Is this lens you just bought as good as it should be? You need to find out this. It’s a very crucial step that many photographers skip.
Testing your new lens isn't about being picky – it's about making sure your investment delivers the magic you paid for.
Even a $2,000 piece of glass can have issues, and discovering them two months after purchase won't help. You have to check it now!
Let me tell you exactly what to test on your new camera lens so you can shoot with confidence, knowing your gear is performing exactly as it should.
Why You Should Test Your New Lens (Even Expensive Ones)
The lens in your hands represents countless hours of engineering and precision manufacturing. But here's the reality that camera companies don't advertise: not all copies of the same lens perform identically.
Even the most prestigious lens manufacturers deal with copy-to-copy variations. Glass elements need to be positioned with microscopic precision, and in mass production, small variations occur.
A lens that passes factory quality control might still have minor focusing issues or optical imperfections that won't show up until you test it.
A thorough evaluation helps you:
Discover manufacturing defects before your return window closes
Understand your lens's unique strengths and limitations
Calibrate your expectations for real-world shooting
Adjust camera settings to complement your specific lens copy
I once bought two identical lenses from the same production batch and found noticeable differences in their corner sharpness. One was tack-sharp while the other showed subtle softness at certain apertures.
So, think of testing as getting acquainted with a new tool. The better you understand its quirks early on, the more effectively you'll use it for years to come.
In fact, thoroughly testing your new lens not only ensures optimal performance for your everyday photography but also prepares you for competitive opportunities. Many photographers eventually showcase their work in photography contests, where technical excellence and image quality can significantly impact success.
Preparation Essentials (Do This Before You Start)
Proper preparation will ensure your results are meaningful rather than misleading.
Clean Your Gear
Start with the basics – both your lens and camera sensor should be spotless. Those tiny dust specks might look like lens flaws in your tests.
Use a proper lens cleaning kit with microfiber cloths and a lens cleaning solution. For sensor cleaning, follow the proper camera sensor cleaning methods to avoid damaging sensitive components.
Stable Environment Setup
Stability is non-negotiable for accurate testing. Use:
A solid tripod (not the wobbly $20 special)
Remote shutter release or self-timer to eliminate camera shake
Consistent lighting (studio lights or steady natural light, not changing conditions)
Technical Settings
For consistent results:
Shoot in RAW format
Disable lens corrections in the camera (you want to see actual lens performance)
Use manual mode for consistent exposure
Turn off image stabilization when on a tripod
Set a moderate ISO (100-400) to minimize noise that might mask lens issues
(If you're new to manual settings, learning how to use manual mode on your DSLR will give you complete control during lens testing)
Give yourself plenty of time – rushing through tests defeats their purpose. I typically set aside a full afternoon for the comprehensive testing of a new lens.
Testing for Sharpness and Focus Accuracy
Sharpness is usually the first thing photographers check, and for good reason. A soft lens is rarely a keeper.
Focus Calibration Test
Set up a focus target (a ruler at a 45-degree angle works well) at a distance appropriate for your lens type:
Portrait lenses: 6-10 feet away
Wide angle: 3-5 feet
Telephoto: 20+ feet
Take multiple shots focusing on the center mark. Examine the results at 100% magnification. The focus should land precisely where you aimed.
If your images consistently front-focus (objects closer than your target appear sharper) or back-focus (objects behind your target appear sharper), your lens might need calibration or could be defective.
Many modern cameras offer micro-adjustment settings to correct minor focus issues.
Edge-to-Edge Sharpness
No lens is perfectly sharp across the entire frame, but excessive corner softness could indicate problems.
Photograph a flat, detailed subject (like a brick wall or bookshelf) with your camera parallel to the subject. Check how sharpness drops as you move from center to corners.
Some falloff is normal – especially at wider apertures – but extreme differences might mean you have a decentered lens element..
Aperture Performance Evaluation
Your lens's aperture affects more than just exposure – it impacts sharpness, background blur, and vignetting.
Optimal Aperture Discovery
Every lens has a "sweet spot" – typically 2-3 stops down from the maximum aperture – where it reaches peak sharpness.
Set up a detailed subject and take identical shots at each full aperture stop (f/2.8, f/4, f/5.6, f/8, f/11, f/16, etc.).
Compare the images at 100% magnification. You'll likely notice:
Softer results at the widest apertures
Peak sharpness in the middle range (often f/5.6-f/8)
Decreasing sharpness at smallest apertures due to diffraction
Knowing your lens's optimal aperture helps you choose the right settings when critical sharpness matters.
Vignetting Check
Darkened corners (vignetting) are common at wide apertures. While easily corrected in post-processing, severe vignetting might indicate issues.
Photograph an evenly lit white wall at various apertures. The vignetting should decrease as you stop down, typically becoming minimal by f/5.6 or f/8.
