Slowest hand-heldable shutter speed with cropped sensors calcuation*

[felix_ing]

Hi there,

 

I remember reading responds by other members that when shooting with crop

sensor, the hand-heldable speed = 1 / {focal length x crop factor)?

 

I was doing some thinking when I was commuting home just now and wondered, the

factor in "crop factor" only does the cropping, so, shouldn't hand-heldable

speed be the same as 1 / focal length on FF?

 

My rationale is that, it's just like taking pic with a FF THEN cropping it

later, thus the shutter speed should remain the same?

 

Comments?

Explainations?

 

Cheers.

[buck_rogers1]

I always doubted the logic behind the 'crop rule' you mentioned. I figure it all depends on how big you will be printing. I think it's about circles of confusion and enlargement size. I think your logic is spot on though.

[DickArnold]

Convential wisdom? Very good question. I don't know the answer except to repeat the conventional wisdom I heard thirty years ago. Maybe somebody has some science somewhere. Now apply that to my 100-400L at four hundred with IS. I would like to know where the line is.

[digitmstr]

The 1.6 rule does apply.

 

Your sensor is smaller which means that any shake from the lens will cover a larger area of the sensor, compared to a FF sensor. Therefore, you must increase the shutter speed accordingly.

[beauh44]

Much will depend on one's technique as well. After 3 or 4 cups of coffee your mileage will probably vary, cropped sensor or not. ;-)

[bobatkins]

You have to enlarge the smaller image more, so if has to start out sharper to end up with the same sharpness is a given print size.

 

So smaller format means you can tolerate less shake, which means you need a faster shutter speed.

 

If you were making smaller prints from the smaller sensor, then you wouldn't need to apply the 1.6 factor. It would be just like cropping the print.

[alec_myers]

Yeah, I wrote something about this last week...

 

Here's another way to think about it:

 

Camera shake is effectively rotation of the camera (a little twist is what blurs the image.) The faster the shutter speed, the smaller the angle turned through by the camera while the shutter is open.

 

The amount of blur in the image depends on the angle of view of the final print compared with the angle the camera turned through.

 

If the camera turned through a tenth of a degree and the field of view was 50 degrees, then that's a blur of 1/500th of the image width. If the camera turned through the same tenth of a degree and the field of view was a telephoto's 5 degree field then that's 1/50th of the image, and much worse. You'd have to shorten the shutter by a factor of 10 to keep the blur at the same level.

 

So for a given acceptable level of blur (1/500th of the image width, 1/1000 of the image width, whatever you like) the shutter speed depends on the angle of view of the image, and nothing else.

 

If you print full-frame in both cases, and to the same image size (in inches, not pixels) and your level of acceptable blur is the same, then the crop sensor needs a faster shutter speed because the angle of view displayed in the print is smaller, and so the rotation of the camera in your hands is more obvious.

[mars c]

Not only it applies to 1.6x factor, but it also applies to smaller sized sensors.

 

Just look at pocket digicams for example, usually their lens start at 6mm, But I'm sure you cant hand hold them at 1/6 sec. without image stabilization. you'll need at least 1/40 sec. to safely handhold a digicam at 6mm lens setting.

[peter_houtmeyers]

"The 1.6 rule does apply.

 

Your sensor is smaller which means that any shake from the lens will cover a larger area of the sensor, compared to a FF sensor. Therefore, you must increase the shutter speed accordingly."

 

Lens and sensor dont move seperately they are a fixed solidly together. Your hands or camera dont move more ore less because the sensor is bigger or smaller. Imho only the focallenght has influence on motion blur. If one would cut a piece out a photo with the exact the same amount pixels and size you would not be able to tell what photo was taken with a crop or full frame.

[digitmstr]

>>Lens and sensor dont move seperately they are a fixed solidly together.<<

 

Yes - but, the enlargement factor to produce equal size prints will be different (i.e. a smaller sensor will require a greater enl. compared to a larger sensor).

[peter_houtmeyers]

Why is everyone bringing motion blur back to print size.Motion blur is caused by displacing your camera from the subject you are photographing.

