I'm still reading up on this cam and trying to get the best picture images possible. I have found out that the LS300 is not Full Frame, but APS-C. As I was reading it says if you are to use a Full Frame lens then we should consider using a focal-length reducer such as a Metabones adaptor. Can be found here in this guide called "Field Report: JVC GY-LS300 4K Super 35 Camcorder":

https://www.thebroadcastbridge.com/content/entry/5040/field-report-jvc-gy-ls300-4k-super-35-camcorder

I got a 50mm FF Roki and I will have to sub it out for the APS-C version. I was lucky and I got the APS-C Roki 35mm.

Just FYI to those this may help to understand which lens is best for the the optimal performance of the cam.

The actual excerpt is:


Lens Type—The LS300 supports three types of lenses: Super 35, MFT, and Super 16. After mounting a Super 35, MFT, or Super 16 lens, you can set VSM to match your lens. However, there is an alternative way to set VSM—use the LS300’s VSM setup tool to guide you to a VSM setting. (Figure 13.)

After attaching an Olympus M.ZUIKO Digital ED 14-42 F3.5-5.6 MFT zoom lens supplied by JVC, I toggled through the VSM settings. With a VSM setting of 89%, I saw no vignetting. Others have also reported no vignetting at 89%, and even higher. JVC, however, warns against setting VSM higher than 80%. (Figure 14.)

My solution—when recording UHD with an MFT lens, I select 86%(4K). This selection, midway between 80%(MFT) and 89%, provides a 3840x2160 capture resolution which 80%(MFT) does not. The setting also avoids making the capture window too large, as does 89%.

It may seem odd this setting dilemma occurs when an MFT lens is used on a camera with an MFT mount. The oddity becomes less so once one realizes there is no issue with MFT lenses when one is shooting SD, HD, or C2K. The oddity disappears when one understands that for those who shoot C4K and UHD, the MFT mount is simply a way of attaching a lens which more completely fills the Super 35 sensor.

APS-C—When shooting 16:9 video with an APS-C lens, the lens projects a 22.2 x 12.5mm image on a sensor with a 25.5mm diagonal. At the 97% VSM setting, the LS300’s sensor’s capture window has a diagonal of 26mm and a capture window resolution of over 10Megapixels. You should consider shooting with APS-C lenses to obtain maximum UHD quality. By using an EF-to-MFT adaptor, Figure 15, Canon EF lenses can be used by an LS300.

Full Frame—VSM is designed to work with lenses that project an image equal to, or smaller, than that projected by a lens designed for Super 35 cameras. Therefore, if you mount a 35mm Full Frame lens on an LS300, cropping will result. (Figure 16.) The focal length of the lens will appear to be 1.5X longer—a crop factor of 1.5. A 50mm FF lens will have an angle-of-view equal to a 75mm lens.

To avoid cropping, attach the lens using a focal-length reducer such as a Metabones adaptor. (Figure 17.) It will reduce the focal length by a factor of 0.71 that will result in the lens acting as though it had a 53mm focal length. As a bonus your lens will gain a stop of sensitivity. Figure 18 shows my Nikon F1.8 lens at work in Vegas.

I have a lot of very good full frame Nikon glass for my DSLRs and that is what I use with my LS300. Yes some of the image circle is wasted on Super35, but the wasted part is the extreme edges and corners, so I'm using the best part of the lens. In my limited experience their 4K image quality is a bit better than that of my MFT Panasonic 12-35 f2.8. DX (APS-C) lenses would work fine but I don't have any.

Thank you for the feedback that is really good information to know. There is nothing like someone that has experience as oppose to one that just has information. I'm looking at my Roki's a little stranger at the moment and already printed out return label for the Full Frame 50mm Roki. Looking to score a few Veydras instead.

Full Frame—VSM is designed to work with lenses that project an image equal to, or smaller, than that projected by a lens designed for Super 35 cameras. Therefore, if you mount a 35mm Full Frame lens on an LS300, cropping will result. (Figure 16.) The focal length of the lens will appear to be 1.5X longer—a crop factor of 1.5. A 50mm FF lens will have an angle-of-view equal to a 75mm lens.

To avoid cropping, attach the lens using a focal-length reducer such as a Metabones adaptor. (Figure 17.) It will reduce the focal length by a factor of 0.71 that will result in the lens acting as though it had a 53mm focal length. As a bonus your lens will gain a stop of sensitivity. Figure 18 shows my Nikon F1.8 lens at work in Vegas.
While that's technically correct, it's misleading. All cameras with APS-C sensors have a crop factor when compared to a full-frame sensor, which for the LS300 is 1.5X. So when you use a full-frame lens, the Field of View is 1.5X times as narrow as the FOV of that same lens on a full-frame camera. That's an equivalent FOV to a full-frame camera with a lens 1.5x times the focal length. It works that way not just with full-frame lenses, it doesn't matter what kind of lens you use. There's nothing incompatible or wrong about it, it's just the way lenses work on cameras. So no, it's not true that "full-frame lenses are not recommended on the LS300".

If you want to use a speedbooster with a full-frame lens on your LS300, it works fine but there's no requirement to do so. That's actually the main reason to use full-frame lenses, and why it can be an advantage to use them rather than cropped-sensor lenses on the LS300.

Agree with Lee, "full frame lenses not recommended" feels a little more sensational than realistic, or overthinking it a bit maybe.

On a lens like the Roki or any full frame lens, a little light spilling over the edge of the sensor isn't going to hurt anything, in fact I've approached it almost the opposite direction like Luke said, the best part of an image is the middle, while the edges give way first, so you're really using the best part of the image, clearer edges and corners.

There are reasons to return the Roki, but sensor size and image circle isn't one, that's the plus. The Roki is a little softer than some other lenses, combined with shooting in J-log and the "auto-sharpening" turned off, it's a little more noticeable, especially if you want to shoot closer to wide open and 4K. Have to be spot on with focus, even moreso in 4K, and can consider a light sharpen filter.

I'd just suggest not locking yourself into thinking full frame only works with Speedbooster, I use the Cannon 24-105 with a regular smart adapter and OIS and it looks and works great

Thank for the feedback gentlemen it really helps.

You use FF DSLR lenses on a RED ONE, so no big deal at all using exactly the same lenses on a LS300