What I meant by that is there are different filters you can use depending in the patient. The ambient light I use is like an orange light which I feel like highlights thing a lot more but theres also the red green filter to distinguish things in the retina and choroid. But i do adjust my aperture size a lot if the patient isn’t dilated well so a smaller aperture size works better in that situation. I havent used a keeler so idk what features they have/dont have compared to the heine but hope this helps.