New Lens and Not Understanding...

[jamiedennis]

I bought Sony DT f1.8 Prime lens a few weeks ago and have been playing around with it since I got it... but I cant figure out why I have these weird occurrences.

The first image only has 1 eye in focus... Not sure why...
The second image I wanted the whole face to be in focus but only got a few parts.
The third image has a weird haze in it that I cant explain.
The fourth iamge only 1 eye is in focus again and half of her hair is in focus while the other half is not.

The settings were all the same:
ISO 200
75mm
f 1.8
1/100s

The light was from the ceiling fan and my on-camera flash.

Now, Im used to using my camera and have done weddings, school proms, and so on. So Im not sure why the above issues occurred... I have no formal training and all my knowledge is based on what I have gotten on the internet and/or from my asking people who have more skills then me.

Any advice would be great!!! Thanks.

[Dennismc]

Shooting at 1.8 at that distance you have a very very Short DOF. Hence the tight focal point and larger area Out of focus.

[doulahallie]

I think its because your shooting at f1.8..... Im not real knowledgeable, but its a depth of field issue from my understanding. Not sure about the pic with the weird haze maybe just being the on board flash lighting you up so much?

Sorry if this totally wrong, lol, just my first reaction to your questions when seeing your settings. Im learning myself!

[dalmorloson]

At f 1.8 your depth of field is very shallow. Either close the aperature more or move back from the subject to make the eyes both in focus. At the distance you are shooting from, the distance from the lens to each eye is different. If you move the subject farther away your depth of field will increase and you can get both in focus. The eyes will still be on the plane that they were but the relative difference is much smaller.
Most people have a general understanding that depth of field is the distance from near to far that an image "seems" to be in focus. This distance can be changed with different f values and distances from lens to subject. If you research depth of field you can get a better understanding of how and why you would want to "play" with different DOF.

[Tito87]

Here you go. Hope it gets you on the right track.Hyperfocal Distance and Depth of Field Calculator - DOFMaster

[jamiedennis]

Originally Posted by Tito87

Here you go. Hope it gets you on the right track.Hyperfocal Distance and Depth of Field Calculator - DOFMaster

Ok, so I got the program dl'd and am trying to set it up for my lens... but so far I cant get it to label f1.8 - which is what my Prime is... How do I go about doing that???

I think this thing will be a HUGE help once I get it figured out - but its just a question of whether or not I can figure it out... ahahaha

Thanks for this nifty app and your help!!!

[zona5101]

What Sony lens is 75mm f1.8?
Don't do the aps lens conversion for the calculator. Use 50mm.

[jamiedennis]

Originally Posted by zona5101

What Sony lens is 75mm f1.8?
Don't do the aps lens conversion for the calculator. Use 50mm.

Its the Sony DT 50mm SAM f1.8 Prime... But for what ever reason the exif data says 75mm...

[Tito87]

Originally Posted by jamiedennis

Ok, so I got the program dl'd and am trying to set it up for my lens... but so far I cant get it to label f1.8 - which is what my Prime is... How do I go about doing that???

I think this thing will be a HUGE help once I get it figured out - but its just a question of whether or not I can figure it out... ahahaha

Thanks for this nifty app and your help!!!

Do what Zona 5101 is asking you to do.

[jamiedennis]

Ok, so that site is awesome!
I now understand what I was doing wrong for the focus aspect - too far with such a small area to focus on. I should have gone up a stop or two to allow more to be in focus.

As for the haze on the one image... Still not really sure what happened in that one. Might be a random event, or something.