High-Resolution Spherical Panoramas with the Sigma 15mm F1.4 DG DN

When it comes to panoramic photography, camera resolution is always an important factor, but it also requires lenses that optically support the given level of detail. However, the release of fisheye lenses, known as a basic accessory for creating spherical panoramas, has not been common recently. Therefore, it was a real surprise to photographers when the new Sigma 15mm F1.4 DG DN diagonal fisheye came out in 2024.

First, let's see the difference between circular and diagonal fisheyes in terms of panoramic photography. The image below clearly shows that while a circular lens covers a part of the camera sensor in the form of a full or partial circle, its diagonal counterpart, although with a smaller angle of view, draws the entire image field.

This means that even four photos with a circular fisheye can cover the 360 x 180 degree spherical panorama, but this results in a significant loss of size due to the unused sensor area. In this case, a camera with a resolution of at least 36MP is recommended.

On the contrary, a diagonal fisheye can only provide a diagonal viewing angle of at least 180 degrees, so not only will more photos be needed horizontally for a full spherical panorama, but you will also need to take an extra shot up and down. In the latter case, it is necessary to use two-axis panoramic heads. The table below illustrates spherical panorama results between different types of fisheye lenses with a simple comparison.

The Sigma 15mm F1.4 DG DN diagonal fisheye lens belongs to the group that does not waste a single pixel of sensor area. This allows you to create highly detailed spherical panoramas from relatively few images.

In terms of lens mounts, it is available in Sony E and Leica L mounts, which provides a fairly wide range of choices for Full Frame cameras if resolution is your priority. Some examples of 61MP cameras include:

• Sigma fp L

• Sony Alpha 7R V

• Leica SL3

The lens size (ø104.0mm x 157.9mm) and weight (1360g) are significant due to its F1.4 aperture and 21 elements, requiring the largest two-axis panoramic head (NOVOFLEX VR-System PRO) for accurate calibration and uncompromising panoramic photography.

The image above shows the camera system used in the test photo shoots with a Sony Alpha 7R V camera. Several things can be observed in this werk photo:

• Due to its weight and size, the lens has a detachable tripod socket. This is very necessary in order to be able to attach it straight to the tilting arm of a panoramic head. This is because the diameter of the lens goes beyond the bottom of the current camera body, where its tripod mounting socket is located. This is more of an advantage, as the camera set mounting is more stable and balanced.

• In the photo above, you can already see the equipment in a fully calibrated position. For error-free panoramic alignment, it is essential that the pivot centers are aligned with the center of the sensor and the nodal point of the lens. The nodal point of the new Sigma diagonal fisheye is located at the top line of the zoom ring. Of course, this also depends somewhat on what focus is set, so fine-tuning the nodal point calibration on location is highly recommended.

• Thanks to the large panoramic head, in this case it was still possible to tilt the camera set to the Zenit position (the position completely perpendicular to the ceiling / sky) without being obstructed by the lower part of the panoramic head. This may not be possible with camera bodies larger than the Sony Alpha 7.

I chosed the Várkert Bazár, located on the Buda side of the Hungarian capital, as an outdoor test location. The following werk photo was taken there, where the nadir position (directed perpendicularly downwards to the ground) of the panoramic head can be seen.

Based on the sensor coverage and angle of view of the diagonal fisheye and the current panoramic head, a total of nine photos in camera directions were needed to obtain a complete spherical panorama. This number came out by shooting horizontally in six directions, up (zenith) in one direction, and two downwards (nadir). Two photos were needed downwards so that the lower part of the panoramic head would block as little of the environment as possible.  This time no extra nadir photo without the tripod was taken, I edited it in post-production.

Technical details of photography:

• Camera: Sony Alpha 7R V (61MP) - Sensor: Full Frame

• Lens: Sigma 15mm F1.4 DG DN Diagonal Fisheye

• Camera orientation: Portrait

• Aperture: f10

• Shutter Speed (0EV): 1/125s

• ISO: 100

• Exposure bracketing: 0EV, -2.0EV, +2.0EV (for HDR)

• Total shooting directions / panorama: 9

• Total photo / panorama: 27

• Number of panoramas: 3

• Panorama size: 27.000 x 13.500 pixel (full 360° x 180° spherical type)

The following virtual tour consists of three high-resolution panoramas photographed on site, presenting one of the tourist attractions of the Hungarian capital in the light of the rising sun.

Click on the picture to view the end result.

