My Rambling Thoughts

Blu-rays update

To my surprise, Studio Ghibli shows are now released by GKIDS in the US.

Nausicaa is the color-corrected version and costs US$17.19. :lol: Although I prefer the original release (with the color-cast) and I don't want any duplicate, I can't resist it at this price. It saves me some time and effort doing my own processing. :-P

Argh, not long after I bought it, the price went down to US$12.99. :duh:

Even the low price cannot entice me to get Kiki's Delivery Service and Totoro. I used to like them, but they have very slow pacing. I'm serious when I say I only want to collect my favourite Studio Ghibli shows.

Recent blu-ray purchases:

  • Cars (US$24.99)
  • Ghost In The Shell 2017 (US$14.99)
  • Guardians of the Galaxy (US$24.99) [not watched]

Cars went down to US$19.99 for a while. GitS 2017 is now US$9.99. This shows how unpopular it is. :-O GotG is now at US$19.99 after running out of early suckers. All in all, I paid US$15 extra!

Lesson: always wait a while for prices to go down.

I'm now waiting for Blade Runner 2049 (US$24.99). No way I'm paying this price! I believe it will come down in price soon as it is not very popular. :-P

I may buy Cars 3 (US$24.38) [not watched]. I doubt this will come down in price any time soon.

Maze Runner: The Death Cure was just released in theatres. By all accounts, it is a very generic rescue-mission action film. I have not watched any of the shows, but I watched some reviews and they changed the parts that I dislike about the second and third books, so they are better! :lol: I'll wait for the Maze Runner trilogy boxset, hopefully at a good price.

Jumanji: Welcome to the Jungle is also on the radar. I've not watched it, but it seems enjoyable.

A game of acquire

Big news in the board game industry: Asmodee just bought over all Mayfair Games IP. They bought Catan in 2016, that was like 70% of Mayfair Games (wild guess), and many people thought it was just a matter of time. That time is now.

(Some larger names that Asmodee has absorbed in the past years: Days of Wonder, Fantasy Flight Games, Z-Man Games.)

Not much will change in the short term, as both companies have MAP (Minimum Advertised Pricing). But Asmodee will have more bargaining power over online retailers now (i.e. either their way or the highway).

For a few months now, board games are no longer at 25 - 40% discount, but a mere 10% off. Asmodee also made clear of its strategy of trading volume for price. This is why counterfeiting scares them so much. But this is also why people turn to fake products. A board game, even a well-produced one like Ticket-to-Ride, does not feel like it is worth US$40. And many niche games are priced at US$50 - $60.

In another news, someone from Mayfair Games said they are working on an expansion to Nuns on the Runs, with a new board and co-op mode. It is due next year. I look forward to it. :-D

Time to run

With my latest acquisition Clue – The Great Museum Caper, I now have a whole slew of "chaser" games:

  • Clue: TGMC
  • Curse of the Mummy
  • Fury of Dracula (2nd ed)
  • Fury of Dracula (3rd ed)
  • Ghost Chase
  • Scotland Yard

Well, I just added one more, Nuns on the Run (2010) [US$31.72]. It did not make the cut last time because I thought it was too similar to the other chaser games that I had. But now I changed my mind. :lol:

Nuns on the Run is often described as Scotland Yard in reverse. All the players (except one) play the invisible "thieves" and try to "steal the valuables" while avoiding the visible "police".

Under the cover of the night, the novices leave their cell to collect their secret wish item and return to their cell within 15 turns. But first, they have to collect a designated key to unlock the chest/cupboard that stores their wish item. That key (as well as any other keys) allows them to unlock doors. They can either stand still, sneak (1 - 2 spaces), walk (3 - 4 spaces) or run (up to 5 spaces). The faster they move, the more noise they make, allowing them to be heard further away. Each novice is also given a blessing card that gives a one-time power.

At the same time, the Abbess and the Prioress are on patrol. They start off by walking (3 - 4 spaces), but they can switch to running (5 - 6 spaces) midstream.

The guards are visible on the board and the novices are invisible, even to one another, except when they are spotted by the guards. The players keep track of their positions in secret. As the guards move one step at a time, the novices indicate if they are spotted (based on line-of-sight rules).

