Minimum Shutter Based on Focal Length


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#1
Hi all,

Many a photographers have told me to use the simple rule "Use a minimum or faster shutter equivalent to the focal length used" which is simple enough I guess. Eg: 100mm @ 1/125 or faster

Please note that I understand this is to minimize camera shake with hand-held dSLR and would not be applicable to long exposure on tripods, etc.

My question is since I'm using a 300D which is a 1.6 crop dSLR, would I need to multiple everything with 1.6. Eg: 100mm would be 160mm on a 300D and therefore my shutter would be 1/160s or faster.

Can someone here enlighten me please ?

Thanks and Cheers to all !
 

dkw

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#2
I think the consensus opinion is, "yes". The reason being that with the FLM, everything gets magnified, including camera shake. Having said that, 1/focal length is only a rough guide. Work on your breath-holding and camera holding technique and quite often you can get away with slower speeds.

Cheers,
 

nightwolf75

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#3
erm... dkw, not really. a common misconception - the FLM does nothing to the lens physically. FLM (or commonly we call crop factor) only affects the way we view things thru the lens. everything, in a sense, gets 'cropped' becos of the small sensor size. a 70-200mm lens is still a 70-200mm lens, not 80-300mm (after FLM) physically. but, a 70-200mm gives u the view of a 80-300mm (depending on the FLM of the cam).

so, the general principle of 1/focal length still applies, FLM or otherwise. ie - if u have a 70-200mm, the guideline is that a shooter does not go below 1/200sec for shutter speed.

here's an article explaining FLM:
http://www.luminous-landscape.com/tutorials/understanding-series/dslr-mag.shtml

here's one talking abt shutter speeds:
http://www.tpub.com/photography1/ph20959.htm

hope it helps? :)
 

ortega

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#4
nightwolf75 said:
erm... dkw, not really. a common misconception - the FLM does nothing to the lens physically. FLM (or commonly we call crop factor) only affects the way we view things thru the lens. everything, in a sense, gets 'cropped' becos of the small sensor size. a 70-200mm lens is still a 70-200mm lens, not 80-300mm (after FLM) physically. but, a 70-200mm gives u the view of a 80-300mm (depending on the FLM of the cam).

so, the general principle of 1/focal length still applies, FLM or otherwise. ie - if u have a 70-200mm, the guideline is that a shooter does not go below 1/200sec for shutter speed.

here's an article explaining FLM:
http://www.luminous-landscape.com/tutorials/understanding-series/dslr-mag.shtml

here's one talking abt shutter speeds:
http://www.tpub.com/photography1/ph20959.htm

hope it helps? :)
I agree with you except for your crop factor calculations.

BTW it is just a general rule, you will still have to train yourself to hold the camera properly, some people can hand hold the camera at 1/15s exposure
 

dkw

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#5
Hi NW,
I am aware that controversy exists on this issue :) . I also generally do not like to use the term "FLM" as it is misleading, as you say it is really a crop. However, this is one situation where I believe the concept of FLM is applicable. I've read through the 2 articles you have provided, and whilst informative, do not really address the issue at hand. Often when one speaks about "sharpness" it is not absolute sharpness but "acceptable" sharpness. An image printed to 4R which appears sharp may not be so sharp at 8R, hence the "crop" (or magnification) does have an effect on perceived sharpness. We can agree to disagree here ;) .

Anyhow, 1/FL is really a rough guide anyhow, and can vary significantly between photogs.

Cheers,
 

nightwolf75

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#6
ortega said:
I agree with you except for your crop factor calculations.

