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Does 1.5x crop factor apply to handheld telephoto reciprocal shutter speed?
Hi all,.

Regarding the reciprocal focal length shutter speed rule (60mm -> 1/60s, 105mm -> 1/125s, 300mm -> 1/300s) is there any argument to apply the crop factor from a reduced size digital sensor (1.5x) to the rule?.

I.e. if I shoot at 300mm, that is a 35mm equivalent of 450mm, so would the rule be 1/450s? Or shooting at 100mm, 35mm equivalent of 150mm, use 1/150s?My guess is no, but I would like to know the opinion of others...

Comments (15)

Arkoc wrote:.

Hi all,Regarding the reciprocal focal length shutter speed rule (60mm ->1/60s, 105mm -> 1/125s, 300mm -> 1/300s) is there any argument toapply the crop factor from a reduced size digital sensor (1.5x) tothe rule?i.e. if I shoot at 300mm, that is a 35mm equivalent of 450mm, sowould the rule be 1/450s? Or shooting at 100mm, 35mm equivalent of150mm, use 1/150s?My guess is no, but I would like to know the opinion of others..

Yes, you should consider the crop factor when using the reciprocal shutter speed rule. A 300mm lens is giving you the same field of view as a 450mm lens, so you will need to compensate for this reduced field of view by using the higher shutter speed. So with the smaller field of view, any camera movement is going to effect this smaller field of view more dramatically, hence you need to use the 35mm equivalent focal length to set your shutter speed.JohnPentax *ist-D, K100D, Fuji F20/31fd, Oly Stylushttp://www.pbase.com/jglover..

Comment #1

Arkoc wrote:.

My guess is no, but I would like to know the opinion of others..

The answer is YES.. !!.

(with respect, this isn't a matter of opinion, it is a matter of fact)..

Anything which increases effective magnification of the image also magnifies any image faults, including blur caused by camera shake or subject movement and so requires higher shutter speeds to mask it. As a result, the guide shutter speed (and it has only ever been a GUIDE, remember) should be increased in line with the crop multiplier..

In this rule we can include any method of magnification or cropping, whether it takes place in camera, after shooting whilst in editing... or even just by walking closer to a picture hanging on the wall..

ALL increased magnification requires higher shutter speeds to reduce visable camera shake.Regards,Baz..

Comment #2

Hmmmm, is the article at http://forums.dpreview.com/...forums/read.asp?forum=1030&message=25108701 suggesting that it does NOT make a difference? I can't get a clear conclusion from that thread.....

Comment #3

Before digital. and that means film the rule was 1/telephoto mm..

Since digital the rule has been modified so that it reads 1/telephoto mm X crop factor..

Since the rule was meant for the increasing effect of magnifiction on steadiness. then common sense says that if you I ncrease magnification your steadiness has also got to increase to maintain the same quality of image. if a 35mm/FF camera has a 300m lens on it, that is 6X, from a standard 50mm. if you move the lens to a c sensor camera with a 1.5 crop factor that means 450mm or 9X. why would you not expect to need more steadiness with the 9X vs 6X?..

Comment #4

The conclusion is this: 100mm is the same whether it's on dx or fx sensor. that said, giving yourself a margin of error (it's better to err on the safe sidepreferably faster shutter speed for sharper image) will give you more play. conventional rule states that shutter speed should reciprocate lens' focal length when handholding the camera. so, 100mm is equal to 1/100 (faster is better) or use a tripod or any accessory or tecnique to stabilize camera when using slower shutter speed. dx sensor does not magnify the image (this is the function of the optics). it only reduces the field of view (this is why your wide angle 20mm becomes 30mm and or 100mm becomes 150mm).

Focal length remains the same (20mm or 100mm) but because field of view is reduced (cropped) by a factor of 1.5, the image projected becomes 30mm or 150mm respectively. http://www.dpreview.com/.../?/Glossary/Optical/Focal_Length_Multiplier_01.htm.

