Olympus TCON-300S 3X Teleconverter Lens

Olympus TCON-300S 3X Teleconverter Lens

Ching-Kuang Shene

Created: March 4, 2007

This page briefly discusses the characteristics of the Olympus TCON-300S 3X teleconverter lens, and only focuses on the "hardware" part without addressing image quality issues, which will be available on another page. The TCON-300S was made for Olympus E-10 and E-20 digital cameras and is of the monoscope type. In other words, its use is similar to the use of a monoscope: one points the lens to a subject and rotates the focus ring to focus. Yes, one has to perform this focusing operation, although focusing does not have to be very accurate as the camera's auto-focusing system can finish the job.

While there are many good quality 3X teleconverter lenses such as the Nikon TC-E3ED for the Coolpix 9xx, 4500 and 5000/5400 cameras, it is difficult to build a good quality 3X lens for high zoom ratio cameras due to many optical, cost and weight challenges. Consequently, when looking for 3X teleconverter lenses for high zoom ratio cameras such as the Panasonic FZ series, expectations should be lower because no such lenses exists on the market. This TCON-300S is no exception even though Olympus has done a respected job in building high quality converter lenses (e.g., TCON-17). In general, high power teleconverter lenses share the same set of problems. The most significant ones are lower resolution, lower contrast, and, in many cases, stronger chromatic aberration (i.e., purple fringing) than lower power lenses. Therefore, if one wishes to have sharp, saturated color, and low chromatic aberration lenses, better stay with 1.7X converters rather than going for a 3X.

Finally, the use of a smaller aperture can always help get better images, although sometimes it may also force to use high ISO sensitivity due to significant light loss of this lens. A new page on image quality will be added sometime later.

The Package

The package contains the following seven items:

  1. TCON-300S 3X lens
  2. TCON-SA1 support arm
  3. Front cap
  4. Rear cap
  5. Lens hood
  6. Carrying case
  7. Instructions
The image below shows the first five items. The lens TCON-300S is on the back row, and the support arm TCON-SA1 is in the middle. The front row, from left to right, has front lens cap, rear lens cap, and lens hood. Note that the lens hood is the screwed-in type with a thread size of 49mm.

The Lens TCON-300S

The left image below is the lens TCON-300S. As mentioned earlier, this lens has a 49mm thread for lens hood and filters. However, the rear end of the lens is a hard rubber tube and has no thread. The middle is the focusing ring. The lens barrel does not change its length, which is very convenient. The right image blow is the bottom part of the lens. This is a mounting bracket and cannot be removed.

The rear part of the lens is a hard rubber tube with no thread as shown in the left image below. Camera (i.e., E-10 and E-20) lens is inserted into the shallow rubber tube. Some tests show that the inner diameter of this rubber tube is 67mm because one can jam a 67mm thread filter into the tube as shown in the middle image below, which shows a 67-58mm step-down ring. The outer diameter is 72mm as shown in the right image below, which shows the lens is inserted into the 72mm opening of a 58-72mm step-up ring. This information help mount the lens to any camera.

The Support Arm TCON-SA1

The support arm SA1 can be viewed as having two sections. The front section (below left) has a screw and two small bins. This screw is to be used with the center hole of the lens bracket, while the two bins are inserted into the other two smaller holes to fix the lens in place. The rear section is for mounting the camera (i.e., Olympus E-10 and E-20). It also has a screw to be inserted into the tripod hole of the camera, and the two bins are used to fix the camera in place. Without these bins, the lens TCON-300S and the camera lens may not align properly, and, as a result, image quality may be affected. However, the two bins in the rear section will have a problem when the support arm is used with a FZ-30 or FZ-50.

If one wishes to use the support arm and do not mind to do some modification work, one may unscrew the four small screws as marked in the right image above. Then, the cover of the rear section can be removed (below left), revealing the two bins. Screwing these two bins a bit, removing them from their holders, and reinstalling the cover would finish the job. The result is shown in the right image below.

Mounting the Lens to FZ-30/FZ-50 Using the Support Arm

If the support arm has been modified as shown in the last section, mounting the TCON-300S to FZ-30/FZ-50 is not difficult. However, there is a catch: The length of Olympus E-10 or E-20 is larger than that of the FZ-30 and FZ-50. If TCON-300S and FZ-30/FZ-50 are mounted on the front and rear sections of the support arm, respectively, there is a gap between the camera and TCON-300S!

