My Rambling Thoughts

Ultra-wide angle eyepieces

The full set of Explorer Scientific 1.25" 82 degree eyepieces comprises of: 4.7mm, 6.7mm, 8.8mm, 11mm and 14mm. The 4.7mm is too high-mag for my scope and the 14mm has a reputation of field curvature (inconclusive, though).

These were the first eyepieces I upgraded to. They are about the most expensive eyepieces I'm willing to buy. Even so, they are only considered mid-tier, not premium, eyepieces. I would have skipped them if I had known I need to pan my head to take in ultra-wide views.

I got them for 620 yuan each (S$123). They are now at least 20% higher. There is also a new series of LER (Long Eye-Relief) 82 degree eyepieces: 4.5mm, 6.5mm, 8.5mm.

The ES 24/68 ep was among the first eyepieces I upgraded to. It has a great reputation and is considered affordable as far as 24/68 ep go. Everyone should have either a 24/68 or 32/50 ep — they give the widest TFOV in 1.25".

Even so, I seldom use it because it is too heavy (330g)! I prefer to use 20/70 ep (86% max TFOV), 23/62 ep (87% max TFOV) or 25/60 ep (92% max TFOV). These are my next widest eyepieces.

I got the Meade 5.5mm 82 degree eyepiece much later when it was on sale on Amazon. I do not really have a use for it as it is a little too high-mag for my scope (273x). It is more to "complete" the 82-degree series. ES was the OEM for Meade's 82d eyepieces, but Meade could not pay their bills, so ES created their own 82d line. The design for the 5.5mm ep remained with Meade.

I got the ES 2x Extender among my first upgrade. My original intention was to use barlow to get higher mag than 7mm. 11mm / 2 = 5.5mm (273x), 8.8mm / 2 = 4.4mm (341x), 6.7mm / 2 = 3.35mm, a whopping 448x mag on my scope, at the expense of being extremely-difficult-to-focus, high shake and low brightness — virtually unusable.

This was before I truly understood that higher mag does not bring out more details. I knew the theory, but like all newbies, I still wanted to exceed the limit. Alas, the law of physics prevailed. The limit for my scope is around 8.8mm ep (170x, 0.70mm exit pupil).

As a result, I seldom use the extender. Also, I found it tedious to switch to and fro. I have no use for it above 7mm as I have a wide range of eyepieces from 7mm to 25mm. Barlow/extender is a great idea to "double" your eyepieces, but it does not really work well in practice. I would skip it.

I got the ME 5.5/82 ep for US$80, the ES 24/68 ep for 560 yuan (S$111), and the ES 2x Extender for 432 yuan (S$86).

Low-end Sky Rover eyepieces

Sky Rover Wide-Angle eyepieces

These are about the cheapest non-kit eyepieces you can get. They are 4/3 (4 glasses in 3 groups) in construction and give 60 degree AFOV. There are four in the series: 8mm, 12mm, 17mm and 20mm. Sky Rover is the OEM's own line of products. They are available under several labels.

The 8mm and 12mm ep used to cost 90 yuan (S$18) each, the 17mm ep 115 yuan (S$23). The prices have gone up slightly. I did not get the 20mm ep as it overlapped with the 20/70 ep.

They show lateral colors off-centre. I would suggest skipping these entirely. The 8mm ep is said to be good for planetary, but I don't find anything special about it (except for the price).

Of the three, I used the 8mm ep most often for Jupiter and Saturn. It gives 187.5x on my scope. It was later obsoleted by the BST Starguider 8mm ep.

Sky Rover Super Wide-Angle eyepieces

These are 70 degrees AFOV and are 5/3 in construction. There are three in the series: 10mm, 15mm and 20mm.

They are better corrected, but their achilles heels is their non-flat plane of focus. The off-axis is out-of-focus when the center is in focus and vice-versa. This defeats the purpose of their wide angle view. They don't have a good reputation online as a result. (These are the cheapest 70 degree eyepieces you can get.)

