TonyM
Well-Known Member
- Joined
- Jul 30, 2013
- Messages
- 5,417
- Reaction score
- 5,095
- Country
- United Kingdom
- Dash Cam
- A139, M1S
I had a hunch that these varifocal lenses were not constant aperture throughout the focal range, although the Treeye listings only state a single aperture? SLR zoom lenses have markings which clearly show whether they are constant or variable aperture.I've actually had my eye on that 6-22mm varifocal myself and in fact recently placed an order for one from Treeye. I plan to experiment with it as a dash cam lens but primarily feel it will be better suited to wildlife observation and am looking forward to sharing it with my environmental center students.
One thing to keep in mind with these varifocal for dash cam use is the aperture. With a zoom lens, the default aperture becomes smaller and smaller the more you rack the lens out to the maximum telephoto focal length so that what starts out as ƒ/1.4 or ƒ/1.6 lets much less light through the greater the magnification. The starlight lenses might be better suited for extreme telephoto use if you want good low light imaging.
I will probably want to use a varifocal from 6mm upwards, as that is about the minimum focal length I've been happy with for a fixed telephoto lens to make it worthwhile running alongside a standard dashcam. If the 6-22 is F1.6 at 6mm, that might be better than the 2.8-12 at 6mm? On the other hand, as you mention I am not likely to want to go beyond 12mm for dashcam use. I might also remove it from the car from time to time for wildlife observation similar to how you have used yours.
I do have a fixed 6mm F1.2 starlight lens, but the clarity of its image is nowhere near as good as your 2.8-12mm lens.