If a guard walks, the novices have to do a noise check after their own movement and after both guards move. If a novice is too noisy (basically, within x spaces of the guard), the guard is alerted to her presence. This is indicated by placing a noise token next to the guard, in the direction of the shortest path to the novice.

The guards may only divert from their set paths if they hear noises or outright see a novice, unless they have a special blessing card to let them do otherwise. There are many times the guard player knows a novice is nearby, but he is unable to pursue her because she is silent. :lol: Once the disturbance ends, the guards resume their set patrol.

If a novice is caught, she is supposed to return to her cell. But she only has to move in the direction of her cell until she is out-of-sight, then she is free to resume her quest. :lol: She loses her wish item if she has it, but not her key. The guards may not follow nor catch her again during this time.

The guard player also win if he catches as many novices as there are players. If there are three novices, he has to catch them four times.

This is a rather light-hearted cat-n-mouse game. The odds are actually in favour of the novices; it is easier for a novice to win than the guard player. The question is, are you the fastest novice?

More eyepieces

Previously, I said there are two ways to see as much of the sky as possible: 32mm 52° and 24mm 68°. And I also list the maximum apparent FOVs constrained by the 1.25" barrel size:

  • 13mm: 100 degrees
  • 18mm: 82 degrees
  • 24mm: 70 degrees
  • 32mm: 52 degrees
  • 40mm: 43 degrees

These give ~1.1° true field. Since we prefer the 24mm to 32mm, why not go all the way to 13mm? Same true field but bigger view. There are in fact such wide eyepieces:

F LenDegMag*True field*WtEye reliefPrice
32mm52°46.9x1.11°Celestron Omni130g?22mmUS$38
24mm68°62.5x1.09°Explore Scientific 68° 24mm329g18.4mmUS$140
16mm82°93.8x0.87°Tele Vue Nagler 16mm WA202g10mmUS$339
13mm100°115.4x0.87°Tele Vue Ethos 13mm UWA590g15mmUS$609

*On a 1500mm scope.

At higher powers, only the best eyepieces will do, and they quickly get heavy and expensive. The Ethos 13mm eyepiece costs more than the scope! But even if you can afford it, do you want it?

Here is one reason why not: doubling magnification reduces brightness by four times. So a 13mm eyepiece is roughly a quarter as bright as a 24mm. You need every bit of light for Extended Objects (i.e. nebulas and galaxies) as they are pretty dim. Stars are not affected as they are point objects.

Extreme high power

After 24mm and 11mm eyepieces, the next range is 7 - 9 mm for extreme magnification for planetary observations.

Unfortunately, Explore Scientific fails us here. They have a 8.8mm eyepiece, which is too "short" (170x) and close to 11mm. Their next eyepiece is 6.7mm (223.9x), which falls into the "are you feeling lucky" category.

If only there is a 7.5mm - 8mm eyepiece... Yes, there is, the Tele Vue Ethos 8mm eyepiece, giving 187.5x magnification. It costs US$575, which is a lot of money for something that will be used rarely, though.

F LenDegMag*True field*Exit pupil*WtEye reliefPrice
11mm82°136.4x0.60°0.93mmExplore Scientific 82° 11mm279g15.6mmUS$160
8.8mm82°170.5x0.48°0.75mmExplore Scientific 82° 8.8mm255g15.6mmUS$160
8mm100°187.5x0.53°0.67mmTele Vue Ethos 8mm UWA430.9g15mmUS$575
6.7mm82°223.9x0.37°0.57mmExplore Scientific 82° 6.7mm228g15.7mmUS$160

*On a 1500mm f/11.8 scope.

Maximum magnification, revisited

Another rule of thumb for maximum magnification is 50 * aperture in inch. This gives 250x for 5" aperture.

However, 3 - 4" aperture can use 70/aperture-inch as they are less affected by air turbulence. 5" aperture can use 60/aperture-inch, giving maximum magnification of 300x. Under this guideline, 224x is well within the limit.

Upgrading eyepieces

The Celstron NexStar 127SLT has a focal length of 1500 mm, aperture of 127mm (1500 / 127 = focal ratio f/11.8) and uses 1.25" eyepieces. It comes with two eyepieces, a 9mm (1500 / 9 = 166.7x) and a 25mm (60x), both 52° FOV.

