desert? Surely the guards will think to search the nearby abandoned structure first?

The middle part is marred for me because of zombies. I don't like zombies.

I like Teresa staying with the group, though she does not have much presence — like most of the cast. There is an all-girls group, and I like that they have their adventure independent of this film and only show up at the end. I also like the resistance group showing up. I like that they explain Thomas's role before he got "wiped". Teresa's betrayal is believable. I don't really like that the resistance group is just a rag-tag team — they should be much more organized than this — and they are virtually wiped out at the end.

The film feels a little slow at times. No wonder, it clocks in at 133 mins.


The first two films are good enough that I will get the blu-rays when the third film is out. The trilogy box set has been announced at US$50! It'll probably drop to US$30 after a while...

A sad day

1935 to 2018.

"I'm going to take a long sleep tonight.", his last words.

Sadly, I last saw my uncle (伯父) six years ago and we didn't even talk that much. Years apart had left us with very few common topics. When I was young, I looked forward to his annual visits.

My earliest cohesive memories were from 5 years old, in a little town called Kulim. It sure was different back then. Idyllic and carefree.

Best Planet viewing time 2018

PlanetOptimal dateOpposition
Mars21 Jul – 3 Aug27 Jul
Jupiter16 Apr – 4 Jun8 May
Saturn10 Jun – 16 Jul27 Jun
Uranus31 Aug – 11 Dec23 Oct
Neptune15 Jul – 30 Oct7 Sep

Jupiter is easily visible now, but it'll be 1/3 bigger on its optimal dates. Mars is also visible now, but it is really small. It will be 4x bigger in July, in fact, at its brightest (i.e. closest) since 2003.

Inner planets:

  • Mercury: 6 – 22 Mar ...
  • Mercury (morning): ... 8 – 29 Dec
  • Venus: 12 Mar – 17 Oct; 20 Sep (brightest)
  • Venus (morning): 5 Nov – 31 Dec; 1 Dec (brightest)

The inner planets show up very often, but they are hard to catch in Singapore as they are low on the horizon and set soon after sunset.