In this post, I’ll show you what to look for when inspecting a used lens that you’re buying in person. The following is a transcript of the video linked above.
New photographers who are passionate about their hobby quickly develop an enthusiasm for lenses and the creative possibilities they open. This desire often leads them to the secondhand market, which offers a cost-effective way to buy photographic equipment.
Unfortunately, when buying a pre-owned lens directly from a seller met through online classifieds such as Craigslist, Facebook Marketplace, and Kijiji, you’re giving up the peace of mind offered by store refunds and manufacturer warranties in exchange for a lower price. Such trades involve items sold as-is using cash-only (or cash-like) transactions. The nature of these deals means it’s your responsibility to confirm that the seller’s description of the item is accurate because if you discover a problem after the sale is complete, you almost certainly have no recourse.
Fortunately, you can protect yourself against a bad trade and confirm that a lens is in good working order by performing a thorough inspection of the lens on the spot. The following is a detailed list of what you should do and check when buying a used lens is person.
1. Bring your camera
Although I recognize that this point is obvious, it bears mentioning: Remember to bring the camera for which you’re buying the lens, and don’t forget the battery and memory card.
This point deserves a short story. A few years ago, I was selling my Canon 85 mm lens and arranged to meet with a young woman at a Starbucks near my home. She was about fifteen minutes late and, crucially, had forgotten to bring her camera. Her realization quickly turned into embarrassment, which threw her off balance. She performed the most rudimentary inspection—confirming that the front and rear glass elements weren’t broken—gave me her cash, and quickly left. I’m honest, so she got a good lens; however, she could’ve easily been ripped off because she didn’t bring a camera to confirm that the lens was functional.
2. Examine the lens exterior for wear and tear, scratches, and dents
Unless you’re buying a rare collectible that’s spent its entire existence in a protective case or a lens advertised as “like new,” most camera lenses will have developed some wear and tear from regular use. Your goal is to establish that the used lens you’re inspecting matches the advertisement. Significant differences from the advertised description and images of the lens serve as a convenient warning that the seller is not entirely trustworthy.
In most cases, the pre-owned lens will match its advertised description, and you can continue with your examination. Wear and tear are inevitable on lenses that see use, especially by professional photographers. For example, it’s normal to find scuff marks and wear of the paint on the filter ring because it’s the front-most part of the lens. The ridges on rubberized zoom and focusing rings wear down with years of use. Hairline scratches and scuff marks on the painted or plastic exterior are also expected and largely unavoidable. Such superficial wear is normal and won’t impact the optical performance and characteristics of the lens.
Dents on the barrel of the lens deserve greater scrutiny because they suggest a more forceful impact or drop. Such force could easily knock the precision optics out of alignment and reduce optical performance. Ask the seller about the nature of the damage, keep it in mind, and continue.
3. Examine the front and rear glass elements.
Remove the lens caps to check the front and rear glass elements. Clean glass is easier to check, so if you find fingerprints, smudges, or dust on the glass, ask the owner to clean them off before proceeding with the inspection.
Examine the front and rear glass elements. Observe how reflections pass along the surface of the lenses. Ideally, the glass should be smooth and free from scratches, abrasions, or thinning of the anti-reflective coating.
In practice, tiny scuffs and hairline scratches, especially to the coating, won’t affect image quality in any measurable way. The only downside to buying a lens with scratched glass is that it may affect your future resale value. Additionally, if such a scratch wasn’t part of the seller’s description of the lens, you could use it to your advantage by suggesting a reduced price.
(For those of you wondering how badly damaged a lens must be before its evident in the photos, take a look at the following picture. Try to imagine what sort of damage caused this degree of softness and loss of contrast. Is it a scratch, or several? Is it a crack, or several? Now take a look at the lens that took the photo. How did you do? As it turns out, it takes significant damage to the front of a lens for the effect of that damage to be readily apparent in practical photography.)
4. Check lens for internal dust and fungus
With the lens caps removed, shine your phone’s LED light through the back of the lens while looking at its internal components through the front. Avoid looking directly at the magnified LED, as it’s incredibly bright.
If you’re in a dimly lit environment, you’ll see the concentrated beam form through the lens elements. You’ll also see a heap of dust and tiny imperfection that will make you regret ever trying this technique. Lenses get dusty, and zoom lenses get dustier. That’s because every time you zoom a lens, glass has to move back and forth, expanding or collapsing the interior volume. This motion displaces air, either pushing it out or sucking it into the lens. (On some cameras, you can feel air “blowing back” into your eye through the viewfinder.)
