Manual Focus Distance Window On Lens

[Garbz]

How would it work? You go to Understanding the Hyperfocal Distance, fill out the details in the chart below. Hit calculate, and hit print

 

[Vautrin]

A focusing screen just lets you see what's in focus easier, or provides gridlines or other useful tools for composition.

It's just a piece of glass you put between the part you put your eye and the mirror / prism -- it'd either be #5 or #6 in the diagram below:

http://images2.wikia.nocookie.net/__cb20060224221425/photography/images/8/80/Slr-cross-section.png

 

[decado]

How would it work? You go to Understanding the Hyperfocal Distance, fill out the details in the chart below. Hit calculate, and hit print

Two things: First which of those would a 500D be considered? Second, I'm not gonna have that calculator (just a simple hyperfocal calculator) when I'm out and about with my Iphone so what would the calculation be for the crop sensor so I can figure it out?

 

[Garbz]

The 500D is a DSLR with a 1.6x crop factor.

The calculator gives you a table of f stops and focal lengths to give you the hyperfocal distance on each lens. You shouldn't have to re-calculate unless you're changing the definition of sharpness or the film spec (35mm, medium format, etc.).

So hit calculate, and then hit print

 

[davebmck]

The hyperfocal distance doesn't have anything to do with the crop ratio of the camera. It is based on the actual focal length and aperture of the lens. If you have an Iphone, there are a few apps that will calculate the hyperfocal distance for you.

 

[Dao]

The hyperfocal distance doesn't have anything to do with the crop ratio of the camera. It is based on the actual focal length and aperture of the lens. If you have an Iphone, there are a few apps that will calculate the hyperfocal distance for you.

It does. Hyperfocal distance is related to Depth of Field (Dof). Dof is related to Circle of confusion (CoC) and CoC is related to medium size. So Hyperfocal distance varies with sensor size.

OP, besides using hyperfocal distance, since you have a T1i/500D, I believe the camera has liveview. And you can also use that to nail your focus (esp on a tripod).

 

[davebmck]

I stand corrected. The hyperfocal distance is based on the effective focal length, not the actual focal length.

 

[Garbz]

I stand corrected. The hyperfocal distance is based on the effective focal length, not the actual focal length.

The hyperfocal distance is based on a definition of acceptably sharp, no more, no less. Variables that feed into that are focal length, aperture, and effective sharpness at a given distance. Effective sharpness encapsulates crop factor, print size, print viewing distance and the eye-sight of the viewer.

 

[Dao]

Effective sharpness encapsulates crop factor, print size, print viewing distance and the eye-sight of the viewer.

:thumbup::thumbup:

And that is how the CoC is defined.

I do not know the exact details, but I think in 35mm world, the CoC was calculated with regular 35mm film size, printed on a regular photo size (i.e. 4x6) and view it at regular distance (such as arm length).

 

[Vautrin]

So can I just ask a stupid question?

If I focus my lens to infinity, and take a photo at f 2.8 and a photo at f 22, will they have the same depth of field, or a different depth of field?

 

[Aye-non Oh-non Imus]

This was an interesting video from Bryan Peterson for story telling photos with wide angle lenses.

You can see it [ame="http://www.youtube.com/watch?v=uQ6DqhPuPpQ"]here[/ame].[ame="http://www.youtube.com/watch?v=uQ6DqhPuPpQ"][/ame]

 

[Vautrin]

Well maybe I should rephrase.

Before Garbz post I had thought hyperfocal distance is a way to get as much in the scene as possible sharp. So you focus to 1m, and you know everything from 0.5m to infinity will be sharp at f22

Maybe I'm misreading the post but Garbz you seem to suggest that everything might not be tack sharp at f22? So if I focus to infinity and f22 will I have more tack sharp depth of field then at f2.8 focused on infinity?

Of when you focus on infinity do you give up the focus before infinity on your lens?

 

[Dao]

You may want to play around with the DoF calculator.

Online Depth of Field Calculator

 

[davebmck]

What Garbz is saying is that the part of the image that is within the DOF is acceptably sharp. Not everything will be tack sharp. At some distance, the image will be the sharpest and the rest will fall into the acceptable range as defined by the circle of confusion.

To answer your question, the image taken at f22 will have a greater DOF than the image taken at f2.8.

 

[Overread]

However you might want to use f8 - f16 with f10 - f13 being the more common apertures used; rather than using apertures smaller than f16. This is because diffraction starts to take place within most lens and camera setups around the f10 point - by f13 its normally still a very usable image - f16 tends to waver either way and going any smaller and diffraction starts to take over.

What is the effect of diffraction? Its simply softness in your image - no matter how well you shoot the softness will be present because its a part of the properties of lens+camera operation. Thus that is why we don't simply stop all the way down to take landscape shots and instead use wider apertures along with hyperfocal focusing to get landscape shots that are acceptably sharp.