Depth of field with a f/1.4 lens

Hello. This may seem like a dumb question, but I don't have a f/1.4 lens to experiment with.

Is it possible to use a lens like this (Sigma 30 1.4 or Canon 50 1.4) wide open (or close to it) and get a person's entire face in focus? At least, both eyes?

I pretty much just take pictures of family & friends. I love my two lenses, but just thought it might be fun to play with a f/1.4 lens. However, I don't want to waste my money. This is just my opinion, but buying a 30mm 1.4 lens and using it at f/2.5 is a waste of my money b/c my Tamron can do 30mm 2.8 and it is super sharp.

Thanks for any input. I appreciate your wisdom.

marmatt1218 wrote in post #12921879
Is it possible to use a lens like this (Sigma 30 1.4 or Canon 50 1.4) wide open (or close to it) and get a person's entire face in focus? At least, both eyes?

You can use a depth of field calculator such as this On-line Depth of Field Calculator to experiment with distances, focal lengths, and aperture settings and see the results of different choices. Make sure you get your camera format entered into the calculator (by entering your camera model).

As always with DoF, shooting distance will be important - the further away you are from your subject, the more DoF you'll have to work with. As far as getting both eyes in focus, yes - this can be done even if you're pretty close to the subject, but the subject is facing you, ie - both eyes are in the same plane.

Haven't you already experienced this with your 85 f/1.8?

Simple answer.... yes.

http://www.dofmaster.c​om/dofjs.html


But, make sure that you're buying a lens for the right reasons... if you're happy with your current lenses... and happy with their sharpness...

hahha

i was going to say the same thing

have the person facing you square on and both eyes will be in focus

if you have an ipod touch or iphone, look up simple dof in the app store. it's $2 and is very handy for depth of field calcuations.

http://itunes.apple.co​m …22730&mt=8&ign-mpt=uo%3D6

Certainly can be done from the right shooting distance. How much of the frame will be filled with just the face may be another thing.

http://www.dofmaster.c​om/dofjs.html is an online calculator which shows that with a 50mm 1.4 lens at 7 feet you will have around 3.76 inches of dof so you could get a person's nose to the front of their ear in focus. Assuming a straight on, driver's license type shot.

http://www.tawbaware.c​om/maxlyons/calc.htm Dimensional Field of View Calculator shows that at 7 feet and 50mm you will have a view of about 2 feet by 3 feet.... so you could take a tight head/shoulder shot and have the entire face in focus.

Now pixel peeping at 100% will most likely show that everything is not as sharp as you might like but the entire face will be inside the depth of field.....

Edit: WOW! Everyone is fast on the draw this morning! I started this when no one had posted and now I am way down on the thread. Advice all seems to be similar though.....

John

Thanks for the depth of field calculator link. That's neat. I'll enter in some numbers to see how this all works.

Most of my pics are of kids - candids - so getting both eyes square to the camera would be tough!

It is true that I tend to use my 85mm at 2.0-2.5 when taking pics of one person.

PWard wrote in post #12921937
if you have an ipod touch or iphone, look up simple dof in the app store. it's $2 and is very handy for depth of field calcuations.

http://itunes.apple.co​m …22730&mt=8&ign-mpt=uo%3D6

If you have an Android based phone, a good tool is PhoforPho ... it's free in the Marketplace.

https://market.android​.com …tes&feature=sea​rch_result