If you read this... - DPChallenge Forums

04/09/2009 04:02:03 AM · #1

If you read this, you will never leave home without a Tripod!

You are fond of shooting Landscapes or travel images, or that of mighty monuments. And you feel that there is no need to carry a tripod, if you are shooting in broad daylight.

Figure this out:
If your subject is say 50 meters from the camera, and your camera tilts by 1/10th of a degree while you click the shutter, It will amount to a subject movement of 87 mm or 3-1/2 inches.
(Calculation: 50000mm x Tan 0.1 degree = 87 mm).

Of course, its effect will be more pronounced when you are using telephoto lens than at the wide angle end.

Imagine, your camera is perfectly stationary, and the Taj is shaking up and down by 4 inches or so!

Will you still leave home without a tripod!

Message edited by author 2009-04-09 04:05:54.

zxaar

04/09/2009 04:45:16 AM · #2

Originally posted by kbhatia1967:

If you read this, you will never leave home without a Tripod!

i read it and i have no escape i have to carry my tripod everywhere i go.
my company has no camera policy, but i guess tripods are okey. Since they do not say anything about them.
Anyway if someone asks i can always tell about how i read this post and now i have to carry it every where ...

Message edited by author 2009-04-09 04:46:04.

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

04/09/2009 05:35:16 AM · #3

Originally posted by zxaar:

my company has no camera policy, but i guess tripods are okey. Since they do not say anything about them.
Anyway if someone asks i can always tell about how i read this post and now i have to carry it every where ...

No, I didn't mean it.
I didn't say that you have to carry a tripod even when you are out on a date, and are not carrying a camera! LOL.

Dirt_Diver

Nikon D3s

04/09/2009 09:00:28 AM · #4

If you press the shutter button half way it's already done its metering so even if you move/shake the camera it will still be metered to the same spot in which you started the button. If something happened when you were waiting to take the shot I could understand but you shouldn't really press the shutter button half way and hold it for very long or you will lose the correct adjustments the camera made when you started it.

Message edited by author 2009-04-09 09:02:26.

LoudDog

Canon EOS-350D Rebel XT

Canon EF 17-40mm f/4.0L USM

04/09/2009 09:37:54 AM · #5

Yes, but how fast would you have to be moving to tilt your camera 1/10 of a degree if you are shooting at 1/100 of a second shutter speed? :)

K3Master

Pentax K-3

Pentax D-FA* 70-200mm f/2.8 ED DC AW

04/09/2009 10:16:43 AM · #6

I don't even HAVE a tripod!

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

04/09/2009 10:47:46 AM · #7

Also, a cop just has to move his laser speed gun by about the width of a human hair to add about 25mph onto your speed. The units usually give an error message in the readout, but not always. It's known as a panning error.

FYI these have not had "Judicial Review" in Ontario, yet the court swears by them and it's impossible for a defendant to refute the results. :-)

Dirt_Diver

Nikon D3s

04/09/2009 02:35:45 PM · #8

Originally posted by Strikeslip:

I don't see how that is possible simply because they use a radar or laser to determine the distance between the gun and the object they point it at.

A normal radar set sends out a radio pulse and waits for the reflection. Then it measures the doppler shift in the signal and uses the shift to determine the speed.

Laser (or lidar, for light detection and ranging) speed guns use a more direct method that relies on the reflection time of light rather than doppler shift.
You have probably experienced the reflection time of sound waves in the form of an echo. For example, if you shout down a well or across a canyon, the sound takes a noticeable amount of time to reach the bottom of the well and travel back to your ear. Sound travels at something like 1,000 feet (300 meters) per second, so a deep well or a wide canyon creates a very apparent round-trip time for the sound.

A laser speed gun measures the round-trip time for light to reach a car and reflect back. Light from a laser speed gun moves a lot faster than sound -- about 984,000,000 feet per second (300,000,000 meters), or roughly 1 foot (30 cm) per nanosecond. A laser speed gun shoots a very short burst of infrared laser light and then waits for it to reflect off the vehicle. The gun counts the number of nanoseconds it takes for the round trip, and by dividing by 2 it can calculate the distance to the car. If the gun takes 1,000 samples per second, it can compare the change in distance between samples and calculate the speed of the car. By taking several hundred samples over the course of a third of a second or so, the accuracy can be very high.

The advantage of a laser speed gun (for the police anyway) is that the size of the "cone" of light that the gun emits is very small, even at a range like 1,000 feet (300 meters). The cone at this distance might be 3 feet (1 meter) in diameter. This allows the gun to target a specific vehicle. A laser speed gun is also very accurate. The disadvantage is that the officer has to aim a laser speed gun -- normal police radar with a broad radar beam can detect doppler shift without aiming.

