Hyperfocal charts and crop factor question...

[RaffiNYC]

I found this hyperfocal distance chart and I had a question about how to use it with respect to crop factor...

http://picasaweb.google.com/lh/photo/SyFkKJIZCOrRy9377xo6Ng?authkey=Gv1sRgCK-G5NeRkpzUQg&feat=embedwebsite

If I am shooting with the Canon Rebel Xsi, which has a crop factor of 1.6, how do I apply the crop factor to the chart? For example, if I am shooting a scene in f/8 and the focal length on the camera is 24mm, how do I use the crop factor to find the hyperfocal distance from the chart?

 

[steephill]

http://www.cambridgeincolour.com/tutorials/DOF-calculator.htm

--
Steve

http://www.pbase.com/steephill

 

[GaryDeM]

try-
http://www.dofmaster.com/charts.html
also-
http://www.dofmaster.com/hyperfocal.html

 

[RaffiNYC]

Thanks!

When focusing at the hyperfocal distance, do I position the center focus point on an object at the hyperfocal distance and autofocus, or do I manually focus the lens so that the ft/m reading on the lens is at the hyperfocal distance? Confused a bit on that.

 

[steephill]

second method - set the focus point of the lens without trying to fcous on a given subject. If your camera has a DOF preview function then also try using that to see if the settings you are about to use are what you want to see.

--
Steve

http://www.pbase.com/steephill

 

[GaryDeM]

you focus on the hyperfocal distance. even if you have to find something that is at that distance. if all else fails, the scene is not too huge, you just find a convienant spot and pace it off. BUT, when done you must turn off the AF altogether and do not touch it till the shooting with the hyper focsl technique is done. if the scene is large and the hyper distance is 50ft away just find something that is near that and use it, then take shot. (note- i know that if i lengthen my normal stride about 10%; i take about a 1 yard step. therefore i simply count when i walk 3,6,9,12,15,etc.)

hyperfocal focussing can be used for a say a hockey game. simply find the near point that must be in focus and determine the fstop needed to get from there to infinity. then focus at the hyperfocal distance and turnoff AF till the game is over. for aperture and fstop, determine what kind of shutter speed is needed to stop the player action. then for fstop use the warmup time to simply focus on 1 player and let the Sv give you the aperture. then switch to manual mode and use those settings. you would then not be focusing or touching the exposure for the entire game, and all the shots are right. just make sure than the arena has the game lights on, and not just any other kind of lighting used for warmup time. if the later happens the one player that does not move is the goalie, he stays in the net so you can use him for the the exposure test. if necessary kick up the iso to make the shutter speed and fstop chosen work.

 

[RaffiNYC]

second method - set the focus point of the lens without trying to fcous on a given subject. If your camera has a DOF preview function then also try using that to see if the settings you are about to use are what you want to see.

--
Steve

http://www.pbase.com/steephill

Are you sure? According to this article I just found it says to focus on an object at the hyperfocal point.

http://www.learnslr.com/slr-beginner-guide/digital-slr-learning-guide/hyperfocal-distance

 

[RaffiNYC]

Another question: Since calculating hyperfocal distance is just a formula with 3 variables, if I know any 2 variables I should be able to get the 3rd. For instance, lets say I was taking a shot where a fire hydrant that is 10 feet away from my position. If I want to ensure the hydrant in focus, then with a given focal length I can calculate the approriate f/stop for the shot since I know the hyperfocal distance and focal length beforehand.

Will this work in most circumstances?

 

[AnandaSim]

second method - set the focus point of the lens without trying to fcous on a given subject. If your camera has a DOF preview function then also try using that to see if the settings you are about to use are what you want to see.

\> Are you sure? According to this article I just found it says to focus on an object at the hyperfocal point.

It does not matter where you use AF or MF to set the lens to Hyperfocal Point. The idea is to set to Hyperfocal Point whatever method you use. MF does not depend on having a subject there. AF depends on a subject there - you can't use AF with nothing there.

SLRs - meaning Reflex cameras became popular because we could do better than DOF charts and scales. SLRs in film allow us to press the DOF button on the camera to see it dim in the viewfinder. D SLRs allow us to press the DOF button to see the effect in LiveView. If you don't have LiveView, you can just use MF and shoot, look at the LCD screen, adjust, repeat.

AF is not good because everytime you press the trigger, the camera will re-focus. Unless your camera has an AF Lock button that locks regardless of how many times you trigger the shutter.

--



Ananda
http://anandasim.blogspot.com/
http://onepicperpost.blogspot.com/

 

[GaryDeM]

Another question: Since calculating hyperfocal distance is just a formula with 3 variables, if I know any 2 variables I should be able to get the 3rd. For instance, lets say I was taking a shot where a fire hydrant that is 10 feet away from my position. If I want to ensure the hydrant in focus, then with a given focal length I can calculate the approriate f/stop for the shot since I know the hyperfocal distance and focal length beforehand.

Will this work in most circumstances?

there is 3 variables. you have the near object, fstop, and lens mm. that is for a 35mm lens at 10ft, you focus at 5ft. the fstop to use is f32.0, this is for 35mm lens on a FF OR 35mm film. there isa differnce if the lens is on a c sensor OR FF/35mm film. as you can see there is one problem-you may not have the fstop the chart wants. if you switch to 20mm lens with the above info then you can use f11.0 which is much more lilkely.

this is why in the above chart that you can download you simply printout the lenses you have or will shoot hyperfocal and read it off you printed chart.

 

[RaffiNYC]

second method - set the focus point of the lens without trying to fcous on a given subject. If your camera has a DOF preview function then also try using that to see if the settings you are about to use are what you want to see.

--
Steve

http://www.pbase.com/steephill

Hi Steve,

I am still trying to grasp this concept. So when you say don't try to focus on a subject in the view finder, you're talking about using the distance markers on the lens, correct?



whether focusing on a subject in the near foreground or using the lens markers, isn't it effectivel the same thing?

 

[RaffiNYC]

Another question: Since calculating hyperfocal distance is just a formula with 3 variables, if I know any 2 variables I should be able to get the 3rd. For instance, lets say I was taking a shot where a fire hydrant that is 10 feet away from my position. If I want to ensure the hydrant in focus, then with a given focal length I can calculate the approriate f/stop for the shot since I know the hyperfocal distance and focal length beforehand.

Will this work in most circumstances?

there is 3 variables. you have the near object, fstop, and lens mm. that is for a 35mm lens at 10ft, you focus at 5ft. the fstop to use is f32.0, this is for 35mm lens on a FF OR 35mm film. there isa differnce if the lens is on a c sensor OR FF/35mm film. as you can see there is one problem-you may not have the fstop the chart wants. if you switch to 20mm lens with the above info then you can use f11.0 which is much more lilkely.

this is why in the above chart that you can download you simply printout the lenses you have or will shoot hyperfocal and read it off you printed chart.

I just downloaded an iphone application, SimpleDOF, which is basically a hyperfocal distance calculator. Just configure the camera type, then plug in the f/stop and focal length and it spits out the hyperfocal distance, and near/far focus points. this is perfect for me since I will be out in the field at Yosemite.