Why 28 mm is the best focal length for travel photography?

If you have no other focal lengths available or have to choose one only

Note: 28 mm is for Full Frame camera. For APSC sensors it is 19 mm and for Micro Four Third [MFT] sensor it is 14 mm.

First let us define what is meant by travel photography. This include different styles of photography like [but not limited to]:

⦁ Landscape [in clear day light, cloudy/overcast, rain etc.]
⦁ Street / city life
⦁ Indoor [museum, underground etc.]
⦁ Fast action [when shooting from moving vehicle/train etc.]
⦁ Night life at city
⦁ Environmental Portrait

Before going into debate of which focal length is best, let us first examine how human eyes see. Scientists say that human eyes’ focal length varies from 35 mm to 50 mm [in full frame camera terms]. Unlike a camera, human eyes see clearly things at the center of our vision and objects in our peripheral vision is blurred. It is important to understand we are talking of what our brain interprets of what our eyes see. To test this, raise your hand so that it is parallel to you ear and then wave your hand. Your eyes can detect the hand movement in your peripheral vision but you can’t see it clearly. This is also why we often can’t find things in our homes unless it falls into our hands or just in front of us.

Online camera forum users often discard lenses because those are not sharp at corners, yet in real life, when humans see photos, people hardly examine sharpness at the corners.

Anyway, coming back to the travel photography. You may think that 50 mm would be ideal for lens. But no – while 50 mm is considered good focal length for portraits, it is too narrow for general travel photography.

In travel photos, we want to capture the surroundings as much as possible. So we need a wide field of vision – but not necessarily an ultra wide angle lens because an ultra wide angle lenses distort perspective, especially at the periphery.

So we need a focal length which is wide enough yet does not distort things – especially human faces because people shoot lots of family photos in holidays.

Most mobile phone cameras have 27-28 mm [full frame equivalent] focal length for their primary cameras. However, you may have noticed, if you shoot selfie while holding phone too near to your face, your face looks bit distorted compared to if someone takes the photo of you holding camera bit far away from you.

Mobile phone manufacturers did lot of research to find out which focal length would keep most consumers happy. Many people now buys smartphones for shooting photos as primary purpose, other than sending messages in chat apps. So having offering a good camera is utmost important for mobile phone manufacturers.

Thus, for most travel shots we want to fit more things in our photos. 28 mm is a focal length which can fit things without distorting them. Go over 28 and it becomes difficult to fit things especially in places where you can’t move backward due to physical barriers or obstacles. Go below 28 and it starts to become too wide angle and thus things start to become distorted at the corners.

There are other advantages of this slightly wide angle focal lengths. Not all consumer cameras have in body image stabilizer or lens stabilizers. In day time, it is comparatively easier to keep hands steady with a short shutter speed, which results in sharp photos. Higher the focal length, more difficult it is to keep hands steady without shaking. Typical thumb rule is that if focal length of lens is f mm, then shutter speed must be less than 1/(f * crop factor). So for a MFT camera with 14 mm lens, the slowest shutter speed you can go is 1/(2*14) or 1/28 or typically 1/25 s to 1/30 s. This is good for night shots because usually in bright day light photos you keep shutter speed 1/125 s to 1/250 s depending on light intensity.

Of course there are special circumstances where you do need telephoto lenses like when you cannot physically reach nearer to your subject – like birds, wild life/safari etc.

However, many cameras offer some kind of built-in zoom features. This could be either digital zoom or tele-converter. With digital zoom, the camera computationally interpolates values so there is a chance of slight fall in image quality. Some proper cameras offer extended tele-converter feature, where effectively you get an in camera crop which does not reduce image quality – though it may reduce the resolution by a little bit due to cropping.

