Handshake


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Jun 18, 2005
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#1
At telephoto, handshake becomes more pronounced. But is it because of the slower shutter speeds usually associated with small apertures at long focal lengths or is it also because of the fact that a long focal length WILL make handshake more obvious?
 

Zaknafein

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#2
try this:

take a laser pointer.
stand 0.5m away from a wall and point the laser at any spot, trying to keep it stable

now try standing 6m away from the wall and point the laser at the same spot

what do u notice?
at 6m, a small movement of ur hand will shift the laser else where from the spot

same theory when shooting with telephoto. hope the explanation helps :)
 

Apr 26, 2005
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Sengkang
#3
megascriler said:
At telephoto, handshake becomes more pronounced. But is it because of the slower shutter speeds usually associated with small apertures at long focal lengths or is it also because of the fact that a long focal length WILL make handshake more obvious?
your shutter speed must be at least 1/focal length.

for example, if your focal length is 200mm, you need at least 1/200 sec to minimise camera shake.

sometimes you need to push up the ISO or ASA if you are using AP mode
 

#4
Zaknafein said:
try this:

take a laser pointer.
stand 0.5m away from a wall and point the laser at any spot, trying to keep it stable

now try standing 6m away from the wall and point the laser at the same spot

what do u notice?
at 6m, a small movement of ur hand will shift the laser else where from the spot

same theory when shooting with telephoto. hope the explanation helps :)
:thumbsup: That's a good analogy man!.. heh
 

Jun 18, 2005
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#6
Thanx everybody. I've thought about it too, using pendulum oscillation as an analogy. But just to make sure so asked you guys.
 

drake336

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#7
vincenthau said:
your shutter speed must be at least 1/focal length.

for example, if your focal length is 200mm, you need at least 1/200 sec to minimise camera shake.

sometimes you need to push up the ISO or ASA if you are using AP mode
Heh, don't forget the crop factor if you using dSLRs! :D
 

Jun 18, 2005
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#8
And why is it so important to be more steady that regular shots for macro?
 

gryphon

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#9
drake336 said:
Heh, don't forget the crop factor if you using dSLRs! :D
Actually need not include the crop factor.
The crop factor does not change the distance of your focusing. The crop factor is due to the fact that your DSLR sensor is not big enough to capture the full image but capture part of the section. This will cause you to capture a zoomed in section of the image whereby "enlarging" it.
Just like when you have a photo but you crop towards the center, then your overall photo appears bigger.
 

roti_prata

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#10
gryphon said:
This will cause you to capture a zoomed in section of the image whereby "enlarging" it.
the blur is enlarged oso:thumbsd: this is different from cropping. try this, shoot at ur camera's max zoom at 1/20sec. then shoot at ur camera's widest end at the same shutter spd and crop to simulate ur max zoom. u'll see the difference in motion blur.
 

roti_prata

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#11
the 1/focal [rule] is conservative. with experience its possible to constantly shoot at half of tt [suggested] spd(not counting IS/VR).
 

donchua

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#12
drake336 said:
Heh, don't forget the crop factor if you using dSLRs! :D
This was in my mind too..
So if 500mm on 1.5X Crop = 750mm, so shutter must be 1/750 at least?
 

sk.images

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#13
donchua said:
This was in my mind too..
So if 500mm on 1.5X Crop = 750mm, so shutter must be 1/750 at least?
The focal length of a lens does not change with the crop factor, neither does perspective. The only that changes is the field of view (FOV), i.e. you see less of the image projected from the back of the lens. so for a 500mm lense, RoT is 1/500sec.
 

drake336

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#14
Correct, focal length and perspective doesn't change, but the image is nonetheless enlarged right?

A small blur which is acceptable in full frame will be magnified by the crop factor right. As such after cropping, you have a smaller image with the blur relatively more distinct, isn't it?

Anyways, I have been using 1 / (FL x cropfactor) all this while for hand hold
 

roti_prata

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#15
donchua said:
This was in my mind too..
So if 500mm on 1.5X Crop = 750mm, so shutter must be 1/750 at least?
lol if like tt u can only use ur bigma at 12nn or iso1600 w/o support:bsmilie:
 

gryphon

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#16
cyber_m0nkey said:
The focal length of a lens does not change with the crop factor, neither does perspective. The only that changes is the field of view (FOV), i.e. you see less of the image projected from the back of the lens. so for a 500mm lense, RoT is 1/500sec.
Yup thats right... now i know wat term to use "FOV"
 

donchua

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#17
roti_prata said:
lol if like tt u can only use ur bigma at 12nn or iso1600 w/o support:bsmilie:
Ok lah, 2 days ago I taken test pic of a airplane letting go white smoke flying
past my flat around 5plus pm at 500mm ISO400, f8, 1/1600.
 

Clockunder

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#18
cyber_m0nkey said:
The focal length of a lens does not change with the crop factor, neither does perspective. The only that changes is the field of view (FOV), i.e. you see less of the image projected from the back of the lens. so for a 500mm lense, RoT is 1/500sec.
Agree that the guide is still 1/focal length and don't have to take the crop factor into account.

For e.g., my Nikon Coolpix 5700 at max. 8x optical zoom has a focal length of 71.2mm which is equivalent to 280mm on the 35mm format. This is similar in calculation to how the focal lenght of lenses on DSLRs with APS sized sensors are multiplied by the crop factor to arrive at the 35mm format equivalent focal length. The crop factor on my camera is actually about 4x. I could easily shoot at 1/60 handheld fully zoom in since the actual focal is only 71.2mm. If the crop factor really needs to to taken into account, then the guide give 1/280 already at full zoom and shooting at 1/60 handheld at full zoom to get steady shots would be unthinkable already.

The crop factor only affects how large the image will appear on the frame (i.e. because of the difference in FOV). How the rays of light in the camera and lens will vary to cause handshake-blur images is only affected by the amount of handshake and the focal length (how long light have to travel in the lens and camera to reach the sensor) but not the crop factor.
 

drake336

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#19
Ok, we really need to confirm this... cos I am quite convince crop factor should be considered... here's my reasoning...

Picturing how light passes through the lens and get focused on the back (film or CCD/CMOS).

If we fit the same lens to both film and digital body and shoot the same object, light from the same point of an object will fall on the same position @ the back since focal length is the same.

Ok, now if our hand shake an equal amount during both shots, the point of light focused @ back will also be shifted equally for both shots, let's say X mm.

But when you consider, X mm on 35mm film and X mm on APS-size will mean different proportion of the entire image (i.e. smaller area = bigger proportion of blur), I really fail to understand how you can use the same guide line for 35mm film and smaller CCD/CMOS...
 

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