Run Shuangyu Tripod Mount Ring for Sigma APO 70-200mm F2.8 II EX DG Macro HSM 71mm

Nothing remarkable about the product itself.It looks well made. It's apparently in cast metal, anodized black. The integrated footplate is large and has and Arca Swiss type edge to the bottom of the foot that, for me, engages quite securely on the ball heads I have. The footplate itself is connected to the base of the ring by means of two Allen screws from the underside of the footplate: be aware of these in case you need to tighten them in future to keep the footplate and ring secure. The underside of the foot had the standard 1/4 20 hole to accept photographic tripod screws; it even had a recess to accept the locator pin that comes with many tripod heads (to prevent the camera from rotating independently of the tripod head): again, it fitted securely with no movement on the photo tripod I normally used. Given it was metal it felt cold in the hand, but the anodized surface felt a little textured/stippled rather than smooth. There appeared to be no sharp or unfinished edges. The screw section of the knob was a little tacky on first being exposed: I assumed that this was a little grease of some description to lubricate the screw whilst in storage.At the top of the exterior profile of the ring itself was a ridge that marks the center-point, which could be lined up with the center-line of what ever lens it was clamped about. A lens was inserted by means of opening the large metal hexagonal knob to one side which released the clamped end of the ring, allowing the ring to open up on a hinge set about 180 degrees opposite the knob: the hinge was integral to the ring and appeared to rotate about a hollow metal pin. The lens was placed into the lower half of the ring and the upper half was closed back around the body of the lens and the knob was screwed in tight to grip the lens. The ring itself was lined with thin, felt-like material to assist with grip and which shouldn't mark the body of the lens. The internal diameter of the lens mount ring was 71mm.Unfortunately, the Samyang 135mm f2 was 70mm in diameter, so there was considerable play in it and the lens was small enough to slide freely in and out of the ring (when it wasn't mounted to a camera), but having read the specs I was already aware of this likelihood. The solution for me was to buy some thin self-adhesive rubber sheet, the stuff that was commonly applied to mounting surfaces to prevent connected surfaces from sliding past each other. I cut a strip a few mm narrower than the depth of the mount ring itself (about 12mm rather than the mount's 15mm depth), and then applied it to one half of the inside of the ring, over the pre-existing felt strip. The grip was better, but not entirely secure, so I also applied a small square to the other half of the ring mount and closed the ring mount again. This time the lens was held securely - I couldn't rotate the lens in the mount without having to release the clamp slightly. The reason I decided to apply the rubber sheet to the mount rather than the lens was to avoid permanently covering up to focus distance markers on the lens: the mount was also a considerably less expensive to deface!The Samyang 135mm lens was a heavy beast (over 750g; or over 1.5 lbs in old money) and barring getting a specific mount for the Samyang 135mm lens, this appeared to be the next best option to preserve the lens mount of the SLR camera. This solution probably applied to other lenses too. However, as with everything, there are caveats.To use this, any lens would need a blank or unoccupied space on its barrel for the ring mount to grasp, free of things like the focus grip of the f-stop ring, and this will need to be at least 15mm deep: not all lenses will have this, so check your lens. For the Samyang 135mm there was a section of the barrel between the focus grip and f-stop ring that was marked with various focus distance numbers which this lens mount effectively covered (not a problem for me as the lens will be mostly left set towards infinity). With the mount ring on, the Samyang's f-stop ring was a little harder to access (spoiler: I also have large-ish fingers), but again for me this wasn't a major issue.The lens must be about 71mm across at the point where you intend to secure the mount. Slightly too small a lens diameter and you'll have to improvise, as I did. Slightly too big a lens diameter, and you'll have to search for another solution (although other, different lens mount diameters exist), as the shaft attached to the locking knob is pretty short.Having only recently acquired the lens ring mount, I can't comment on its durability. But from a first fit point of view, it holds my Samyang 135mm lens securely and has relieved the inevitable strain on my SLR lens connector that having such a heavy lens incurs. Whether this is a worthwhile long-term solution is in the lap of the gods; but it's certainly a solution for the time being.

Ottimo prodotto(molto solido anche non originale)

Lo he comprado para sujetar un adaptador anamórfico Sankor 16F en un sistema de raíles y que no se gire mientras enfoco con el dioptrio variable.Encaja como un guante, está hecho de buenos materiales y en general me sirve para lo que necesitaba, le doy las 5 estrellas que merece.

Ricevuto senza il foro per il treppiede, difettoso, sono dovuto andare da un mio amico e filettarlo perchè avevo urgenza.

The collar does not fit my Sigma 70-200 very snug. It does the job at keeping me from holding the camera and lens all day, but it does not fit tight enough. It will allow up and down movement of the camera and lens in the collar. It also lets the lens roll to the right with the weight of your hand on the camera. This would not keep me from ordering another one, but it would help if it was a little tighter.