Sometimes you may find even 28 mm is not wide enough to capture the vista of a landscape. Usually you can use panorama feature in your phone or camera. If no such feature available in your camera, you can still achieve it albeit with few steps. Use [AE-L] or Auto Exposure Lock facility in your camera. Turn it on and make you exposure remains the same while you take few shots by panning your camera. Then on your computer you can stitch those photos to produce a stunning panorama.

If you shoot with a zoom lens in your camera then having an ideal focal length is less of an issue. Though, depending on camera and lens set up, such combination can be quite big and heavy to carry on. Hence, a small camera with a prime lens (which has single focal length) reduces the burden of camera gears to a great extent.

If you travel with interchangeable lens camera [ILC] then 28 mm [or equivalent] prime lenses often have large apertures, allowing you to capture enough light for night/low light photos. Tpically kit zoom lenses don’t have such large apertures [barring few pro lenses, which are usually heavy and expensive].

If you want to buy a prime lens for your camera and confused which focal length to use, hopefully this article will help you decide that.

Majority of single focal length cameras use focal lengths around this value. For example,

⦁ Fuji X100 series camera uses 23 mm lens [35 mm FF eqv.]
⦁ Fuji X70 camera with 19 mm lens [28 mm FF eqv.]
⦁ Rico GR III camera uses 18 mm lens [27 mm FF eqv.]
⦁ Leica M2 camera uses 28 mm lens [FF]
⦁ Sony RX1R camera uses 35 mm lens [FF]

Abbreviations used
FF = Full Frame camera
APSC = APS-C sensor camera
MFT = Micro Four Third camera
FL = Focal Length

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Can phone camera photo quality is same as those from bigger cameras?

With nearly everyone on the planet now shooting with phone cameras and standalone camera sales falling gradually, there is question everyone is asking whether proper camera takes better photos!

 

The, short answer(s)

In bright daylight and in outdoor, a good phone camera takes nearly as good photos as more expensive proper camera (with some caveats).

In low light (e.g. night) and some challenging situations (e.g. sports, wildlife etc.), a proper camera takes much better photos than phone cameras.

Now lets us delve into the details.

Phone cameras have tiny sensors. Sensors are analogous to films in flim cameras (if you can still remember them) which actually receive the light and capture the images. Thumb rule is that, bigger the sensor, better the light gathering capability and better the image quality. However, besides sensors, the lenses play a big role too. A better lens gathers better light without any distortion which makes images sharper. A larger lens with larger opening (known as aperture in photographic terms) will gather more light which would result in better photo – especially at low light.

 

Different cameras have different sensor sizes. This is shown in following table.

Sensor type	Sensor area (sq. mm.)
Full frame/ 35-mm equivalent High end DSLR/mirrorless cameras Nikon FX, Canon D, Sony A7	860
APS-C (Advanced Photo System – Crop) Most entry level DSLR cameras like Nikon DX, Canon EF, Fujifilm X, Sony A6	368
Micro Four Third (MFT or M43) Panasonic Lumix, Olympus PEN/OM-D	225
1 inch Sony RX, Panasonic FZ etc.	116
appx 1/2.5 inch Many compact and phone cameras incl. Apple iPhone, Samsung Galaxy etc.	25

Note: Often same manufacturers have cameras with different sensor sizes. So, always check the spec sheet before buying a camera.

 

As you can gather, a phone camera typically has sensor size (area) which is 10-15 times smaller than sensors in typical DSLR (APS-C) cameras! Thus, a phone camera will gather that much less light compared to an APS-C sensor size camera.

 

Now, considering larger cameras have bigger lenses, field of view i.e. how much you can capture in your frame, is also larger. With a phone camera you may find struggling to fit all of your friends in a group photo but with a proper camera and wide angle lens, you can easily push your friends back (optically – no physically) to get the shot. Phone cameras are useless for wild life (unless it is stuffed animal). Larger cameras with telephone lens can bring animals closer (optically) to you for the great shots. This is indicated by the crop factor in above table.

