Testing Kenko Teleplus HD DGX 2.0x tele converter in Aeroplane Spotting - a review by Juan Pablo Muñoz

Staff Blog

Testing Kenko Teleplus HD DGX 2.0x tele converter in Aeroplane Spotting - a review by Juan Pablo Muñoz

May 22, 2018

Next time you visit an airport or the surroundings look closer and you will probably find one or few photographers taking pictures of the airplanes arriving or departing the terminal.  Aircraft or airplane spotting is a hobby of tracking aircraft, nowadays usually accompanied by photos of the airplanes.
The origins of the hobby came from World War II when some countries encouraged citizen to observe and track airplanes as they were a public security threat, because usually they came as part of a bomb attack or similar.  That tracking slowly went from a security action to a hobby, and recently has gained more enthusiasts because of the opportunity to practice photography of planes and publishing in sites like www.airliners.net, www.jetphotos.com or www.airplane-pictures.net, which are highly specialized in the hobby and focused on the quality of the photos.


Those websites have created procedures to review the photos and accept the publishing of them depending on the technique and certain line-ups that guarantee the quality of the picture.  Horizon, sharpness, noise and composition are just few criteria considered   for a photo to be screened and latterly published in these websites.
Getting images of airplanes could be difficult depending on different factors which usually we need to consider: heat over the runway, speed during landing or take off, natural light, composition and, of course, distance between the aircraft and the spotting location.
Because of the last one, usually the pictures for this hobby are done by using telephoto converters.  Here is where the Kenko Teleplus HD DGX 2.0X is of great help to increase the focal length of the lens, allowing you to shoot from a longest distance without losing quality.
Depending on the spot chosen for taking the photos, the distance will allow you to get better details of the action over the runway or to just take the opportunity to get a great photo using sunlight over the aircraft.

The Telephoto Converter

The unboxing of any photography item is really great feeling and experience and for Kenko telephoto converter in particular the quality will not disappoint you.  In my particular scenario I used Nikon gear, so the version selected was for Nikon mount. However Kenko has options available for Canon mount too.
The telephoto converter comes with a convenient black pouch that let you storage and have your telephoto converter safe anytime, reducing the chances of getting dust over the lens or any scratch that could potentially impact the quality of the image.
The structure of the telephoto converter is pretty solid, including a grip around its body that prevents the telephoto converter to accidentally fall off.
This DGX series is able to transfer and convert data from the lens to the camera, so it let you record your EXIF data and, depending on the lens you are using, will let you use the Auto Focus function of the lens. For example I used a Nikkor 70-300mm and shot at 300mm giving the result of 600mm with the telephoto converter.
The telephoto converter has a dot that indicates how to install it on your camera and also how you should install your lens on the telephoto converter. Once the telephoto converter is attached it will keep your lens safe because of mount construction, which is actually pretty solid and mostly designed to handle heavy telephotos.

Technical Details

This telephoto converter has a  2.0x magnification, so it means that it will double the actual focal length, allowing you to expand your focal length range but sacrificing couple of features depending on the devices you are using and the shooting conditions.
The f-stop of a lens is the value that determines how much light a lens can let in. Basically it is determined by dividing the focal length of the lens by the diameter of the pupil, so considering we are expanding the focal length by 2x by using the telephoto converter, we can do the math and this basically means that the telephoto converter will increase f-stop by 2 stops.
This means that if you have a lens with F4 max aperture, you will be able to shoot with F8 as minimum, so as a collateral effect, you will be reducing the light that the lens is able to pass to the sensor.
Light reduction is not the only thing you need to consider while using the telephoto converter. The Automatic Focusing system may not work as accurate as expected for some lenses. This is because DSLR cameras needs the lens to be at max aperture and with a necessary light flux width secured when measuring the distance to the shooting object. F5.6 is a generally guaranteed aperture for secured AF, but there are also lenses that can support F8. By installing a tele converter, the resulting aperture increases and the light flux width becomes narrower, thus the accuracy of AF decreases. However depending on the object, this should not represent a major challenge.
Also, Kenko has a list of compatible lenses that will be able to handle the auto-focusing function without any problem due the electrical contacts that allow you to communicate with your lens and control couple of functions as the focusing system. If you want to check the compatibility of your lens and functionality of the Automatic Focus, you can conveniently check it here.
The Kenko Teleplus HD DGX 2.0X is NOT too heavy and doesn’t add considerable weight to your telephoto lens. It has a total weight of 171g including 5 elements made with high quality multi coated glass, which improves the quality of the images compared to the previous MC4 or MC7 versions of the product.