Fortunately, the dust found inside lenses is meaningless to photographers because it’s too small to matter and doesn’t resolve in your pictures. You want to look for fungus, which can show as soft fluffy dots or fuzzy fibres or webs sprinkled throughout the interior glass. Fungus spores find their way into a lens on dust and proliferate after extended periods of storage in warm and humid environments. The fungus can grow and permanently damage the glass of your lens unless it’s professionally cleaned. Always store your lenses in cool and dry environments.
5. Examine the electronic contacts for signs of wear and dirt (where available)
The electronic contact points found on the back of modern lenses facilitate communication with the camera. Ensure that the contacts are clean and don’t exhibit signs of corrosion. The presence of dirt and other deposits on the electronic contacts of a lens can wear down the thin gold-plating and cause data communication errors, which can result in loss of aperture control, autofocus, optical image stabilization, and lens-related metadata. You can clean dirty pins, but corroded ones require repair.
6. Examine the lens mount for damage
A lens is attached to a camera using the mount, which provides a secure point of attachment and ensures that the lens and camera are correctly aligned. The vast majority of modern lenses have metal mounting rings, but a few budget-oriented lenses feature plastic mounts.
When you’re examining a lens with a metal mount, visually confirm that there’s no deformation of the metal tabs at the base of the lens. This kind of damage could prevent the lens from securely attaching to the camera, or worse, damage the camera’s mounting ring if forced. Additionally, check to ensure the lens mount is firmly attached to the lens barrel—the attachment screws shouldn’t loose or missing.
Plastic mounts are less likely to deform but more likely to crack, chip, or wear down. Examine the plastic mount and tabs for signs of cracks, and confirm the mount is firmly attached to the lens barrel.
Now it’s time to attach the lens to your camera.
7. Make sure the lens attaches tightly and locks into place with a click
Attach the lens to the camera body and make sure it locks into place with an audible click. The lens should fit relatively tightly, although a tiny amount of rotational give is normal. With that said, there shouldn’t be any tilting or sagging; the lens axis must always remain perpendicular to the image sensor.
8. Confirm that the focusing ring works
Inspecting the focusing ring requires some understanding of what you’re buying. To help you, I’ll cover the three main categories.
Manual focus lenses:
Many vintage and some third-party or special-purpose lenses are focused by manually rotating the mechanically coupled focusing ring. Since there’s no autofocus fallback, it’s essential to confirm that the focusing ring works correctly and focuses the lens. With the camera switched on and your eye to the viewfinder, rotate the focusing ring from one extreme to the other. The scene in the viewfinder should shift in and out of focus. Additionally, the focusing ring should rotate smoothly across its entire range of motion without any grit or sense of slack.
Autofocus lenses (with mechanically coupled focusing rings):
The majority of autofocus lenses designed for SLR cameras feature focusing rings that are mechanically-coupled to the optical system. These types of lenses often have a focus mode switch on the lens barrel that let’s you select between manual focus and autofocus shooting. In most cases, the focusing ring will always work regardless of the focus mode. (Keep in mind, there are some exceptions to this, so know what you’re buying!)
Switch the camera on, turn the focus mode to Manual Focus (MF), look through the viewfinder, and rotate the focusing ring from one extreme to the other. Then, repeat those with the focus mode turned to Autofocus (AF). In either case, the scene should shift in and out of focus and the focusing ring should move smoothly across its range of motion.
Autofocus lenses (with “focus by wire”):
There’s a small but growing class of autofocus lenses with electronically coupled focusing rings. These types of lenses are informally called “focus by wire” because there’s no direct mechanical connection between the focusing ring and the internal lens elements. Instead, your inputs are transmitted electronically to the motors driving the focusing system.
Turn the camera on, set the focus mode to Manual Focus, look through the viewfinder, and rotate the focusing ring. Since there’s no physical connection, you’re mostly confirming the electronic connection is intact, that the motors work, and that the focusing ring rotates smoothly across its range of motion.
9. Confirm that autofocus works
Unfortunately, autofocus errors can occur on both DSLR and mirrorless cameras—even on brand new lenses. For example, the zoom lens I use to make these videos is my second copy. The first one had an autofocus so faulty that every two out of five shots were misfocused. I was lucky to notice the problem before my 14-day return period ended. Sadly, there’s no return policy when buying a used lens from someone you meet on Craigslist. So don’t be shy about carrying out a thorough inspection when buying an item that’s sold “as-is.”
