using 50mm 1.8 or larger aperture


#1
Hi,

i have got 1 newbie question...

i am using Canon 50mm f1.8 to show some portraits.

i am just trying to shoot only in f1.8

seems like i cannot have focus on the subject face.

eg. i focus on eye, but the other eye and nose will be out of focus(can see this when i zoom in).

the subject fill up around 1/3 area of my viewfinder.

is this consider normal? or any other tip to improve this(except for increasing f)

thanks.
 

fmeeran

New Member
Nov 5, 2010
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Clementi, Singapore
#2
i am just trying to shoot only in f1.8

seems like i cannot have focus on the subject face.

eg. i focus on eye, but the other eye and nose will be out of focus(can see this when i zoom in).

the subject fill up around 1/3 area of my viewfinder.
Uh... that's what the f/1.8 is supposed to do. It decreases depth of focus.

If you need more depth of focus so that you can get the whole face in focus, you need to decrease aperture and go to something like f/3.6 or f/6.

Else, you can try moving away fro the subject, but you will get more of the background in the picture.

Why you so insistent on shooting at f/1.8 anyway?
 

Kiwira

Senior Member
Aug 24, 2009
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#3
you have to position your model parallel to your plane to get both eyes in focus brudda :cheers:

the 50 1.8 is not very sharp wide open, try 2.8 and it'll make you smile haha
 

skyrn99

New Member
Apr 6, 2011
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#4
I assumed you are trying to get nice bokeh, that's what you get at f1.8, blurred foreground and background.
 

Cowseye

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Mar 7, 2010
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#5
I lean more towards that TS did not have enough lighting but wants to maintain enough shutter speed :p

I was like that before and end up all my shots are blur
 

#9
i have already used Canon speedlite...

the problem is only a very small area is in focus.

eg 2. i take snap on my pen. the point that i manual focus on(exmaple the cap), will be sharp, but further abit, like connection between cap and pen body will start to be blurred..

even if i increase my shutter speed to 1/200, f1.8 iso 100, it is still the same
T_T
 

voxies09

New Member
Apr 11, 2010
651
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Singapore
#10
i have already used Canon speedlite...

the problem is only a very small area is in focus.

eg 2. i take snap on my pen. the point that i manual focus on(exmaple the cap), will be sharp, but further abit, like connection between cap and pen body will start to be blurred..

even if i increase my shutter speed to 1/200, f1.8 iso 100, it is still the same
T_T
read this
 

Rashkae

Senior Member
Nov 28, 2005
19,105
12
0
#11
i have already used Canon speedlite...

the problem is only a very small area is in focus.

eg 2. i take snap on my pen. the point that i manual focus on(exmaple the cap), will be sharp, but further abit, like connection between cap and pen body will start to be blurred..

even if i increase my shutter speed to 1/200, f1.8 iso 100, it is still the same
T_T
Please don't be stubborn. Read what the others have posted! Your problems is NOT shutter speed, it's aperture! You need to stop using f/1.8 or know how to handle such a thin depth of field!!!
 

Mar 28, 2011
78
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0
Konoha Village
#12
Hi,

i have got 1 newbie question...

i am using Canon 50mm f1.8 to show some portraits.

i am just trying to shoot only in f1.8

seems like i cannot have focus on the subject face.

eg. i focus on eye, but the other eye and nose will be out of focus(can see this when i zoom in).

the subject fill up around 1/3 area of my viewfinder.

is this consider normal? or any other tip to improve this(except for increasing f)

thanks.
Hi Newbie here , I assume you are using the EF 50mm F1.8 Mark 2. I have this lens as well. Maybe you can share with us what is your shutter speed setting , mode of shooting (M , Av or Tv etc), type of focusing mode (one shot , Ai , servo etc.) .

Thanks.
 

catchlights

Moderator
Staff member
Sep 27, 2004
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Punggol, Singapore
www.foto-u.com
#13
i have already used Canon speedlite...

the problem is only a very small area is in focus.

eg 2. i take snap on my pen. the point that i manual focus on(exmaple the cap), will be sharp, but further abit, like connection between cap and pen body will start to be blurred..

even if i increase my shutter speed to 1/200, f1.8 iso 100, it is still the same
T_T
hello, please read the Photography Notes For Newbies, post #5.
 