The first impression is that the 9mm is too shaky (close to the limit of this scope) and while the 25mm is nice (just right for the Moon!), the viewing window is too small — it is like looking through a porthole.

A few things to look for in an eyepiece:

  • Focal length
  • Field-of-view
  • Eye relief
  • Price

The scope imposes three limits. First, the maximum usable magnification is 254x (rule of thumb: 2x aperture in mm). However, the atmosphere further limits it between 150x (1500 / 150 = 10mm) on normal days and 250x (6mm) on good days. This is true for all telescopes.

The second limit is maximum true FOV (often shortened to true field) — the area of the sky seen through the scope. It is ~1.1 degrees (field stop 27.5 mm / focal length 1500 mm * 57.3 degrees/radian = 1.05 degrees).

Third, the maximum (apparent) FOV is constrained by the 1.25" barrel size:

  • 13mm: 100 degrees
  • 18mm: 82 degrees
  • 24mm: 70 degrees
  • 32mm: 52 degrees
  • 40mm: 43 degrees

(Apparent) FOV determines how wide the view looks. The bigger the FOV, the bigger the viewing window. As mentioned earlier, 52° is like looking through a porthole. 68° is nice, 82° is wide (immersive) and 100° is way too wide (too big, heavy and expensive).

For a given eyepiece, the true field is FOV divided by magnification, capped by the maximum true field.

For this scope, the usable eyepiece focal length ranges from 5.9mm (254x, limited by max magnification) to 32mm (46.9x, limited by max true field).

There are two ways to see as much of the sky as possible: 32mm 52° and 24mm 68°.

32mm covers the max area of the sky (52 / 46.9 = 1.11°), but 52° FOV means the viewing area is very narrow. 24mm 68° is the sweetspot for 1.25" eyepiece. It covers 1.09° true field (almost same area), the image looks bigger due to higher magnification (62.5x vs 46.9x) and gives a larger viewing area (due to its 68° FOV).

24mm 68° is definitely the better choice. The only issue is cost. One of the better yet still affordable eyepiece is Explore Scientific 68° 24mm eyepiece (329g) with 18.4mm eye relief. RRP US$140, on sale for US$112.

Getting this eyepiece will render the bundled 25mm eyepiece useless. There is also no need to get a (cheap) 32mm 52° eyepiece.

After settling the wide field part, we now look at high power part. We want the second eyepiece to be around 11 - 14mm (136x to 107x). Anything below 11mm is hard to use (sturdy tripod, good seeing).

In this range, I prefer the 11mm for its higher power. The question is, 68° or 82°? If cost is not a matter, definitely 82°. :lol: A good eyepiece is the Explore Scientific 82° 11mm eyepiece (279g) with 15mm eye relief, giving true field of 0.60°. This is big enough to fit the entire Moon into view! RRP US$160, on sale for US$128.

This replaces the bundled 9mm eyepiece for most part.

If we get the 11mm eyepiece, we will probably skip both 14mm and 16mm (68°) as they are too close. The ES 82° 14mm (US$160, 256g) has a true field of 0.77° with 15.6mm eye relief, so it is better than the ES 68° 16mm (US$140, 158g) that gives 0.73° true field. The latter also has very little eye relief at 11.9mm.

The only downside to using a pair of 24mm and 11mm is that they don't barlow (i.e. 2x extender) well. They give 12mm (too close to 11mm) and 5.5mm (exceeding resolving power). They work well with 1.5x extender though, giving 16mm and 7.3mm.


Cost is definitely an issue. The two eyepieces cost US$300 at RRP, which is 66% the price of the scope. :sweat: But think of the scope as the camera and the eyepiece as the lens. In film photography, the lens is always more expensive than the camera. :-O With digital sensors and post-processing, the lens is not as important anymore.

What about exit pupil?

Exit pupil is the diameter of light cone that exits from the eyepiece. Human eyes accept 0.7mm to 5 - 7mm, depending on age. Anything wider is lost. The optimal range is 1mm to 4mm.

Exit pupil can be calculated by telescope aperture divided by magnification.

For this scope, the exit pupil ranges from 0.5mm (127 / 254) for 5.9mm eyepiece to 2.71mm (127 / 46.9) for 32mm eyepiece, so it is never an issue.