The example in the above link shows a bird with the same size at 200mm in both dx and fx sensor. however, the bird at 200mm is still smaller than the bird at 300mm. but look at the extent of the borders (blue color) in relation to the bird, the cropped 200mm is the same as 300mm (in both images, the wings of the bird are almost touching the borders but the overall area is smaller in the dx sensor). so, focal length magnifies the image, field of view does not. thanks...

Comment #5

Victor beato wrote:.

Snipped.

.... focal length magnifies the image, field of view does not. thanks..

Your comments, whilst no doubt well intended, were not helpful, Victor, because you are quite wrong..

It really does not matter which focal length produces any one Field of View, it is ONLY the Field of View itself which matters when it comes to safe handheld shutter speeds. This is because using a smaller image field does require extra magnification to fill the standard print sizes..

Cropping is therefore the same as any other means of magnifying... there is no difference.Regards,Baz..

Comment #6

Ther are so many good points about this issue. here's another healthy and sensible discussion about this topic. very interesting exchange of ideas and facts (?). http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00J5MN..

Comment #7

Victor beato wrote:.

The conclusion is this: 100mm is the same whether it's on dx or fxsensor..

Great, then there is no need for IS on compact superzooms, since they are only 70mm on the long end. Who cares that it offers the same field of view as 450mm on 35mm, that's just field of view, not magnification..

Right?.

Nope. Field of view is it. If you shake a camera 0.1 degrees in some fixed time period, that shake will show up a lot more on a lens that offers a 5 degree field of view as compared to one that offers a 50 degree field of view..

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #8

Victor beato wrote:.

Ther are so many good points about this issue. here's another healthyand sensible discussion about this topic. very interesting exchangeof ideas and facts (?).http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00J5MN.

I'm not sure what posts you are agreeing with, but if it is the last post on that thread, it's actually disagreeing with you..

80-100mm on 6x9 gives about the same field of view as 32 to 45mm on 35mm. 1/25s isn't terribly far off 1/35mm focal length, especially considering they probably weren't talking about reflex cameras with their inherent mirror slap..

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #9

Nickleback wrote:.

Victor beato wrote:.

The conclusion is this: 100mm is the same whether it's on dx or fxsensor..

Great, then there is no need for IS on compact superzooms, since theyare only 70mm on the long end. Who cares that it offers the samefield of view as 450mm on 35mm, that's just field of view, notmagnification..

Right?.

Nope. Field of view is it. If you shake a camera 0.1 degrees insome fixed time period, that shake will show up a lot more on a lensthat offers a 5 degree field of view as compared to one that offers a50 degree field of view..

Seen in a fortune cookie:Fear is the darkroom where negatives are developed.

The link's example clearly shows that the sensor is the media (film). the magnification takes place in the lens (which regulates or bends the light). otherwise, we won't need more than one lens (if sensor affects the size of the image). the media (regardless of it's size) only records the image this is why digital zoom feature is not very good this is why nikon put the vr in their lenses (it's just more effective)pressing the shutter of the camera is akin to your computer's "save" or "save as". without the lens, there is nothing to record or save. the lens sees the image; it magnifies or reduces the image.

Shutter speed/focal length "rule"is from the actual focal lenght of the lens (not field of view). the lens' actual focal length dictates the image size (see the link) and the 1/f rule (field of view or cropped field of view does not). the basic rule of photography still applies digital or not. the image size is the same at any given focal length regardless of the sensor size. there is no separate rules between digital and basic photography.

However, just like any other "rule" in photography, be it rule of third, sunny sixteen, etc, it is just a starting point, a guideline. photography is art, as well as science. thanks...

Comment #10

Arkoc wrote:.

Hmmmm, is the article at.

Http://forums.dpreview.com/...forums/read.asp?forum=1030&message=25108701 suggesting that it does NOT make a difference? I can't get a clear conclusion from that thread....

