The Entaniya Fisheye HAL 220 series (HAL 220 PL / HAL 220 LF) can change the focal length. To change the focal length, use the zoom spacer ring.
The zoom spacer ring is not a common lens, so this article explains how the zoom spacer ring should be used.
Spacer to change focal length
The zoom spacer ring is a spacer that changes the focal length of the lens.
Each zoom spacer ring has a different thickness and can be changed to any focal length by using the spacer designated for each focal length.
For HAL 220 PL, the focal length can be changed in steps from 6.14 mm to 8 mm,
for HAL 220 LF, the focal length can be changed in steps from 9 mm to 12.6 mm
The size of the image circle can be changed.
As the focal length changes, the size of the image circle changes. The smaller the focal length, the smaller the image circle. As the focal length increases, the image circle also increases.
This means that the angle of view can be changed to suit the purpose or application, depending on the sensor size of the camera.
How to change the zoom spacer ring
How to read the zoom spacer ring
HAL 220 LF
The HAL 220 LF has six zoom spacer rings, each engraved with the thickness of the zoom spacer ring.
This thickness determines the size of the focal length (image circle) (see table below).
Zoom spacer rings are available in 1mm, 2mm, 3mm, 4mm, 5mm, and 10.4mm.
Normally, only one piece is used, but when used with 6mm, 7mm, 8mm, or 9mm, two pieces are used.
| Thickness（mm） | Image Circle（mm） | Focal Length（mm） |
| Without Spacer Ring | 46.3 | 12.6 |
| 1.0 | 44.6 | 12.1 |
| 2.0 | 43.1 | 11.7 |
| 3.0 | 41.6 | 11.3 |
| 4.0 | 40.2 | 10.9 |
| 5.0 | 38.9 | 10.6 |
| 6.0 | 37.7 | 10.3 |
| 7.0 | 36.6 | 10.0 |
| 8.0 | 35.5 | 9.7 |
| 9.0 | 34.4 | 9.4 |
| 10.4 | 33.1 | 9.1 |
HAL 220 PL
The zoom spacer ring on the HAL 220 PL is engraved with the focal length and the image circle sizes of 180° and 220°. 14 zoom spacer rings are available. Only one spacer is used.
- Focal length
- 180° image circle size
- 220° image circle size
The more the spacer is inserted, the closer the bottom part of the lens will be to the sensor side. As a result, when using a lens with a focal length of 7mm or less, the lens may interfere with the filter inside the camera or may not be attached due to the internal structure of the camera. This is not a problem for cameras with short flange backs (RF mount, E mount, etc.).
| Focal Length（mm） | Image Circle@180°（mm） | Image Circle@220°（mm） |
| 8.03 | 25.0 | 29.8 |
| 7.70 | 24.0 | 28.6 |
| 7.55 | 23.5 | 28.0 |
| 7.40 | 23.0 | 27.4 |
| 7.25 | 22.6 | 26.9 |
| 7.12 | 22.1 | 26.3 |
| 6.99 | 21.7 | 25.8 |
| 6.87 | 21.3 | 25.4 |
| 6.74 | 20.9 | 24.9 |
| 6.63 | 20.5 | 24.4 |
| 6.51 | 20.2 | 24.0 |
| 6.40 | 19.8 | 23.6 |
| 6.30 | 19.5 | 23.2 |
| 6.20 | 19.2 | 22.8 |
| 6.14 | 19.0 | 22.6 |