Hyperfocal Distance (for dummies)

Sigma 18-200mm f/3.5-6.3 DC for Canon

05/02/2007 08:17:20 AM · #1

Hi,

Got hold of a 5D and Sigma 12-24 EX DG. Ive been looking at the hyperfocal distance calculator (on-line somewhere) and to be honest.......I have no Idea what Im doing!! My main interest is wide angle landscapes (hence the 12-24). If I want to get EVERYTHING in focus near to far and the sharpest Apeture seems to be F9 - how far should I set the focus ring.....??

Thanks

Tim

Nigel

Canon EOS-40D

05/02/2007 08:27:41 AM · #2

The hyper focal distance is 1.79ft at 12mm (according to www.dofmaster.com/dofjs.html ) - wide angle lenses have a large dof

Edited to add: If you set the focus ring at 1.79ft, everything will be in focus from 0.895ft to infinity.

Message edited by author 2007-05-02 08:31:46.

goc

Apple iPhone 4

05/02/2007 08:59:01 AM · #3

interesting ! the link > //www.dofmaster.com/dofjs.html

hankk

Sigma 24-70mm f/2.8 EX Aspherical DF for Canon

05/02/2007 12:28:06 PM · #4

I've got the 5D and 12-24. There is a DOF scale on the lens for the 12mm lens length. Just set the aperature for f/9, and look on the lens body near the scale for the two number "8"s. f/9 will be a little wider than they are, but the numbers inside the scale show focal distance. If you set the infinity mark over the "8" on the right, then look over the "8" o the left to find the near focus point (between 1.25 and 1.5 feet). You can also set the distance to the closest item over the "8" on the left, but don't move infinity to the left of the bar in the center (which at f/8 gives about 2 1/4 feet for the close focus distance.

I guess in other words, focus almost doesn't matter at f/9. Also, I've found f/16 gives ok results. You get a whole lot more DOF at f/16 :-)

05/03/2007 08:38:50 AM · #5

Great advice guys,

Will attempt this evening.......!

Tim

05/03/2007 09:03:19 AM · #6

A bit of practical advice... the linked DoF calculator is a fantastic tool, but in practical use, if you want objects near infinity to be crisp, you need to change one of their assumptions. Instead of selecting the camera from the list, select "CoC = 0.016mm." This is a more conservative setting, and you should find it gives you better results. For example, selecting the camera (CoC 0.030mm), 12mm, and f/9, the hyperfocal distance is 1.7 feet. Selecting 0.016mm instead, the distance becomes 3.3 feet. Try both settings and see what you get.

Sigma 18-200mm f/3.5-6.3 DC for Canon

05/06/2007 05:26:46 AM · #7

Originally posted by hankk:

So, if you set the apeture at f/16, and f-length of 12mm where do you set the focus ring ? Are you saying that you can set the focus ring almost anywhere to get infinate Dof sharpness???

Still confused..... :)

Tim

Nigel

Canon EOS-40D

05/06/2007 06:43:49 AM · #8

Yes, with a setting of f/16 at 12mm and the focus ring set to the hfd ( 1.02ft with a coc of 0.030), everything will be in focus from 0.66ft (half of the hfd) to infinity.

If you compare that to setting the focus ring to infinity the dof will be from 0.98ft to infinity. So at f/16 the focus ring is virtually redundant.

Depth of field is reduced with wider apertures and longer focal lengths. When using a 50mm lens the dof will be much less than the 12mm lens, so setting the focus ring to the hfd will maximise the dof, whilst maintaining focus at infinity.

Message edited by author 2007-05-06 06:46:45.

datcat

Canon EOS-5D Mark II

05/06/2007 07:17:42 AM · #9

Edited to remove link to an article on depth of field, which makes it very easy to grasp, I came across it via a camera club but searching around I found that it is actually a pay to view lesson. don't want to step on any toes. Its at a site called exposure36 anyways.

Message edited by author 2007-05-06 08:21:15.

05/06/2007 08:46:22 AM · #10

Here, on the same site as the previously-linked online calculator, is a page with some articles on DoF and hyperfocal distance.

hankk

Sigma 24-70mm f/2.8 EX Aspherical DF for Canon

05/06/2007 09:16:44 PM · #11

Another thing to consider is what you will do with the resulting images.

If you are printing at 16x24, DOF is shallower than if you print at 4x6 -- this relates to circle of confusion, or COF.

If you are downsizing for display on the web, your DOF gets wider.

As far as f/16 goes, I'd say set the lens to focus on the most interesting thing, but still keep near and far in the DOF range. For example, lets say there's an old water pump is 12 feet away, and a bard 35 feet away, and there are some trees on the horizon. If you want to shoot the barn, focus on that. The pump will still be in focus. If the pump is more important, focus on that. Everything will be in focus unless you crop severely or make a barn sized print.

Message edited by author 2007-05-06 21:21:30.

Canon EF 100mm f/2.8 USM Macro

05/06/2007 09:35:59 PM · #12

Originally posted by hankk:

True, and true. Often, though, we don't have our ultimate use for the image clearly in mind when we shoot, or we decide later that something originally intended only for the web, or small prints, needs to be printed larger.
Because of these situations, It's my recommendation that:
1.) The photographer choose a CoC that maintains sharpness at 100% on-screen view (the smallest CoC it really makes sense to use). This is the basis of my suggestion of twice the sensor pixel pitch. For the technically inclined, this is derived from the Nyquist limit.
2.) Set the hyperfocal distance and verify the sharpness for both near and far objects on the LCD on a test shot before beginning to shoot the pano.

alexgarcia

Canon EOS-350D Rebel XT

05/13/2007 07:47:16 AM · #13

So kirbic, you recommend that in my Canon 350D I should use 0.010 instead of 0.019?

Thanks.

Ã�lex

Originally posted by kirbic:

Originally posted by hankk:
Another thing to consider is what you will do with the resulting images.

If you are printing at 16x24, DOF is shallower than if you print at 4x6 -- this relates to circle of confusion, or COF.

If you are downsizing for display on the web, your DOF gets wider.

True, and true. Often, though, we don't have our ultimate use for the image clearly in mind when we shoot, or we decide later that something originally intended only for the web, or small prints, needs to be printed larger.
Because of these situations, It's my recommendation that:
1.) The photographer choose a CoC that maintains sharpness at 100% on-screen view (the smallest CoC it really makes sense to use). This is the basis of my suggestion of twice the sensor pixel pitch. For the technically inclined, this is derived from the Nyquist limit.
2.) Set the hyperfocal distance and verify the sharpness for both near and far objects on the LCD on a test shot before beginning to shoot the pano.

Canon EF 100mm f/2.8 USM Macro

05/13/2007 09:21:56 AM · #14

Alex,
Your sensor's pixel pitch is .0064mm so probably 2*0.004=0.013 is a good starting point.

alexgarcia

Canon EOS-350D Rebel XT

05/13/2007 11:55:51 AM · #15

Thanks a lot kirbic. I'll try.

Ã�lex.

Originally posted by kirbic:

Alex,
Your sensor's pixel pitch is .0064mm so probably 2*0.004=0.013 is a good starting point.