Advantages / Limitation of the Canon EF25 II Extension Tube
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| Canon 6D / Extension Tube EF25 II / EF 70-300mm f/4-56L USM Lens |
Introduction: What Is the Canon EF 25 II Extension Tube?
The Canon EF 25 II Extension Tube is a lightweight ring (25 mm thick) that fits between your camera body and lens to increase the distance between the lens and the image sensor. This simple mechanical extension allows your lens to focus much closer than it normally can—delivering significantly greater magnification without lowering optical quality. Despite containing no optical elements, it maintains full electronic communication with compatible EF and EF-S lenses, preserving autofocusing and exposure functionality.(The-Digital-Picture.com, Canon South Africa, Wikipedia)
Amazing Magnification with No Extra OpticsExtension tubes work by altering the lens-to-film/sensor distance, which in turn reduces the minimum focus distance and increases magnification. The relationship is proportional: magnification ≈ extension length ÷ focal length.(Wikipedia, camerawarehouse.co.za)
For example:
- A 50 mm lens + 25 mm tube → ~0.5× additional magnification(camerawarehouse.co.za, Reddit)
- With a Canon EF 100 mm f/2.8 Macro lens, the tube boosts magnification from 1:1 to roughly 1.39×, while reducing the maximum focusing distance to ~606 mm (2 ft)(Wikipedia)
A blogger's practical table shows:
- 0.68× magnification on a 50 mm lens
- 0.39× on a 70–200 mm zoom at 70 mm
- And up to 1.22× on a 24 mm wide-angle lens (where the tube still works)(anders-larsson.blogspot.com)
Cost-Effective Macro Capabilities
One of the most appealing advantages is affordability. You gain significant macro functionality for a fraction of the price of a dedicated macro lens or teleconverter. The EF 25 II can be a great stepping-stone for exploring macro photography without a hefty investment.(vernonchalmers.photography, cameraworld.co.uk)
Maintains AF and AE (for Most Lenses)Unlike some third-party options that might disable autofocus (AF) or auto exposure (AE), Canon’s EF 25 II maintains both—with compatible EF and EF-S and TS-E lenses. Camera behavior like exposure adjustment continues to work seamlessly.(The-Digital-Picture.com, Canon South Africa, B&H Photo Video, DPReview)
Lightweight, Compact, and ConvenientThe tube is highly portable—roughly the size of a Canon 1.4× extender—with caps and a storage pouch included. It’s compact enough to carry in your kit without adding bulk.(The-Digital-Picture.com, cameraworld.co.uk, B&H Photo Video)
Versatile with a Wide Range of LensesYou can use the EF 25 II with most EF, EF-S, and TS-E lenses (with some exceptions, especially ultrawides and fisheyes). It even works—via appropriate adapters—with EF-mount lenses on EOS R and EOS M mirrorless bodies.(Canon South Africa, cameraworld.co.uk)
Just be mindful:
- It’s not compatible with some lenses like EF 15mm fisheye, EF 24mm f/1.4L II, MP-E 65mm, EF 20mm f/2.8, etc.(Canon South Africa)
- Wide-angle zooms like EF 16–35 mm or EF-S 10–18 mm may face limitations or vignetting(Canon South Africa, DPReview)
You can stack the EF 12 II and EF 25 II for even more extension (up to 37 mm). While Canon doesn’t officially recommend stacking (due to possible exposure and communication quirks), many photographers explore it for enhanced macro performance.(Canon South Africa)
This opens up creative possibilities—like close-up portraits, textured still lifes, insect studies, and imaginative macro compositions.
Good Optical Quality (Mostly)Because the tube has no lens elements, it doesn’t add distortion or degrade the optics—assuming you’re using a high-quality lens. That said, the increased magnification does enlarge existing lens imperfections. In macro, most photographers stop down to increase depth of field, which helps maintain sharpness.(vernonchalmers.photography, Canon South Africa, DPReview)
8. Light Loss and Depth-of-Field Trade-Offs
- Light Loss
By increasing lens-to-sensor distance, tubes cause light falloff—though modern cameras typically compensate through automatic exposure (TTL).(B&H Photo Video, Wikipedia, camerawarehouse.co.za)
- Very Shallow Depth-of-Field
Some observations:
“Extension tubes only reduce the minimum focusing distance of a lens... even when I manually focus to infinity, the actual focal plane is almost touching the lens.”(Reddit)
“You lose light with every mm.”(Reddit)
Thus, precision and sometimes focus stacking become important for usable images.
Limitations and Considerations- Focus Breathing & Zoom Problems: On zoom lenses, focusing and zooming can lead to unpredictable results. Macro specialized lenses are generally better.(DPReview)
- Manual Focus May Be Required: In some cases (especially with third-party tubes or cameras) autofocus fails, forcing you to revert to manual focus.(DPReview)
- Potential Vignetting: Especially on full-frame bodies, corners may darken at high magnification.(camerawarehouse.co.za, DPReview)
- Incompatibilities: Double-check your lens compatibility list to avoid frustration.(Canon South Africa)
Real-World Insights
From DPReview forums:
“Extension tubes draw the range of focus inward... working distances were not simply too short... extension tube is great from 50 mm up to 400 mm... neither tube usable for lenses <24 mm.”(DPReview)
On other forums:
“I regularly use the Canon EF25 II with a 70–300mm L IS lens without any significant image quality sacrifice.” (vernonchalmers.photography)
Reddit users share other practical tips:
- Light compensation is often automatic, but careful lighting or stacking helps with shallow depth of field.
- While extension tubes are fun, alternatives like Raynox macro adapters or microscope objectives may yield higher magnification with fewer compromises.(Reddit)
| Benefits | Considerations / Trade-offs |
|---|---|
| Low-cost macro capability | Significant light loss (needs exposure compensation) |
| Maintains AF & AE (most lenses) | Very shallow depth-of-field at close focusing distances |
| No image-degrading optics | Focus breathing on zooms; may need manual focusing |
| Compatible with many EF/EF-S/TS-E lenses | Not compatible with some wide-angle and fisheye lenses |
| Compact, lightweight & portable | Potential vignetting at high magnification |
| Creative flexibility (stacking, adapters) | Requires tripod and precision control for sharp macro shots |
Final Thoughts
The Canon EF 25 II Extension Tube is an accessible, lightweight, and cost-effective way to explore macro photography using your existing lens collection. It opens the door to meaningful close-up work—be it flowers, insects, textures, or products—by turning standard lenses into near-macro tools.
While it’s not perfect and does introduce challenges like shallow focus and light loss, the creative and financial advantages are compelling—especially for hobbyists, educators, or anyone curious about macro without investing in a dedicated macro lens.
If you'd like help choosing compatible lenses, lighting tips for macro work, or how to perform focus stacking for better results, I’d be happy to guide you further" (Source: Chat GPT 2025)
Top Image: Copyright Vernon Chalmers Photography