 

For normal travel photos, phone cameras are find in 80-90% of the cases. People usually visit famous landmarks in daylight where phone cameras do good enough jobs.

 

If you view your photos in iPad size screen, you may not see the difference between phone camera and proper camera photo quality. But if you view in large screen HD TV screen (e.g. 50 inch and above) you are likely to see the difference. Phone camera photos are likely to demonstrate visible grains.

 

Are prime lenses over hyped?

In case you are not aware, a prime lens is a fixed focus lens i.e. not a zoom lens.

Your phone camera is a prime lens. If your phone has 2 lenses then each of those are prime lenses.

Many older film cameras and some modern digital cameras come with a fixed prime lens.

Photographic world is mad about prime lens and often you will be crucified if you speak against prime lens and in favour of zoom lens :o)

But in this post, I shall explain why prime lens is not for everyone.

The prime lens is adored by photographers because of its simplified optical construction (compared to a zoom lens) resuting in better image quality i.e. more sharpness etc.

That claim is true – prime lens does produce better image over most zoom lenses. They also have larger aperture like F/2.8 or even F/1.4 (but not always). Larger aperture allows you to take better shots in low light.

Purists also claim that a prime lens will make you a better photographer as you have to move around for best composition/framing.

Then everyone should only shoot using prime lenses – right?

Well, not always – especially if you are an amateur photographer and use your camera for shooting travel photography with family.

• Loss of flexibility – A zoom lens provides flexibility. Most of the time zoom lens come with your camera (kit lens) and is good enough for general/travel photography. It allows you to successfully frame a wide architectureal shots and also a portrait when needed – without changing lense. Most kit zoom lenses are 18-55 (in APS-C cameras) or 27-70 (in full frame) which offers both wide and medium telephoto ends. A zoom lens is way more versatile.
• Price – While some prime lenses are cheaper they often cost more than kit lenses. So buying a prime lens (unless you have specific use in mind) purely based on internet forum advice, is an unnecessary expense.
• Image Quality – Yes, prime lenses take better shots than kit lenses. But not to that extent as purists in internet forums make you believe. If you view photos side by side (prime vs zoom) with 100% blown up in large computer/TV screen, you would most likely see some difference. But for most folks who views photo no larger than iPad or 50-60 inch TV screens or prints at most A4 sizes, such image quality improvement would be visible. Purists often compare by shooting charts and brick walls where defficiency of zoom lens is more visible. But in real life, such quality difference is hardly noticable – especially where what you shoot is more important than little bit of extra sharpness.
• Confusion – With a zoom lens, on an instant you can choose your focal lenth by rotating lens dial. But with prime lens you will have following confusion:
  • Which focal length (of prime lens) to buy? Should it be 16 mm, 23 mm, 35 mm or 85 mm?
  • Purists will advise you to buy all of those for different situations.
  • You will end of spending a lot of money to buy all those.
  • You will carry lot of weight by lugging all those lenses on your shoulder bag during holidays.
  • You will end up missing scenes and getting dust in sensors while changing lenses in outdoors.
  • You will end up wasting time on internet forums to analzye whether sharpness is as it should be in your photos.
  • By doing all the above, you will shoot fewer photos and enjoy less during holidays (OK – not for everyone but for most).
• Variation – If you shoot all your holiday photos with same focal length (assuming you carry only one lens) then your shots could become boring to look at. Now this is somewhat contentious. Many people do shoot amazing photos with their fixed lens smartphones. A good photographer can produce masterpieces with any camera. But an average photographer will do better with zoom lens. Also, often you can’t physically zoom with your feet (as purists often advice) due to structural constraints. Again, purists will argue to that this should force you to shoot creatively. But for most people, bringing back memories of family standing in front of whole Taj Mahal is propbably more important than shooting only one minerate (depending on your fixed focal length) with one kid outside the frame! You can simulate same creativity by locking your zoom lens into specific focal length and by behaving as if you are shooting with prime. If you get frustrated and feel the urge to rotate the zoom lens for desire focal length, then prime lens is not for your. Purists will mock you by saying lazy if you don’t move around for getting best angle, but I think there is nothing wrong in being lazy.
• Fast lens can be counter productive – You can get some amazing background blur (bokeh) using large aperture like F/1.8 but it will also turn your depth of field very narrow! You can shoot candle light portrait using that aperture but to keep your kids as well as Eiffel Tower on background in focus, you need to shoot using smaller aperture (e.g. F/8 etc.) where prime lens has not much advantage over a zoom lens on same aperture.

