Time and Technology March On Together As They Say.
It’s 9 years since my last outing with the Sony 500mm f/8 Reflex Super Telephoto Lens at Duxford. I bought the lens back in 2010 as I had come across on the internet a translation from a Japanese web site that said that Sony had finished the production run for this lens so it was a case of get one now before the price went up due to rarity or there was no stock left. Back then I was using a 14.2MP Sony Alpha DSLR-A450 which was released in early 2010. Today I use either a Sony Alpha a6000/a6300 Mirrorless Digital Camera with a 24.2MP APS-C Exmor CMOS Sensor and BIONZ X Image Processor. The lens is designed for Sony cameras with an A mount. The a6000/a6300 has the smaller E mount. With a built-in auto focusing motor, the lens requires a Sony LA-EA4 adapter for the auto focus to work with the Sony E-mount cameras. The LA-EA3 does not have a motor which means manual focusing with that one. The LA-EA4 has translucent mirror in it to separate a small portion of the light coming through the lens and direct it to the AF sensor in the adapter.
With the aperture fixed at f/8, I use Shutter Priority usually using the rule of thumb in that the shutter speed is equal to the focal length of the lens so 1/500th second not taking into account the crop factor which would take it up to about 1/700th second, but with years of practice using cameras and lens with no inbuilt stabilisation, I usually have the shutter speed around 1/320th second for a bit of prop blur. Any slower than that and the image can be blurred and probably caused by shutter shake when a long focal length is used. 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 and it also reduces the ISO. Adding positive Exposure Compensation increases ISO and I have the ISO on AUTO set to a maximum of 1600. There is no lens profile for the Sony 500mm in the Lens Correction Module in Lightroom 6 that I use so any problems like distortion, perspective correction (not that there is much due to the lack of lens), chromatic aberration, vignetting etc., need to be carried out manually. The colours out of the camera can be a bit muted and need to be returned in processing, by adding a bit of contrast and saturation, so shooting in RAW is preferable when using this lens.
The lens comes with two filters, Normal and ND4 or Neutral Density, in holders. These slide into a slot just in front of the lens mount. Sony say these filters are figured into the element count for the lens, and you have to have a filter installed to have the lens function correctly. The filters are in fact a throwback to the days of film when the ND filter was used to reduced the amount of light reaching the film. I don’t use them and have the filter slot they go into covered by black electricians tape. As I said above, I use negative/positive ‘Exposure Compensation’ to control the light reaching the sensor instead of the filters.
The autofocus is quite impressive, though the LA-EA4 adapter locks the camera in to Center Auto Focus only. Looking through the viewfinder, you see a little green square in the centre. If it's not green then the focus is not locked. You may have difficulty fixing on a moving target, however with Continuous AF engaged, once the focus has locked on, there is no trouble staying with the subject. To aid the focusing process I use Back Button Auto Focusing (BBAF). When the shutter button is pressed half way down, then auto focus is activated and locks on until the shutter button is pressed fully down to take the picture. BBAF separates the AF activation from the shutter release. I have the AEL button on the back of my a6000/a6300 set for BBAF, easily changed in the MENU, as it’s within easy reach of my right thumb. When following a flying aeroplane, I press the AEL button and the auto focus locks on and when the aeroplane gets closer then press the shutter button. When using the lens, hold it by the metal body and not the rubber coated lens hood. The hood rotates as part of the auto focus procedure.
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 instances give an almost 3-D effect to an aircraft in front of it. Fortunately there is not much distracting background in flying shots.
Sony a6000/a6300 + Sony 500mm f/8 Reflex Super Telephoto Lens
The Sony 500mm f/8 Reflex Super Telephoto Lens was designed for Sony A mount, mirrorless cameras both full frame and crop sensor which gives an APS-C equivalent of 750mm. 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 and then doubles back and hits a convex mirror located on the back of the black disk at the front of the lens and then travels through a hole in the concave mirror to finally reach the sensor. It’s the only reflex lens in any make that has auto focus. There is a down side though. The aperture, unlike a zoom lens, is fixed at f/8 so exposure is controlled by the shutter speed and because of the arrangement of the mirrors, the Bokeh (out of focus background) can appear unusual and also as small doughnut shapes caused by the front lens element. Not to everyone's taste. First introduced in 1989 as the Minolta Reflex 500mm f/8, it was rebranded, with a few tweaks by Sony reportedly to be updated coatings and an improved autofocus algorithm, as a Sony lens in 2006 when Sony bought out Minolta. Although discontinued in 2010, the Sony or Minolta 500mm lens are still ocassionally available for sale on e.bay.