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

04/09/2009 03:01:10 PM · #9

Originally posted by Dirt_Diver:

Originally posted by Strikeslip:
Also, a cop just has to move his laser speed gun by about the width of a human hair to add about 25mph onto your speed. The units usually give an error message in the readout, but not always. It's known as a panning error.

FYI these have not had "Judicial Review" in Ontario, yet the court swears by them and it's impossible for a defendant to refute the results. :-)

I don't see how that is possible simply because they use a radar or laser to determine the distance between the gun and the object they point it at.

A normal radar set sends out a radio pulse and waits for the reflection. Then it measures the doppler shift in the signal and uses the shift to determine the speed.

Laser (or lidar, for light detection and ranging) speed guns use a more direct method that relies on the reflection time of light rather than doppler shift.
You have probably experienced the reflection time of sound waves in the form of an echo. For example, if you shout down a well or across a canyon, the sound takes a noticeable amount of time to reach the bottom of the well and travel back to your ear. Sound travels at something like 1,000 feet (300 meters) per second, so a deep well or a wide canyon creates a very apparent round-trip time for the sound.

A laser speed gun measures the round-trip time for light to reach a car and reflect back. Light from a laser speed gun moves a lot faster than sound -- about 984,000,000 feet per second (300,000,000 meters), or roughly 1 foot (30 cm) per nanosecond. A laser speed gun shoots a very short burst of infrared laser light and then waits for it to reflect off the vehicle. The gun counts the number of nanoseconds it takes for the round trip, and by dividing by 2 it can calculate the distance to the car. If the gun takes 1,000 samples per second, it can compare the change in distance between samples and calculate the speed of the car. By taking several hundred samples over the course of a third of a second or so, the accuracy can be very high.

The advantage of a laser speed gun (for the police anyway) is that the size of the "cone" of light that the gun emits is very small, even at a range like 1,000 feet (300 meters). The cone at this distance might be 3 feet (1 meter) in diameter. This allows the gun to target a specific vehicle. A laser speed gun is also very accurate. The disadvantage is that the officer has to aim a laser speed gun -- normal police radar with a broad radar beam can detect doppler shift without aiming.

Check it out: //www.speedcameras.org/video/InsideOutFinal.wmv

BrennanOB

Canon EOS-1D Mark II

04/09/2009 03:05:18 PM · #10

Most of the problems with radar guns have to do with how they are used. They measure the speed of an oncomming motorist by pinging light off them, and measuring how fast it returns. Errors come from substituting what that something is. Point it at a car, then a tree gets between the car and the gun, and the something just leapt forward at light speed! Ticket that car! Or that tree.

If the cop is hiding behind trees or lamposts, you have a hope of beating it. But not much of one

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

04/09/2009 03:19:06 PM · #11

Originally posted by BrennanOB:

From what I've heard, it's no use contesting it in court, so I won't. I will ask the laser cop if it has had Judicial Review yet as part of my cross examination, but only so I can add it to my list of much better evidence leading to reasonable doubt and the ultimate dismissal of my charge. ;-)

GeneralE

Canon PowerShot S3 IS

04/09/2009 03:45:49 PM · #12

Originally posted by Strikeslip:

Originally posted by BrennanOB:
Most of the problems with radar guns have to do with how they are used. They measure the speed of an oncomming motorist by pinging light off them, and measuring how fast it returns. Errors come from substituting what that something is. Point it at a car, then a tree gets between the car and the gun, and the something just leapt forward at light speed! Ticket that car! Or that tree.

If the cop is hiding behind trees or lamposts, you have a hope of beating it. But not much of one

From what I've heard, it's no use contesting it in court, so I won't. I will ask the laser cop if it has had Judicial Review yet as part of my cross examination, but only so I can add it to my list of much better evidence leading to reasonable doubt and the ultimate dismissal of my charge. ;-)

You can also ask when it was last calibrated -- I think there are usually some guidelines they have to follow for the results to be considered valid.

Dirt_Diver

Nikon D3s

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

04/09/2009 03:57:21 PM · #13

Originally posted by GeneralE:

You can also ask when it was last calibrated -- I think there are usually some guidelines they have to follow for the results to be considered valid.

