FAQ - Frequently Asked Questions |
Look through the list of questions below for assistance |
| ExpoAperture General Questions |
| 1. |
Will the ExpoAperture Depth of Field Guide work with my digital SLR or film camera? |
| 2. |
How durable is the ExpoAperture Guide? |
| 3. |
What circle of confusion or Sensor Size is used in the ExpoAperture Depth of Field Guide calculations? |
| 4. |
The shortest focal length on the guide is 15mm; will it work with focal lengths less than 15mm? |
| 5. |
My digital camera does not have a full size sensor; can I still use the guide by multiplying the actual focal length of the lens by the camera's equivalent focal length factor? |
| 6. |
What kind of warranty comes with the ExpoAperture Guide? |
| What's New with the ExpoAperture2? |
| 1. |
What are the differences between the original ExpoAperture Depth-of-Field Guide and the new ExpoAperture2 Depth-of-Field Guide? |
| Medium and Large Format Cameras |
| 1. |
How do I use the ExpoAperture2 with Medium Format 4x5 and Large Format 8x10 film cameras? |
| Depth of Field and Focal Plane |
| 1. |
My understanding is that depth of field extends twice as far behind the focal plane as it does in front. Calculations made with your guide give different results, which is correct? |
| OR... click here to ask your own question using our contact form. |
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| ExpoAperture General Questions |
| 1. |
Will the ExpoAperture Depth of Field Guide work with my digital SLR or film camera? |
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Yes. The ExpoAperture Depth of Field Guide will work with all full-frame 35mm and digital SLR cameras where the image sensor is approximately the same size as a full 35mm frame. You may also use the Guide with digital cameras with a 1.3, 1.4, 1.5, 1.6, or 1.7 equivalent focal length by referring to the Guide's Focal Length Conversion Table or, with medium format film (120/220) and large format film cameras. |
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| 2. |
How durable is the ExpoAperture Guide? |
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Unlike other depth of field guides which are made out of paper or card stock the ExpoAperture Guide is constructed out of durable plastics that will last for years. The rear dial (Zone Dial) is made out of PVC (polyvinyl chloride) plastic with a protective clear-coat. The front dial is made out of glossy Lexan plastic. |
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| 3. |
What circle of confusion or Sensor Size is used in the ExpoAperture Depth of Field Guide calculations? |
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The proliferation of different size image sensors in digital imaging has resulted in the loss of depth of field scales from nearly all modern DSLR lenses. To help photographers overcome the absence of these scales, along with the difficulty of adjusting for different sensor and film sizes, the ExpoAperture2 Depth-of-Field Guide was designed to allow the user to adjust for a camera's specific sensor, or film size. An included reference chart provides the conversion factors necessary to use the Guide with nearly any camera, regardless of sensor size or film format -- from the 4/3 system to APS-C sensors, to full frame 35mm, to medium and large format film sizes. |
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| 4. |
The shortest focal length on the guide is 15mm; will it work with focal lengths less than 15mm? |
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Yes. We should point out that lenses with such short focal lengths inherently have very large depth of fields to begin with. Therefore it was decided that inclusion of such short focal lengths would not enhance the Guide's usefulness. However it is still possible to use the Guide to determine depth of field or aperture settings with focal lengths less than 18mm.
Here's how - If starting on the front of the Guide: set the Guide's focal length to twice the actual focal length of the lens you are using; read the number of zones under the f-stop you want to use; multiply the number of zones by four; on the Zone Dial center the number of zones you just calculated around your focal point; and, read the depth of field. If starting on the Zone Dial: center the number of zones you want in focus around the focal point; on the front of the Guide set the focal length to twice the actual focal length of the lens you are using; divide the number of zones you used on the Zone Dial by four; and, read the f-stop required above the number you just calculated. |
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| 5. |
My digital camera does not have a full size sensor; can I still use the guide by multiplying the actual focal length of the lens by the camera's equivalent focal length factor? |
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No. The equivalent focal length factor (or multiplier) is based on the linear relationship between the size of a full 35mm frame and the camera's image sensor. The formulas used to determine depth of field, however, are based on the exponential relationship of focal length to aperture size. Therefore multiplying the actual focal length by the camera's equivalent focal length factor will not result in the correct answer for your camera. |
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| 6. |
What kind of warranty comes with the ExpoAperture Guide? |
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All ExpoImaging products come with a limited warranty to be free of defects in workmanship and materials for a period one (1) year from the date of original retail purchase. If the product proves defective within the warranty period, then it will be replaced. Click here to see the details. |
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| What's New with the ExpoAperture2? |
| 1. |
What are the differences between the original ExpoAperture Depth-of-Field Guide and the new ExpoAperture2 Depth-of-Field Guide? |
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The ExpoAperture2 Depth-of-Field Guide is a new product that has been completely redesigned to make it easier to use.
