Using only natural lighting and no cropping as well as no photoshop usage. Let's see what you can do with your camera! Use your imagination! Next time I will challenge you to Themes! Enjoy and have fun!
The way i understand the challenge is No lighting added, no editing in software, do the very best you can in your camera within its capabilities.
Using the right glass the right settings and above all as cropping is not allowed its imperative that the composition be done to the very best possible.
Getting it right in camera to the very best you can is the objective.
This puts pressure to select the right time to photograph in order to optimize light and colour along with avoiding shadows where necessary.
Selecting the optimum combination of time light and speed for sharpness, colour, exposure.
Let me know if i am off course here please.
With DSLRS or Mirror Less or any camera that is used other than film, the shots have to be in JPEG or RAW or TIFF etc.
Ok JPEGS by default are slightly optimized in camera compared to raw.
The internal settings available in picture quality ie: sharpening, contrast, saturation brightness etc etc have an influence on JPEGS only not RAW.
The main challenge is composition, natural lighting, exposure, tolerable has to be JPEGs, unless the challenge is only for film which i find unlikely to be the case.
The objective is to get great usable photos with out editing in PS LR or using added external lighting, the answer is absolutely you can, you just need skill sets, something these new cameras are eroding and slowly introducing new computerized controls requiring different skill sets more IT based.
I can produce out of a Z8 Z9 Z7II a perfect JPEG fine image in camera using a 50mm 1.8S in P mode, iso is defaulted to 12800 auto.
My girlfriend can nail money shots with this set up, and she doesn't even know anything about photography or the camera or how to use it other than when i tell her
" hold it up, look in the back screen till you see what you like in the way you want it and then push the big button on the top right hand side"
Instant money shot......her reaction
boring she says i would rather use my I Phone LOL
If its getting the best in camera with out editing in software or using lighting externally or cropping then hey love it, its what we do in the club sometimes.
Only an opinion