I understand I shall be frowned upon by purists but this is my opinion based on experience.

Why film cameras are making a comeback?

…

Film cameras at the moment covers only a niche corner in photography market. However, in recent years, their popularity has gone up for the first time after the mass consumption of digital photography.

The major disadvantages of film photography are:

1. Not being able to view the photo immediately after shooting. So no corrective action is possible while being on the spot.
2. Film speed (ISO) is fixed for the whole of shooting. In digital cameras, it is possible to change ISO for every photo depending on lighting condition.
3. Limited photos that can be shot from each roll of film.

However, there are advantages of film photography:

1. Due to limited photos available in each film, you will be forced to think about composition as not to waste film. This can, subjective though, can turn into a better photographer.
2. 35-mm film cameras are cheaper than full frame digital cameras.
3. 35-mm film cameras are often smaller than full frame (or even APS-C) digital cameras. This is because image processing happens outside film camera (during negative development) whereas in a digital camera, manufacturers need to put an image processing mechanism inside the camera. This makes digital cameras larger than film cameras.
4. Flim photos last longer. Printed album is less susceptible to file corruption than digital forms.
5. People are more likely to browse their printed photos compared to digital photos.
6. Some people find hands-on film development more rewarding as hobby.
7. Film cameras have nostalgic values to some people and they feel proud of that. Some shooters also feel film cameras can differentiate them from the digital camera mass crowd.
8. Mechanical film cameras can operate without batteries.
9. Longevity – digital cameras have typical life of 10 years whereas mechanical film camera can lasts over 50 years.

Happy shooting.

How to run Windows apps in Mac/Linux (and vice versa)?

If you are running Linux and want to run Windows application, then you have following choices.

1. Install Windows via virtualization software. Then install your Windows application on top of it.
   1. Pros
      1. No need for dual booting.
      2. You can switch from Linux apps to Windows.
      3. You can share files between Linux and Windows (some configuration required).
   2. Cons
      1. You need a valid copy of Windows.
      2. Virtualization is resource intensive. Unless you have high amount of RAM (16 GB or more) and fast hard disk (e.g. SSD) performance will be poor.
2. Install Windows via dual boot partition.
   1. Pros
      1. No performance penalty.
   2. Cons
      1. You can either work in Linux or in Windows.
      2. Need to have a valid copy of Windows.
      3. You are effectively running a Windows PC under this route.
3. Run Windows application natively on Linux.
   1. Pros
      1. No copy of Windows needed. This can be achieved by some Windows emulator software in Linux like WINE, Crossover etc. These software install a Window-like layer on top of Linux as a sandbox.
      2. You just need a valid copy of Windows application – which you will install via emulator in Linux.
      3. You can easily switch between Windows application and Linux in same session.
      4. If you have the Windows version of application software already, then usually no further cost associated with it (unless you choose a commercial version of an emulator)
   2. Cons
      1. This option could be buggy. Not all Windows application can be run in this way. Some manual trial and error with configuration settings is expected.
4. Buy your OS specific version of the application.
   1. Pros
      1. Guaranteed to work. For example, Microsoft sells Office software for Mac OS too.
   2. Cons
      1. You are paying for the software again for different operating system.
      2. Some format compatibility issue may still come up if both software versions were not compiled using same code base.

So which option do you choose for your favorite application?

