The Fotga Macro AF Auto Focus Automatic Extension Tube Set DG for Kenko Canon EF EF-S lenses is a fascinating tool for macro photography enthusiasts. These extension tubes do not have optics but are used to alter the distance between the camera body and the lens, thereby allowing the lens to focus closer than its normal minimum focusing distance. This results in greater magnification for close-up photography.

Here are the notable features:

1. Compatibility: The extension tubes are designed to work with Canon EF and EF-S mount lenses, ensuring a wide range of compatibility with various Canon DSLR cameras.

2. Construction: The set typically includes three tubes of different lengths (12mm, 20mm, and 36mm), which can be used individually or in combination to achieve varying levels of magnification.

3. Auto Focus and Aperture Control: Unlike simpler extension tubes, the Fotga Macro AF tubes maintain electrical contacts between the camera body and the lens, preserving autofocus and aperture control functionality. This is crucial for maintaining ease of use and flexibility in macro photography.

4. Durability: Constructed with high-quality materials, these tubes are designed to be robust and reliable, standing up to the rigors of frequent lens changes and macro shooting sessions.

5. Ease of Use: They attach and detach easily, making them convenient for photographers who need to switch between macro and regular shooting modes quickly.

6. Price Point: Generally more affordable than dedicated macro lenses, these extension tubes offer a cost-effective way to explore macro photography without a significant investment.

Interesting Trivia:

Did you know that extension tubes were originally popularized by early macro photographers who adapted various objects, like bellows from large format cameras, to achieve greater magnification? Modern extension tubes like the Fotga set bring this old-school technique into the digital age with enhanced functionality and ease of use.

Practical Tip:

When using extension tubes, the depth of field becomes very shallow, so it’s essential to use small apertures to increase it. Additionally, a tripod can be extremely helpful to stabilize the camera and achieve sharp focus, especially in low light conditions.

The effective magnification achieved with extension tubes like the Fotga Macro AF Auto Focus Automatic Extension Tube Set DG for Canon EF and EF-S lenses depends on the focal length of the lens being used and the total length of the extension tubes.

The formula to calculate the effective magnification (M) is:

$𝑀=\frac{𝐷}{𝐹}$

where $𝐷$ is the total length of the extension tubes and $𝐹$ is the focal length of the lens.

For example, let's say you are using the entire set (12mm + 20mm + 36mm = 68mm) with a 50mm lens:

$𝑀=\frac{68}{50}=1.36$

So, the effective magnification would be 1.36x, meaning the image would be 1.36 times larger than the lens's original magnification capabilities.

General Guideline for Different Lenses:

• Shorter Focal Length Lenses (e.g., 24mm): Higher magnification because the extension tubes represent a larger percentage of the lens's focal length. For instance, with 68mm of extension on a 24mm lens, the magnification is approximately 2.83x.

• Longer Focal Length Lenses (e.g., 100mm): Lower magnification because the extension tubes represent a smaller percentage of the lens's focal length. For instance, with 68mm of extension on a 100mm lens, the magnification is approximately 0.68x.

Practical Examples:

1. 24mm Lens with 68mm Extension: $𝑀=\frac{68}{24}\approx 2.83$

2. 100mm Lens with 68mm Extension: $𝑀=\frac{68}{100}=0.68$

These examples illustrate how extension tubes offer flexible and significant increases in magnification, especially beneficial for capturing fine details in macro photography.

Using extension tubes such as the Fotga Macro AF Auto Focus Automatic Extension Tube Set DG for Kenko Canon EF EF-S lenses at further distances, such as 100 meters, is not practical and generally not recommended. Here's why:

Optical Behavior and Limitations:

1. Loss of Infinity Focus: Extension tubes effectively move the lens further from the camera sensor, which is designed to allow closer focusing distances for macro photography. However, this adjustment means that the lens can no longer focus at infinity. This makes it impossible to focus on distant subjects, such as something 100 meters away.

