Big Mike's BM-SLY420NK-K2 420-1600mm
The constant f/8.3 aperture across its 420-1600mm zoom range provides consistent exposure, aided by an included 2X teleconverter for extreme reach. Its lightweight 989g build and multi-coated optical glass offer surprising portability and flare reduction for a super-telephoto lens at a minimal cost. This lens is best for budget-conscious Nikon DSLR wildlife photographers who need massive focal length from a stationary position and can work within its manual focus and fixed aperture limitations.
Snapshot
The 30-Second Version
This lens gives you an absurd 1600mm reach for pocket change, but the image quality is soft and the fixed f/8.3 aperture is punishing. The stabilization is a nice surprise, but dicey compatibility and a cheap build make it a risky buy. Only grab it if you're a manual-focus tinkerer who values extreme zoom over sharpness.
Pros & Cons
Pros
- Insane 420-1600mm reach for under $200 is the definition of a budget super-telephoto. 86th
- Image stabilization is surprisingly effective for a lens in this price class. 82nd
- The main lens barrel and adapter are solid aluminum, not cheap plastic.
- Includes a 2x teleconverter and T-mount adapter right in the box.
Cons
- Fixed f/8.3 aperture is painfully slow and useless in anything but bright light.
- Optical quality is soft and hazy, landing in the bottom 20% of lenses we've tested.
- The plastic tripod mount feels flimsy and is a common failure point.
- Compatibility is a gamble, with many reports of it not working on listed Nikon bodies.
What owners think
The Word on the Street
The proof
Performance
The optical performance is where the budget price really shows. It lands in the bottom 20th percentile for optics in our database, which means image quality is soft, especially at the long end. You'll get some shots if you nail manual focus on a tripod, but don't expect anything sharp wide open. The constant f/8.3 aperture is a real limitation, forcing you to shoot in bright daylight or crank your ISO. On the plus side, the stabilization is a standout feature for this price bracket, ranking in the 82nd percentile, which helps a bit with the long focal lengths. The build quality is a real low point, sitting near the very bottom of our rankings, and that plastic tripod mount is a known weak spot.
Specifications
Full Specifications
Optics
| Type | Telephoto |
| Focal Length Min | 420 |
| Focal Length Max | 1600 |
Aperture
| Max Aperture | f/8.3 |
| Min Aperture | f/8.3 |
| Constant | Yes |
Build
| Mount | Nikon F |
| Weight | 1.0 kg / 2.2 lbs |
AF & Stabilization
| AF Type | Autofocus |
| Stabilization | Yes |
Focus
| Min Focus Distance | 420 |
vs Competition
Stacking this against a modern all-in-one like the Tamron 28-300mm or a kit zoom like the Nikon 16-50mm is almost unfair. Those lenses have fast, silent autofocus and modern optics that run circles around the Big Mike. They're sharper, faster, and infinitely more practical for daily shooting. The only thing this lens wins on is sheer, unadulterated focal length. If you need to photograph a bird on a distant planet and have a budget of $150, this is your only option. For everything else, a used consumer telephoto from a name brand will serve you much better.
