Kowa

The circular shape formed by light that is gathered together as it passes through a lens is known as the image circle. Cameras take photographs by clipping images from this circular shape as quadrilaterals with proportions of 3:2 or 4:3.
In general, the center of the image circle has the best resolution and the image quality decreases as you get closer to the periphery. Specifically, there will be a reduction in the sharpness and contrast, and a decrease in the amount of light will cause the image to appear darker towards the outside edge. The phenomenon seen in lower-priced telephoto lenses and wide angle lenses where the four corners of the image appear darker is caused by the insufficient amount of light at the periphery. The peripheral image quality can be improved by closing down the aperture by 1-2 stops but in lenses that already have darker full aperture F values, closing the aperture will risk causing a reduction in shutter speed or an increase in ISO sensitivity and thereby decrease the picture quality. Lenses that have no reduction in peripheral image quality even at the maximum aperture are of superior quality.

As explained previously, because the image quality is better closer to the center of the image circle, when using the same lens, cameras with smaller frame formats will realize better image quality from the lens. However, in digital cameras the effect on the overall image quality of the camera’s image sensor is large, so the full frame camera can be said to be advantageous.
Because full frame cameras utilize the image circle right up to the periphery, serious consideration is given not only to the central area, but also to the peripheral areas. In addition the large sensor areas of full frame cameras require a high level of image planarity. In zoom lenses having large numbers of lenses and complex features, image planarity may not be maintained and partial blurring may occur.
Kowa’s PROMINAR 500mm F5.6 FL lens (PROMINAR 500mm) realizes high resolution in the central area and almost no reduction in image quality even in the periphery. Because the image planarity is also high, it is possible to achieve satisfactory results with full frame cameras that require high dimensionality from the lens performance.

After that slightly long introduction, in my shooting assignment this time I took the Nikon D3X, which incorporates a 24.5 megapixel full frame sensor and the PROMINAR 500mm to the Shinshu region of Japan. My focus was to verify the compatibility of full frame cameras and the PROMINAR 500mm lens by capturing the poetic charm of autumn represented by seas of clouds and autumn colors.
In autumn there is a large difference in temperature between daytime and nighttime and fog will often appear close to the ground on nights when the sky is very clear and there is no wind. In valleys that have rivers flowing through them, there is often high moisture content in the air and cold air tends to collect there so that fog will frequently develop and spread. When looking down on these valleys from locations at higher elevations, they will appear as a sea of clouds. Since the cloud sea is most beautiful during the period from before sunup to immediately after the sun rises, you should set up your tripod before dawn and wait. Especially from around 30 minutes before the sun rises, the cloud sea flowing in this blue-colored time band looks fantastic, and the PROMINAR 500mm proved highly effective at capturing images from the most beautiful parts of these flows.

Because the basis of landscape photography is to capture detailed depictions at the lowest ISO sensitivity you should avoid shooting at higher sensitivities even in the low light conditions before sunrise. As autofocus will not operate correctly under these low light levels even when using an AF camera/AF lens combination, manual focusing will be necessary for photographing. In addition, because manual focusing using Live View will give better results even in daytime, autofocus will not always be a necessary function in landscape photography.
Since the mirrors in full frame cameras are also large-sized, the shake that they cause will also be extensive. For best results it is best to take photographs using mirror lock.
Additionally, in order to completely suppress any movement, I also use a type of monopod called a long lens supporter on the camera to support the lens.
By carefully implementing the focusing and movement countermeasures in this way, it will be possible to accurately evaluate the descriptive power of the lens.
Although it is obvious from viewing the sample photographs, from the results of my shooting I could truly sense the favorable image definition and sharpness of focusing and the adequacy of the peripheral light amount and excellence of the peripheral image quality when using the full frame camera.

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• Image showing use of the long lens supporter, which is highly effective for reducing movement

Although the most common focal lengths used in landscape photography are in the wide-angle to medium telephoto ranges of 28-70mm and 70-200mm, photographs taken with these lenses tend to be average because they have an angle of view and sense of distance that is close to what we see with our eyes.
If you want to take photographs that have real impact, I would recommend that you try using telephoto lenses with focal lengths of 300mm or longer, particularly 500mm class lenses. Extreme close-ups cannot be easily composed with lenses smaller than 300mm, whereas 500mm telephoto lenses can be effectively used in all kinds of situations, including the previously described close-up shots “cloud seas”, mountain ranges that appear like layers lying on top of one other, close-ups of leaves and fruits hanging from trees and celestial objects including the moon and sun. From now throughout the winter, people living on the outskirts of Tokyo may try using these lenses to take “Diamond Fuji” photographs when the sun appears to set exactly on top of the summit of Mount Fuji, while others may wish to try capturing the annular eclipse that should be visible over a wide area of the Japanese Archipelago in May next year. Because the ability to provide detail is required for landscape photography, zoom lenses that cover
the range up to 500mm will be ultimately insufficient for these purposes.

Then again, 500mm F4 lenses are too heavy and are also very expensive. In this situation, the compact and high resolution PROMINAR 500mm is the best option. By adding the PROMINAR 500mm to a standard set of 28-70mm and 70-200mm lenses when setting out into the field, it will be possible to take photographs of most landscape scenes. It is also convenient to be able to change the TX10 mount adapter to the TX07 in situations where the 500mm focal length is too long, which will allow the lens to be used as a 350mm F4 lens.

Perhaps because the summer heat lasted longer than usual, the coloring of the red and yellow autumn leaves has been generally poor this season and it was not possible to take good photographs. However, the PROMINAR 500mm is very useful for taking close-up photographs of colored leaves and fruit hanging on trees. By perfectly focusing with the manual focus utilizing Live View and as long as movement can be completely suppressed, the PROMINAR 500mm will provide you with unbelievably detailed images. I recommend the PROMINAR 500mm as a super-telephoto lens for landscape photographers who want to take impressive pictures.