Difference between Indian and Western music notation

New musicians, especially who studied Indian swaralipi first and trying to study Western staff notation (and vice versa), often get very confused about how to align Indian swaralipi with western staff notation.

The key thing to understand here that in Western Music notation, each symbol represents an absolute note. For example, in a staff notation you always see whether it is C4 or C5.

However, in Indian swaralipi (= sa re ga ma pa dha ni) is made of relative notes!

The Sa can be C, D, E, F, G, A, B anything! In fact it can be C# or Ab too.

When you play a western staff music notation, you are expected to play exactly as it is written. That means, staff notation shows whether you will have to play C4 or G#3 etc.

However, when you play a Indian swaralipi, since only relative notes are shown, it is up to the player to choose which scale s/he wants to play in!

For example, here is Indian swarlipi notation for national anthem Jana Gana Mana (first line)

Sa Re Ga Ga | Ga – Ga Ga | Re Ga Ma – |

Now it is the player’s discretion whether s/he wants to start Sa in C or D or E or whatever.

Suppose, you have staff notation for this tune in C major. If you follow that notation, you have to play in C major. However, one can still play it in other scale like D major, F major etc. – by transposing it to a target scale (software like MuseScore can do it by flick of a menu).

In a way, the Indian notation is easier since it is entirely relative and you are free to play at any scale of your choice. Western staff notation is more rigid in this aspect (though you can re-write it by transposing – as mentioned earlier). However, staff notation is very rich and can convey timings, rhythm, chords etc. in much more details compared to swaralipi.

Any Indian tune or swaralipi can be always converted (manually) to staff notation. The reverse is also true, though you are likely to loose some complex information as there is no swaralipi equivalent of some concepts of staff notation.

There is a dearth of good quality written Indian tunes (compared to western music whether you can get notation of almost any popular tune). This is because Indian musicians predominantly play by ear where as western counterparts play by ear and/or sight as well.

If you are an Indian musician but unable to read staff notation, I strongly recommend that you learn it. It is not only versatile (in spite of steep initial learning curve) but universal too. People from anywhere can exchange music using this format.

Free software like MuseScore, make it very easy to compose music using staff notation.

PS: full scale example

Indian swaralipi and Equivalent Western notes (in C major)

Sa – C (C4 if mapping it with piano’s middle C key)
komal re – C# or Db
Re – D
komal ga – D# or Eb
Ga – E
Ma – F
kori ma – F# or Gb
Pa – G
komal dha – G# or Ab
Dha – A
komal ni – A# or Bb
Ni – B
Sa (next octave) – C

Indian swaralipi and Equivalent Western note (in D major)

Sa – D
komal re – D# or Eb
Re – E
komal ga – F
Ga – F#
Ma – G
kori ma – G# or Ab
Pa – A
komal dha – A# or Bb
Dha – B
komal ni – C
Ni – C# or Db

 

What are different types of watches?

Watches are broadly of 2 types – mechanical or quartz.

The easiest way to identify a quartz or mechanical watch is to look at the movement of second hand. Quartz watch will have second hand which jumps every second where as in a mechanical watch, the second hand moves continuously.

Mechanical watches don’t have batteries so they need regular winding to make them work. Obviously, in modern world such action is bit awkward. So there is a different watch type, called automatic. They are also mechanical watches but they are powered by normal hand movement as part of your standard day to day life.

AccuracyExtremely accurateCan gain/lose few seconds every day.

Feature	Quartz	Mechanical
Identification	Second hand jumps or digital display.	Second hand moves continuously and analog display.
Popularity	85-90% of all watches in the world are quartz.	Only 10-15% of world’s watches are mechanical.
Power source	Battery (some are rechargeable via light)	Stores energy in springs via manual winding or normal hand movement (automatic).
Maintenance	Don’t require any maintenance (other than battery replacement if necessary)	Besides winding, these watches require servicing in every few years.
Like for like cost	Cheaper	Expensive
FeaturesAlso called “complications” in watch industry terms	Can offer lots of features like multiple times, alarm, stopwatch etc.	They can offer similar features too but such watches tend to be too expensive.
Manufacturing	Automated via tools	Some manual craftsmanship is often required.
Longevity	Can last 10-20 years.	With proper servicing, can last 50-100 years.
Accuracy	Very accurate	Can gain/lose few seconds every day.