If i have a full sized sensor with 5 megapixels an a cropped sensor with 10 megapixels where does your theory fitt in now about the print. If i have a canon 5D and a 1DmarkIIn with the same pixelsize but different sensor size. I tape of the part from the 5D sensor that is bigger than the 1D sensor and take a photo with both camera's . If i use exact the same lens on both body's and i would make a print of both photo's wich show exactly the same subject. I can not comprehend why the smaller sensor would show more motion blur than the full sized sensor pic.

[andy_jones2]

Peter,<p>

The "guideline" of 1/FL as the slowest shutterspeed came from pre-digital days when

photographers used "film"; it was found that for many people this was a useful guideline

- it is nothing to do with physics, and everything to do with physiology (hence the caffeine

comment).

<p>

It was based on the same general assumptions that were used to calculate DoF - full

frame acquisition (in this case 35mm full frame ) and ~8x10 print viewed at ~12-15" (the

exact numbers vary depending on lens manufacturer). If something were perceived as

"sharp" or "in focus" based on the eye's typical acuity, it was considered to be in focus, all

else was "outside the DoF".

<p>

Whether you blur the image by it not being in focus, or by moving the camera axis while

exposing the shot, the ability to detect the resulting blur determines whether the shot

appears

sharp or blurred. If the image is blown up more (from a crop camera) to the 8x10 then

there is a "level" of blur that will be detectable in the 1.6 x enlargement that is not quite

detectable in the 1x version.

 

HOWEVER

 

If you use number of pixels to determine your print size and accept , let's say, 240 original

pixels from the sensor per inch of final print then you've already gone beyond the original

8.5x linear enlargement for the "standard conditions" either for the 1/FL or for calculating

DoF. This table shows the linear geometric enlargement factors for the various Canon

models at either 240 ppi or 300 ppi, from the sensor dimension to the print dimension

 

<img src="http://www.fototime.com/0E5ADB25F5B2C9E/orig.jpg" >

<p>

 

So, print size, pixel density on the sensor and print resolution now all play a role in

determining how much blur can be seen in a print and the conditions are no longer

"standard"

 

Which brings us full circle to " it's a guideline and everyone should determine EMPRICALLY

for themselves what factor to use for which camera - if you usually make an 8x10(or12)

print with a FF camera and the 1/FL works for you, then 1/1.6xFL should work on a 1.6x

camera IF YOU also make an 8X10 from that image.

 

IOW it's not that simple any more!

[andre_reinders]

I once asked someone about the 1/focal length rule for hand-hold-ability, and they said that rule of thumb was created in the era of nice heavy manual cameras. AKA 20 years ago + (presumeably like my Nikkormat FT2).

 

They were inferring that the modern cameras are lighter and may require even faster shutters.

 

...and yes to the crop factor ;)

[Spearhead]

There is no such thing as the 1/fl rule. Ask for proof, or even a reasonably controlled test, and there is nothing. It's folklore, something that some unknown person developed as a way to say something about hand holding.

[fred_c1]

>they said that rule of thumb was created in the era of nice heavy manual cameras. AKA 20 years ago + (presumeably like my Nikkormat FT2). They were inferring that the modern cameras are lighter and may require even faster shutters.

 

Don't forget that many of those cameras didn't have mirror damping as good as current models.

 

Besides, weight can improve steadiness only up to a certain point. If you've been lifting a bowling ball all day long, you won't be too steady anymore. ;)

[andre_reinders]

It really comes down to YOU knowing what YOUR slowest acceptable shutter speed is. This idea has had lots of attention with the discussions of Image Stabilized lenses.

 

Some steady photographers may be able to hand hold 1/30th sec. for a 100mm lens. Others may get a blurry image at 1/125th.

 

Do some testing of yourself and your ability.

[alec_myers]

"I can not comprehend why the smaller sensor would show more motion blur than the full sized sensor pic."

 

In your example Peter you talk about "taping off" the larger sensor to be the same size as the smaller one. In real life you can (and would) use the *whole* of the image of the larger sensor, so the same sized blur occupies a lesser proportion of the print. That makes it less, relative to the whole image.

[DickArnold]

Andy Jones I appreciate your thoughtful answer. It makes some sense to me. I do not like anecdotal one line answers with no explanation. I don't know how much trust to put in them.

[beaglefur]

It has been my experience that I can handhold a crop body and my 5D at pretty much the same shutter speed with the same lens. I use 1/focal length as a guideline for both cameras.

