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Danielle10
08-12-2010, 7:33am
My 50mm f1.8.

So, I was playing with my new toy last night and trying to get some shots of our chrissy tree (for fun) there was low light and I was trying to add light with exposure compensation but it still came out a bit blurry coz the shutter speed wasnt quick enough. I was on Apperture setting of f1.8 (thinking this would allow more light to come in) but it wasnt doing what I thought it would do. i pumped up the ISO to 400 and 800 but still didnt make a difference. well, maybe a bit but not what I expected, What am i doing wrong?

i was hoping to use this lens when i go to gigs to get shots of bands ect with no flash.

Can someone please shed some "light" on this for me (scuse the pun LOL)

and also any other tips on getting the most out of this lens would be FABULOUS
Cheers

kiwi
08-12-2010, 8:07am
I think going through the lessons in the ntp program will help

Your exposure is determined by shutter speed, aperture and iso in combination

Each time you double your iso your shutter speed will also double if your apperture remains constant

If you are handholding I'd recommend a minimum shutter speed of 1/100s whilst learning

Wayne
08-12-2010, 8:11am
For really low light, a tripod is essential. Think that the 1.8 aperture will let more light in that say an f4 max aperture, but you need to consider how many stops of additional light.

If you shoot at say f5.6 in aperture priority mode and get a shutter speed of 1/100, then the wider apertures of a smaller f-number will allow more light in and thus a faster shutter speed. Each extra full stop of light, will offer approx double the shutter speed.
eg;

As above at f4 will give a s/s of 1/200
f2.8 = 1/400
f2 = 1/800
f1.4 = 1600

you can see this affect by pointing your camera (best on tripod) at an object and using aperture priority, set the f/stop to f8 and look at the shutter speed it gives, then change aperture to f4 and look at shutter speed again and so on.

If you have Lightroom or an application that will show you the exposure values a pic was taken with, then you can look through your library for a blurry one that you feel needs more light to increase the shutter speed, and look at the aperture value and s/s that was used to take it. Now you have that info, calculate the shutter speed you would likely get from opening up your aperture to the f1.8 of the 50mm see if that is suitable for the shot to freeze movement etc.

William
08-12-2010, 1:54pm
Hi Danielle, You should be able to get it , This was taken with my 8.2 mp 30D in full manual, ISO 800. f 1.8 , 1/80th sec outside @ 10pm with a yellow Fluro Light with my 50mm 1.8 , Hand Held , After a few beers the day I got the lens , Just testing

LJG
08-12-2010, 1:58pm
The other thing is the nifty fifty at f1.8 has a very narrow depth of field, so only a small portion of the image will be in focus. Also working against you is the fact they are not a sharp lens wide open either. Mine does not get sharp till it is higher, well in to the 2's. That is one reason why I brought an f1.4 instead.

*EDIT, you just beat me William. Yours is a pretty close in shot featuring a small area, I am assuming Danielle is standing back so she gets the whole tree in, so at f1.8 it is never going to have a wide area of focus, just the area around the focus point only.

William
08-12-2010, 2:21pm
Yep mine was taken pretty well at the Min Focus distance , And yes what you said is true about standing back, Very shallow DOF at f 1.8 , So everything other than the focus point will be Out of focus , You just have to learn how to control it to an advantage ;)

Danielle10
09-12-2010, 7:40pm
I am assuming Danielle is standing back so she gets the whole tree in, so at f1.8 it is never going to have a wide area of focus, just the area around the focus point only.

No i was up close getting a shot of a bauble thing. I'll put up some pics soon for some CC - so I can work out what the hell im doing LOL

I get the focus points and that at 1.8 its very narrow. Anyway, im just playing and hoping for the best. I sure the penny will drop soon

Thanks for your help everyone