 

The world of watches is very fascinating. Read about it on the internet in your spare time.

What are common analog world time watches?

In modern times, you can download apps in your smart phones to show time anywhere in world. This is somewhat negated the necessity of having a traditional watch which can show times in multiple zones around the world. But don’t ever think that such watchmakers are losing money! A lot of people still prefer elegant and prestigious looking of branded watches on their wrists! In this post, I shall list some very common world time analog watches. Typical characteristics of world time watches:

1. Should be able to show at least dual times at once.
2. Seeing time for any time zone should not be overly complex.
3. There should be a mechanism to swap primary and secondary time quickly.
4. Should be able to cater for all time zones (including half hour GMT offsets like India – which is GMT+5:30)
5. Accurate (should be radio controlled or able to pick signal up via GPS – not all watches have these facilities)
6. Solar powered is preferred so that you don’t have to change battery.
7. Affordable (you should not have to sell your kidney to buy one)

We shall see in this post how difficult it is to achieve all those parameters within budget. Please bear in mind that there are probably over hundred models of such analog world time watches. Some of them are very expensive. Not all of them offer half hour GMT offset. A quick way to figure that out is to look at dials and see if Delhi is featured. It should feature between Karachi and Dhaka. If Delhi is missing, that means the watch cannot show half hour GMT offsets! This means, in those watches, the minute hand for second time will be always synchronized with primary time. Even some very expensive watches have these problem! Some watches can only show GMT/UTC as a second time. You can’t set second time zone as any city in the world. Ok, enough talking, now let’s see some watches. Note: Prices shown are RRP on July 2014. Specific models may be retired anytime although other models in same series usually available in market for a long time. If you can find deals, often you can buy them at cheaper prices. The list is not in any particular order.  

Citizen eco-drive World Time AT 9010-52L [£379]   This is a typical world time watches. It does feature Delhi so covers all time zones. The smaller dial shows secondary time in 24-hr format (this is common for many of such watches).  The main dial shows time in 12-hr format but a separate dial (at upper left) indicates whether it is AM/PM via a 24-hr needle. The watch allows you to check time at any shown city by pressing couple of buttons. It also allows to swap primary and secondary cities by pressing 2 buttons at once.

Seiko Astron SAST003 [£1995] This watch picks up GPS signal (as long as it can see sky) and automatically adjusts the time! This one is solar powered too. Mind that, there is a difference between radio controlled time and GPS controlled. Radio signals are emitted from only few places (typically USA, Germany, Japan etc.) and from the world and watch needs to be within 1500 km of that zone. However, a GPS signal can be picked from anywhere in the world – as long as access to sky is available. All satellites have atomic clocks in them – the signal that is picked up by this watch. So, in theory, this watch never needs time adjustment.

 Casio Edifice EQS-500DB-1A2 [£226]

This one is also solar powered.  

Patek Phillippe 5110 Worldtime [£18000]

Yes, you read the price right! More of a glamor statement than utility watch. The clever design here is at middle ring, which rotates counter clockwise. In the above image, the home time is Paris (indicated by Paris being at 12 o’clock position. The time at home is 10:09. As per dial, it is 12:09 at Moscow and 00:09 at Anchorage. Note that, this watch can’t show half hour offset zones – in spite of hefty price tag!  

