Is The Digital Tele-Converter Feature In Your OMD Camera Worth Your While?

Full image from a RAW file (click to enlarge)
Olympus E-M1, Olympus 12-40mm f/2.8 lens @ 40mm; ISO 400; 1/200th sec. @ f/5.6

Both the Olympus OM-D E-M5 and OM-D E-M1 come with a 2X digital tele-converter built into the camera.  This feature can be accessed on both cameras in Shooting Menu 1.  I started wondering if it was a feature worthwhile using.  There is only one way to find out—use it and find out.

I have owned and still own digital cameras that have various digital tele-converters built in.  I have never been particularly interested in that feature and have never used it. I haven't even experimented with it to see if it is something that I could use on occasion. I have always been a RAW format user as I always try for the highest available technical image quality.  Digital tele-converters work with the JPEG format and not the RAW format.  I almost never make images as JPEGs.

Recently, I noticed the 2X digital tele-converter feature in the menu system of my E-M1 but really didn't give it a second thought at the time.  However, over the last few days, I continued to mull over the option in my mind and decided, since I had never used it before, could using a digital tele-converter in my photography have, on occasion, some utility? 

Over the past couple of days, I went out and tested the feature.  Unfortunately, every day has been pretty heavily overcast, so my results are limited to overcast days and how the camera and in-camera processing reacts in that type of weather.  I'll have to test the same feature on a sunny day in the future.  But, from what I have seen so far, I think the results would be similar.

If you don't care to read farther or examine the included examples, the answer is that Olympus did a very good job with the feature.  In fact, I was unable to get better results manually using Photoshop to create the same process.  The other thing I discovered is that the digital tele-converter doesn't just crop the center out of the frame and present it to you.  It crops to the center 1/4 of the frame, then resizes that 1/4 frame back to full size.  It does it very well.  It would be worth your while to check it out and use it if needed.

I first went out with my E-M1 set to record RAW + LF JPEG.  The JPEG settings were mostly set at their default level, but I set the sharpening to +1, mainly because that is the best setting I had found experimenting with JPEGS in my Fujifilm X-T1.  The contrast and curve was set at the factory neutral setting.

When I looked at the preliminary images in Lightroom, the JPEGS were too contrasty (even on a overcast day) and the sharpening was too high as the image looked crunchy.  I would not recommend factory default settings for this experiment, at least under the conditions in which I used them.

I also found out that not only does the camera provide you with a center crop of 1/4 of the overall image, but then the camera automatically resizes the cropped JPEG to full size.  For example, a RAW image from my camera measures 4608 pixels X 3456 pixels, almost 16mp. The JPEG produced by the camera using the digital tele-converter is exactly the same pixel dimensions.  

I then cropped one of the RAW images as closely as I could to match the image cropped using the digital tele-converter.  Its dimensions were 2316 pixels X 3456 pixels, about a 4mp image. That means the camera is increasing the cropped image 400% in area.

That is quite a bit of interpolation and creating content where none previously existed. How does that affect image quality?  Would it be better to crop a RAW image, then uprez the image to the size of the original?  Read on and decide for yourself.

The image at the top of the post is the full frame taken using RAW, composed as I probably would compose it in-camera.  It was then edited to make the best image I could in Lightroom 5.7.1.  (It was a really bad day so it really isn't a very good image, I have to admit)

The image immediately below is the digital tele-converter and made using JPEG.  I did edit this image also to make the best possible.  Here is a difference, and an important difference, from my first results.  I turned the JPEG settings in the camera to their minimums.  I turned the sharpening to -2.  I turned the contrast to -2.  I changed the "gradation" in the Super Control Panel to Low.  Right out of the camera, this JPEG looked very, very similar to the RAW image right out of the camera.  So, if you are using JPEG and want to preserve as much detail as possible, you may want to experiment and try my settings.  Again, this was on a heavily overcast day.  There might be a difference on a sunny or partly sunny days.  The key is you experiment using your gear, your normal subject matter and the weather in your part of the world.

Image from the digital tele-converter and a JPEG file; edited in Lightroom 5.7.1.  (click to enlarge)

The next image is from the RAW file, cropped as closely as I could make it to match the image above, then resized back to full image's original size which matches the above image using "preserve details" in Photoshop CC 2014, brought back into Lightroom, then edited. Pardon the small overall color difference between the two images. (click to enlarge)

(click to enlarge)

Here is a side by side comparison of just the statue.  The manual crop and resize is on the left and the JPEG digital tele-converter image is on the right.

(click to enlarge)

This match pretty closely.  I don't see any advantage in using RAW, cropping, resizing then editing than editing the in-camera digital tele-converter image.

These two extreme crops match pretty closely.  I would say close enough that it doesn't really matter if you use the digital tele-converter or use RAW, crop, resize in Photoshop, then edit the final sized image in Lightroom.  In this example, there are some very slight differences, but in Lightroom, you are able to fine tune your adjustments to make them match just about perfectly.

Here is another series.  This first image is the full image made from the RAW file.

Full frame from the RAW file. (click to enlarge)
Olympus E-M1; Panasonic 35-100mm f/2.8 lens @ 100mm; ISO 200; 1/25oth sec. @ f/5.6

This is from the digital tele-converter generated JPEG image, edited in Lightroom (click to enlarge)

This is from the original RAW image, manually cropped to match the tele-converter image above, then resized
back to the original in Photoshop CC 2014.  Finally, it was edited in Lightroom. (click to enlarge)

Here is a comparison.  The manually cropped and resized image from the RAW file is on the left,
while the in-camera crop using the digital tele-converter image is on the right.
You decide how much of a difference there is. (click to enlarge)

I realize looking at comparison images on a web based blog is pretty useless.  But sometimes it is better to put up something rather than just words.

I'm not a lab rat.  I'm not so technical that I would spend 30 minutes trying to find any differences in the two images represented by RAW files cropped and resized versus in-camera cropping using the digital tele-converter feature.  Whatever Olympus is doing, they are doing it right, in my opinion.  I don't think I could do better than whatever algorithm Olympus developed to enable this feature.

You will have to decide for yourself how much of a difference you see.  As for me, from what I have seen in these images and others, I see almost no difference and it makes a lot of sense to use RAW + LF JPEG and use the digital tele-converter if you don't have a lens long enough to make the image you desire.  I believe you will save yourself a lot of time and effort not having to go through a RAW workflow to crop, resize and edit. 

Let me add one caveat to the above paragraph.  JPEGs are 8-bit and RAWs are 16-bit. JPEGs will work if you don't have major editing to do.  If you do, you are better off using RAW.  Using JPEGs and making extreme color, white balance, or other changes may produce banding and other anomalies.  So, it pays to get it right in the camera if you want to use JPEG for anything.

Additionally, if you need a quick image to send over social media, this method also makes sense.  Personally, I would never photograph without the RAW image as my primary file, but in the future, I would consider using this feature if the situation presented itself.  But that is just me.

Thanks for looking.  Enjoy!

Dennis Mook

Many of my images can be found at www.dennismook.com.  Please pay it a visit.  I add new images regularly.  Thank you.


All content on this blog is © 2013-2015 Dennis A. Mook.  All Rights Reserved.  Feel free to point to this blog from your website with full attribution.  Permission may be granted for commercial use.  Please contact Mr. Mook to discuss permission to reproduce the blog posts and/or images.