Help me with this lens!

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ButtonsMama's picture
Joined: 12/05/05
Posts: 283
Help me with this lens!

Ok - so, I got my 50 1.4 today and was playing with it tonight at Abby's ballet class. I LOOOOVE how it helps with my indoor shots! And I love the really pretty bokeh that it makes. As I suspected, though, I'm having trouble nailing focus. I'm toggling my AF point, and even with that, it's SO much harder to get those eyes sharp with such a wide open ap. So, help me out - what are your secrets? Here's a few from tonight.

1/250; f/2; ISO 100; 50mm

1/100; f/2; ISO 400; 50mm

This is the best one, I think:
1/160; f/2.2; ISO 400; 50mm

Joined: 10/20/07
Posts: 480

A HUGE part of focus is shutter speed and exposure. For a moving kiddo (and most adults) my SS is rarely below 250. I would rather raise my ISO than sacrafice SS in most cases. I am not sure what happened with the first one, it looks like the focus his his forehead, but my guess is SS and underexposer on the second. The third has harsher light, and the comp is lacking, but focus is much better.

CJWilkes's picture
Joined: 01/04/09
Posts: 880

I agree - raise your iso and speed up your ss.

Joined: 04/23/06
Posts: 485

I just got my 50 mm 1.8, and I am having the same issues. I think the girls are right about the ss, and I also think it's just going to take some serious practice to get those eyes tack sharp.
Love #2, such a sweet photo!

ButtonsMama's picture
Joined: 12/05/05
Posts: 283

Ahhhh - I never realized that ISO would play into the focus. Very interesting. So, as you open up your ap, you have to increase SS and ISO along with it - am I getting that correctly?

Oh, and I know my comp sucks on most of those - they're just snaps, really. I'm really trying to figure out how to get focus on the eyes with this lens before my shoot tomorrow morning. I'll be so mad at myself if I get them home and everything is OOF. There is a bit of a learning curve when you go from a kit lens to a 50mm 1.4!

mlark1128's picture
Joined: 05/09/07
Posts: 742

Shooting wide open also just takes a lot of practice. If your subject moves just a little bit once you've focused your lens you'll end up with an OOF picture. So the best bet is to properly expose with a high shutter speed, and then be pretty quick. Smile It just takes practice, practice practice though. You'll get there! Smile

Joined: 10/26/01
Posts: 3467

I don't have anything new to add - practice, practice, practice!

But have fun and don't worry too much! Also, remember that you can still get really nice bokeh with a smaller aperture, so when in doubt, just close up a little more (say as much as f/3.5). You'll find w/ the faster lenses like that one that even when you close up a bit more, if you pay attention to distance - between camera and subject as well as between subject and background - you can still get very nice results.

Have fun!


La123's picture
Joined: 04/11/08
Posts: 815

My suggestion is to close up a little more. Lenses are usually sharpest a few stops up from wide open. Try shooting at at least f2.0. Another thing that helped me is to re-focus each shot... even if you and your subject are in the same spot. Remember that the lens will not always focus at the exact spot your focal point is on. It will focus to the closest contrasty area that grabs it, so you really have to force it. I find having great light in the eyes helps too. I hope this made sense.... Smile

JDBabyHopes's picture
Joined: 02/16/09
Posts: 1149

Everyone gave some great suggestions! I've had my 50mm 1.8 for a month, now, and I'm still getting used to it! Are you focusing and recomposing, or toggling? I've found (and read on a few photog blogs) that when you're wide open like that (even up to 2.8 or so), you want to compose and toggle instead of focusing and recomposing. Any little jostle at that ap can send your image soft. I had to reconfigure myself for that! I was a focus and recompose gal, but I've since become a toggler.

And yeah, practice practice practice! Unfortunately, small children are difficult practice subjects for a lens like that! Wink I try to shoot DS (14 months) around 3.5-4.0 to give myself some padding, but that's simply because the word 'still' is not in his vocabulary!

Good luck with it! Smile