Dec 11, 2010
948
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0
#14
i have already used Canon speedlite...

the problem is only a very small area is in focus.

eg 2. i take snap on my pen. the point that i manual focus on(exmaple the cap), will be sharp, but further abit, like connection between cap and pen body will start to be blurred..

even if i increase my shutter speed to 1/200, f1.8 iso 100, it is still the same
T_T
Hi there, why the insistent on using 1.8? I think you should up your aperture. Adjusting your shutterspeed, ISO, metering and adding a flash gun won't help your DOF, and no, neither would using a tripod. Your DOF is affected by the aperture size.

Try reading up some literature in DOF, or depth of field... might help you to realise why everyone's advice is about the same.

if you are really insist on 1.8, then re-position your subject such that the eyes lie on the same plane or reposition yourself. if you're concerned about bokeh, F2.8 can give you a bokeh too. try it before you crap it =)
 

Last edited:

kei1309

Senior Member
Apr 12, 2010
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#15
i believe Newbie just wants to use f1.8. bright conditions, dark conditions, just f1.8.

TS, to understand why your shots are all blurred at certain areas, you need to know what happens at f1.8.

firstly, your Depth of Field is very thin. you want more DoF, you need to stop down, or get your subject to move backwards.

don't be stubborn at sticking to f1.8

other than that, read up on all the links the seniors have given you.
 

Cowseye

Senior Member
Mar 7, 2010
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Singapore
www.ttlo-cowseye.com
#16
Sorry guys, I think it's my fault for the confusion. I think it's pretty common for one who had been shooting in F/3.5 and above to dive and try the wow capabilities of shooting at F/1.8.

The seniors here words are true. F/1.8 is a very thin DOF. I think you should test yourself by shooting the same subject at different F-stop starting from F/5.6 to F/1.8. Your magic F-stop should be somewhere in the middle. Of course, once the subject move or you re-compose, things might change. Experiment and try. Be like a scientist in photography, it's the fun part as well.
 

Diavonex

Senior Member
Sep 23, 2008
3,641
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Admiralty
#17
mokkinhong, see these 2 samples to better understand your problem.

First picture taken with F1.8

Second picture taken with F16



 

Rashkae

Senior Member
Nov 28, 2005
19,105
12
0
#18
Please also note that every DSLR camera manual out there, when you flip to the section about Aperture, will also tell you about DOF.

In other words, RTFM. :)
 

#19
mokkinhong, see these 2 samples to better understand your problem.

First picture taken with F1.8

Second picture taken with F16



Thanks for all the reply.
be it you all understand my question or not.

this little orange picture really speak out!

my question is only the central part of the orange is in focus. other part all consider out of focus(around maybe 20% at central).
this is consider normal?

by the way, i do know how aperture works.. that's why i ask is there any other tips that i can use if i would like to stick to f1.8 and get more things in focus(ass the focus area is that small).

other lens at f1.8 will also have the same result? ==> just curious whether it is my lens problem...

seems like there is none, except for increasing aperture~
 

Rashkae

Senior Member
Nov 28, 2005
19,105
12
0
#20
Thanks for all the reply.
be it you all understand my question or not.

this little orange picture really speak out!

my question is only the central part of the orange is in focus. other part all consider out of focus(around maybe 20% at central).
this is consider normal?

by the way, i do know how aperture works.. that's why i ask is there any other tips that i can use if i would like to stick to f1.8 and get more things in focus(ass the focus area is that small).

other lens at f1.8 will also have the same result? ==> just curious whether it is my lens problem...

seems like there is none, except for increasing aperture~
If you DO know how aperture works, you would NOT be asking those questions or saying it's a lens problem! So it is obvious you do NOT understand how aperture works. If you did understand it, you would also know that distance and focal length play a part as well (so if you switch to a 135mm f/1.8 or stand further away from your subject you'll get a different DOF).