Time and Technology March On Together As They Say.
It’s 5 years since my last outing with the Samyang 300mm lens at Duxford and then I was using a 20MP Sony a3000 and a 16MP Sony Nex-6 mirrorless cameras. Today I have a 24MP Sony a6500 Mirrorless Compact Systems Camera which has 5-axis in-body image stabilisation, something the other two cameras did not have. As there is no exif information transfer between the lens and camera you have to dial into the camera the focal length of the lens, 300mm in this case, so the image stabilisation knows by how much to compensate camera movement for. Due to the lack of heavy glass in the lens, there is very little weight to help counter any movement of the lens so to alleviate camera shake a bit, I use a selfie-pod as a shoulder rest to further help steady the camera and lens.
Manual Focus Assist.
I have the center button in AF/MF toggle switch assigned to Manual Focus Assist as it’s easy to access with my right thumb. MF Assist takes a crop of the sensor and magnifies the subject image between 5.9x and 11.7x respectively to help with focusing when viewed through the Electronic View Finder or the rear LCD screen. Downside is that any movement of the camera and lens is also greatly magnified.
Focus Peaking works by detecting edges of highest contrast in your scene, and therefore the most in focus, by highlighting them in a bright color which helps greatly as there is a very fine/minute tolerance between in and out of focus. Used with MF Assist this is a great aid to manual focusing.
Apart from manual focus, a downside to a mirror lens for a lot of people is the Bokeh (out of focus background). Because of the arrangement of the mirrors it can appear messy and distracting and depending on the background and lighting conditions, defocused areas of the image can produce small doughnut like shaped rings. Not to everyone's taste I know. A plus point thought is that the blurred background can, in some situations, give an almost 3-D effect to an aircraft in front of it.
With the aperture fixed at f6.3, I use Shutter Priority using the rule of thumb in that the shutter speed is equal to the focal length of the lens, 300mm, so 1/400th second taking into account the crop factor but I usually have the shutter speed around 1/320th second or a bit lower for a bit of prop blur. I have the ISO on AUTO set to a maximum of 1600. With a slow shutter speed, a lot of light is getting to the sensor so I dial in some negative Exposure Compensation to darken the image a bit. Vignetting, dark corners, can be present but easily corrected in processing. I use the Lens Correction Module in Lightroom 6 which, once you pick the correct lens as there is no exif info to automatically pick it, corrects problems like distortion, chromatic aberration, vignetting and perspective correction. Something I didn’t have in 2014. The colours out of the camera can be a bit flat and muted and need to be returned in processing by increasing contrast and saturation, so shooting in RAW is preferable when using this lens.
The Samyang 300mm f/6.3 ED UMC CS Reflex Lens, first announced in June 2013, is designed to fit the Sony E, Canon M, Fujifilm X, MFT Compact Systems Cameras which use crop sensor lens. It's a catadioptric or 'mirror' lens which basically means that light enters the front of the lens, around the black disk, reflects off a concave mirror situated at the back of the lens then doubles back and hits a convex mirror located on the back of the black disk at the front of the lens and then goes through a hole in the concave mirror and finally reaches the sensor. This allows the body to be very small, 74mm(2.9”) and light, 320g(12.6oz), for its focal length but restricted to a fixed aperture of f6.3. It's a manual focus lens providing a 35mm equivalent of 450mm. It has a metal and plastic construction with the lens featuring 9 lenses in 9 optical groups, including one Extra-low Dispersion element to compensate for color fringing especially at high magnification. The latter together with Ultra Multi Coatings reduces chromatic aberration, ghosting and flare. It has a minimum focusing distance of 0.9m(2.95ft) and has an angle of view of 5.4deg.