yo, congrats on the 5D IV!! i've had mine for a while and honestly, it's such a workhorse. so basically, the big thing to know about the specs is that the SD slot in this body is only UHS-I, which is lowkey a bottleneck for buffer clearing during events. if you want the best performance, you totally gotta use the CF slot as ur primary because it supports UDMA 7. i've been using the SanDisk 128GB Extreme Pro CompactFlash Card 160MB/s and it works well for keeping up with burst shots without the lag. for the L-bracket, if you want low bulk, check out the SmallRig L-Bracket for Canon 5D Mark IV 2202. it's way slimmer than some of the more expensive brands but still super solid for ur landscape work. and since you mentioned long exposures, i literally can't live without my Canon RS-80N3 Remote Switch... it's basic but it's a total necessity to stop that tiny bit of shutter shake. anyway, hope that helps, gl with the new gear! 👍

Respectfully, I'd consider another option. The SanDisk Extreme 128GB CompactFlash 120MB/s is way cheaper. Honestly, the 5D IV write speed caps around 100MB/s anyway... so expensive cards are kinda overkill, i think?

Jumping in with some technical specs that might help. Since the 5D IV has that specific dual slot setup, your workflow really depends on how you handle the data overflow. If you want something that isnt the standard SanDisk or Lexar route, I have found a few alternatives that work just as well for pro use.

• For the CF slot, I recommend the Delkin Devices 128GB Black CF Memory Card. It is built for rugged environments and has better sustained write speeds than most mid-range cards, which is huge for buffer clearing during fast event bursts.
• Regarding the L-bracket, check out the Sunwayfoto PCL-5DIV L-Bracket. It is a bit more affordable than the high-end boutique brands but still custom-molded so it wont twist when you switch to portrait orientation on a tripod.
• Since you mentioned bulk, consider skipping the grip and using the Tether Tools Case Relay Camera Power System for your landscapes. You can power the camera via a standard USB power bank, which is way more efficient for long exposures than swapping internal batteries in the dark. One tiny thing people forget is the glass on the back. Get the Vello Screen Protector Ultra for Canon 5D Mark IV since it is actual tempered glass and doesnt mess with the touch sensitivity of the screen. Its a life saver for event work and keeps the body looking new.

Quick reply while I have a sec! Seconding the recommendation above. That SD slot bottleneck is lowkey annoying... In my experience, you really gotta rely on the CF slot for event speed. - I've tried many and the Lexar Professional 1066x 128GB CompactFlash Card is super reliable. I'm always paranoid about card failure, so don't risk the cheap stuff.
- For landscapes, don't use universal L-brackets—they slip. I'd suggest the Really Right Stuff B5D4-L L-Plate for Canon 5D Mark IV. It fits the body contours perfectly.
- If you want a grip, maybe stick with the Canon BG-E20 Battery Grip. I've seen third-party ones mess up the weather sealing, and it's just not worth the risk on a pro body. Anyway, hope that helps! You're gonna love the image quality... it's a beast. 👍

unfortunately the 5D IV internal architecture is a bit of a letdown because that SD slot is totally stuck on old UHS-I tech. its a massive bottleneck that throttles the write speeds regardless of how fast your card is. had issues with buffer lag way too often... really disappointing for a pro workhorse. honestly just get any pro-grade CF card from SanDisk or Lexar and youll see a huge jump in performance. dont even look at the budget brands for the cards. for the landscape stuff, definitely grab an L-bracket from Kirk or SmallRig. the fit and finish on those is just way better than the generic junk you find online and they actually lock into the body properly. let me know if you want me to look up the specific write speed benchmarks for you, happy to chat more about it tho!

I have to respectfully disagree with the idea that high-end cards are overkill here. When you look at the market analysis for CF cards lately, the quality control on the mid-tier value lines has really tanked as manufacturers shift focus to CFexpress. Basically, you arent just paying for that peak burst speed; youre paying for the VPG rating and better heat dissipation. If youre shooting a high-stakes wedding or long event, that thermal management is what prevents the buffer from locking up your 5D IV entirely. I’ve seen way too many people lose data on those cheaper cards because they cant handle the sustained write cycles during heavy use. Also, a word of caution on the grip situation—if you go third-party to save on bulk or cash, watch out for the weather sealing and the battery communication pins. A lot of those off-brand grips dont have the same tolerances as the native magnesium alloy builds, and they can actually cause a slow parasitic drain on your LP-E6N batteries even when the camera is off. For long-exposure landscape work, thats a recipe for a dead camera right when the light gets good. Honestly, focus on reliability over saving a few bucks on legacy formats.