Originally posted by Tony Belding I'm just curious because I've been trying to work out the best practices for shooting on bright, sunny days. I already know that Highlight Correction is beneficial in these situations. (It also helps skies to look blue instead of turquoise!)
Lower ISO means lower noise. Highlight correction does a little trick - it labels ISO one stop higher, but shoots at a lower ISO, then digitally brightens the photo, while taking care not to burn the highlights. This is why you cannot choose ISO 100 if you have highlight correction enabled - but when you choose ISO 200, camera actually shoots at ISO 100.
However, doing things like adding brightness and contrast digitally will make the noise more apparent, more noticeable.
Anyway, for blue skies, I would suggest you just take care what settings you use. I don't think an ND filter is needed for regular summer outdoor photos. ND is usually used when you want super fast aperture in sunlight (like f1.4, for shallow DoF) or if you want to take long exposures to make movement blurry (like a waterfall, river). A better choice would be a polarizer. Polarizers will make the skies appear more.. deep, blue, dark. But you need to learn how to use them. And polarizers are not useful on ultra wide lenses, as the sky will appear blotchy (I do mean ultra wide, not just wide).
Using a lens hood can also help with overall image contrast and colour saturation, especially if you are using older or cheap third party lenses.
If you shoot jpeg, you might want to add shadow correction, and then use EV+/- to underexpose (like -1). This will make the whole photo a little darker (including the skies) but will bring up the shadows a little. I usually just shoot raw and check histogram to make sure highlights aren't blown, and then use software on computer for any digital changes, like adding brightness, darkening the sky, whatever. You can even add a digital graduated ND in most software (to make just skies more contrasty and dark).
---------- Post added 30th Jun 2016 at 15:12 ----------
Ah, you just made a reply as I was typing mine. Well, take from it what you can.
Originally posted by Tony Belding And most lenses seem to be sharpest around F4.
True, but I would suggest you use f8 on bright sunny days. f8 is good because it gives you a wide DoF, good sharpness, good CA control, but it does not yet suffer from diffraction. So even if f4 is technically sharper on your lens, f8 might still render a photo that
appears to have more detail. And in photography, its all about appearance. f4 is often too shallow DoF for landscapes and street photography, and it is too bright for very sunny days, high altitude or desert travels
Tl;dr: Use circular polarizer filter of a good brand, shoot f8, use lens hood, lowest ISO, check histogram to make sure highlights are recoverable in post, use EV+/- to avoid blowing highlights. Since you shoot raw, disable all jpeg things like CA correction, distortion correction, shadow correction.