How can you manually focus a lens like the Opteka 6.5mm circular fisheye lens that features virtually useless distance markings along the focus ring?
The Opteka "User Manual" includes the following information in the section entitled "Focusing Aides."
Many compatible cameras provide aides for manual focus precision. The two most common aides are Focus Peaking, and/or a Focus Magnifier. Be sure to consult your camera's user manual for assistance with configuring these features. Source Credit: Opteka 6.5mm f/2.0 HD Multi-Coated Lens User Manual, p. 6.
In my experience "focus peaking" and "focus magnifier (Focus Check)" are easier to use under controlled conditions such as a photo studio. Nonetheless, I'll tell you how to use those features on Fujifilm X-Series cameras, then I'll tell you about a simpler/better "hack" for focusing the Meike/Opteka lenses that just works for "all sky" photography.
Here's how to set "focus peaking."
Fujifilm X-T5MENU/OK, AF/MF SETTING, p. 2/3, MF ASSIST > FOCUS PEAK HIGHLIGHT > RED (HIGH)
Here's how to enable/disable "focus magnifier (Focus Check)."
Fujifilm X-T3, X-T5Focus magnifier: press rear Command Dial; toggle on/off.
"Hack" for manually focusing Meike/Opteka 6.5mm lenses
It's possible/probable the Opteka 6.5mm circular fisheye lens is a rebranded version of the Meike 6.5mm circular fisheye lens, given the similarities in the physical appearance and specifications of the two lenses.
Apparently the Meike 6.5mm looked like this during September 2019.
 |
| Photo Credit: Shutterbug. |
The iteration of the Meike 6.5mm circular fisheye lens that I bought from B&H Photo during May 2026 looks like this. Notice the labeling on the focus ring changed to include a few distances in feet (ft) and meters (m).
 |
| Photo Credit: B&H Photo. |
Finally, the Opteka 6.5mm circular fisheye lens that I bought from Opteka/Circuit City/Amazon during August 2026 is advertised to look like this.
 |
| Photo Credit: Opteka/Circuit City/Amazon. |
But wait, that's not the way the Opteka 6.5mm lens that was delivered to me looks. Actually it looks like this, similar to the 2019 iteration of the Meike 6.5mm.
 |
| Photo Credit: Walter Sanford. |
Gee, notice any similaries in appearance between the Meike 6.5mm lens and Opteka 6.5mm lenses? I think it's safe to say they are the same lens with different labeling on the focus ring.
Both lenses have virtually the same "focus throw."
In photography and cinematography, the term "throw" usually refers to focus throw, which is the total physical distance or angle a lens's focus ring must rotate to move from its minimum focusing distance all the way to infinity. Source Credit: Google AI Overview.
As an aside, I would say both the Meike and Opteka lenses have a relatively short focus throw of ~90 degrees. This is better for videography than photography, which might explain why the aperture- and focus rings are clickless.
Anyway, because the Meike 6.5mm and Opteka 6.5mm lens have the same "focus throw" it's reasonable to think they focus identically, meaning when the Meike focus ring is rotated so it's focused on a given distance, say 3 ft, the Opteka works the same way.
Here's some practical advice. With the camera/lens facing forward, slowly rotate the focus ring clockwise until it stops turning at the index mark on the lens barrel. From that point, measure 4.1 to 4.2 cm along the focus ring; that point, which should be aligned with the middle of the infinity mark on the Opteka 6.5mm circular fisheye lens, is equivalent to the 3 ft label on the Meike 6.5mm circular fisheye lens.
Why set the focus ring to 3 ft?
Because the hyperfocal distance of a 6.5mm lens is so remarkably short, focusing this lens manually is incredibly forgiving. If you align your focus ring to roughly 1 meter (3 feet) while shooting at f/8, your total depth of field will stretch from just a few inches in front of the lens element all the way out to infinity. [1, 2] Source Credit: Google AI Overview in response to my query "At an aperture of f/8 what is the hyperfocal distance of the Meike 6.5mm circular fisheye lens?"
In case you'd like to know/mark other Meike/Opteka equivalent distances, use the following measurements along the Opteka 6.5mm focus ring: 0.7 ft = ~7-8 mm; 1 ft = 2.2 cm; 3 ft = ~4.1-4.2 cm; ∞ = ~4.9-5.0 cm.
In a nutshell, my "hack" for manually focusing the Opteka 6.5mm circular fisheye lens is set the focus ring for 3 ft, that is, rotate the focus ring until the infinity symbol (∞) is aligned with the index mark on the lens barrel -- everything from a few inches in front of the lens to infinity will be acceptably in focus. Ignore the fact that it looks like you set the focus ring for infinity (∞). You didn't. It's set for three feet (3 ft), the hyperfocal distance for both the Meike 6.5mm and Opteka 6.5mm lenses when the aperture is set for f/8.
Related Resources
- What's wrong with this picture? - a blog post by Walter Sanford
- Opteka 6.5mm circular fisheye lens - first field test - another blog post by Walter Sanford
- Opteka 6.5mm circular fisheye lens - more field testing - yet another blog post by Walter Sanford
- Posts on Walter Sanford's Blog with the label "Opteka 6.5mm."
- Posts on Walter Sanford's Blog with the label "all sky."
- Meike MK 6.5mm f/2 Circular Fisheye Lens Review, by Jon Sienkiewicz. Shutterbug.
Copyright © 2026 by Walter Sanford. All rights reserved.
No comments:
Post a Comment
Comments are invited and wlecome.