To MC or to Crop ?

As primarily a wildlife photographer my most used lens by some margin is the excellent Olympus M.Zuiko 300mm f/4 Pro.  For a 600mm full frame equivalent lens it is light and compact these being the key reasons why I use m43 cameras.  It is as sharp as any lens I have ever owned, including Canon’s big whites, and the optical image stabilisation combined with the IBIS of my OMD EM1 mkII is nothing short of astonishing.

However, even at 600mm FF equivalent more often than not when photographing birds it is just not long enough.  In such circumstances there are, in essence, five options available:

1. Crop in the final image in post production
2. Crop in by using the cameras built-in digital teleconverter (the manual says to “nearly” double size)
3. Extend the focal length by 1.4 times by using the MC14 teleconverter
4. Extend the focal length by 2.0 times by using the MC20 teleconverter
5. Use a longer lens e.g the Panasonic Leica 100-400mm zoom

In the vast majority of occasions where I feel the need for the extra focal length I will just crop-in in post-production, but in truth the reason for this is that I simply don’t want to demount the 300mm and couple up one of the converters or indeed an alternate lens in the field, it generally just feels like too much hassle and of course risks the dreaded dust getting on the sensor.  That said there are occasions, perhaps where I know that I will need the extra focal length for a number of shots, where I will mount one of the converters to give me the extra focal length.

What I have never done, however, is to actually look in detail and compare the image quality that is achieved with the options lisited above, and whilst I have read online reviews of the MC14 & 20  I have not seen a good review that actually compares the results with their use against actually just cropping in on the native lens.  So in this blog post that is exactly what I am setting out to do with exception of a comparison with the Panasonic Leica lens that I shall save for a separate blog post.

Methodology

I mounted the 300mm lens directly to a sturdy tripod so that all images were taken from the same distance.

Images taken on the Olympus OM-D EM1 mkII.

All image stabilisation was turned off, IBIS & OIS.

All images were captured with the lens wide open i.e native lens @ f/4, with the MC14 @ f/5.6 and with the MC20 @ f/8.

ISO was kept constant at 800 (to maintain a sensible shutter speed).

Images were captured in manual mode.

The elecronic shutter was used so as avoid any camera shake, shutter speed was adjusted in each case so as to ensure constant exposure (as far as possible), 1 stop for MC14 and 2 stops for MC20.

Autofocus was used, as this is what I use 99% of the time, with the single centre focus point in SAF mode.

The shutter, in single shot mode, was fired with a 12 second delay to avoid any vibration.

Images were captured in RAW and imported into Adobe Lightroom with no adjustments and sharpenning set to zero (although see results below vis RAW images and the digital converter).

Images were captured indoors so as ensure no environmental impacts.

The target, Her Majesty the Queen, was at a distance of approximately 6m.

Results

The first surprise is that the digital teleconverter doesn’t work with a RAW file at least not when brought into Lightroom, only a JPEG image shows the magnification, so if shooting RAW the digital converter appears to be of no use.

NB: No sharpening has been applied to the RAW images and click on the images to see them larger.

Firstly here is the full frame as taken with the 300mm bare.

 

Next the 300mm bare heavily cropped

 

Next the 300mm with the MC14 1.4 converter, cropped to match the 300 bare crop – it is fairly obvious that the MC14 produces a sharper image, there is clearly more detail in the Queen’s face.

 

Next the 300mm with the MC20 2.0 converter, cropped to match the 300 bare crop – once again it is fairly obvious that the MC20 produces a sharper image than the bare 300mm cropped, there is clearly more detail in the Queen’s face.  What is more interesting is that the MC20 also produces an image which is noticably sharper than the MC14, again there is clearly more detail in the Queen’s face.  One other thing to note however is that the image with the MC20 is slightly less well exposed than the bare and MC14 images suggesting that the MC20 does cost slightly more than 2 stops of light.

 

So in conclusion – If you need extra length on the 300mm lens so long as the light will allow (2 stops plus a bit will be lost) the MC20 produces notable better results than the simplt cropping the bare 300mm lens in post production. What’s more the MC20 appears to be sharper than the MC14 a result that does not surprise me as my in the field experience suggested that this might be the case.

Now I thought it would be interesting to compare the JPEG images that the cameras digital teleconveter produces compared with simply cropping the RAW in post and using the MC20.

In order to do this it is necessary to apply some sharpening to the RAW images as the out of the camera JPEGS have some sharpening applied. I have sharpened the RAW images with Lightrooms default sharpening parameters as these are what I tend to use on the vast majority of images (amount 40, radius 1.0, detail 25).

So here is the full frame JPEG as taken with the 300mm bare but with the digital teleconverter.  The first thing to note is that it is suprisingly sharp !

 

Next the 300mm bare with the digital converter cropped, again this is very sharp indeed and if you were shooting JPEGs I would say certainly sharp enough for virtually any purpose.

 

Next the 300mm bare RAW image cropped and sharpened – interestingly the out of camera JPEG is perhaps just a little sharper but this is probably simply due to the camera applying more aggresive sharpening that the default Lightroom settings.

 

Next and perhaps more interestingly the 300mm lens with the MC20, again cropped and sharpened.  Here there is no doubt that the MC20 does produce a sharper more detailed image than the JPEG with the digital converter.

 

So in conclusion – If you are shooting JPEGs the digital converter does a decent job although whether it is any better than simply cropping in post really just depends upon the amount of sharpening that you apply.  If however you want the best possible quality it is still better to use the MC20.

As always these results are based on my copy of the lens and converters – your mileage might vary !