Looking for the sharpest landscape lens for my Canon 5D Mark IV.

Question

So my uncle basically just handed me his old Canon 5D Mark IV because he said he's switching to mirrorless, whatever that means, and now I have this giant heavy camera and I really want to use it for my trip to Zion next month. I've been practicing in my backyard but the pictures just don't look like the ones I see on Instagram where everything is super crisp and you can see every single leaf on a tree from a mile away. I have this lens that says 24-105mm on it but I read online that for real landscapes I need something wider or sharper? Honestly I'm lost. I dont even know if sharp is the right word or if I'm just bad at using the camera but I want to buy one really good lens that I can just leave on the camera for the whole trip and not worry about it.

I have about $1000 saved up for this but I could maybe go up to $1300 if it's like, life-changingly better. Sorry if this is a total beginner question but I really have no idea where to start and every time I google it I just get more confused by all the technical talk. Here is what I think I need:

Something that makes the mountains look really clear and not blurry when I zoom in on my laptop later.

I'm gonna be hiking a lot so I don't want like five different lenses to carry around, just one good one.

Is it better to have a lens that zooms or one that stays at one length? Someone told me the prime ones are better but then I cant zoom? That sounds hard for a beginner.

I really want to try and take pictures of the stars too if that's possible with the same lens?

I keep seeing stuff about L series with the red ring and my current lens has that but maybe I need a different one for the wide views? Everything is so expensive and I dont want to waste money on something that's too professional for me to even understand how to use. Also I saw some lenses that said RF and some that said EF and I dont even know which one fits this camera...

Lqrwfat · Accepted Answer

Building on the earlier suggestion, I spent a lot of years chasing that perfect corner-to-corner sharpness on the 5D Mark IV before I finally realized how much the glass matters over the body. In my experience, Zion really demands something wider than your 24-105mm because those canyon walls are just massive. Youll find yourself backing into a cliff trying to fit everything in with a standard zoom. If you want the absolute best technical performance for both landscapes and those star shots, the Canon EF 16-35mm f/2.8L III USM is basically the gold standard. I remember switching to the Mark III version and the difference in resolving power was night and day... the way it handles chromatic aberration (those weird purple fringes on tree branches) is just incredible. It has an f/2.8 aperture which is huge for astrophotography because it lets you keep your ISO lower so the sky stays clean. If thats pushing your budget too far, check out the Sigma 14-24mm f/2.8 DG HSM Art. It is a heavy beast to carry but the technical data shows its incredibly sharp for the price.

Bukmekersk_ywsi · Answer

First off, be super careful not to buy any RF lenses... they wont even click into your 5D Mark IV. You strictly need EF mount. Honestly, if you want that crazy sharp every leaf look plus stars, you might want to consider the Tamron SP 15-30mm f/2.8 Di VC USD G2. Its a bit of a tank, but its way more budget-friendly than the Canon equivalents and the sharpness is legit. If you really want that red ring tho, try to find a used Canon EF 16-35mm f/2.8L III USM. Just make sure its the Mark III version, because the older ones can be a bit mushy in the corners. Also, grab a cheap tripod if youre doing stars! Even a $1300 lens looks like garbage if the camera moves during a long exposure. TL;DR: Only buy EF mount. The Tamron 15-30mm f2.8 G2 is the best bang for your buck for landscapes and stars.

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Looking for the sharpest landscape lens for my Canon 5D Mark IV.