Shutter speed.

[Joe]

Lets all stick on 8mm fisheye lenses and shoot at 1/8sec shutter speed

[robski]

Originally Posted by Joe

Lets all stick on 8mm fisheye lenses and shoot at 1/8sec shutter speed

LOL - I bet young Peter can go even slower

On a different note I've noticed on high magification lens as sort of "eye - brain - hand" servo loop effect. When I first look through the view finder everything is steady. But the longer I concentrate on a point I find things start to drift and then I end up over compensating for the movement. To stop this I have to look away from the viewfinder and start again.

Main reason why I lug and use a tripod 99% of the time.

[Derekb]

I'm sorry, but I can't see what MP count has to do with image stability, as for me it's simply down to technique - which if you work on it can be improved. I watch, ask, then learn from others and there's plenty of help out on the internet to help you.

I'm willing to bet Nigel (Blake) gets a lot of his shots by good hand holding technique which again I'm sure he obtained by learning and practicing.

[postcardcv]

Originally Posted by robski

In this example let us assume the camera shake causes a 1mm vertical movement of image on the sensor which will be true for both full frame and APS-C sensor. In the case of full frame this movement equates to 4.1% of the frame and 6.6% for APS-C. It is only when you use different scaling to make the same size print from each system the shake becomes more apparent.

I keep coming back to this, both here and the thread on BF, but I just can't get my head round it... in your example blur caused by camera shake is more visable in prints from a crop camera (have I got that right)? That means that there is some camera shake.

What I am saying is that if I can shot at a given speed on a full frame camera and completely eliminate camera shake then surely this shame shutter speed would be fast enough to do the same on a crop camera.
For example, say I can shoot at 1/400th at 400mm on a full frame camera and completely eliminate camera shake then the sensor would not have moved. So the system of scaling the movement becomes irrelevant and the same shutter speed would be needed for a shake free image on a crop camera.

[robski]

Yet another angle on this problem this time just considering the Pixel point of view.

We have 3 models of camera fitted with the same lens and shutter speed, a full frame, a 1.3 crop factor and a 1.6 crop factor.

A person is the subject in this case and stands at an appropriate distance from each camera so that their image just fills the frame in each case. From each camera we want to make a 10"x15" print at 300dpi so that we should have 3 identical looking prints to compare the camera shake. Again as in our previous examples we have a 1mm vertical movement for the camera shake.

The attached Table shows the figures for each model of camera to produce the print and the number of pixels the movement blur is over.

For the 1.3 crop factor the blur is 1.3 times greater than the full frame model.

For the 1.6 crop factor the blur is 1.6 times greater than the full frame model.

Therefore sensor Pixel density has no effect on the observed blur on the print.




In Peter's Post #6 he is cropping the area of the sensor and using the same scaling factor
so his statement is true in this case.


When you look at the world at the atomic level things are never completely still so in theory you will never get 100% camera shake free image. This is partially true in the field of measuring things, you are unlikely to get 2 measurements the same. So what we do is take hundreds of measurements and perform some analysis on the numbers to get a realistic value.

For much the same reason Camera sensor noise will never be zero (unless you want to operate at -273 degree C or 0K) it is a question of reducing it an acceptable level.

It really is a question of getting acceptable sharpness, i,e sharper than the eye see, when the eye can perceive blur it becomes unacceptable.

[postcardcv]

Originally Posted by robski

When you look at the world at the atomic level things are never completely still so in theory you will never get 100% camera shake free image. This is partially true in the field of measuring things, it is unlikely to get 2 measurements the same. So what we do is take hundreds of measurements and perform some analysis on the numbers to get a realistic value.

It really is a question of getting acceptable sharpness, i,e sharper than the eye see, when the eye can perceive blur it becomes unacceptable.

OK so you can't 100% eliminate shake, but a movement of 1mm on the sensor is huge. Surely any shot with this much movement would so far too much blur regardless of crop factor. For me accpetable sharpness would be looking sharp when viewed at 100% (then I know I can print as big as I want) and I can acheive this at the same shutter speeds regardless of crop factor.

[robski]

I used a figure of 1mm just as an example. If the movement is less than a pixel then it will never register.

The limit of the human vision system is said to be 7 lines per mm.
Therefore a fair amount of shake can occur before the eye perceives it.

The bulk of the human vision system is down to the brain and not the eye. So some vision defects are due to the brain rather than the eye.

[miketoll]

Originally Posted by postcardcv

For me accpetable sharpness would be looking sharp when viewed at 100% (then I know I can print as big as I want) and I can acheive this at the same shutter speeds regardless of crop factor.

That is the council of perfection but how do you get a pixel sharp BIF even on a tripod? Also I do not routinely carry a tripod on a walk which may be lax but I am not as young and fit as I was (or dedicated enough) so the shutter speed for hand held shots is what matters to me, the old formula never was intended for tripod shots. Print size obviously does come into it as well as the eye of the beholder so as a rough guide it looks better to allow for the 'crop' factor?

[robski]

Mike you have to admire those who can get perfect hand held telephoto shots. I've tried and binned more shots than I care to mention. I get the results I want with a tripod and I don't mind lugging it. On my local patch not too many opportunities for Birds in Flight shots.

I sometimes practice on the Black Headed Gulls when folk feed the wildfowl in the park.

My research and calculations basically show that camera shake is more apparent with crop cameras. A 5 pixel shake on full frame becomes an 8 pixel shake on a 1.6 crop camera. Therefore the perceived wisdom to use a higher shutter speed seems good advice.

[robski]

I saw this today on the topic of this thread

http://www.bobatkins.com/photography...ter_speed.html