To confirm that the electronic focusing system works and the lens can autofocus accurately, set your camera to use a single autofocus point and take several pictures of near and far objects, changing between them with every shot. Review each picture at full magnification to verify that the autofocus was consistently accurate.
Pro-tip: you can shift between photos while reviewing them at full magnification by rotating the main command dial on your camera.
10. Check the zoom ring for function and smoothness
The majority of zoom lenses have mechanically coupled zoom rings. Switch on your camera, look through the viewfinder, and rotate the zoom ring from one extreme to the other and confirm that your angle of view changes. The zoom ring should rotate smoothly with an even amount of resistance throughout the range of motion. You shouldn’t sense any underlying grit, impingement, or slack.
Since some zoom lenses extend outwards at longer focal lengths, it’s a good idea to inspect the newly exposed part of the barrel for abrasions, damage, and debris. Generally speaking, there shouldn’t be much give or wobbling, even at its maximum extension. However, some lenses can slowly extend when pointing down or slowly retract when pointing up.
11. Can the lens communicate with your camera?
When inspecting an electronic lens, it’s necessary to confirm that the lens can successfully communicate with the camera. In a sense, you’ve already confirmed this by engaging the autofocus. However, since there are some manual focus lenses with electronically controlled apertures, it’s a good idea to be specific.
You can confirm that a camera recognized an electronic lens when it displays an aperture value other than 0. As another option, you can take a picture and look at its metadata. When everything works correctly, the camera should display the zoom range, set focal length, and set aperture value in the picture’s metadata.
12. Does the aperture work?
It’s important to make sure the aperture changes in size when adjusting the aperture value. Don’t assume that putting the camera into Aperture Priority mode, rotating a dial, and watching the f‑numbers change corresponds to a functioning iris diaphragm. Regardless of the f‑number you set, a modern lens will keep its aperture fully open up to the point that you push the shutter button to take a picture. The aperture’s size is adjusted to your chosen f‑number only when you push the shutter button. This behaviour facilitates more accurate autofocusing in darker environments and provides a brighter view in the finder.
The following method should work for both DSLR and mirrorless cameras, even those without a depth of field preview button. Put the camera into Manual Exposure mode, select a large f‑number and a slow shutter speed (something like 2 to 4 seconds), look into the lens from the front, and press the shutter down to take a picture. Take note of the aperture’s size during exposure, and then take several pictures more. The iris should close down to the same size consistently. Any deviation in aperture size without a corresponding change to the f‑number could spell trouble for the consistency of your exposures.
13. Does the optical image stabilization work?
If you’re checking a used lens that features optical image stabilization, verify whether it operates by turning the switch on and off while looking through the viewfinder and half-pressing the shutter button. And if you happen to be inspecting a variable focal length lens, make sure you’re fully zoomed in, because the stabilizing effect is more obvious at longer focal lengths.
You can also place the camera into Shutter Priority Mode, select a relatively slow shutter speed, and take several handheld photos with the stabilization featured enabled and then several with it disabled.
When functioning correctly, image stabilization should reduce or eliminate the motion blur associated with a shaky camera.
And now it’s time for the bonus round of quick tips.
Many vintage lenses have mechanically-coupled aperture rings. When checking such lenses, ensure the aperture opens and closes all the way and consistently, and make sure the detents indicating intermediate steps are clicking.
If you discover that the lens comes with a UV or “protection” filter already attached, ask the seller to remove it. Removing the filter accomplishes two things: it gives you a better look at the condition of the lens underneath, and it demonstrates that the filter threading isn’t damaged. Imperceptible dents can damage the threading and make it practically impossible to remove or attach a filter.
If the lens features “weather resistance”—often designated by the characters WR—check the condition of the rubber flange around the lens mount for cracks, tears, or notches. This type of damage will essentially nullify the weather-resistance of both your lens and camera.
If the lens has a focus distance window—which is a clear plastic window with focus distance markings underneath—make sure that turning the focusing ring or using the camera’s autofocus moves the underlying display.
Lastly, it’s tremendously important to understand what you’re seeking to buy. Before meeting with anyone, read reviews of the lens you’re considering so that you can tell the difference between normal quirks and flaws or faults. Such basic research could inform you, for example, that the focusing system of the Fujifilm 90 mm ƒ/2 lens can wobble about when there’s no power to the lens—and that it’s a completely normal.
Now you should know what to check for when buying a used lens in person. If you have requests for topics, let me know in the comments, and I’ll consider them for future videos. In the meantime, you can learn more about photography by joining on of Exposure Therapy’s group photography lessons.