| Spec | Big Mike's BM-SLY420NK-K2 420-1600mm | Tamron Di III VC 28-300mm f/4-7.1 VXD | Sigma Contemporary 18-50mm f/2.8 DC DN | Nikon NIKKOR Z 17-28mm f/2.8 | Panasonic Leica DG Vario-Elmarit H-ES12035 | Sony E 18-135mm f/3.5-5.6 OSS |
|---|---|---|---|---|---|---|
| Focal Length | 420-1600mm | 28-300mm | 18-50mm | 17-28mm | 12-35mm | 18-135mm |
| Max Aperture | f/8.3 | f/4 | f/2.8 | f/2.8 | f/2.8 | f/3.5 |
| Mount | Nikon F | Sony E | Sony E | Nikon Z | Micro Four Thirds | Sony E |
| Stabilization | true | true | false | false | true | true |
| Weather Sealed | false | true | true | true | true | false |
| Weight (g) | 989 | 590 | 290 | 450 | 306 | 326 |
| AF Type | Autofocus | VXD linear motor | stepping motor | Stepping Motor | Autofocus | Linear motor |
| Lens Type | telephoto | zoom | zoom | zoom | zoom | zoom |
| Compare | Compare | Compare | Compare | Compare |
| Product | AF | Bokeh | Build | Macro | Optical | Aperture | Versatility | Social Proof | Stabilization |
|---|---|---|---|---|---|---|---|---|---|
| Big Mike's BM-SLY420NK-K2 420-1600mm | 53.9 | 48 | 6.1 | 62 | 20.2 | 49.8 | 86.2 | 63.9 | 82.4 |
| Tamron Di III VC 28-300mm f/4-7.1 VXD Compare | 98 | 78.3 | 65.2 | 85.8 | 96.7 | 66.4 | 97.7 | 54.8 | 82.4 |
| Sigma Contemporary 18-50mm f/2.8 DC DN Compare | 86.9 | 82.2 | 86.1 | 91.7 | 82.2 | 84.3 | 78.5 | 89.5 | 36.8 |
| Nikon NIKKOR Z 17-28mm f/2.8 Compare | 86.9 | 87.4 | 75.2 | 85.8 | 88.2 | 84.3 | 68 | 68.9 | 36.8 |
| Panasonic Leica DG Vario-Elmarit H-ES12035 Compare | 53.9 | 82.2 | 85.4 | 51 | 86.5 | 84.3 | 80.5 | 85 | 96.9 |
| Sony E 18-135mm f/3.5-5.6 OSS Compare | 98 | 75.8 | 72.5 | 40.3 | 78.5 | 77.7 | 95.8 | 89.5 | 82.4 |
Price
Value & Pricing
For the price, which hovers around $140 to $218, you're getting a lot of metal and glass. It's a tempting entry point for someone who just wants to see what 1600mm looks like without selling a kidney. But calling it good value is tricky when the image quality is so compromised and the compatibility is a coin flip. You're essentially buying a fun experiment, not a reliable tool.
Read more
Overview
Big Mike's BM-SLY420NK-K2 is a budget super-telephoto that promises a whole lot of reach for very little cash. We're talking 420mm to 800mm natively, and a staggering 1600mm with the included 2x teleconverter. On paper, that's a wildlife photographer's dream for under $200. In reality, it's a manual focus, fixed f/8.3 lens that demands a lot of light and even more patience.
Common Questions
Q: Will this lens autofocus on my Nikon D5600?
No, this is a fully manual focus lens. You'll need to focus using the ring on the lens barrel, and your camera won't give you any electronic focus confirmation.
Q: Can I hand-hold this lens at 800mm or 1600mm?
Realistically, no. Even with the built-in stabilization, the extreme focal length magnifies every tiny shake. You'll absolutely need a sturdy tripod to get a usable image.
Q: Is the image quality good enough for bird photography?
It can be, but only in perfect conditions. You'll need bright sunlight to compensate for the slow f/8.3 aperture, and even then, images will be noticeably soft compared to a modern telephoto lens.
Who Should Skip This
If you need a lens that just works out of the box, skip this. The compatibility issues with common Nikon bodies are a deal-breaker. Anyone who values sharpness or shoots in anything less than full daylight should look for a used name-brand telephoto instead, because this lens's optical performance is a real letdown.
Verdict
The Big Mike's BM-SLY420NK-K2 is a novelty lens for the deeply curious on a strict budget. It's for the hobbyist who already knows their way around manual focus and wants to play with extreme focal lengths without a major investment. If you have a compatible camera, a sturdy tripod, and a sunny day, you can pull off some fun, if soft, moon shots. Just don't expect it to be your daily driver.