First, we split the dial into two separate versions, one covering 15-135mm (Standard), and the other covering 70-600mm (Telephoto). Having each dial cover a narrower range of focal lengths improved the accuracy and usability of the ExpoAperture2 by allowing more space between the focal length marks and permitting us to include more total marks.
We also increased the size of the ExpoAperture2 by about 25%. The larger size allowed us to insert Aperture marks in 1/3 fstop increments on the front of the dial, and to increase the space between the distance marks on the back.
To accommodate the wide variety of sensor sizes now utilized in today's DSLR cameras, and to accommodate a wider variety of film cameras, we added a third dial that compensates for the change in sensor/film format by allowing the photographer to select a desired sensor, or film size.
Finally, the ExpoAperture2 Depth-of-Field Guide is now color coded to facilitate quickly referencing desired information.
Together, these changes greatly improve and enhance the ExpoAperture2's usability.
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| Medium and Large Format Cameras |
| 1. |
How do I use the ExpoAperture2 with Medium Format 4x5 and Large Format 8x10 film cameras? |
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The ExpoAperture2 was designed specifically for use with cameras utilizing sensor or film sizes requiring 15 to 60 microns of resolution in their circle of confusion depth-of-field calculations. The 15 to 60 micron range printed in the green film format/sensor setting region of the ExpoAperture2 represents all modern DSLR cameras, and most film cameras, including 1/2 size 35mm film, 35mm film, 4x4, 6x4.5 and 6x6 format.
Two film camera formats not explicitly included on the ExpoAperture2, specifically the medium format 4x5 and the large format 8x10 require 120 microns, and 240 microns, respectively, to accurately perform depth of field calculations.
While we did not extend the green sensor size/ format setting region to include 120, and 240 microns, it is still possible to perform depth-of-field calculations for the 4x5 and 8x10 format cameras using the ExpoAperture2.
For medium format 4x5 film cameras, the simplest method for making depth-of-field calculations requires moving the sensor size/format dial to the angle occupied by the f64 aperture marker. This position on the dial represents 120 microns, the angle recommended for calculating depth-of-field for medium format 4x5 film cameras. If you are using a 4x5 format film camera, set the sensor size/format dial to the f64 position, then use the ExpoAperture2 normally when performing desired aperture, or resulting depth-of-field calculations.
Similarly, for large format 8x10 film cameras, simply set the sensor size/format dial to the angle occupied by the f32 aperture marker. The f32 position on the dial represents 240 microns, the angle recommended for calculating depth-of-field for large format 8x10 film cameras. If you are using 8x10 format film cameras, set the sensor size/format dial to the f32 position, then use the ExpoAperture2 normally when performing desired aperture, or resulting depth-of-field calculations.
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| Depth of Field and Focal Plane |
| 1. |
My understanding is that depth of field extends twice as far behind the focal plane as it does in front. Calculations made with your guide give different results, which is correct? |
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It is a common misperception that depth of field extends from ⅓ in front to ⅔ behind the focal plane. Consider this… When a lens is focused at the hyperfocal distance there is a finite distance in front of the focal plane and an infinite distance behind the focal plane. That certainly doesn’t fit the ⅓ in front, ⅔ in back rule.
So when is this widely disseminated rule applicable? Almost Never! The rule is only good when the lens is focused at a point equal to ⅓ the hyperfocal distance.
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