BTW it is just a general rule, you will still have to train yourself to hold the camera properly, some people can hand hold the camera at 1/15s exposure
problem with no calculator... :bsmilie:

okie - here goes.

with x1.6 (eg canon EOS 300D) 70-200mm ~ 112-320mm
with x1.5 (ed nikon D70) 70-200mm ~ 105-300mm

dats the reason why some reviewers online said dat DSLR might be a boon to wildlife shooters but a bane to landscape shooters.

dkw - no sweat. i'm cool abt it. i know many shooters out there are still arguing till they are blue in their faces abt this issue. heck... as long as, as a shooter, one understands (which ever way u wanna interpret crop factor/FLM) the principle during shooting can already. ortega is rite to point out dat training oneself to have steady hands and steady breathing is more impt than tech details like this. ;)
 

anirtac

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wow then It'll take me forever.... my hands always tend to shake/jerk/etc.... hehehe :(
 

anirtac

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#9
what's a monopod... sorrie i very green.
 

Winston

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#10
dkw said:
I think the consensus opinion is, "yes". The reason being that with the FLM, everything gets magnified, including camera shake. Having said that, 1/focal length is only a rough guide. Work on your breath-holding and camera holding technique and quite often you can get away with slower speeds.

Cheers,
Actually its NO

at 125mm, the min shutter to avoid shake is 1/125, the "cropping idea" behind the DSLR...is that the sensor only takes a "portion" of this Full frame 125mm pic. in the case of Nikon this translates to only 2/3 of the orinigal image size.

so 2/3 x ? = 1
Where 1 = a full size 35mm film
the answer is 3/2 (which is 1.5)
So that is why the Term FLM, Focal Length MULTIPLER, comes in.
The DSLR's focal length is based on the cropped View of the lenses, Multipled by the "VALUE NEEDED" to MAKE IT LOOK LIKE A 35mm

Hence the value is 1.5


And when u enlarge this small portion of the orinigal 125mm focal length image (from 35mm POV), the ENLARGED image will "LOOK-AS-IF" it is taken from a 125mm x 1.5 = 188mm focal length, (If based on a 35mm film)

The Optics is Still at 125mm focal length and hence all rules are based on 125mm
 

Winston

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#11
anirtac said:
what's a monopod... sorrie i very green.
Mono = one
Tri = three

Tri-pod = 3 legged
Mono-pod = 1 Legged

Its a 1 legged camera stand, meant to hold the weight of the camera and lenses so that the photographer can shoot with more "steady hands" so to speak
"Steady hands" refers the avoidance of camera shake at lower shutter speeds.
 

anirtac

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okokok I may be green but I do understand what "Steady Hands" mean...

Thanx for your advice.
 

dkw

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#13
Winston said:
Actually its NO

at 125mm, the min shutter to avoid shake is 1/125, the "cropping idea" behind the DSLR...is that the sensor only takes a "portion" of this Full frame 125mm pic. in the case of Nikon this translates to only 2/3 of the orinigal image size.

so 2/3 x ? = 1
Where 1 = a full size 35mm film
the answer is 3/2 (which is 1.5)
So that is why the Term FLM, Focal Length MULTIPLER, comes in.
The DSLR's focal length is based on the cropped View of the lenses, Multipled by the "VALUE NEEDED" to MAKE IT LOOK LIKE A 35mm

Hence the value is 1.5


And when u enlarge this small portion of the orinigal 125mm focal length image (from 35mm POV), the ENLARGED image will "LOOK-AS-IF" it is taken from a 125mm x 1.5 = 188mm focal length, (If based on a 35mm film)

The Optics is Still at 125mm focal length and hence all rules are based on 125mm
Hi Winston,
thank you for your comments. Sharpness is relative to the size you are printing/viewing, what may appear to be acceptably sharp at 4R size (i.e. acceptable amount of camera shake, OOF), may not be so at 8R. You are right, the enlarged image will "LOOK-AS-IF" is was 188mm, with all its attendant shake, OOF magnified by that 1.5x, and "may" no longer be "acceptably" sharp. There are 2 schools of thought on this and I believe the jury is still out. Personally, I shoot at about 1/FL (lens, not FLM), but do not go less than 1/30s, even for FL less than 30mm.