Bingo... Here in the states if you get pulled over you can ask the cop when the last time he's had his speed gun checked and he is supposed to tell you. Now if he was going to let you off with a warning and you ask him about the gun then chances are he will write you the ticket. However you can contest the ticket in court and ask him to produce the validation ticket where the gun was calibrated but if you want to go through the trouble you can. Chances are the cop that pulls you over had his gun calibrated before he left for patrol but if you learn the times of rotation and shift changes along with which cops are usually where and you know that there is a good chance the gun that he caught you with just after he left your house at 6am in the morning hasn't been calibrated then you could get off, :)

But again depending on how fast you were going you may just want to help the county police pay for their banquet and pay the fine.

04/09/2009 04:47:59 PM · #14

In Ontario they are required to calibrate at both the beginning and end of the shift, or so I was told by an officer I have beers with every Wednesday night. I will be sending registered letters asking for their calibration logs as well as a host of other info that they are required to give me if I ask... (Disclosure) ;-)

This is all about the court experience for me, so I probably won't be taking a plea bargain. I tend to go all-in, so I'll either have the charge dropped, or pay the whole fine and get 4 demerit points on my license along with some nasty insurance rates for the next few years. We'll have to see how I feel that day to say for sure, though. ;-D

Canon EF 24-70mm f/2.8L USM

04/13/2009 04:05:49 AM · #15

Originally posted by Strikeslip:

How do you get this 'Helpful' sign in forum posts?

Simms

Canon EOS-5D Mark II

04/13/2009 06:19:05 AM · #16

Originally posted by kbhatia1967:

Originally posted by Strikeslip:
In Ontario they are required to calibrate at both the beginning and end of the shift, or so I was told by an officer I have beers with every Wednesday night. I will be sending registered letters asking for their calibration logs as well as a host of other info that they are required to give me if I ask... (Disclosure) ;-)

This is all about the court experience for me, so I probably won't be taking a plea bargain. I tend to go all-in, so I'll either have the charge dropped, or pay the whole fine and get 4 demerit points on my license along with some nasty insurance rates for the next few years. We'll have to see how I feel that day to say for sure, though. ;-D

How do you get this 'Helpful' sign in forum posts?

It is in his signature... nothing Slippy says is ever deemed useful.

Bear_Music

Samsung Galaxy S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

04/13/2009 10:31:57 AM · #17

Originally posted by LoudDog:

Yes, but how fast would you have to be moving to tilt your camera 1/10 of a degree if you are shooting at 1/100 of a second shutter speed? :)

Well, I don't have a number for that but it's a noticeable phenomenon. When shooting telephoto especially, it's easy to get blur in from body movement even at 1/250 exposure times. If you *have* to shoot hand-held at 200+ mm, your best bet is to shoot in burst mode, because usually the second exposure will be noticeably sharper than the first one.

Heck, if you're being REALLY critical about camera shake, you need to use mirror lockup. Just the vibration from mirror slap is enough to cause a slight degradation of image quality. This is especially noticeable in macro work, btw...

Bottom line, for me, is I always use the tripod when I'm shooting with the 70-200mm, and whenever possible when shooting with everything shorter.

R.

BTW, guys, way to hijack a thread! LOL...

R.

Message edited by author 2009-04-13 10:32:29.

NikonJeb

Nikon D850

Nikon AF-S Nikkor 28-300mm f3.5-5.6G ED VR

04/13/2009 12:47:51 PM · #18

Originally posted by Strikeslip:

They have this catchy little revenue generator here in Pennsylvania....it's a semi-unknown statute known as "Failure to obey traffic control devices".

It's a handy little thing for small towns to up their revenue without drawn out court meetings, unhappy citizens, and protracted battles.

The speeding ticket, or other moving violation like going through a yellow light (Wink, wink) that add points to your license and cause your insurance rates to skyrocket can be lessened to this plea, generally with a tet-a-tet with the arresting officer fifteen minutes before your case is to be heard....where by you pays your fine, and wander off relieved that you get no points, and the local constabulary gets their revenue.

Funniest thing.......almost everyone shows up early for their case! Go figure!

Canon EF 24-105mm f/4.0L IS

04/15/2009 06:30:32 AM · #19

Originally posted by Bear_Music:

Bottom line, for me, is I always use the tripod when I'm shooting with the 70-200mm, and whenever possible when shooting with everything shorter.

R.

I know a famous Landscape Photographer, who uses Tripod even with a 12-24 mm lens!

Message edited by author 2009-04-15 06:30:51.

Mousie

Canon EOS-5D Mark II

04/15/2009 01:14:10 PM · #20

I don't even use a tripod to shoot macro! Run and gun, baby!