(Drag on the Slider/Click on the Image for Before After Comparison)
(I) A Journey For A Pano Combo
It’s quite a journey on the quest for the best lens-body combination for spherical panoramas. Initially I started with a 4.5mm Fish Eye to be used on a DSLR camera with an APS-C sensor, then finding out that an 8mm F3.5 fish eye would be the better option. After ditching the APS-C sensor camera system due to weight considerations I switched to Micro Four Thirds and continued to optimize there. Continuing to use with the 4.5mm lens I still found the resolution not to be optimal. I did go for the Samyang 7.5mm for MFT to do some Panoramas: Even as i found the lens quite capable it took 6 round shots to get a spherical panorama (and not talking about the Zenith/Nadir holes you’d get with this lens).
So I went on to use the Meta Bones Speed Booster to squeeze the Field of View of the 8mm Circular Fish Eye onto the MFT sensor finally getting some decent results with only 4 round shots and good coverage of Zenith and Nadir (check out my comparison of Pole Panoramas taken with the MFT mirror less system).
And now SONY A7, *sigh* … good thing, though: All the lenses for Nikon mount can be adapted for the full frame sensor camera as well. However, using the 8mm Sigma fish eye will give you a circular image on full frame, so for spherical Panoramas you’ll lose quite some resolution in your final panorama. So, having come to no other feasible options yet, I also tried to use the Tokina 10-17mm zoom fish eye lens (there’s a version available without the lens hood) for now, which would give you good results at 12mm focal length.
But in the meantime I came across another solution …
An established method is to use a fish eye lens designed for a smaller camera system on a camera having a bigger sensor (The trick is using a larger portion of the lens image circle than originally designed). This will often give you larger portions of the image circle with some pronounced black round edges. Used as a single image, such an image will be of no use. However, the combination of utilizing a larger image area combined with an edged image circle spanning over 180 degrees field of view (FOV) is ideal for stitching panorama images.
That’s the reason why the 8mm fisheye lens from Sigma is ideal to be used for cameras with APS-C sized sensors. Similarly, the 7.5mm Samyang lens for MFT can be used on Sony alpha cameras to give this mixture of large sensor image coverage alongside with the edges marking the 180 field of view boundary.
(II) Shaving A Samyang Lens
And now, the Samyang 8mm F2.8 lens (either Version I or II). Knowing the good qualities of the 7.5mm lens i gave this tiny lens a try (my first lens with a native E mount!). Originally designed for Sony APS-C cameras is a very good candidate to be used on the full frame A7 camera. The biggest obstacle of using this lens on a Full Frame Camera is the fixed lens hood, that will give you some heavy vignetting obscuring some significant portions of the image circle.
The solution is to “shave” the lens, a term denoting removal of a fixed lens hood. Not really talented with doing such mechanical stuff, I came across the lens shaving service from Tobias Vollmer.
It’s not often, that I’ll actively promote such services, but in this case I’ll make an exception. Ordering a lens shave was as painless as going to a good barber shop and within days I had a perfectly shaved Samyang lens without a lens hood. Find some before-after comparisons in the following section (click on the knob and drag the slide or click on the image):
Samyang Lens 8mm F2.8
Image Circle Before and After
Here’s a shot taken from the inside of a light tent to show the enhancement of the visible image parts,
It can be clearly seen, that after shaving large portions of the image circle can now be utilized as input for spherical panoramas:
(III) Nodal Point Measurements
Having received the new lens, i took the opportunity to again measure the no parallax points NPP (=location of the entrance pupil) for my lenses in stock and mounted on the Nodal Ninja ultimate R1 Tilt head . I was determining them using the method of aligning close and remote points (for descriptions check wiki.panotools.org ) for different combinations of camera-lens, adapter tilt (-2.5°,0°,+5°) and number of rotations (3 or 4 corresponding to 120° or 90° rotations):
In order to have the numbers available out in the field, I printed the settings on a self adhesive paper and placed them directly on the NP adapter (for the Samyang, i glued the settings on the lens cap).
Worth to notice
* Settings differ slightly when using 3 instead of 4 rotations
* NPP settings are the same for the 8mm Sigma Fish Eye when using on Full Frame or in combination with the Speed Booster (which should be expected as the speed booster doesn’t alter entrance pupil location)
* NPP will differ at different tilt angles of the NPP adapter
(IV) Weight considerations
Initially , i started optimizing my gear with respect to weight as well. For my own panoramic combos -consisting of camera body, adapter, lens and adapter ring, as mentioned above and listed below- I did some weight measurements (remember: 450g = 1 pound) and found the following results:
All of the combinations roughly will have a weight of 1100g (~2,5pounds), with the exception of the A7-Samyang 8mm combination with 780g (1.7 pound). Seems like I can shed some weight off my back pack with the new lens here …
Outlook: So much for the outer qualities of the new Fisheye Lens. How is it performing comparing to the other combos? Go to the second Blog Post covering some testing out in the field 😉
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