My Rambling Thoughts

It's all about exit pupil

Third post on Cloudy Nights with some corrections:

Bright and/or high contrast objects can defy the usual law of useful magnification, but the rest, such as Jupiter and Saturn, have to obey them.

A commonly quoted limit is 1.3 x aperture-in-mm. At this magnification, the scope is already at full resolution. Anything higher is simply to make it bigger for you to see, but it will not be more detailed. For your Mak, it would be 234x (using 11.5mm eyepiece). You can turn this around and think of this as the minimum magnification to use. :-D

So, what stops you from using higher magnification? One word: exit pupil. As magnification increases, the image gets dimmer, more blurred, and floaters become more visible. At some point, they are not worth it anymore. (Mount and seeing issues aside.)

Another way to phrase 1.3x aperture-in-mm is 0.77mm exit pupil.

Another limit is 0.7mm exit pupil, the lower bound for our eyes to detect low contrast features. This is important if you want to view the low contrast features of Jupiter and Saturn. Higher magnification works, but you may see less. This is 257x (10.5 mm eyepiece) on your Mak.

These numbers will vary by person, but I guess they won't deviate by much.

While it is good to experiment with extreme magnification, after a while, you may find that you don't need very high powers after all.

I can see the two main belts of Jupiter at 60x (25mm EP), with a hint of a third belt below. It had not dawned to me to look for the GRS at 60x, but I see it distinctly — it is really pale — at 75x (20mm EP). To see anything else, I need to use 188x (8mm EP). Somewhere between 170x (0.74mm exit pupil) to 188x (0.68mm exit pupil) Jupiter dims just enough to reveal gradual shading (I didn't try 176x [17mm / 2, 0.72mm exit pupil]). I have used as high as 448x (6.7mm / 2), but it just shows more-of-the-same (the image quality is still surprisingly okay).

For Saturn, I see the Cassini Division distinctly at 60x and a hint of the equatorial band. At 88x (17mm EP), I can see A ring is much fainter than B ring. (I didn't try 20mm.) Sadly, that's all I can see, no matter how much power I use, but I haven't spent much time on it.

It took me a while before I realized the futility of using too-high magnification. The truth: the scope forms the image, the eyepiece magnifies it. 0.7mm exit pupil is the max for every scope. Want to see more details? Get a bigger scope.

Piling on debt

News: Malaysia's debt at alarming level of S$337 billion, says Dr Mahathir

Date: 22 May 2018. Source: Today.

Malaysia's debt has reached an alarming RM1 trillion (S$337 billion), said Malaysian Prime Minister Tun Dr Mahathir Mohamad on Monday (May 21), as he pledged to restore the nation to its former glory.

Blaming the previous government led by former protégé Datuk Seri Najib Razak, who now faces domestic graft investigations, Dr Mahathir said important measures must be taken for the South-east Asian country to quickly recover from the situation, pointing out Malaysia had debts of about RM300 billion only when he was previously prime minister for 22 years.

"We find that the country’s finances for example, was abused in a way that now we are facing trouble settling debts that have risen to a trillion ringgit," he said in his maiden address to civil servants of the Prime Minister's Department.

"We have never had to deal with this before. Before we never faced debts higher than RM300 billion, but now it has climbed to RM1 trillion."

The next few months will be very interesting. Introducing fuel subsidy and doing away with GST will make it worse.

In other news, Finance Ministry has been paying 1MDB debt since April 2017 (for a total of RM6.98 bil), and the next payment, RM143.75 million, is due 30 May. And the next payment is RM810.21 mil (of interest!) between September and November.

And these are small potatoes compared to its guaranteed debt of RM38 billion (US$9.54 bil). And even this pales against the country's debt of RM1 trillion...

I won't be surprised if Dr Mahathir pulls a rabbit out of his hat — something he has done in critical situations before. 1MDB has to be contained somehow.

Update: Dr Mahathir has decided to cancel the HSR project.

Peak bazaar rent

News: Rising rents worry some Geylang Serai bazaar stall owners

Date: 21 May 2018. Source: ST.

Rent for 2.7m by 2.7m food stall has doubled from $10,000 in 2014 to $20,000 this year

The annual Hari Raya bazaar in Geylang Serai has drawn huge crowds in recent years, but stall owners say they have had to pay a price for the bustling event.

They say rental costs have jumped by at least 10 per cent to 20 per cent from last year, and some even claimed to be paying more than double the rate.

The Straits Times interviewed 13 hawkers at the bazaar, which officially opened last Thursday - the first day of the Muslim holy month of Ramadan - and runs until June 14.