At the time of the shooting (summer 2024), the lens correction profile for the lens was not yet integrated in Camera Raw, so I used the one available on Sigma's official website. Of course, in most cases it was not much needed, since with a narrower aperture the vignetting disappears completely. Regardless, it is important to shoot in RAW and do not forget to turn on lens correction when processing image by image! The exception, of course, is Distortion Correction, which is not a defect in the case of fisheyes, but a peculiarity, so it must be kept off with zero value.

When choosing a fisheye lens for high-resolution panoramic photography, it is important that the lens's is sharp across the entire image area. Especially when there is less overlap between adjacent images. The higher the resolution of the finished panorama, the more visible this type of imperfection becomes due to the wider zoom range.

As an indoor location, I had the opportunity to capture some of the stunning interiors of the Kimpton BEM Budapest Hotel, just a few days before its grand opening in 2024.

Technical details of photography:

• Camera: Sony Alpha 7R V (61MP) - Sensor: Full Frame

• Lens: Sigma 15mm F1.4 DG DN Diagonal Fisheye

• Camera orientation: Portrait

• Aperture: f9

• Shutter Speed (0EV): 1/30s (Depending on the location, this may have varied)

• ISO: 800

• Exposure bracketing: 0EV, -4.0EV, -2.0EV, +2.0EV, +4.0EV (for HDR)

• Total shooting directions / panorama: 9

• Total photo / panorama: 27

• Number of panoramas: 13

• Panorama size: 27.000 x 13.500 pixel (full 360° x 180° spherical type)

In contrast to outdoor 360 panorama photography, the angle of view of the lenses used is even more important for indoor. Above a certain focal length, it is difficult to ensure that both parts closer and farther from the camera are sharp. Of course, the limits of this can be extended by using an even narrower aperture (f10 - f32), but in many cases this can lead to a loss of quality.

Another factor that makes it advisable to minimize the number of shooting directions indoors is that most of the time a single exposure is not enough. Large brightness differences were common in the hotel interiors, so I used a series of five exposures. This is necessary for creating wide dynamic range HDR panoramas, but it also multiplies the number of images.

The following virtual tour will guide you through the ground floor of Kimpton BEM Budapest Hotel using 12 indoor and one outdoor panorama.

Click on the picture to view the end result.

You may wonder why a hotel or other interiors might need spherical panoramas larger than standard resolution. The key word is detail, which can further expand the range of users of virtual tours. The creation of a luxury hotel requires the collaborative work of many creative individuals, all of whom wish for the completed masterpiece to be represented with the level of detail it deserves. This is one of the most versatile types of virtual presentation in the field of architecture and interior design.

Among the controls on the lens, a useful feature is the Manual Focus Lock (MFL) switch, which disables the focus ring operation in manual focus mode. This prevents accidental focus shifts between two panorama shots when shooting with a fixed focus. Since focus can also affect the lens's nodal point, using this function is highly recommended after an indoor nodal point calibration.

Let's take a look at a brief summary of the aspects that make the release of the Sigma 15mm F1.4 DG DN stand out as a rarity after many years and countless fisheye lenses:

• the world's first diagonal full-frame fisheye lens with an F1.4 aperture

• outstanding image sharpness across the entire 180-degree field of view

• special lens coatings ensure high contrast and flare-free images, even in strong backlight

• complete absence of chromatic aberration

• fast and silent autofocus system that remains accurate even in low light and at wide apertures

• excellent build quality with dust- and splash-resistant sealing

• front lens with an oil- and water-repellent coating

These are the features that make the new Sigma lens stand out among fisheye lenses, particularly diagonal fisheyes. The test results aligned with the specifications provided by the manufacturer, and all key characteristics and functions of the lens performed as expected in real-world use.

Summary

With the creation of the Sigma 15mm F1.4 DG DN diagonal fisheye, the manufacturer has undoubtedly achieved a technical feat. The only question is: who would benefit from this truly unconventional lens? If we consider the question from the perspective of panorama photography, there are two possible answers:

• For photographers who care about weight and don't want to take advantage of the F1.4 aperture and don't like to push megapixels to extremes, a simpler full-frame fisheye may be suitable. Especially if they are looking for a lens exclusively for spherical panorama photography.

• But if you're looking for a premium fisheye that's uncompromising and timeless in terms of resolution and versatility, then this Sigma lens is the ideal choice for you.

I would like to thank Tripont Foto Video Kft. for their support in expanding the group of panoramic photography device tests with another article.

I'm grateful to Hama Kft. as the Hungarian importer of Sigma products for providing me with this lens for the test.

Thank you to Sony Magyarország for allowing me to test this lens with a Sony Alpha 7R V.

In addition, I would like to thank the Kimpton BEM Budapest Hotel team for providing a truly special location for my test-related panoramic photography.

Attila Farkas

PHOTO-REAL.com

- 2025 -