[si-motion]

Hi all ching,

I have never used Canon before and want to try 5d mkii, but the question always in my mind is that with only 9 focus points and so closely packed in the middle of the frame, how do you all ching ensure the subject outside of the focus points area will be in focus? In my mind it will seem almost impossible if using lens with aperture like 1.2 or 1.4... do you have to manual focus to compensate??

Thanks very much....

[william_lau]

用其中一point（中間，或最接近你想影主體嗰個對焦點）半按快門，唔好放手，咁就會鎖實個對焦點，然得移動相機再構圖影相。

[waving_odd]

william_lau:

> 用其中一point（中間)... 半按快門，唔好放手，咁就會鎖實個對焦點，然得移動相機再構圖影相

si-motion said he has concern on focusing with an ultra-thin DOF at 1.2 / 1.4.

> it will seem almost impossible if using lens with aperture like 1.2 or 1.4...

If you just use the central AF point, lock-focusing a subject in the center and then reframing the subject to the edge under DOF at 1.2 / 1.4 is **likely** to have your subject out of DOF, hence out-of-focus.

But what you said about "最接近你想影主體嗰個對焦點" is more correct.

What you can do for ultimate sharp focusing on 5D2 (Only when you can take your time on focusing subject, e.g. posing a model. If you are snapshooting some quick moments, it won't work coz it's too slow) is:

1. use tripod if possible

2. 用最接近你想影主體嗰個對焦點, 半按快門，唔好放手，咁就會鎖實個對焦點，然得移動相機再構圖影相

3. switch to Live View

4. zoom 10x on your subject's face or eyes or whatever area (assuming your subject is a person)

5. MF to adjust

6. take the shot

[waving_odd]

> 5. MF to adjust

5. switch from AF to MF to adjust

[叮噹仔]

大光圈定焦, 大多都有全時手動對焦
首先好似上面c hing咁講,
對焦, 構圖, 之後再微調焦距,

並唔需要轉用MF!!

另外, 好似有樣野叫裂像對焦屏咁既野,
對手動對焦, 有一定既用處,
不過我未用過~

[look_yau]

>>> 用其中一point（中間)... 半按快門，唔好放手，咁就會鎖實個對焦點，然得移動相機再構圖影相

x2 - 用得多就冇問題

[si-motion]

Thank you everyone.... looks like it does require a bit of manual work to get razor sharp photo on the 5dmii with big aperture lens....

Hopefully the new 5D will have some additional focus points...

[waving_odd]

> 並唔需要轉用MF

only if you are still locking the focus by pushing the shutter halfway down...

> 用得多就冇問題

right - it's usually not a big deal in practice...

> looks like it does require a bit of manual work
> to get razor sharp photo on the 5dmii with big aperture lens

not really - unless you are ultra picky... i won't usually go too crazy in MF except when playing with my Tilt Shift to get everything in focus!

> Hopefully the new 5D will have some additional focus points

unlikely to happen! even if it does, it's not 5D3. it will be called 1Ds4 and you have to pay a premium for that.

[waving_odd]

> 並唔需要轉用MF

only if you are still locking the focus by pushing the shutter halfway down... what i meant is that you let go of the shutter button after AF has initially done its job. then you reframe (no button is pressed at this point). therefore there is no full-time MF now. then the rest of zoom-in on live view and MF are just some techniques that are commonly used by photogs who shoot with Tilt Shift a lot.

> 好似有樣野叫裂像對焦屏咁既野

it's still good for subject in the center only. it's not too relevant to original poster's concern of reframing the subject after being focused...

[si-motion]

waving_odd.....

Thanks... but how come so certain that new auto focus system won't be on 5D3? Don't hate me for saying this... but Nikon is very good in this aspect, having 51 ponits... at least is good for people who are like me, very picky on sharp focus (I use 1.4 lens a lot)

[ks chung]

To 樓主,
亞waving_odd是無講錯. 當你玩番幾年Canon之後你知. 你講的point就是Canon和Nikon的分别喇!!!

[hkklchan]

影人單點對焦就夠..
其實如果影花,動物, 或者影其他任何野..全相都係清, 咁D人點解要大光圈散景??
咁多點係影賽車果D先有用..影相要有目的, 重點, 用相..表達..你所想既野, 想紀錄既野先係重要.

[photowing]

雖然51點得15 點為十字可選自動對焦點雖然小D
但手動對焦就可用晒51個對焦點

如果canon都出多D只對應手動的話都幾好

[Obi-Wan]

http://visual-vacations.com/Photography/focus-recompose_sucks.htm

[si-motion]

Obi-wan....great, that's exact my point along the way.

hkklchan, i think you mis-understood my meaning. Having many focus points is not to get everything sharp, it is so that we could use more area of the frame to pin-point the object that we need to be sharp and not needing to recompose as much. And that's why I said the 9-points on 5dm2 creates a limitation/issue when using wide aperture lens (unless it involves some additional focus adjustment).