The bazaar features more than 800 stalls which sell food, cookies, traditional clothing, jewellery, rugs and many other items.

It cost about $10,000 to rent a 2.7m by 2.7m food stall in the bazaar in 2014, but that figure has doubled to $20,000 this year. Clothing and decoration retail stall tenants had to fork out an average of $9,000 for the same space this year.

This HWZ forummer puts it much better than I can:

Singapore is well known to be an extractive rent-seeking economy in which significant wealth is accrued by individuals who are economically unproductive relative to those they are collecting rent from, namely the biggest landlord, the government and its cronies.

This is Singapore's downfall as capitalism is in essence meant to reward those who are most productive, not those who can pass laws and regulations to sap wealth from other productive working individuals.

Of course, the biggest landlord, its cronies, rent seekers and other obvious direct beneficiaries of rent seeking behavior here will strongly disagree with me or maintain their silence.

Everyone aspires to be a landlord because they see how easy and profitable it is.

I'll calling peak rental this year, as there are now not enough stalls to fill up the whole space (gap between stalls).

Depreciating day by day

News: There is still value in older HDB flats

Date: 17 May 2018. Source: CNA.

There is still value in older HDB flats which can be unlocked for retirement, said Minister for National Development Lawrence Wong in Parliament on Thursday (May 17).

Speaking during the debate on the President's address, he said there have been concerns about the impact of lease expiry on HDB resale prices.

Quoting transaction data over the past year, he said that an older 4-room flat with less than 60 years remaining on its 99-year lease would sell for around S$300,000 and a 5-room would sell for around S$400,000 in non-mature estates.

For flats in more popular locations, prices can be significantly higher, he added. "So the transacted price depends not just on length of remaining lease, clearly, but also many other attributes," he said, adding that factors like location, storey height, and the condition of the flat are all relevant.

Whatever the price, the sales proceeds would be "more than sufficient" to purchase a smaller flat, he said.

There is no sugar coating this. Once the lease hits the magic 60 years left, a whole bunch of restrictions kick in and it reduces the appeal of the flat.

The most restrictive rule is the max CPF. For a 30 year old, the calculation is as such: (59 - (55 - 30)) / 59 = 57.6%. He can only use 58% of the max allowed CPF. He won't feel it upfront, but he will need to use cash to pay his installment much earlier.

It'll take another 3 to 5 years before this fact sinks in.

The other rule that age + remaining lease >= 80 years will only be felt when the lease has 45 years left. It restricts buyers to 35 and older. :-O

Will prices come down much? Maybe not. Suppose you buy a 30 year old flat at $700k. Ignoring interest (which is substantial), it works out to be $10k a year, or $833/mth. It is much cheaper than rental.

HDB flat ticking time bomb

News: Old HDB flats: Assets losing their value?

Date: 13 May 2018. Source: CNA.

When Mrs Y L Dong and her family moved into their resale five-room Housing Development Board (HDB) flat 20 years ago, she was certain they had found their ideal home. The Ang Mo Kio apartment may have been 17 years old, but its age did not bother her.

"We have all the necessary conveniences like coffee shops and wet markets nearby. It's a really friendly neighbourhood with a cosy feel and it is also really convenient to get to town from here," she said.

But last year, when she approached a property agent with the intention of selling her flat, the response was poor.

"After realising that the lease of the house was reaching its 40-year mark, most buyers weren't keen at all. They were afraid they might not be able to sell it off in the future," said the housewife who has two teenage children.

"Even though the flat is spacious and opposite Bishan Park and near prestigious schools, no one wanted to buy."

Oops. Lease expiry was never a problem until Lawrence Wong brought it up last year (Mar 24). Then suddenly it was.

Personally, I think HDB will have to extend the lease by 50 years at least due to the high number of expiring HDB lease within the same time frame. However, the Government is purposely quiet on this issue now because it fits in their agenda to force HDB prices down.

It is not well known, but there are loan restrictions once a HDB flat has less than 60 years lease remaining:

  • Can use CPF only if age + remaining lease >= 80 years
  • No CPF can be used if remaining lease < 30 years
  • Max CPF = remaining lease when owner turns 55 / remaining lease at point of purchase


Also, banks will typically loan until 35-years lease. In other words, no bank loan if the lease is shorter than that. Also, if the lease has 50 years left, you can only take a 15-year loan.

Let's see who still dare to buy old properties. :-O

What this means is that once a property has less 60 years lease left, it should (i) have a marked discount (maybe 20%?), (ii) start to depreciate (linearly?) yearly.