So yeah, +1 to what ppl said about the “portrait look” being nicer when you step back a bit. I tried the 50-ish vs 85-ish thing indoors and learned quick:
- 50: easier in tight rooms, but faces get a lil weird if you creep too close
- 85: cleaner compression, BUT you need space + watch shutter shake
- super-wide apertures: honestly not “safer” indoors… missed focus happens, eyelashes sharp / eyes soft

I ended up shooting a lot at like f/2–2.8 for reliability and less redo stress lol

Exactly what I was thinking

For your situation, I’d go Canon EF 50mm f/1.4 USM vs Canon EF 85mm f/1.8 USM vs Canon EF 100mm f/2 USM. 50/1.4: workable indoors, decent blur, AF is… kinda fragile if bumped. 85/1.8: best “portrait look,” fast AF, but tight rooms can be rough. 100/2: sleeper pick—similar look to 85, a touch more reach. Honestly, f/1.8 is plenty on 5D4, less AF drama than f/1.2 stuff.

For your situation, I’d suggest Canon EF 85mm f/1.8 USM as the “one lens” portrait pick on the 5D4… even indoors. I know, 85 sounds long, but in tight spaces it’s actually kinda nice because it forces you to back up and you get a more flattering look (less nose/face stretch vs 50). Background separation is legit, AF is fast/reliable, and it’s usually like $250–$350 used, so you’re not sweating it.

Option A: Canon EF 85mm f/1.8 USM → Pros: great compression, creamy enough bokeh, quick AF, cheap. Cons: you’ll need a bit of room; in a tiny living room you might hit a wall (literally lol).

Option B: Canon EF 50mm f/1.8 STM (~$125 new) → Pros: dirt cheap, sharp, flexible indoors. Cons: doesn’t scream “portrait lens” on full frame; for headshots you’re close and it can get a little unflattering.

Option C: Sigma 85mm f/1.4 DG HSM Art for Canon EF (often ~$650–$900 used) → Pros: reallyyy pretty bokeh/contrast. Cons: bigger/heavier and AF can be a bit more “depends on your copy” (i mean… it’s usually fine).

Re: f/1.2–1.4 vs 1.8… honestly, f/1.8 is the sweet spot for cost + AF sanity. You can always shoot 1.8–2.2 and it just works. good luck tho!

@Reply #6 - good point! The spatial geometry of a small room really dictates the technical feasibility of using longer glass. I have owned the Canon EOS 5D Mark IV since it launched and you should definitely be cautious about the working distance requirements before you invest. Honestly, you might want to just check YouTube for this specific comparison. There is a very detailed video if you search for 5D Mark IV portrait lens shootout or 50mm vs 85mm for small studios. It should be one of the first results and it breaks down all the sharpness data and autofocus reliability stats in a way that is much more comprehensive than a forum post. I watched it a while back and it covers exactly what you are asking about regarding background separation and frame compression on this specific sensor. Probably better to see the actual visual side-by-side tests there before you make a final decision.

Ugh, reading this is like looking in a mirror. Honestly its ridiculous how we have to deal with this constant struggle between physical space and that perfect look. Ive been an enthusiast for a long time and I still havent found the goldilocks setup for my 5D Mark IV in my spare bedroom studio. It drives me crazy because you spend all this money on a solid body, and then the lens market feels like such a scam lately. Everything thats actually sharp is either massive and weighs a ton, or the price is just insulting for tech thats essentially ten years old. And the compatibility concerns? Man, it feels like they are just leaving us 5D owners in the dust. I am so tired of buying glass only to find out the autofocus is mostly reliable but fails right when the lighting gets interesting or the subject moves an inch. Its such a headache trying to bridge that gap without spending five figures on a whole new system... just feels like we are being squeezed from both ends tbh. I am literally sitting here with the same frustration, just staring at my gear bag feeling totally defeated by the whole thing.

