Needing some advice on what I need for macro shots.....

FiggeB wrote:

Check macrophotography.net.

I believe you mean https://photomacrography.net/

They have a forum with tips for beginners. Everything about extension tubes, macro lenses, reversed lenses, stacking lenses, macro rails, working distances, focus stacking, etc.. Also closeup filters which are available in achrochromatic versions. Much better than cheap single lens filters which are to be avoided. I have dedicated macro lenses but also use a 77 mm Canon 500d with my 70-200/2.8. Nice combination. Nisi have similar filters which are reported to be good. Nikon filters are good, but I do not know if they are still available.

I'm pretty sure Canon 500Ds aren't available either, these days.

The currently available 77mm achromats are Marumi and (as you mentioned) NiSi. I have a Marumi: quite pleased with its quality.

If I remember correctly, most of them were only available in 52 mm.

Nikon achromats were available in 52mm and 62mm. This is usually fine even for larger lenses, because you're almost never going to shoot wide open, so you can get by with a step-up ring.

Note that you can't do this with the Sigma 52mm achromat, because it's only about 35mm in diameter, mounted in what is essentially a permanent 52mm step-up.

I no longer use extension tubes. They are mostly of bad quality in my opinion, are fiddly to use and you loose a lot of light.

You don't really lose any light: that's a common myth.

Remember, macro is almost always done at apertures near the diffraction limit, and what matters at such apertures is physical aperture size and magnification. If you have a 20mm physical aperture and you're shooting at an effective f8 to keep from losing resolution to diffraction, it really doesn't matter if you get there by extending a 60mm f/2.8 until you're at 2x, or if you've put a strong achromat like the Raynox DCR-250in front of a 100mm to get close to 2x, you''re still going to have to shoot at an effective f8, unless you're stacking. That changes the game and you may want a larger physical aperture. My Zeiss 100mm f/2 has a 50mm aperture, which is huge, and if I were stacking at 2x (yes, with 150mm of tubes) I might shoot it wide open at an effective f6 to keep the resolution up. If I were shooting without stacking, I'd drop it down a stop.