The Chen Adapter Tube

The Chen Adapter Tube

This adapter tube is made by Mr. Chen Min-San, aka Brother San, and is popular in Taiwan known as the Brother San Tube. You can find more and updated information here. Unfortunately, Mr. Chen's web is only available in Chinese. Actually, Mr. Chen has three products: the tube assembly, a thin ring for mounting a Sigma 28-105 petal type lens hood, and a specially made 62-55mm step-down ring for 55mm converters (e.g., Olympus TCON-17 and WCON-07).

The Adapter Tube

This adapter consists of three pieces, two larger tubes and a ring, all made from aluminum. See the left image below. The conical shaped tube (i.e., the lower portion) is the tube for mounting on a FZ-10, while the left cylindrical tube (i.e., the upper portion) is screwed on to the conical one to form a lens hood. The right image below shows a comparison of the tube and FZ-10's lens hood. As you can see, they have identical geometry.

The ring does not have a specific functionality. When it is screwed on to the conical tube as shown below left, one cannot screw the lens hood portion onto the conical tube, because this ring occupies the thread completely. I guess this ring is basically used for preventing the user from mounting the lens hood and a converter lens onto the conical tube at the same time. In general, if the lens hood is not used, which is very common among teleconverter users, one can always screw this thin ring onto the conical tube.

The right image above shows the conical tube (with the ring mounted) on a FZ-10. It looks like any other adapters (e.g., Yoshida, PD62 and PA62). The only difference is that the conical tube is the lower half of the FZ-10 lens hood! The conical tube has a 62mm thread. The images below show Olympus TCON-14B and WCON-08B mounted on the conical tube. Like the FZ-10 lens hood, the cylindrical portion of this Chen tube has a 72mm thread to be used with 72mm filters and other lens accessories; however, it is not a good practice to mount a filter so far away (on the lens hood) from the lens glass element. Click here for more details.

This is a very well made adapter. I have never had any problem (e.g., jammed filter and/or converter). Everything fits nicely and it does not jam the manual focusing ring either.

Many of us may not like the Panasonic lens cap when an adapter is mounted since we need to insert our fingers deeply into the tube. The best lens cap replacement is the Tamron snap-on version. It is available in 52mm, 55mm, 58mm and 62mm. The following image shows a 62mm Tamron lens cap on the Chen adapter tube.

The 62-55mm Step-Down Ring

Since this adapter tube has a 62mm thread and since many popular converter lenses (e.g., Olympus TCON-17 and WCON-07 and Canon TL-55) use 55mm thread, a special 62-55mm step-down ring is available separately (below left). This 62-55mm step-down ring can be mounted directly on to the lower conical tube as shown in the right image below.

When screw this special step-down ring onto a 55mm thread converter lens, the ring does not add much depth. In other words, the rear element of the lens can be very close to the front glass element of the camera lens. Here is an example. The left image below shows the Chen 62-55mm step-down ring on an Olympus WCON-07, and the right one has a generic conventional thicker 62-55mm step-down ring on the same lens. It is clear that in the case of a generic step-down ring the rear lens element is a few millimeters deep, pushing the rear lens element away from FZ-10's lens and increasing the chance of vignetting.

The following images show a TCON-17 and a WCON-07 mounted on a Chen adapter tube.

Due to its design, we can have this 62-55mm step-down ring and the cylindrical tube (i.e., lens hood) on the conical tube at the same time without vignetting. This is very convenient since we do not have to remove the lens hood portion in order to mount a 55mm converter lens. The left image below shows the 62-55mm step-down ring "inside" of the lens hood, and the right one shows a Olympus WCON-07 mounted on the assembly. In fact, I found out that when the lens hood portion is mounted, one can use Sony VCL HGD1758 with a 55-58 step-ring and TCON-14B and WCON-08B without any problem.

Matching Petal Lens Hood

To use a petal type bayonet lens hood, one must find some way to convert a thread mount to a bayonet mount. You can certainly find a petal type lens hood and put it on the lens. However, it can easily fall off from the lens. Mr. Chen designed a very thin metal ring as shown below that converts a thread mount to a bayonet mount. Then, one can mount a Sigma petal lens hood for the Sigma 28-105 lens on the adapter tube. To do so, a 62mm filter is needed. The following images show both sides of the ring. The marked rectangular shapes are used to provide a bayonet mount. A collar starting from a rectangular shape and extending to some length are marked by red squares.

The first step of mounting the matching Sigma petal lens hood is to cover the lower portion (conical adapter tube) with the ring as shown in the left image below. Make sure the edge of one of the rectangular shapes is aligned with the center line of the lens. Then, fasten a 62mm filter so that the ring cannot rotate (right image below).

Now, turn to the right side of the camera and locate the end of the collar. Then, align the small triangle on the Sigma lens hood with the end of the collar of the ring as shown in the left image below. Then, push the hood firmly into position (below middle). Finally, turn the lens hood clock-wise until the small triangle is at the center line (below right). In fact, once the small triangle reaches the center line, you would not be able to turn the hood further because it is blocked by the rectangular shape. You can loosen the filter a little bit to fine tune the origination of the hood.

A successful installation will give you the following results. Reverse the above procedure to remove the lens hood. Since the ring is very thin, handle it very carefully. If you wish to use other filters, you can add them on top of the mounted one.

While this is a cool product, there are some shortcomings:

  1. This Sigma 28-105mm petal lens hood is not good enough to shield stray light rays when the focal length is above 105mm (or 3X), and, as a result, flare and ghost images are still potential problems. Shoot carefully with this hood when the focal length is longer than 3X and the lens points to a strong light source. Or, switch to a better lens hood. See the Lens Hood page for more details.
  2. This Sigma lens hood is not listed on Sigma's web site. You may have some difficulty to find one. Consequently, Mr. Chen also sells the Sigma hood. See his web site for more details.
  3. The use of a 62mm filter to fasten the ring seems a little clumsy, although it is perhaps the cheapest way of converting the thread mount to a bayonet mount. If you wish to use another filter (e.g., polarizer), you have to stack them together and the thickness increases. This would also increase the chance of vignetting. If this happens, you might want to use thinner filters such as a slim polarizer. Moreover, if you do not want to have one more glass in front your lens, you can buy a cheap, thin protection filter, remove its glass, and use it to fasten the ring!

A Warning from Mr. Chen

Mr. Chen knew there are some copycats in Taiwan and China producing very similar products. He pointed out that many of these products could jam the manual focusing ring or may not allow filters or converters to be screwed to the best possible position.