I got the 10mm ep for 220 yuan (S$44), 15mm ep for 240 yuan (S$48), 20mm ep for 260 yuan (S$52). AFAIK, these are OOP. I wanted to buy a second 20/70 ep for bino-viewing a few months later, but it was OOS.

I use the 10mm ep (150x) and 15mm ep (100x) most often for Jupiter and Saturn. I do not use the 20mm ep (75x) much, but I distinctly remember I had my best view of Jupiter and the Moon with it. The seeing was exceptional on those nights.

I still use the 15mm ep as my low-mag positioning ep before stepping up to either 8mm or 9mm ep directly. I used to step up to 10mm first, but found it pointless most of the time. I may consider using the 20/70 ep as the starter ep, as it gives 98% TFOV (true FOV) of the 23/62 ep. It is much heavier, though.

I actually wanted to buy the 10mm 65d UF (Ultra-Flat) eyepiece for 268 yuan (S$53) instead of the 10/70 ep, but the seller thought I wanted to buy a full set of 10/15/20 ep and shipped me the wrong ep. He refunded me the difference.

Cheap good eyepieces

The Ultrawide 6mm and 9mm eyepieces get great praise. They are supposed to be very sharp, but they suffer greatly from SAEP (Spherical Aberration of the Exit Pupil). You need to look straight down at the correct distance, or the corners will dim out. This has a nickname: kidney bean.

They perform great if the object is only in middle of the view, e.g. planets.

There are two other in the series, 15mm and 20mm. They are fair only. I did not get them.

The gold-band ones are 66 degrees, but recently rebadged to red-band and 68 degrees! They are likely to be the same eyepieces.

The Celestron 23mm 62 degrees aspherical eyepiece is a kit eyepiece. The eye lens is aspherical (though plastic), contributing to its sharpness. The 10mm eyepiece is not too bad too, but the 4mm is trash. This set is really cheap. The 23/62 ep is now my starter eyepiece, replacing the bundled 25/52 ep. It has ~9% wider FOV.

The Celestron Plossl 32mm 50 degree eyepiece is a standard lens, but I include it here as it is a cheap way to get max FOV in 1.25". The alternative is an expensive and heavy 24/68 eyepiece.

If I had started with BST or X-Cel LX, I would have skipped the UW 6mm and 9mm ep, and maybe the Asp 10/62 ep too. But I would still get the Asp 23/62 and PL 32/50 ep.

Update: I bought the 6/66 ep and 9/66 ep for 130 yuan (~S$26) each, 23/62 ep for 60 yuan (~S$12), the 32/50 ep for 110 yuan (~S$22).

Starter eyepieces

It is easy to get caught up on the hype on ultrawide eyepieces and overspend.

Start with something simple.

It turns out that ultrawides are not really my style. All eyepieces can only give a direct FOV of around 65 degrees. To see more than that, you need to move your head and pan around. It turns out that I like to look straight down, motionless and staring. (I wished I knew that before I bought a bunch of ES 82D eyepieces...)

There is not one, but two, very good lines of budget eyepieces: the Celestron X-Cel LX and the BST Starguiders. Both are 60 degrees AFOV.

The X-Cel LX lineup: 2.3mm, 5mm, 7mm, 9mm, 12mm, 18mm, 25mm, 2x barlow, 3x barlow. The best are said to be the 7mm, 9mm and 25mm, but the entire line is fine in slow scopes (f/10 and above).

The Starguider lineup: 3.2mm, 5mm, 8mm, 12mm, 15mm, 18mm, 25mm, 2x barlow. The 8mm and 12mm are said to be the best, but the others are also fine in slow scopes. 25mm is noticeably the worst of the bunch.

These two lines can be used for life; they can supplement more expensive eyepieces in the future. They cost around S$70 each. Don't waste time / money with anything cheaper — except for a handful of cheap-but-good eyepieces. Don't buy anything more expensive until you are sure you need them.