Background Blur Quality
For portrait and creative photography, the quality of background blur (bokeh) matters
tremendously.
Test your lens on subjects with specular highlights in the background (like distant lights or sunlight through leaves). Examine how the out-of-focus areas render:
Are the highlight circles smooth or angular?
Do they have harsh edges or "onion rings"?
Is the transition from in-focus to out-of-focus pleasing?
Remember, "good bokeh" is somewhat subjective, but harsh or distracting background blur rarely makes for pleasant photos.
(Understand depth of field fundamentals to better evaluate how your lens performs at different apertures.)
Optical Issue Detection
Beyond basic sharpness, several optical issues can affect image quality.
Chromatic Aberration Test
Those purple or green fringes along high-contrast edges? That's chromatic aberration, and while correctable, severe cases indicate potential problems.
Photograph dark objects against bright backgrounds (like tree branches against sky). Check edges for color fringing at 100% magnification.
Flare Resistance
Point your lens toward bright light sources (carefully, never directly at the sun) and see how it handles flare.
Some flare is inevitable, but excessive ghosting or significant loss of contrast might indicate poor coating quality or internal reflections.
Distortion Assessment
Straight lines should remain straight – unless you're using a fisheye lens.
Photograph architectural subjects with clear horizontal and vertical lines. Look for:
Barrel distortion (lines bow outward)
Pincushion distortion (lines bow inward)
Mustache distortion (complex waviness)
Most modern lenses have profiles that correct distortion digitally, but knowing your lens's native characteristics helps you understand its optical quality.
Real-World Scenario Testing
Lab-style tests matter, but how your lens performs in actual shooting conditions matters more.
Low-Light Performance Evaluation
Take your lens into challenging lighting conditions and assess:
How easily can you achieve focus?
Is image quality acceptable at higher ISOs?
Does the maximum aperture deliver enough light for your needs?
A lens that's tack-sharp in daylight but unusable in dim conditions might not suit your shooting style.
(To thoroughly assess low-light capabilities, try some night photography settings to see how your lens performs in extreme conditions.)
High-contrast Scene Handling
Photograph scenes with both bright highlights and deep shadows. Check how your lens maintains detail in these challenging conditions.
Great lenses preserve subtle details in both extremes without excessive washout or muddiness.
Backlit Subject Testing
Shooting into light sources tests a lens's contrast and flare control. Can you still capture a well-defined subject when facing toward light?
This test often separates good lenses from great ones – premium optics maintain contrast and color fidelity even in challenging lighting.
Moving Subject Tracking Capability
If you shoot action, test how well your lens focuses on moving subjects. Fast, accurate focus acquisition can be as important as raw sharpness for many photographers.
Weather Sealing Verification
If your lens claims weather resistance, consider testing it in light rain or dusty conditions (within reason – don't risk expensive equipment unnecessarily).
Specialized Testing Based on Lens Type
Different lenses require different testing approaches.
For Wide-Angle Lenses: Distortion and Corner Sharpness
Wide-angle lenses often struggle with distortion and edge sharpness.
Test by photographing architectural scenes with straight lines extending to frame edges.
Examine how people near the edges look – do they appear unnaturally stretched?
Wide-angle lenses excel in landscape photography, so test with appropriate settings for this genre.
Pay special attention to corner sharpness, as wide angles often suffer more in this area than standard focal lengths.
For Telephoto Lenses: Stabilization and Reach Tests
Telephoto sharpness is heavily affected by camera shake and atmospheric conditions.
Test stabilization effectiveness by shooting at progressively slower shutter speeds to find your practical handheld limit.
For super telephoto lenses, test the resolution on distant subjects with fine detail to ensure you're getting the reach you paid for.
For Macro Lenses: Minimum Focus Distance and Magnification
Verify that your macro lens achieves its advertised magnification ratio.
Test focus breathing (some macro lenses change effective focal length when focusing close) and working distance (the space between lens front and subject at minimum focus).
For Zoom Lenses: Sharpness Throughout the Zoom Range
Zoom lenses often have varying performance across their range. Test at both extremes and several points in between.
Check for focus shift while zooming – does the focus point stay consistent when you zoom in or out?
Comparing Results with Manufacturer Specifications
After thorough testing, compare your findings with what the manufacturer promised.
Most manufacturers publish MTF charts showing theoretical performance. While you can't directly reproduce these tests, your real-world results should generally align with
expectations.
If your lens significantly underperforms compared to published specifications or trusted reviews, you might have received a subpar copy.
Don't hesitate to contact the seller about a replacement if your lens shows clear defects or underperformance.
Final Note
Trust your own results over online reviews. Your specific photography style, techniques, and expectations matter more than someone else's experience.
The tests outlined here provide objective information, but your personal assessment of the images you create remains the ultimate verdict.
Once you've mastered your equipment, explore ways to make money as a photographer by leveraging your technical knowledge and unique creative vision.
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