Jumping in here because I've spent way too many hours analyzing the technical side of this exact setup. Over the years, I've tried basically every focal length on the 5D series and I've learned a few things the hard way:

• I used to obsess over f/1.2 glass for the bokeh, but my data showed that my keeper rate for sharp eyes on the 5D4 dropped by nearly 40 percent compared to using a solid f/1.8 prime.
• I once tried to force a longer focal length in a 12-foot studio and found myself literally backing into a closet to get the framing right. It was a total nightmare for workflow and made the subject feel super awkward.
• In my experience, technical specs like focus breathing and minimum focus distance matter way more in tight spots than the maximum aperture. Some lenses zoom in so much when focusing close that you lose all your wiggle room. Ngl, I spent way too much time chasing the gear when I should have been looking at the spatial geometry of my room. I eventually found a setup that worked for my specific distance, but it took a lot of trial and error and measuring my floor space with a tape measure.

Same boat, watching this

Totally agree that 50mm is the sweet spot for indoor flexibility, but the older Canon f/1.4 is pretty dated now and the AF can be a bit flaky. If you want a real technical jump in sharpness and that "pro" separation you’re looking for, you should seriously look at the Sigma 50mm f/1.4 DG HSM Art. It’s a beast on the 5D4 and handles that high-res sensor much better than the budget options. Since you mentioned being worried about AF reliability, the real DIY enthusiast move here is to pick up the Sigma USB Dock. Instead of sending your kit off for professional service if the focus is slightly off, you can calibrate the lens yourself at home. It lets you adjust the AF firmware at four different focal distances, which is way more precise than the standard AF Microadjustment in the 5D4’s menu. Also, if you find 85mm too long but still want stabilization for those low-light window shots, look at the Tamron SP 85mm f/1.8 Di VC USD. Honestly, having VC (Vibration Compensation) on a prime is a game changer when you're shooting handheld in tight, dimly lit rooms. It basically lets you drop your shutter speed without the blur, which might be more useful for your setup than an extra stop of aperture.

Ugh, I'm literally in the exact same spot right now and it’s been so frustrating. I've been searching for months for a portrait prime that actually hits focus reliably in my tiny home studio on my 5D Mark IV, but everything I try is either too soft wide open or way too tight for the room. Honestly, I'm desperate for that 85mm compression but I'm literally hitting walls, and the 50s just dont give me the same separation. I still haven't found a lens that actually checks all the boxes for me and I'm starting to think the perfect indoor setup is just a myth.

Adding my two cents here since I've spent way too much time looking at focal length physics and AF hit rates for the 5D4. You mentioned tight spaces but honestly that term is a bit of a wildcard. To give you a solid recommendation based on the optics, I really need to know what kind of working distance you actually have in that room? Like, how many feet can you get between your sensor plane and the subject before you're hitting a wall? Also, are you aiming more for tight headshots or do you need to fit in waist-up or full-body shots too? The 5D4's autofocus system is a tank but it's definitely not as forgiving as the newer mirrorless stuff when you're shooting wide open, so knowing your framing goals helps determine if hunting for f/1.2 or f/1.4 glass is even worth the lower keeper rate. Just trying to figure out if we're solving a physics problem or a light gathering one lol.

Tbh I'm still relatively new to the 5D4 compared to some of you guys, but I’ve been reading through this and it basically seems like everyone is torn between that classic 85mm look and the practical side of a 50mm in a tiny room. Its a tough call because while the 85mm gives you that *wow* factor, if youre constantly hitting the wall behind you, you’ll end up hating it lol. I’ve found that over the long term, I actually reach for the lens that's easiest to use rather than the one with the biggest aperture, especially since the 5D4 is already a bit heavy. Before you pull the trigger though, I’m curious—exactly how many feet of working distance do you actually have in your studio setup? Also, are you looking to do mostly tight headshots or are you trying to get full-body shots in that small space too? I think knowing that would really help narrow it down!

Just catching up on this thread and honestly, I have to disagree a bit with the 50mm vs 85mm struggle. When I first started shooting in my cramped apartment, I felt so limited by those lengths. I was always backing into my bookshelf or tripping over my bed trying to get the shot. I eventually tried out a wider 35mm prime and I've been so satisfied with it. No complaints at all. It lets me capture the whole scene in a way that feels more natural for a home studio, and I can still get that separation if I just step in a bit closer. My current setup works well for me because it stopped the physical struggle of the room size. Sometimes the traditional portrait rules just don't fit a tiny space. TL;DR: I went with a 35mm for my small room instead of the usual portrait lengths and it's been the best decision for my workflow.

Any updates on this?