Since it might have relevance to what follows, here is what I use: Lumix DMC-FZ300 (set at 12mp; 4000x3000), Dell XPS 15 with external 27” Ultra HD Display, Windows 10 (16GB), Lightroom CC version 3.2.

I’m not a professional and am primarily interested in travel, nature and wildlife photography.

Until now, I've only shot JPG, but with a major trip looming, I want to decide if I should plan to shoot in RAW. So, I took a number of pictures at a marina in RAW+JPG to compare them in post processing in order to "see for myself" if RAW was worth the disadvantages.

In Lightoom CC I compared the effects of various edits on many of the pairs. Bottom line: I saw very little (almost no) difference between the edited JPG’s and RAW’s. Only at the far end of a few of the edit sliders, say the last 5-10%, could I see a difference.

The strongest difference was in the exposure slider where I was able to reveal slightly more detail (with the slider all the way to the right) in the heaviest shadows in the RAW files.

I also compared the pairs after randomly applying some of the presets, and really saw no differences at all between a JPG and a RAW after any preset had been applied.

Lightroom has an “Enhance” feature that works only with RAW images. I tried that on a couple of images and although it made a difference, I can’t say that I preferred the enhanced images. But I can see that there could be images that this feature might improve.

In summary, the RAW advantages that might have some potential value are for images where desired details are hidden in very heavy shadows and for images that would be improved by using the “Enhance” feature, although for the latter I don’t know what those would be.

That didn't seem like much. Hence, the question in the topic title – what am I missing?

What else can I experiment with that would show me some major advantages of RAW? I did not compare the images after severe cropping, or, alternatively as very large prints. Is that where significant differences show up?

On the other hand, with my camera at least, RAW is not without cost. There is a loss of functionality when shooting RAW or RAW+JPG. The “Handheld Night Shot Mode” is disabled, as is the iHDR mode. I have benefited from these modes extensively, particularly iHDR.

Other features that I’m not so dependent on are also not available when shooting RAW, including Super High Burst Mode and digital zoom.

For me the disadvantages far outweigh the advantages of RAW unless someone can help me find other advantages I currently don’t see.

An extender will not improve, and in fact reduces image quality. But everything is a trade-off. In this case - for me - does the cost, and weight + bulk advantage in the camera bag, of a TC vs. another lens give me an advantage?

I tested this quite easily - could I reduce weight and bulk if I used a 100-400+TC rather than carry a 150-600? Also for me, my default lens is a 24-105 so I would have a continuous focal range of 24-600+ with 2 lenses. In fact I sold a good 150-600 Tamron after buying the x1.4 TC for the 100-400 as IQ of Canon +TC was better than the excellent Tamron (and anyone could argue 'so it should be given the total cost'.)

As to IQ, that was also easy to test providing you can get access to the kit.
- I checked side by side image quality centre and corners at 100% of the 100-400 at 400. This is baseline and I expected to be best.
- I then repeated the test with the lens +TC combo at approx 400 (so I could compare like for like with the bare lens and lens+TC.)
- then checked at max lens + TC (640mm)
- also checked a crop of the bare lens with lens+TC enlarged to similar size
- for curiosity as I had the lens I compared with the Tamron 150-600 (v1)

Results were pretty much as you would expect - bare lens was best,lens+TC results at similar focal length were not as good, and at max were also less sharp but much better than I expected and perfectly good for display or printing at 100% or less. The all important crop enlargement was not as good as the lens+TC (otherwise whats the point of a TC if an enlarged crop of the same area is as good or better!)

Initially, the main surprise was that the Canon 100-400+TC was better than the Tamron at 600 - again on reflection this is not surprising given the huge cost differential and that the Canon was a new v2 lens and the Tamron an older v1.

I would also mention with my camera/lens combinations there was no noticeable impact on focusing because even with TC the maximum aperture was withing the autofocus range (a x2 would not have been and would have hunted or probably failed to focus.)

I would emphasise my testing though careful, was empirical and subjective, but I would always advise before anyone spends shed loads, to test the actual equipment they intend to purchase!

Here are a couple of frames. Hand held, lighting with LED desktop lamp, so no great images! Didn't even clean the watch (see fingerprint over date.)

Only processing is to convert raw to jpg with Fastone Image Capture for this post. Exif from FS capture shows 1st with 150mm lens, 2nd is with canon extender x1.4 III. Apeture set at f/8, shutter speed and ISO auto. Taken at about the same distance. Images have not been resized if you wish to zoom to 100%, but if you really want to check IQ at this magnification it should be taken with a tripod of course.