The Tests - Tips and Tricks

The Kenko Teleplus HD DGX 2.0X was tested outdoors during a Plane Spotting Photography session with early morning light that allows you to get reflected gold light on the airplane from a max of 40°, thus allowing you to get better detailed photos and well illuminated aircrafts from the ground.
For the testing we have used a Nikon D7500 APS-C size, a choice that actually is very common in plane spotting because it offers an enlarged image than when using same focal length with full frame sensor. Also we have used an intermediate range telephoto, the Nikkor 70-300mm f/4.5-5.6G IF-ED VR, which has a focal length very common in Plane Spotting Photography.
The tests performed and the techniques applied during this review were primary focused on plane spotting photography. However, some of them could be used in different scenarios.
Another important thing to highlight is the measure of the distances used for the test, which allows you to have an idea of the capabilities of the telephoto converter. So here is an estimation based on the same spot but with different targets:

Target #1 - Runway header | Approx Distance:  650 mts


Target #2 - Runway Landing Threshold | Approx Distance: 360 mts


Target #3 - Runway Front View | Approx Distance: 130mts


Target #4 - Taxi Way | Aprox Distance: 230 mts


Target #5 - Distance Test Objective: | Approx Distance 2550 mts


Auto Focus Tests

The first test done was to check AF system using the Nikkor 70-300mm lens. Even knowing that with this lens MF mode only is fully supported when used with the telephoto converter, the AF functionality works and is able to focus the objects depending of the light and couple of details we will share here. The mechanism is NOT accurate and keeps focusing in and out because of the measuring, so the focusing system keeps searching for a while and when a focusing point is found then it turns unstable.
Now, here comes the first tip that will allow you to use one of my tricks for shooting in AF mode: once the autofocus goes this state you can release the focusing button just at the moment that the camera has properly focused. 
Then, depending on your camera settings you have 2 options. Using your AE-L/AF-L button to lock the focus and press the shutter; or pressing the shutter button very fast when the object is already focused, that will skip the focusing stage and force the camera to release the shutter.
This workaround is not easy and I would suggest using it only if you have good control of what is happening with your subject, for example: the subject is not moving or you know what is going to be the next movement.

Manual Focus 

Next test was really challenging for me mostly because I am very used to the AF shooting and manual focusing is not my best skill. By switching off the AF mode I started noticing that it takes some time until you get use to those focusing tasks while composing and exposing your shot.
After few minutes I improved my technique but noticed something I was not expecting:  while increasing the focal length of the lens, it increases the difficulty to focus properly the objects because the margin of the focusing ring reduces considerably, so even a little movement of the ring makes the object out of focus.
The following sequence shows the behavior described above: I pointed at our Distance Test Target #5, which actually has some signs and letters that can be used for focusing:


Google Maps Distance Measure | Target # 5


Lens Focal Length: 140mm (using Kenko Teleplus HD DGX 2.0.x  tele converter)


Lens Focal Length: 200mm (using Kenko Teleplus HD DGX 2.0.x tele converter)


Lens Focal Length: 270mm (using Kenko Teleplus HD DGX 2.0.x tele converter)

DSC_1612.jpgLens Focal Length: 400mm (using Kenko Teleplus HD DGX 2.0.x tele converter)

DSC_1611.jpgLens Focal Length: 600mm (using Kenko Teleplus HD DGX 2.0.x  tele converter)

It is important to highlight the fact that the object was at the considerable distance of 2550 mts, so it was a real challenge to get the signs in focus because every little movement of the focusing ring will immediately get the object blurred. Based on the experience with this telephoto converter as you increase your focal length the focusing ring will get more sensitive to any movement.

So it’s time for a second tip when using the Kenko telephoto converter in Manual Focus mode:  to use the electronic viewfinder in your camera while setting up the focus, as it will be easier to get your objects in focus this way, and believe me for that a tripod will be incredibly useful.


