Back to the basics 3.5G (exclusively for Moon Cake Festival)

Maybe u wil realize Back to basics 3 i dint mention about upcoming topic
here is it.. same day, u get 2 moon cakes...
chinese says, good thing comes in pair

The topic is quite a basic and maybe it is totally useless to all of us.
Still, I try to tell a story on this

Manual focus is not history because it is still useful up to today
At least Macro shooting and sifu in portraiture still rely on it

while young man like me, I prefer Auto Focus
then i try to look for more info on AF because i find it is so amazing
how can a camera knows the exact distance between the sensor and the subject and then justify the focus locked?

so, the topic today is AF mechanism
Auto Focus needs an AF sensor hide inside the camera.. either left or right hand side when u look into the lens mount.
then, when we wanna do focusing, the aperture of our lens is closed at f/5.6-f/6
yes, this is while the hole is so narrow until u press the shutter button, only it opens wide or close narrower depends on the aperture u set at camera. and this also explain why fast lens have back focusing. because the blades open in very high speed, cause slight movements.

when the lens closed at f/5.6-f/6, the AF sensor emits an invisible ray to the desired AF point we choose, then the reflection of that ray will back to the sensor

this entire process takes less than milliseconds.
so, i really salute on Nikon 51 AF technology and rumours said, it is going to be 61 AF nx yr


Next topic (when i remember to post here)
The sharpest of your lens

Wow.. thanks for the mooncake festival special.. now i know something extra... Thanks and lpease keep it up~!

nice topic on AF... do you have any tips for MF... ?? would like to learn.. some of the time wanna use but can't get the right focus in time.. moment passed

actually for MF part i tot of doin it nx time
nvm, since u wanna know
i will share it now

Manual focus is quite a challenging part especially for ppl who breathe heavily like me.
I will suggest manual focus only at enough shutter speed. Refer to my another topic to know the reciprocal rule.
for example, using 50mm lens, shoot at 1/50 at least
by shooting at 1/5 is a risk unless your hand is steady like a tripod

shooting Manual focus is not a trial and error practise
u must be confident. unless you shoot landscape or macro then it is fine
if u shoot portrait, u will OOF a lot and start to get nervous bcoz the model already change her posing.

so, i see most of the Manual Focus pro users did few modification on their camera.

if u r using fast lens, f/2.8 or faster, change the focusing screen to match the lens. then u can see brighter and more details from the viewfinder

lastly, and this is the must do part. Get a 1.15X magnification glass to attach on your viewfinder.

all sifus, pls correct me if i m wrong
explanation above is made based on 1 fren who do macro and 1 fren who shoot model with MF only.

Just sharing wad i know but correct me if i'm wrong.

For macro shots normally i will using MF rather than AF, i think it's easier to do focusing by setting on focal length and move ur camera forward backward to get the correct focal point. Normally moving a little bit the focal point will be shifted quite a lot already so u can adjust and shoot fast.

For normal shooting using MF what i usually do is turn the apeture wide open to the max for focusing 1st and then step down to the DOF require after done the focusing and shots. It's because when the apeture is wide open the DOF will be very narrow so it's easier to monitor the focal poinf shifting.

Correct my if i'm wrong as i also in learning progress...

georgewong wrote:actually for MF part i tot of doin it nx time
nvm, since u wanna know
i will share it now

Manual focus is quite a challenging part especially for ppl who breathe heavily like me.
I will suggest manual focus only at enough shutter speed. Refer to my another topic to know the reciprocal rule.
for example, using 50mm lens, shoot at 1/50 at least
by shooting at 1/5 is a risk unless your hand is steady like a tripod

shooting Manual focus is not a trial and error practise
u must be confident. unless you shoot landscape or macro then it is fine
if u shoot portrait, u will OOF a lot and start to get nervous bcoz the model already change her posing.

so, i see most of the Manual Focus pro users did few modification on their camera.

if u r using fast lens, f/2.8 or faster, change the focusing screen to match the lens. then u can see brighter and more details from the viewfinder

lastly, and this is the must do part. Get a 1.15X magnification glass to attach on your viewfinder.

all sifus, pls correct me if i m wrong
explanation above is made based on 1 fren who do macro and 1 fren who shoot model with MF only.

Newbie question about the reciprocal rule, does it mean on a crop sensor 50mm = 75mm which means at least 1/75 shutter speed?

no, it is still 1/50
crop factor is for APSC or APSH user to untung a bit to hunt for gals

Why not?

50mm is like 75mm on a full frame. Full frame will need 1/75, why crop factor can maintain at 1/50 instead?

the lens itself is label 50mm
will it label change to 75mm when u put on D90? no rite?

http://www.tipsfromthetopfloor.com/forum/viewtopic.php?t=7913

Found my answers. Thanks anyways.

Another interesting webbie, http://singleservingphoto.com/2007/05/22/focal-length-reciprocal-rule/

weird, it is not the same as i was told
since there is web said that, i would say let consider both
PLAY safe is better
and i will stick with my 1/50 haha
thanks CY

Cause I was thinking,

What a full frame can frame on a 75mm is the same as what a crop sensor can frame at 50mm. So technically it is a 75mm equivalent, which means should be a 1/75 instead of 1/50.

Basically this is how I sort of understood it hehe.

georgewong wrote:when we wanna do focusing, the aperture of our lens is closed at f/5.6-f/6

hey bro
i tot the aperture is wide open (maximum) when focusing?
ie: if u using 24-70/2.8, the aperture is 2.8 all the time during focusing. When u press the DOF button, then the aperture only change to the desire size for previewing the DOF.
please correct me if i am wrong

erm, wat i know is if u change your focusing screen to a brighter one... it shows real DOF for fast lens. the rest may be vary on system we used