Hard time focusing 50mm/f1.8

[matt62485]

So I recently got a 50mm/f1.8 for my D40, fully aware it would not autofocus on this body. However, I'm having one hell of a time getting this thing to focus. Being a prime with a fixed focal length and no auto focus, is a tripod neccessary to really make this thing shine?

Any advice?

 

[Goontz]

Tripod isn't necessary, but sometimes just the amount you "sway" while holding it can throw the focus off and it can be especially hard to nail focus with real large apertures. Are you aware of the focus light in the bottom-left corner of your viewfinder that tells you when you're in focus?

 

[KmH]

Kevin raises a good point.

At f/1.8 your DOF (depth-of-field) will be shallow. Very shallow if you are close to your subject.
According to DOF Master at f/1.8 and 2 feet from your point of focus your total DOF is only .03 feet or about 1/3 rd of an inch and 1/2 of that is in front of the focus point and 1/2 is behind the focus point.

If you move back to 10 feet from the point of focus, with the aperture at f/1.8 the total DOF is now about 16 inches for the same aperture.

 

[Big Mike]

and 1/2 of that is in front of the focus point and 1/2 is behind the focus point.

Actually I think it's closer to 2/3 behind the focus point and 1/3 in front....but who's counting?

 

[matt62485]

good gracious. no wonder, that makes perfectly good sense. thanks!

and Goontz, yes I'm aware of it, thats what I go by and 99% of the time, upclose at f1.8 its such a slight bump of the focus ring, it kinda of blinks in and out bc im apparently not to steadhand

 

[KmH]

and 1/2 of that is in front of the focus point and 1/2 is behind the focus point.

Actually I think it's closer to 2/3 behind the focus point and 1/3 in front....but who's counting?

As a general rule, but at short working distances and wide apertures (2 feet at f/1.8) it's virtually 50/50.

 

[shanemono4]

Tripod isn't necessary, but sometimes just the amount you "sway" while holding it can throw the focus off and it can be especially hard to nail focus with real large apertures. Are you aware of the focus light in the bottom-left corner of your viewfinder that tells you when you're in focus?

can you tell me more about this focus light in the bottom left corner? Is it d40 specific?

 

[SushiWarrior]

It's a light in the bottom left corner of the screen - it'll flash green. My technique is setting it on continuous shooting mode and taking a burst while moving the ring, which generally gets at least 1 in focus shot.