Depth of Field

Schlemm

Howdy people,

2 very basic questions about DoF:

Does anyone know how to tell how much is in focus from reading the settings on your lens?
I am trying to teach myself depth of field (using a very old autoreflex tc, the lens on it looks like this http://mshoup.us/wp-content/uploads/2008/03/imgp1046.jpg but I can't figure out for the life of me how much is going to be in focus when I change the aperture).

and...

To change the exposure, I am roughly using an exposure chart and trial and error! The lightmeter doesn't change when I change the aperture (should it?). How to you estimate what shutter speed to use when you change the aperture?
I consulted the internet and felt like I was back in leaving cert physics, waaaaaay out of my depth (har har) so I guess any very practical tips would be welcome!

Soz about the silly questions, I am trying to figure DoF out with a lot of trial and error...I literally have to write down what I do for every shot and take it a bunch of times with different settings, any DoF successes I've had have been by accident so I guess I just wanna figure out how to get around that!

Cheers folks! :pac:

Stephen

Does that camera have a DOF preview button? Not familiar with old film stuff at all, but if it does that will cause the aperture to close to whatever you have it set to so you can see what the result should be like through the viewfinder.

ThOnda

That lens does not have marks showing you depth of field, as far as I can see. You would have to use some charts.

AnCatDubh

try www.dofmaster.com for understanding of DOF. put a few focal lengths / apertures / distances into the online calculator and study the results. to find out exactly - this is what you need to do. eventually you will get more comfortable with it and 'know' that f9-f11 is good for portraits, f11-f22 for landscapes, and f1.4-f5.6 for very narrow DOF.

i'd recommend picking up 'understanding exposure' if you can or request it at the local library.

ThOnda

If you are looking for very long DoF, try some wide lenses :-)

nilhg

This site has some examples of how to use the DO scales on your lens, looks quite similar to the example you linked to.

Also a quick and dirty guide to guessing your exposure based on the sunny 16 rule.

melekalikimaka

As I recall from a very quick lecture, correct me if wrong, If the dog is say 10 cm when a meter away, it doubles for ever meter you step back?

ThOnda

mele...: It varries on sensor/film size and focal length of the lense. It is very hardware dependant.

CabanSail

The lens in that link has DOF marks on it to show you roughly what will be in focus for a shot.

The front ring is the focus, on the lens is set to a bit under 7 meters (Meters in White, Feet in Yellow)

The ring closest to the body is to set Aperture, in this case set to AE which will give Auto Exposure in a similar way to Shutter Priority on a more modern camera.

In between the two rings there are some markings. There is a Red Line in the middle & on either side it reads 4 8 16 22. If you have the lens set to f16 then & the lens if focused as it is now, then everything from 2 Meters to Infinity will be the Depth of Field. Change it to f4 & it will now be from about 5 Meters to 7.5 Meters.

As to the light meter, it may be faulty on an older camera like that. If you leave it on AE then it will compensate the Aperture to suit the light as far as possible so will not vary.

ThOnda

We are looking for marking on the lens like this or this. But I really cannot see it on the pictured lens.

CabanSail

The numbers are there but no lines.

quilmore

just see what distance is right opposed to the f number on the second ring

for instance, your focus on that picture is at just before 7 meters, if you're doing f8 the DOF will go from 10 feet (3 meters) to infinity

btw, I still have my dad's camera, exactly the same as the picture, including the same lens, nice to remember it as it was the first camera I ever used

Schlemm

brilliant thanks for all the replies folks! Plenty of food for thought.
I guess it's a learning curve...maybe some day the L-plates will come off my camera hehe!

@quilmore...it's my Dad's old camera too! Held together with duct tape, the winder gets stuck sometimes at the end of the roll (often with interesting results when the pics are developed if you're lucky) and is missing the flash, but it's doing the job until I get a fancy pants dslr someday! Absolutely love it, it's taught me so much.

Thanks again!

quilmore

built in flash you mean?

I still have the old national PE-3066G in use with a brolly and use it almost every day
it has a cord that plugs to the side of the camera and a bracket that screws to the tripod mount

I have to admit I've missed the focusing point so many times with that camera that nearly put me off photography all together (I'm not a MF person...)