There is no need to be completionist and buy the entire line. Just get what are needed. For my scope (1500mm f/12.5), after using focal lengths from 3.35mm (447x) to 32mm (47x), I found that I can get by with just two eyepieces: 9mm and 25mm — the same focal lengths that are bundled with the scope.

After trying many high-magnification eyepieces to tease out details on the Moon and Jupiter (look at my lineup above), I finally understood the saying, the telescope forms the image, the eyepiece magnifies it, with my eyes.

Whether 25mm (60x) or 9mm (167x), the details are the same, because I'm looking at the same image formed by the scope, just at different magnification levels. I do not see more at 167x. Of course, it may be easier to see tiny details at higher magnification. But it also means harder to focus, more shaky and dimmer.

On my scope, 9mm gives 0.72mm exit pupil (9 / 12.5), which is about the max useful magnification for any scope.

You know the saying: if only I knew then what I know now. I wouldn't have ended up with 31 eyepieces... :sweat:

Choosing monitor by PPI

There are three common resolutions for a 27" monitor: FHD (1920 x 1080), QHD (2560 x 1440) and UHD (3840 x 2160). Which to buy?

If you are okay with 1080p on a 13.3” or 14” notebook:

  • 13.3" -> 1920px over wd 11.3” -> 169.9 px/inch
  • 14" -> 1920px over wd 12.2” -> 157.4 px/inch

If you are okay with 1080p on 24” monitor:

  • 24" -> 1920px over wd 21” -> 91.4 px/inch

(This is a little low, IMO.)

What it means on a 27” monitor:

  • 27" -> 1920px over wd 23.5” -> 81.7 px/inch
  • 27" -> 2560px over wd 23.5” -> 108.9 px/inch
  • 27" -> 3840px over wd 23.5” -> 163.4 px/inch

Civil war

America is still a racist country, but America is no more racist today than it was when Barack Obama was president. A lot of American police are brutal, but no more brutal than when Obama was president. America didn’t radically change the day Donald Trump was sworn into office. All that has changed is the official narrative. And it will change back as soon as Trump is gone and the ruling classes have no further use for it.

Never let a crisis go to waste.

The Demoncrats only need one incident to 'win'. Trump, on the other hand, needs to survive all of them.

All Lives Matter.

On nCoV

I wrote the following in a forum in April. The entire thread was removed, so just going by the main points.


Lockdown is a very drastic step. It sacrifices the economy for public health. Does it work?

China locked down Wuhan for 76 days from Jan 23. Despite that, it did not manage to eradicate nCoV. Lockdown without eradication means the virus will flare up again in the absence of immunity. We will be back at square one, except now the economy is trashed.

But we need lockdown to "flatten the curve" so as not to overwhelm healthcare services, in which case more people will die, right?

When China locked down, the authorities already knew nCoV killed off the elderly in large numbers. What they didn't know was whether the young would survive. A lockdown was a desperate attempt to halt the spread.

We now know. They will.

Stats from Sweden, as of 18 June (using the most current):

Age group#infected#deaths%age

The overwhelming number of people who die are the elderly (i.e. those over 70 years old). It is similar worldwide.

In other words, if we shield them properly, we can avoid most of the deaths without lockdown. Nor do we need to "flatten the curve" — there is no curve to flatten. (The young only need medical observation, not intensive care.)

This is the great failing all over the world. Everyone wants to make this the doomsday virus. We pretended that it affects everyone equally and failed to protect the elderly.

On herd immunity

In the absence of cure or vaccine, we need herd immunity if we are ever to return to normal life.

There is a great deal of backlash with this approach. To many people, they still think getting infected is a death sentence. Stats have proven otherwise. Most will fall sick and recover without need for medical care. Many are even asymptomatic.

Two of the biggest obstacles are, no immunity even after infection, and long-term health effects. Are these true? There is a lot of fearmongering. nCoV is a coronavirus. Have we forgotten how it works?

Just like the strong bias against existing cheap drugs that show some effectiveness. There's no money in that. Everyone is racing to find a cure or vaccine. That's big money. They want the pandemic to last until then.