2. Magnification of Near Subjects: The primary purpose of extension tubes is to increase the magnification of close subjects by reducing the minimum focusing distance of the lens. For distant subjects, the magnification effect of extension tubes is essentially nullified because the lens can't achieve focus at those distances.

3. Decreased Image Quality: Even if you could theoretically use extension tubes for distant subjects, the resulting image quality would likely be significantly degraded. Extension tubes are optimized for close-up photography and not for maintaining sharpness or clarity at long distances.

4. Focusing Challenges: Autofocus systems may struggle or fail entirely when extension tubes are attached, especially at longer distances. This is because the electronic communication is designed to support close-up focusing adjustments, not those required for far-off subjects.

Practical Example:

Let’s assume you try to focus on a subject 100 meters away using a 50mm lens with the entire set of extension tubes (68mm):

• Without extension tubes, a 50mm lens on a Canon camera typically has a maximum focusing distance (infinity) that allows it to focus sharply on distant subjects.
• With 68mm of extension tubes attached, the lens's focal plane is shifted significantly, reducing its focusing capability to very close distances (within a few centimeters to a couple of meters at most, depending on the combination).

Thus, trying to use extension tubes in this manner would result in an out-of-focus image because the lens cannot adjust to the required focal plane for a subject that far away.

Conclusion:

Extension tubes are designed explicitly for close-up and macro photography. Using them for subjects at long distances, such as 100 meters, is ineffective and impractical. For such distant subjects, using a telephoto lens without extension tubes would be the appropriate choice to achieve clarity and focus.

The quality of Fotga Macro AF Auto Focus Automatic Extension Tube Set DG for Canon EF and EF-S lenses can vary, but generally, Fotga tubes are considered a good budget-friendly alternative to Canon's own extension tubes. Here’s a comparison based on several key factors:

Build Quality:

• Fotga: Constructed with durable plastic and metal mounts, Fotga extension tubes offer solid build quality for their price. However, the overall material and construction might not be as premium as Canon's.
• Canon: Known for high-quality construction, Canon extension tubes are typically made from robust materials like high-grade plastics and metals, ensuring long-lasting durability and a professional feel.

Electrical Contacts:

• Fotga: These tubes maintain electronic connections between the camera and the lens, allowing for autofocus and aperture control. The reliability of these contacts can vary, with some users experiencing occasional issues with autofocus speed and accuracy.
• Canon: Canon tubes are designed to seamlessly integrate with Canon lenses and cameras, providing consistent and reliable electronic communication for autofocus and aperture control, usually with no compatibility issues.

Optical Performance:

• Fotga: Since extension tubes contain no optical elements, they do not degrade image quality in terms of sharpness, chromatic aberration, or distortion. However, the mechanical fit and electronic functionality can sometimes cause slight issues, especially in fast-paced shooting environments.
• Canon: Canon extension tubes also lack optical elements, ensuring no loss in image quality. The precision of Canon's manufacturing means better fit and reliable electronic performance, contributing to a more seamless user experience.

Price:

• Fotga: Fotga extension tubes are significantly more affordable, making them an attractive option for amateur photographers or those on a budget who want to explore macro photography without a large investment.
• Canon: Canon extension tubes are more expensive, reflecting their premium build quality and reliable performance. They are often preferred by professionals who require consistent and high-quality results.

User Experience:

• Fotga: Generally positive, especially among budget-conscious photographers. Some users report occasional issues with the electronic contacts, but these are usually minor.
• Canon: Highly positive, with consistent praise for their reliability, build quality, and performance.

Conclusion:

Fotga extension tubes provide a cost-effective way to delve into macro photography, with generally good performance and build quality for the price. However, Canon extension tubes offer superior build quality, reliability, and integration with Canon systems, justifying their higher price for those who need professional-level performance and durability.

Ultimately, the choice between Fotga and Canon depends on your budget and specific needs in macro photography. If you require absolute reliability and premium build quality, Canon is the way to go. For a more budget-friendly option that still offers good performance, Fotga is a solid choice.