One may need step-up rings to solve this problem. As mentioned earlier, since the outer diameter of the rubber tube is 72mm, one may use a 55-62mm ring followed by a 62-72mm ring. Use the 55mm for the camera and the 72mm for the lens. Any step ring combinations should be fine as long as the combination goes from 55mm to 72mm. However, not all step rings are created equal, and some are thicker (or thinner) than the others. Therefore, one has to try a few combinations so that the resulting length is just good enough so that the lens and camera can be mounted properly. Since this combo does not have thread to connect the camera and the lens, always make sure the lens is aligned properly with the camera lens. Otherwise, one side of the images may be blurred due to misalignment. Also try to add about 1mm between the camera and the support arm if one could not align them properly.

The following shows the resulting configuration. Note that he Olympus E-10/E-20 (1,190 g) and the lens (780 g) are both heavier than the FZ-30/FZ-50 (740 g), and the tripod hole of the support arm is close to the camera. This could make the combo front heavy when it is mounted on a tripod. Therefore, use this combo with care.

Mounting the Lens with a Bogen 3420 Telephoto Lens Support

The Bogen/Manfrotto 3420 Telephoto Lens Support was made to support the older version of the Nikon AF 80-200mm f/2.8 that does not have a tripod collar. The following image shows the lens support and the quick release plate (part number 3157n):

To remove the quick release plate, one must pull the small gold bar out to unlock the large black lever, and pull the large black lever out (below left). Then, one can put the quick release plate into the slot and push the lever (and then the gold bar) back to lock the plate. The right-hand side of the Bogen is a knob used to tilt the lens up and down. In my opinion, this Bogen lens support is more convenient than the support arm, although it is bigger. This is especially true if one does not want to modify the support arm.

Since the outer diameter of the rubber tube is 72mm, one may use step rings to bring the size to 72mm. The configuration below used a 55-62mm step-up ring and a 62-72mm step-up ring. Then, the hard rubber tube of the TCON-300 is inserted into the 72mm opening of the step-up ring. Since the TCON-300 does not stay firmly in the 72mm step-up ring, it would be better to mount the combo in the following way. First, mount the camera on the Bogen first and make sure the knob is loosen. Second, jam the TCON-300 into the 72mm opening of the step-up ring, and slowly put the combo down to the lens support. Third, fasten the Velcro belt so that the lens does not move, and then fasten the knob so that the camera will not move. The advantage of using the Bogen is that there are multiple tripod holes in the bottom of the support so that one can easily mount the combo near its center of gravity.

Handle this combo with care. Do not lift the combo by holding the camera nor by the lens, because the lens and camera may separate easily. Moreover, when unmount the combo, make sure to hold the TCON-300 and remove it from the support first. Otherwise, it may fall easily.

Mounting the Lens with Multiple Step Rings

The use of support arm is very mobile; however, it is heavy. Fortunately, there is a better way! Since the rubber tube of the TCON-300 has a diameter of 72mm, one may put a step-down ring of 72mm around it. Then, with multiple rings, one could mount the lens directly onto the camera. The left image below shows a 77-72mm step-down ring mounted on the rubber tube. A bit force may be needed to push the step-down ring toward the front of the rubber tube, which is good as the lens won't wiggle in the step-ring. The next step is to find some step rings to convert from 77mm to 55mm. A natural guess is a 72-77mm step-ring. Unfortunately, it will not work because the inner opening of a 72-77mm step-ring is smaller than 72mm. To overcome this problem, one must use a larger step ring. The right image below has the following rings (going from left to ring): 72-77mm step-down (hidden), 86-77mm step-down (now the outer diameter being 86mm), 77-86mm step-up (the size becoming 77mm), and 55-77mm step-up (the size returning to 55mm).

After combining these rings, the total length increases as shown in the right image above. Therefore, one might want to push the rings toward the front of the lens. If thinner rings are used, one may be able to push the rings all the way down so that the rubber tube is fixed in the "tube" formed by these rings. The following is an example.

The image below shows this combo mounted on a Bogen lens support. Since the rings can fit tightly around the lens, the problem mentioned in the previous section will not happen. In other words, one may securely lift the setup with the step ring tube.

Moreover, one may mount the combo on a tripod using the bracket of the lens. Because it does not require the support arm, this combo is lighter and can be easily handled.

However, like all configurations mentioned above, one must make sure the lens and camera are aligned properly aligned.


