Magfilter adapter on G7X II
IMO, CPL filters are much more important than perfect sharpness on corners. So as to adapt filters on a G7X / G7X II / G5X and more, I have found the Lensmate solution and the Magfilter solution. Both permit to adapt threated filters. I've chosen Magfilter mainly because I was afraid to hurt the lens if the attached lensmate hooks on something.
But the Magfilter comes into 3 sizes : 52mm, 55mm, 58mm. What should you choose ? Contacting the Magflter support by mail is usless : they don't seem to have tested the product on a variety of cameras. Anyway, the 58mm would be larger than the lens ring, and probably would exceed the bottom of the camera. So... 55mm or 52mm ?
Basically, up to that point, it is about vignetting at WA. I've ordered a 55mm so let me show my conclusion. You would have liked to read clear points about that, so I post for future Google searches.
I've taken a quick snap out of my window : with the Magfilter in red, and without the Magfiter in blue. On the Magfilter, I've put a CPL filter (Marumi DHG Super Circular PL 55mm). It is quite slim, but thicker than an ultra slim UV filter.
So... the results.
24mm, lens distortion 100% corrected
So far, so good.
Wider than 24mm, lens distortion 100% corrected
The G7X lens is sharp but heavily distorted. And OOC JPEGs are produced from a sensor crop. By reading the whole sensor outpout, one gets a significantly wider angle, at the expense of corner sharpness (no free lunch). So, what's going on with the Magfilter if one wants to unleash the G7X wide angle ?
Full sensor capture, uncorrected distortion
So as to figure out how much the Magfliter vignetes at widest angle, let's have a look at the full sensor capture, without lens correction.
Widest angle without vignetting, adapted correction percentage
Here, we try to show the widest possible angle with a 2/3 aspect and without vignetting. To do so, the lens distortion correction percentage is adpated to maintain the widest angle, yet eliminating vignetting.
- With the 55mm, there won't be vignetting with an OOC picture, nor with an image processed by a basic RAW interpreter such as Lightroom.
- If you want to retain lines straight, then the Magfilter won't prevent you from going a wider as the G7X lens can go (perhaps like 22mm or such).
- It's only when you relax the "straight lines" constraint vignetting might become a concern.
So 55mm is probably the best size with a G7X :
- With the 52mm, the feature (2) would probably not be verified
- The 58m is too large for the body
Hope it helps...