 

If it was just a function of sensor size, the converse would apply to medium format cameras...

[joe_fikes]

Yes, the 1.6 applies, etc. but...

 

I saw something Ansel Adams wrote a number of years ago and he said that when he used "miniature cameras", i.e. Hasselblad, etc., he wouldn't dream of using a speed slower than 1/500 sec.

 

That may seem a little extreme, and it runs completely counter to conventional wisdom. But old Ansel wasn't a conventional photographer.

 

Joe

[peter_houtmeyers]

"In your example Peter you talk about "taping off" the larger sensor to be the same size as the smaller one. In real life you can (and would) use the *whole* of the image of the larger sensor, so the same sized blur occupies a lesser proportion of the print. That makes it less, relative to the whole image.

 

Sure it would be less visible in the total photo bacause there's a different frame filling( less magnification with the full frame), but never the less the displacement of the camera remaines exactly the same per pixel. If pixelsize is the same in both camera's than the area of motion blur is in both cases evenly wide. So if one asks me is motion blur higher with a crop camera and the same lens i would have to say no...

[andre_reinders]

I think the idea about saying "yes" to the 1.6x crop applying, has to do with the enlargement size.

 

A image from a 20D enlarged to an 8x10, would be enlarged more than the same image from a 5D.

 

The same comparison from APS film to 35mm, or 35mm to 120, etc. Because there is more enlargement from the smaller film or sensor (recording device) Any 'imperfections' will also be magnified more.

 

In the medium format world, many people will choose to use 400 speed film because the enlargement to an 8x10" (for example) is a smaller enlargement factor (compared to 35mm) and the grain would be less noticable, than using 35mm film and enlarging to 8x10".

 

2 1/4 film is 58mmx58mm, or about 34 square cm.

 

35mm film is 24x36mm, or about 8.5 square cm,

 

and 8x10 = about 20x25 cm, or 500 square cm...

 

So, from a Medium format 2 1/4" negative, you would enlarge about 15x to get an 8x10, and from 35mm you would enlarge about 60 times. Whether it is grain, noise, camera shake, or a peice of dust, it will show up more when enlarging from a smaller image capture size. This logic applys to the 1.6x crop vs. full frame as well.

 

Consider that a less than perfect image may look great on the LCD screen, or a 4x6" print - but may look awful at 8x10".

[joe_vanderwaart]

With regard to Peter Houtmeyers' taping off part of a 5D sensor: Sure, if you use the same lens on two different cameras and utilize the same amount of sensor area to capture the light at the same shutter speed, then you'll get the same picture, motion blur and all. This is assuming that once you have the digital files you crop the 5D one to get rid of the black part you taped off, and then resize the two windows so you can compare the images side by side. You've controlled for all the differences between the two cameras, so the results you get will be the same.

 

But that's not the real-life situation. Consider two photographers sharing a tripod, one using a 30D and the other an undoctored 5D. Never mind lenses for a second. Suppose they manage to set up their cameras so that they see the exact same thing looking through their viewfinders. Then they each make an exposure at the same shutter speed. Suppose that during exposure the cameras "shake" through the exact same motion so that at every instant they are capturing the exact same view; then they will get the same result, with the same amount of blur. Now look at the lenses: the 5D guy used a 1.6x longer lens! Therefore, they cannot use the same formula to calculate that shutter speed starting from the focal length.

 

In fact, 30D's shutter speed = 5D guy's shutter speed = 1/(5D guy's focal length) = 1/(1.6*30D guy's focal length).

 

Hope this helps.

[phule]

<<It really comes down to YOU knowing what YOUR slowest acceptable shutter speed is.>>

 

Spot on.

[alec_myers]

"Sure it would be less visible in the total photo bacause there's a different frame filling( less magnification with the full frame), but never the less the displacement of the camera remaines exactly the same per pixel. If pixelsize is the same in both camera's than the area of motion blur is in both cases evenly wide. So if one asks me is motion blur higher with a crop camera and the same lens i would have to say no..."

 

LOL - so who is "right" depends only what factors you keep the same as you switch from one size sensor to the other - the printed size of each pixel (the blur stays the same) or the size of the final print (the blur gets worse for the crop sensor.)