....look what I caught...
Another image from the Pentax 1.4tc + Sigma 500/4.5 combo. Around 80% of the original image.
A benefit of being able to keep a lot of pixels, is that the image then takes editing really well e.g. noise reduction, capture sharpening, shadow lifting or color enhancements. Having +/- 5000px available is also a plus when printing A3+ that I regularly do.
This was when watching a pair of Great Crested Grebe fish for some time.