(Hydroxychloroquine and zinc together are said to be pretty effective.)

On face mask

Face masks work. Period. There is still misconception that it only protects others from you. No, it protects you from others as well.

The reason face masks work is because the virus is not airborne, but is transmitted via micro-droplets. The droplets are absorbed by the face mask. Surgical masks provide virtually 100% protection, but any face mask will help.

Health authorities all over the world know this, but due to worldwide shortage, they lied so as to keep surgical masks for medical workers. There is little spread in Taiwan and Hong Kong. Guess why?

After denying its usefulness over two months, Singapore finally made it mandatory to wear face mask outside of home after it managed to procure sufficient quantity of reusable face masks for all residents — no mean feat.

The virus can enter via eyes too, so for full protection, we need to wear goggles. Short of that, face shield.

Micro-droplets can linger in the air and build-up in unventilated enclosed environment. So minimize time staying in the same spot indoors.

On Singapore

Singapore would not have entered lockdown on April 7 if not for the spread in densely packed dormitories.

Think Diamond Princess cruise ship is bad? Singapore has the equivalent of 43 cruise ships, total ~200,000 foreign workers. Given the infection rate of around 20% in cruise ships, that's around 40k infections.

Since it has already happened, it is a good chance to see if nCoV is really as deadly as feared.

I am optimistic. I predict zero deaths and zero cases in ICU. (The foreign workers are mostly in the prime of their life.)

Hopefully this will let health authorities make more rational decisions.

Will swallowing disinfectant kill you?

Fresh air is a disinfectant.

For some reason, we have forgotten everything we know about coronavirus, how it spreads and what it is weak against.

Coronavirus is broken down by sunlight and fresh air.

It is transmitted through droplets. Droplets have a short range and drop to the ground quickly. Micro-droplets can linger and build-up in the air indoors, especially if poorly ventilated.

This is why it helps to wear face mask. A surgical mask does not filter virus, but filters droplets and particles. If you interact with people, you want to wear a full face shield too — protect your eyes.

My guess is that it takes a certain concentration to infect. If it is lower than that, there is no infection even if the virus is present.

The perfect bio-weapon

Wanted traits:

  • Long incubation period (up to 14 days)
  • Asymptomatic during incubation period
  • Infectious even in asymptomatic phase
  • Transmissible via respiratory droplets, airborne (aerosol), feces
  • Hard to diagnose; good at hiding in various parts of the body
  • Three-week illness duration; first week mild, second week recover-or-get-worse, third week critical (recover or die)
  • Multiple organ failure; immune system attacks own organs
  • Able to re-infect after recovery; only weak anti-bodies produced
  • Organs weakened after first infection, more likely to be serious on re-infection
  • High mutation rate to thwart vaccine or cure

After a long search, we finally found one promising candidate...

The Novel Coronavirus (2019-nCoV), now named COVID-19, is extremely lethal to the elderly (60 years old and above), those with pre-existing health conditions, and those with over-reactive immune system.

Fatality rate of risk group: at least 10% — don't risk it, trust me. Fatality rate of non-risk group: 0.2% (10x higher than seasonal flu). You'll probably shrug it off.

Except we still need to improve its deadliness... perhaps by combining it with Ebola (fatality rate 66.7%).

We should take utmost precaution to avoid unleasing such a virus accidentally, shouldn't we?

The US CDC test kits were found to be severely flawed; they gave a high rate of false negative. Were they that incompetent? Possibly. That's what hiring by affirmative or diversity instead of competency gets you.

But here's a tinfoil hat theory: what if their test kits were based on a different strain? Something from their lab... hmm...

2019 in red

My secondary savings account nearly went out of money in 2019:

2019Sav a/cCCMs CCOutIn

I did not pay attention to it because it was supposed to be "revenue neutral".

I estimated I'm $15k in the red for the entire year. In other words, not only did I not save, but I spent from my savings.

Tasks in 2020:

  • Use one account for expenses for ease of tracking
  • Watch expenses — both CC and non-CC expenses are very high