Rolex GMT Master II [£5500]

  Another glamorous watch! On a quick glance, it does not feel like it can show world time. In fact, it is just a dual time watch. You can see the main home time screen. The outer bezel rotates manually. The blue hand with triangular pointer  is GMT hand. You can set this hand to show any other city’s time.  But here as well, as you only have an hour hand for dual time, the minutes hand is same for both home and secondary time zone – which in turn means this watch too can’t show half hour GMT offsets. I think now it is fair to say that spending more does not automatically mean having more functionality!

Casio SPF60 [£75]   This is also not a true world time watch but a dual time watch. The analog and digital times can be set independently. However, alarm/calendar works only on the basis of digital time. The watch also provides reading for barometer (with last few hours trend), altimeter and a thermometer.

Citizen Eco drive Skyhawk AT [£350]

   This watch can show 3 times at once. The main one, GMT/UTC in upper middle and another one for selected city (showing TYO in above image). The home time can be set against any of world’s main cities. In above image, it was set for NYC. However, the GMT/UTC will always show UTC (in 24-hr mode) and you can’t set it to show any other time.

Casio AQ-S810W-1AVEF [£55]  Even though you can’t immediately recognize it, this is actually a world time watch! There is only one analog dial though. The second time is displayed digitally (not shown in above image). The digital time can be set for any of world’s main cities. However, you can easily toggle between home (analog) and secondary (digital) time zones. For example, if you set your analog hands for LON and digital for DEL and then you went to Delhi, then you can easily toggle analog hands to show Delhi time and digital one showing London time. This is a solar watch and also available with steel band.

 Nomos Glasute Tangomat GMT [£3100]  Another watch which, in spite of high price tag, can’t show true world times. The smaller window shows home/second city but because there is no secondary minute hand, it can’t show half hour GMT offset times. The main dial shows time for selected city (at 9’o clock position).

Ball World time GM2020D-LCJ-BK [£2400] Another watch where Delhi is missing!

Vacheron Constantin Patrimony World Time [£26000] This is another status symbol! This has got 37 world time zones (including half hour offsets which are marked in red). You can rotate the city name dials. In the above image, the home town is set for Geneva (because it points to black triangle at traditional 6-o’clock position). You can now read time at any of world’s cities in 24-hr format.

Blancpain Villeret [£9500]

As you can see in the dial, this one can show half hour GMT offsets. This is an automatic watch with 8 days of power reserve.   There are many other similar watches at varying price range. By now you must have got some good idea of what to look at world time watches. My advice: For functional and affordable watches, stick with Casio, Citizen or Seiko. For glamor statements, buy whatever your bank balance permits.

Why do smart phones freeze (or hang or lock up)?

Old Nokia phones (also known as dumb phones or features) almost never froze! I had a Nokia phone which froze only once (worked fine after restart) in 7 years of use! That is pretty impressive.

However, most smart phones often freeze. Some freeze quite often while some other freeze only occasionally.

Let us understand why it happens.

All smart phones are mini computers inside. They have an Operating System (OS) which interacts with the phone hardware. Users interact with the phone via application layers.

The core of OS is known as “kernel”. This is low level assembly language core which translates users’ requests (via apps) so that hardware can process it. For example, when you dial a number (via dialler app) the request is sent to kernel which instructs the hardware to perform the phone dialing operation. Both Android and iOS runs on highly customized flavors of Unix OS inside them.

The old dumb phones also had similar concept but there was a big difference. Those phones were only allowed to perform few predefined tasks like dialing a number, receiving phone calls and sending texts (along with alarm, calendar etc.).

But modern smart phones are expected to do a lot of things! As a result, it is often very difficult to predict what each app will request to kernel. There are just millions of instructions possible. When many apps send some instruction to kernel, it may get overloaded (takes too long to process which manifests as phone slow to respond) or just get confused (manifests as phone freezing). The freezing often happens due to kernel going into an infinite loop (and does not know how to come out of that) or just bogged down by too much work.

