f1.8 or f2.8??

[slardar]

Hi all.. i have a 50mm f1.8 lens, and im quite confused about the apertures.. under what circumstances will you use 1.8 or 2.8?

For those who dont wanna read, Concluding my question, for the 3 scenarios below, just between 1.8 and 2.8, which will you use?:
1. Good light (daytime)
2. Bad light (night time/indoor, cant use flash)
3. Using flash


Really need advice from the pros here..
Sorry for the long winded post, but i have to get things right..


Am i right to say that
at 1.8
- faster shutter speed allowed (since more light are let in)
- smaller dof, better bokeh
- dof too small, easy to get oof
- good for isolation of subjects
- good when taking photos in low light, where hand shake is a problem due to slow
shutter speed

However, i started comparing f1.8 with f2.8, and found f2.8 to be sharper and brighter than f1.8. Pictures look more appealing at f2.8.. Also, when taking photos with flash, those at f2.8 are brighter than those at f1.8. Is this normal? I will post comparison photos if required.

Thanks a million

[zac08]

f2.8 is stopped down and thus you'd get better sharpness and image quality than from wide open at f1.8

And when you use flash, there is already light from the flashgun itself and thus, you can even stop down lower to say f4 or f5.6 to get better DOF and image quality.

[slardar]

thanks for the quick reply.
ahh.. so its best to use f2.8 for most circumstances?
and use 1.8 only when the lighting is very poor or when theres a need to isolate subjects?

ive always heard people talking about the POWER of the 50mm f1.8, and posting uber sharp photos taken with it. Thats why i wanna know the optimum settings for it.

Thanks once again.

[ExplorerZ]

Originally Posted by slardar thanks for the quick reply. ahh.. so its best to use f2.8 for most circumstances? and use 1.8 only when the lighting is very poor or when theres a need to isolate subjects? ive always heard people talking about the POWER of the 50mm f1.8, and posting uber sharp photos taken with it. Thats why i wanna know the optimum settings for it. Thanks once again.

try them out yourself... it is 101% better than listening to anyone here. Try to understand when you will really need f1.8 and when to choose between f1.8 or 2.8

[loadingbay]

I have a question too.
For f1.8 or f2.8 which is more expensive ?

[ExplorerZ]

Originally Posted by loadingbay I have a question too. For f1.8 or f2.8 which is more expensive ?

what do you think? ain't it obvious? provided this is the only variable.

[slardar]

yeah, i guess i have lots to learn.. for now, from some test shots taken at home, i prefer shots at f2.8.
I gotta go out experiment by taking more real-world shots..

[zac08]

Originally Posted by slardar yeah, i guess i have lots to learn.. for now, from some test shots taken at home, i prefer shots at f2.8. I gotta go out experiment by taking more real-world shots..

Well, you got your answer... even in dim light, I normally will still take pics at at least 1 stop smaller thant the maximum wide. E.g. f2.8 with a f1.8 lens and f4 with a f2.8 lens...

[slardar]

Quote: Well, you got your answer... even in dim light, I normally will still take pics at at least 1 stop smaller thant the maximum wide. E.g. f2.8 with a f1.8 lens and f4 with a f2.8 lens...

i see.. i took many pics at chinatown at f1.8 cos i saw yilishengxian taking mostly at f1.8 with what he called The One Lens. Hoped to get the results similar to his, but guess my skill is still waaaaay lousier. lol..

1 photo to share at f1.8.

[zoossh]

both are fast lens capable of shortening shutter duration. the overall brightness depends on your metering, exposure compensation and PASM mode.

what differs is the depth of field. depends on your focus subject, if perpendicular, can use 1.8. if straddle across a distance, 2.8 or more.

[zac08]

You'd like to try f1.8 with a f1.4 lens... Also do take care on the handshake and very shallow DOF.

[slardar]

i think f1.4 is too shallow for my needs..
At the completely same settings (iso, exposure, metering etc), same focal length and same aperture, i found that the 50mm took much better pic compared to the 18-70mm kit lens at 50mm. Now i know why prime lens are so highly rated. Haha..

[Vulpix0r]

BTW, just to answer the TS, aperture does not affect the quality of the bokeh. Many factors will affect the quality of a photo's bokeh, but most of the time it's the quality of the lens.

[slardar]

Quote: BTW, just to answer the TS, aperture does not affect the quality of the bokeh. Many factors will affect the quality of a photo's bokeh, but most of the time it's the quality of the lens.

oh! thanks for enlightening me! Ive always thought that the wider the aperture, the smaller the dof which leads to a better bokeh.. I see.. So a small dof doesnt always mean the bokeh is good, just that its blur.

thanks

[ExplorerZ]

Originally Posted by Vulpix0r BTW, just to answer the TS, aperture does not affect the quality of the bokeh. Many factors will affect the quality of a photo's bokeh, but most of the time it's the quality of the lens.

actually it does affect, if you aperture diaphragm ain't a perfect circle, stopping down the lens might cause bokeh of spot of light to be in hexagon shape or etc.

[Youhong]

Originally Posted by slardar ive always heard people talking about the POWER of the 50mm f1.8, and posting uber sharp photos taken with it. Thats why i wanna know the optimum settings for it. Thanks once again.

You should look at the pro's pictures... Really an expert of 50mm...
http://www.pbase.com/teetoo/root

[slardar]

cool.. thanks for the weblink.
Certainly gives me the "push" to explore and experiment the lens in-depth