Video test of C-mount Fujinon 17,5-105 f1.8 (C6X17.5) parfocal zoom lens with Panasoniс GH5.
Shot in 4K 30 fps, with EX-Teleconversion function in GH5 (crop factor 1.4x (2.4 in FF equivalent)). On full M4/3 sensor lens has slight vignette.
Panasonic GH5
Fujinon 17.5-105 1.8 (C6X17.5)
Tiffen 77mm Variable Neutral Density Filter (with step up rings - size of the thread on this lens is 58mm)
Shot handheld. From the start till 53 second - added stabilisation in Adobe Premiere (warp stabilizer). From 54 second till the end - no stab in post.
In camera stabilizer set to 50mm.
V-log L.
You can use this lens only with m4/3 sensor cameras. On cameras with larger sensor this lens will vignette havely.
To use this lens on m4/3 camera you will need a c-mount to m4/3 adapter.
In order for the lens to be Parfocal, you need to find a slim c-mount to m4/3 adapter (this adapters are all different - some of them will be to thick or too slim)
Adapter thickness directly affects Parfocal abilities of the lens.
I suggest you to buy several different c-mount slim adapters, just in case.
There's a way to define what adapter you have - the slim one or too thick one:
1. Zoom in your lens to 105mm.
2. Focus on some object.
3. Gradually start to zooming out and watch were your focus going:
- If while you zooming out your focus goes further from the object you were focusing on step 2 - your adapter is too slim, and you need some shim between the lens and your adapter for the lens to be parfocal.
- And if while you zooming out focus goes closer from the object you were focusing on step 2 - your adapter is too thick, and you need the slim one.
This method works on all C-mount Zoom lenses.
There's a chance that your adapter will fit your lens perfectly and you will no need in adjusting it to make it parfocal, but don't count it - it's really a small chance.
So in order for your lens to be parfocal, you need to find slim c-mount adapter, and add a shim for adjusting parfocality. (There's no way to your lens to be parfocal adjusted with thick adapter)
About the shim: you can do it yourself using thin plastic, or electric tape or just a paper, also you can buy this shims:
[ Ссылка ]
(I'm suggesting you to buy several shims with different thickness).
When you finally get your slim adapter and make (or buy) the shims you need to add this shims, layer by layer, between adapter and the lens, add the shims until the lens becomes Parfocal.
All this instruction may seem difficult and complex, but when you get all the tools you need - it's really not that difficult at all.
The lens worth it.