When you use heavy weight apps in lower end (or budget) smart phones, due to slow CPU and small amount of RAM, the hardware gets overloaded. So, those phones often become slow over times. When you install newer versions of apps, they usually take up more space and thus strains hardware even more!

Different manufactures try to handle this problem in different ways. Apple implements a strict control of what its apps are allowed to do and what hardware goes inside the phone. That’s why iOS is more restrictive and iOS users see less frequent freezing. Internally, iOS apps work in a sandbox mode. Each app gets a space in phone storage and it can’t access anything outside of its own sandbox. Once you delete the app, all its traces are gone. This is also the reason why users can’t access iOS file system (unless you jailbreak). Apple also doesn’t allow usage of external memory card which is often responsible for corrupt file systems and thus causing problems.

Android system (even though derived from Unix) is more like good old desktop Windows OS in its behavior. Apps can often access an equivalent of Windows registry style things. Various apps dump garbage in cache, which fills up phone’s internal storage (like hard disk) and phone becomes slower over time. Even if you install an app in SD card, it still leaves traces in internal storage space due to OS design. Android also allows access to file system (just like desktop PCs) which means users can fiddle with its system and may accidentally delete system files!

Microsoft has taken iOS like “sandbox” approach in its Windows phone system. So, in theory, Windows Phones are supposed to crash less! However, these still allow external SD cards so such issues will remain to some extent. Also, as Windows phones have less market share at present, it is difficult to predict if they are indeed superior to Android or iOS.

From empirical evidence, it can be stated that:

• Apple phones crash the least. However, internet browsing is often unpredictable and quite often iOS browser just crashes but this does not usually lead to entire phone freezing up.
• Blackberries and Android phones crash often. Lower end Android models crash more if you fiddle with them too much for the reason described in this article.
• Less matured OS crashes more. For example, Windows phones OS have good architecture but it is still maturing so it may crash unexpectedly.
• Poorly designed OS will crash often. This is why Nokia’s Symbian based smart phones were notorious for freezing!

If you are an Android user, make sure you clear cache often, manage your applications so that it does not store too much data in phone’s internal memory and refrain from heavy browsing or playing hardware heavy games. This should lead to less crash, especially in budget hardware Android models.

If you are an iOS user (iPhone or iPad), there is not much you can do to prevent freezing (if that happens at all). Sometimes one or two rogue apps may cause problem. In that case, simply get rid of those apps. Some apps when updated, tend to make use of newer features of latest OS. If your OS is older version, you may see apps crashing (but not entire device freezing up).

Windows phones are still maturing so nothing can be advised at this moment.

How a steam loco differs from diesel-electric loco?

A diesel-electric (DE) loco is a constant power machine. We know that, Power = Force x Velocity. This means, when hauling heavy loads (especially on an uphill), a DE loco can increase draw bar pull by reducing speed. This also shows why most shunting locos are DE locos as they need to haul heavy load but at low speed.

 

However, due to the way a steam loco is designed (i.e. its boiler, piston and other mechanisms), a steam loco behaves as a constant force machine up to cruising speed (usually around 25 MPH or 40 km/h). Beyond that, a steam loco behaves like a constant power machine like a DE loco.

 

This difference is crucial. For a steam loco to haul heavy load (or on an uphill), if it can’t deliver enough draw bar pull, it has no way to increase the force like a DE loco, because for steam loco, force is constant at low speed. So, a steam loco won’t be able to climb a slope like a DE loco. It will literally run out of puff under such circumstance. However, once a steam loco has crossed its cruising speed, it will have no problem pulling heavy trains as it behaves in same way as DE loco i.e. constant power loco.

 

There are obviously other differences between these two types of locos. A DE loco is more thermally efficient than a steam loco. The later requires far more maintenance than the former and needs more crews to operate them.

 

No wonder, due to these reasons, most of old steam locos have been replaced by DE locos in all but heritage routes. Please note that a pure electric loco will also behave similarly as of a DE loco.