Target #2 | Lens Focal Length: 140mm (using Kenko Teleplus HD DGX 2.0.x tele converter) with Manual Focus.

With the tests done using same gear and configurations, I noticed something interesting that only happens when using long focal length lens (usually more than 200mm). The object was properly in focus but only in specific sectors of the frame. This will be imperceptible at first view; however this will be something you need to consider while looking for high quality photos at really long distances.
In order to sort this I am sharing with you another interesting tip for you to use with Kenko telephoto converters: focus and frame your photo using the camera viewfinder brackets.


Everything that is within the brackets at the viewfinder is nice and sharp, however if you have part of your object out of that brackets it could be out of focus.
Will this tip create death spaces in your frame? Yes, but this can be corrected in post processing.  If you don’t center the object using the brackets, here is how it will look like:


Target #1 | Lens Focal Length: 280mm (using Kenko Teleplus HD DGX 2.0.x tele converter)


Front part and front landing gear of the aircraft are out of focus.

However, by applying the steps mentioned before you could get the following image that offers you a real good close up on the aircraft, that is at 650mts of distance. Not bad, right?  That’s what you could get with the help of Kenko Teleplus HD DGX 2.0X tele converter.

DSC_1641-Edit.jpgTarget #1 | Lens Focal Length: 270mm (using Kenko Teleplus HD DGX 2.0.x tele converter) with Manual Focus)

As you can see on the previous photo we used a closer focal length of 280mm, however the aircraft was out of the viewer brackets, causing the distortion. This picture is taken from the exact same location and parameters but the focal length was reduced to 270mm to center the aircraft between the brackets. Later I corrected the death space by cropping a bit the photo.



During that test we were also able to confirm the other fact that you need to consider for any tele converter you use:  F-stop range is increased, reducing the light that passes through the lens.
In this particular scenario our lens was originally capable of max aperture of f/4.5 at 70mm and f/5.6 at 300mm. However after staring using the Teleplus HD DGX 2.0x tele converter, the max aperture was of f/9 at 140mm and f/11 at 600mm.
So it’s really important that you consider the light conditions while shooting with the telephoto converter, otherwise will be required to slow your shutter speed or increase the ISO, that’s why we have done the tests only with light enough to use high shutter speed and low ISO that guarantee the quality required for plane spotting.


Target #2 | Lens Focal Length: 280mm (using Kenko Teleplus HD DGX 2.0.x tele converter) with Manual Focus

The picture above was taken at F9.5, 1/400 and ISO 100. Those settings let you capture the movement and specially the heat generated by the engine thrust during the take off. So you can check that even with decreased amount of light, we can still use those fast shutter speed settings that allow having high quality photos.

The results

After playing a while with Kenko Teleplus HD DGX 2.0X tele converter, I can say it is very useful for Airplane Spotting and many other scenarios where you need to cover more distance with your actual gear.
Even when the tests were done by using an intermediate lens in manual focus mode, it was great to achieve good aircraft images taking advantage of the focal length that this telephoto convert gives you. So now imagine what can be done with such fast lenses like Nikkor 70-200mm f/2.8 VR II or the Nikkor 300mm f2.8 VR II.
I really hope that all the tricks mentioned during this review allow you to take great photos of airplane or other objects, when quality and distance are important factors to consider.


Target #3 | Lens Focal Length: 170mm (Using Kenko Teleplus HD DGX 2.0.x tele converter) with Manual Focus

Juan Pablo Muñoz

Juan Pablo Muñoz is a computer science engineer located in Costa Rica, very passionate for photography and an aviation enthusiast who always keeps looking for technical details of airplane spotting photography .He has provided his photos to big North American airlines, pilots and many other companies related to aviation industry.

Want to know more about Juan Pablo’s aviation work, it’s just one click away:

Airliners | http://www.airliners.net/user/jpms87/profile/photos
Jetphotos | https://www.jetphotos.com/photographer/79699/photos
Airplane Pictures | https://www.airplane-pictures.net/photographer.php?p=16153
Instagram | https://www.instagram.com/jpms_aviation/