The use of this combo is fairly easy. Since it extends the focal length of FZ-30/FZ-30 from 420mm (in 135 film equivalent) to 1,260mm = 420×3, hand-holding the combo must use a shutter speed equal to or faster than 1/1260 second. Even with the OIS system on, it may not fully compensate the magnified camera shake from this 3X lens. In fact, some kind of support, preferably a tripod, is highly recommended.

The most basic operation in using this monoscope type converter lenses is that focus the lens approximately and let the camera auto-focus system finish the job. More precisely, rotate the focusing ring on the TCON-300S so that the image on EVF/LCD is reasonably sharp. Then, half-press the shutter release button to active the auto-focus system to finish the job. Some may prefer the use of continuous focusing; however, my experience shows that it is not absolutely necessary unless one is shooting a moving subject.

This approximate focusing can also be done with the focus scale on the lens. See the image below. There are three marks on the scale, namely: 2m (6.6 ft), 4m (13.1 ft) and infinity. If the focusing ring is set to one of these three marks, the range from that mark to its marked lower distance can be focused by the camera. For example, if the 4m mark is selected (i.e., aligned with the mark on the lens barrel), the camera will be able to focus from 1.6m (5.2 ft) to 4m (13.1 ft). However, this scale is designed for the E-10 and E-20, it may not work well with the Panasonic FZ-30/FZ-50. At least I did not verify if this scale still holds for the FZ-30/FZ-50. Therefore, use the EVF/LCD for approximate focusing is perhaps the best way.

When matched with a FZ-30 at focal length 420mm, the TCON-300S can focus down to about 80 inches (approx. 2 meters). This performance is better than all telephoto converters discussed on the Other High Quality Telephoto Converter Lenses page.

Light Fall-Off, Vignetting and Light Loss

Light fall-off (i.e., the corners being darker than the center) is likely unavoidable with most teleconverters. Matching the TCON-300S with FZ-30/FZ-50 does not cause a significant light fall-off. Thus, vignetting (i.e., four black corners) is not a problem at maximum focal length. However, as the camera lens is zoomed back, light fall-off becomes worse. When the lens is zoomed slightly below 5X, vignetting (i.e., four black corners appear) will occur because the camera lens starts to "see" the barrel of the converter lens (i.e., the angle of view being large enough to cover the lens barrel).

Light loss is significant. Conventional teleconverter lenses usually have an ignorable amount of light loss that does not affect the chosen aperture and shutter speed. However, this monoscope-like TCON-300S may have a light loss about 2.7 EV to 3 EV. In other words, if one uses f/11 and 1/500 sec without the lens, then one has to use f/4 and 1/500 sec or f/11 and 1/60 sec with the lens mounted.

TCON-300S on Other Cameras

The mounting methods discussed above can also be used with other cameras. This is particularly true with the methods that do not require the support arm because not all cameras have their tripod holes on the line of view of the camera lens. The Nikon Coolpix 8800 was tested fine using Nextphoto's two-section 62mm adapter (see here). The Coolpix 8800 can focus properly with a minimum working distance slightly more than three meters. Do the same for the Panasonic FZ-10/FZ-20 with a 62mm adapter. Please see my FZ-10 user guide for the details.

This TCON-300S was also used on a Sony R1; however, due to the extending lens barrel, my experience is not entirely positive unless the camera lens is fixed at the longest focal length (i.e., 120mm) in which case the maximum focal length is 360mm. At 120mm, the Sony R1 has a bit vignetting at the corners if a 67-72mm step-up ring is used and the TCON-300S is inserted in the 72mm opening of the ring. Vignetting can be significant if one uses the multi-ring approach (i.e., multiple rings surrounding the rubber tube).

In summary, the TCON-300S may be used on a camera as long as one can use step rings to provide a 72mm thread so that the lens rubber tube can be inserted into the 72mm opening. However, if the camera lens extends while zooming, one may only use the camera lens at the maximum focal length.

Technical Data

The following technical information is taken from Olympus TCON-300S instruction guide.

Item Olympus TCON-300S
Number of lenses 10 elements in 9 groups
Magnification Approx. 3X
Combined focal length 1,260mm (135 film equivalent)
Rear Thread Size none
Front Thread Size 49mm
Size Lens: 176mm (L) × 72mm (W) × 75mm (H)
Support Arm: 270mm (L) × 84mm (W) × 26.5mm
Weight Lens: 780g (27.5 oz)
Support Arm: 370g (13.1 oz)