That thread is stating the obvious fact that the focal length of the lens does *not* change when used on a 1.5x DSLR. A 300mm lens remains a 300mm lens whether it is used on a 35mm camera, a disc film camera or an 8x10 view camera. The field of view shown by the lens onto the film or sensor is what changes. This change in the field of view appears to be a magnification but what you are actually seeing is just s smaller portion of the overall image. You are cropping out a portion of the field of view when compared against what would be sen in a 35mm film camera..

So, although the focal length of the lens does not change, the field of view does change, giving a smaller field. So any movement in this smaller field of view will be magnified by a factor equal to the crop factor of the field of view. Remember, the rule of thumb we are talking about here was developed for a 35mm film. Cropped DSLRs are equal to an APS-C sized sensor, so the rule of thumb would have to be adjusted to take into account the smaller sensor.JohnPentax *ist-D, K100D, Fuji F20/31fd, Oly Stylushttp://www.pbase.com/jglover..

Comment #11

Field of view takes into account the "crop" ratio and is equal to the 35mm equivalent field of view. It is the field of view that you must take into account concerning the "1/focal length" rule. Period..

If this was not the case, you could hand hold any small point and shoot camera with a lense of 4.6-23mm (28-140mm equivalent) at 1/4s. You cannot do this. Proof by example..

A 100mm lense with a 1.5 "crop factor" will require 1/150s safe shutter speed as per the "1/focal length" rule. Period..

Tim'Be the change you wish to see in the world.' -Mahatma Gandhihttp://www.flickr.com/photos/timskis6/..

Comment #12

Victor beato wrote:.

The link's example clearly shows that the sensor is the media (film).the magnification takes place in the lens (which regulates or bendsthe light)..

The link neglects to mention that enlargement also takes place upon display. That's where the sensor (or film) size matters..

This is why digital zoom feature is not very good.

Digital zoom is a separate subject, including whether it is good or not (short answer: it depends)..

This is why nikon put the vr in their lenses (it's just more effective).

You seem to like to change the subject. (short answer: both sensor ad lens shift systems have their advantages and disadvantages, not to mention that when Nikon VR lenses were introduced they still sold mostly film cameras, and it harder to do VR on the "sensor" when your sensor is a film strip)..

The lens'actual focal length dictates the image size (see the link) and the1/f rule.

OK, try 1/f rule with a 1/2.5" sensor camera and get back to me..

And as mentioned in the link you gave, in 1925 with 6x9 film the rule is about 4/f. Why's that? Have we gotten less steady in the intervening 80 years? Or maybe, just perhaps, field of view does matter, not focal length..

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #13

Thanks to all who contributed to the discussion. I had no idea this would end up such a contested topic..

I have a lot of respect for the people who presented their points here. Ultimately, what won me over was a voice of reason in another thread, here:.

Http://forums.dpreview.com/...forums/read.asp?forum=1002&message=25148747.

My contribution, contextually mirrored here was:.

While trying myself to see if it made a difference, I realized I had been trained as a biathlete, hollowing out dimes with a .22 at 50m while trying to control my pounding heart from skiing 5km. Holding steady is second nature to me, and I've recently quit coffee..

All of a sudden it dawned on me that it was a rule of thumb, not a rule. I deliberately tried to blur an image at 70mm with 1/500s by holding the camera poorly. And I pulled off a blurry image quite successfully. There's nothing saying a well trained, disciplined individual couldn't hold a camera as steady as a tripod - sounds like a great exercise for one of my kung-fu friends. (They're always doing zany discipline stuff like remaining unmoving while people break planks of wood on their heads.).

So, I guess I will just find out how well I can hold a camera, and bump up the speed if I drink coffee first..

Clearly there is a technical and a practical aspect to this question. For the practical, clearly it is a rule of thumb. My thanks and respect to the individuals who replied...

Comment #14

Arkoc wrote:.

Clearly there is a technical and a practical aspect to this question.For the practical, clearly it is a rule of thumb..

Bingo!.

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #15

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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