The combination of the high pixel count R5 body with the optical excellence of the RF 100-500mm L lens creates opportunities for some alternative approaches to photographing birds and other wildlife.
Many birds are difficult to photograph in their native habitat. They are very small creatures which flit about at high speed. The subjects of this post are yellow faced honeyeaters and bell miners in the Sydney region. These birds rarely perch for more than a few seconds at a time. They forage for food in the foliage of the trees providing a challenge for the camera’s AF system to figure out what is bird and what is foliage. Most of the time the R5 manages this which is remarkable given that the leaves of the eucalypt trees are similar in size and outline shape to the birds.
A long lens is required to render the bird sufficiently large on the frame.
In DSLR days one might have used an EF100-400mm f 4.5-5.6 L with an extender on one of the 5D bodies. The 5D4 has a 30.4 Mpx sensor.
The EF 1.4x extender gives a maximum focal length of 560mm at f8.
The EF 2x extender gives a maximum focal length of 800mm at f11.
I use an RF 100-500mm f4.5-7.1 L lens on an EOS R5 body which has 45 Mpx.
The RF 100-500mm lens will accept extenders but only if the focal length is set to 300mm or more.
The RF 1.4x extender gives a maximum focal length of 700mm at f10.
The RF 2x extender gives a maximum focal length of 1000mm at f14.
But wait, there is another way.
The R5 can enable an in-camera sensor crop of 1.6x. This gives an effective maximum focal length of 800mm at f7.1 with 17.3 million imaging pixels.
I tried this out yesterday and managed to produce some quite good results, a few of which you can see here.
All were hand held, Servo AF, High speed + drive mode, shutter speed around 1/500sec, Auto ISO, Stabiliser Mode 1 on the lens barrel, animal detect+eye detect for most shots, or Spot AF when needed.
I will run further tests with this setup which does raise the possibility of dispensing with extenders altogether.
Cropped sensor vs extender vs crop in post processing
Both these technologies utilise the center part of the image projected towards the sensor through the lens, discarding the periphery from the final picture. However each goes about this in a different way.
An extender (a.k.a.teleconverter) is a diverging lens inserted into the column of light rays passing from the main lens back to the sensor. The whole sensor is used for imaging. This produces a loss of optical quality as only part of the imaging information coming from the lens is presented to the sensor.
An in-camera crop uses the center part of the sensor for imaging, discarding the information from the periphery of the sensor. There is no loss of optical quality but many pixels are discarded. In the case of the R5 pixel count drops from 45 million to 17.3 millon, which by the way is still sufficient for good quality images.
One can achieve the same result by shooting full frame then cropping in post processing.
So why bother setting a 1.6x crop ?
One reason might be that the bird or other subject appears larger in the viewfinder and thus might be easier to identify in foliage.
Another reason might be more accurate metering as extraneous subject and background material is excluded from the metering calculation.
There is also a potential disadvantage that at an effective focal length of 800mm the angle of view is very small so considerable scanning around the foliage is required to find the bird..
At this stage I have not had an opportunity to compare image quality of extender vs cropped sensor but I hope to be able to do this soon.
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This is a crop of a crop with the lens at 500mm. Pixel dimensions are 1426x1878 giving 2.7 Mpx which is only 6% of the full resolution of the sensor. |
The bell miner was in the shade and appears as a silhouette in the original Raw file. Again this is a crop of a crop. File size is 1752x2002 pixels, giving 3.5 Mpx. Considering the difficult light the R5 and 100-500mm have done a really good job with feather detail and color rendition.