Cheers,
 

wainism

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#14
nightwolf75 said:
erm... dkw, not really. a common misconception - the FLM does nothing to the lens physically. FLM (or commonly we call crop factor) only affects the way we view things thru the lens. everything, in a sense, gets 'cropped' becos of the small sensor size. a 70-200mm lens is still a 70-200mm lens, not 80-300mm (after FLM) physically. but, a 70-200mm gives u the view of a 80-300mm (depending on the FLM of the cam).

so, the general principle of 1/focal length still applies, FLM or otherwise. ie - if u have a 70-200mm, the guideline is that a shooter does not go below 1/200sec for shutter speed.

here's an article explaining FLM:
http://www.luminous-landscape.com/tutorials/understanding-series/dslr-mag.shtml

here's one talking abt shutter speeds:
http://www.tpub.com/photography1/ph20959.htm

hope it helps? :)
hi,

i am abit confused here,hope u guys can enlighten me!
as NW said, the lens doesnt change PHYSICALLY. so wat i gather is... when i look thru the view finder, i see the VIEW of a 80-300mm? but when my pics develop, its actually the range of 70-200mm?

eg. when i zoom all the way, i get a 300mm VIEW, but when i develop its only a 200mm view?

is that what u r saying night wolf?
 

Winston

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#15
wainism said:
hi,

i am abit confused here,hope u guys can enlighten me!
as NW said, the lens doesnt change PHYSICALLY. so wat i gather is... when i look thru the view finder, i see the VIEW of a 80-300mm? but when my pics develop, its actually the range of 70-200mm?

eg. when i zoom all the way, i get a 300mm VIEW, but when i develop its only a 200mm view?

is that what u r saying night wolf?
No no no...

(Frankly I cant blame you for thinking that way...cos I did thought it was that way once... :p)

The View you see Thru the viewfinder of the DSLR is ALREADY CROPPED.
(I think somehow the either the pentaprism/mirror might have cropped the view from in from the lens before it enters your eyes)


so you will STILL get a WYSIWYG (What You See Is What You Get) image
(EXCEPTION: some lower end DSLR only have a 92% or 95% coverage so do expect some bit of "loss" unless you're using a Pro-level camera with 100% viewfinder coverage)
 

nightwolf75

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#16
wainism said:
hi,

i am abit confused here,hope u guys can enlighten me!
as NW said, the lens doesnt change PHYSICALLY. so wat i gather is... when i look thru the view finder, i see the VIEW of a 80-300mm? but when my pics develop, its actually the range of 70-200mm?

eg. when i zoom all the way, i get a 300mm VIEW, but when i develop its only a 200mm view?

is that what u r saying night wolf?
no lah.. :bsmilie:

ur DSLR, depending on the FLM, will see and capture the view of a (abt)112-320mm lens if u use a 70-200mm on a x1.6 FLM DSLR like a 300D.

(okie - this is where dkw and i differ. and so do many people on wat FLM/crop factor is. bear with me)

a DSLR 'sees' differently from a normal film SLR is becos of the sensor size. in a 35mm SLR, the sensor (ie the film) measures 36mm by 24mm. in a DSLR (canon), the sensor (ie the CMOS or CCD) is smaller - 22.7mm by 15mm. this means that wat is being captured on a DSLR is, essentially, a smaller (hence cropping) area than a film SLR. dats why your 70mm lens gives u a 112mm view on a DSLR. dats how i understand it, in a layman's point of view.

your lens dun change. its still 70mm. wat changes is the view, or image area, dat is being captured by the sensor. the easiest way to understand this is to take a film SLR and a DSLR and mount the same lens on them. look thru the viewfinder, and u'll be able to see the differences in the way the camera sees the same object. ;)
 

user111

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#17
all this is just a rough guide
 

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#18
i agrue until my face turn blue the last time, my school of thought like user111 its just a rough guide, what focal lengths you are comforatable with, use it.
 

ortega

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#19
Take a film camera witha 200mm lens and take a photo
print the photo full frame
and then crop off the all four sides

ta da FLM explained in simple terms
 

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