The 24-70 is an incredibly good lens - it's as sharp wide-open as just about any prime at every focal length across just about its entire field.

But it's only 24-70. As you're talking about a full-frame Canon, that's as wide (16mm * crop factor of 1.5 = 24mm), but you'll be losing a lot of length at the telephoto end - your 90mm on APS-C is equivalent to 135mm on full-frame. Speed-wise, f/2.8 on full frame is about equivalent to f/2 on APS-C so there won't be a significant difference there except for your currently incredibly fast 35mm f/0.95.

To me, the main reason to change to a zoom lens would be if you're missing shots because you're having to change lenses. If you (and your clients if you are doing this for money) are happy with your current output, then there's absolutely no reason to change because a "professional" told you something - just because they do something for money doesn't mean they know more than you, especially about your personal preferences. I'd just politely ignore them.

You might also want to take into account the following:

• That 24-70 mm doesn't cover even half your current range.
• You really like the 90mm for portraits, and 90 mm is outside that recommended range? At best you'd have to adapt your shooting to that new lens
• An incredibly sharp lens is only useful if you use that sharpness for e.g. larger prints. If you never make large prints (say A4 and larger) I'm not sure you'd see any difference with regards to your current equipment.
• How much would the Canon+24-70 mm weigh? (and how long before you'd want to add a 90mm or longer to your kit?)

I am looking to purchase a camera and have been Googling about far too much. My conclusion is to go Fuji. I found many people switching from Canon to Fuji, but not the other way. Gear size is a big thing sited, eg for carry on luggage, being noticed by security people in the street with a massive camera, arm ache. Professionals seem to start off with a Fuji backup camera and then end up selling the full-frame kit.

Mirrorless over DSLR-> smaller camera. APS-C over 35mm -> one stop less light, smaller,lighter, less-expensive, lenses.

You have to make very large prints for the difference in picture quality to be noticable.

The other comment I found was for DSLR-APS-C, being the worst of both worlds, as you may end up using full frame (heavy expensive) lenses (also not made for APS-C).

So plenty of 'pros' using Fuji. The other arguement put forward is the 'well anything smaller than medium format is junk', and since that is so much bigger than 35mm, then 35mm can't be any good, if you think it is then the jump to APS-C is a much smaller one. But I think this is using the medium format as a decoy (classic selling technique).

This is my paraphrase of what the Internet told me, so it must be true, right?

This does not really answer your question, but rambles in the direction of saying Fuji is a pro-tool/system and often the best one to select.

I can't answer about your lenses specifically but typically primes have less distortion than zooms. Zooms can cause barrel or pincushion distortion depending on the focal length used. While this is not typically noticeable in e.g. landscape or street photography it can cause problems with portraits (distorting faces is not a good idea).

Primes also typically allow wider apertures than zooms, particularly at the longer end of the zoom's range, which is useful for portraits.

In general, because of the advantages of primes, it's quite acceptable to use a prime if know you're only going to shoot at one focal length (or there's a particular focal length that you like to use a lot). What I can't comment on is how the quality of your existing Fujifilm equipment would compare to Canon equipment and whether a Canon zoom (and accompanying body) would be better overall than a Fujifilm prime (and body).

Whatever you do, don't let anyone else tell you what to do. If you're concerned about giving up your existing lenses that you like, then don't. The suggested lens doesn't even include your preferred focal length.

Stupid advice

This "pro" just sounds like an idiot with a camera. Don't listen to him.

Canon is indeed a good brand with many great lenses, but so is Fuji (and Nikon, Sony, ...).

Lenses

The 24-70 is a jack of all trades lens. It's a great lens indeed if you only want to bring one lens and still want to take environmental portraits, landscape or architecture shots.

It's very good for many things but doesn't shine anywhere, though. In particular, it's heavy, large, kinda slow compared to primes and wouldn't deliver better pictures than the 56mm f/2, the 90mm f/2 or even the 18-55 f/2.8-4 kit lens.

Sensor size

The typical advantages of full-frame cameras have been :

• shallow DOF
• good image quality
• large viewfinder

The X-T2 offers excellent image quality and actually has a larger viewfinder than many full-frame cameras (e.g. Canon 5D, 6D or Nikon D850). If you want shallower DOF, the 56mm f/1.2 is an excellent lens.

Better portraits

If you want to take better portraits, you should:

• learn everything about light. There are many books, DVDs or entire websites that can help you.
• learn to take better portraits. Learn many jokes, learn different poses, learn how to make your subjects comfortable, learn how to act stupid so that they don't feel stupid, teach them how to feel confident about their looks, teach them how to flirt with the viewer through the lens. This DVD has way more information than you'll ever need. It costs a fifth of the suggested lens and can bring your portraits to a whole new level.

Strictly answering your question:

Would switching to full frame Canon and getting that lens be an upgrade over my Fujifilm gear?

• It is an upgrade, because FullFrame SLRs are better and faster than APS-C mirrorless. You have dedicated AF points and measurement tools improved for a very long time.
• It is and downgrade, because SLRs are larger, heavier and more prone to mechanical failure than mirrorless because they rely on (moving) mirror and (moving) shutter.

Haven't I answered your question? Correct, there is no answer to this question.

Let's modify the question slightly:

Would switching from my Fujifilm gear to full frame Canon and getting that lens be a good move?

Then consider questions:

• Are you happy with your current gear?

• Are you proficient with your current gear?

• Do you think switching from a couple of primes to one zoom will not improve your proficiency?

• Are you not thinking of entering new field (pets, wildlife, astro, whatever) where new gear is needed?

If all your answers are yes, then (politely) decline the advice, there is no good for you at the time. More likely, the change will decrease your proficiency and quality. You are about to learn to operate the new gear - there is a different handling of a camera and different strengths and weakness of the gear.

I usually only changes lenses between mini-sessions. I most often photograph cosplays at events. The models will nearly always be up for posing and generally don’t mind waiting for a lens change during a longer shoot.

This comment you've made backs up the reasons not to change the gear. This 90mm session followed by, say, 135mm session is a perfect strategy for using the primes! Your models have time to relax, rearrange or whatever while you change the lens and relax as well.

If you want to reduce the switching time "like-a-pro", consider buying another body. You can change the lens by just swapping the camera resulting in shorter times and fewer opportunities for a dust to enter your camera and, in case of a breakdown, you'll have a spare camera!

Primes are an excellent choice and allow you to zoom with your feet, framing things the way you want. I wouldn't trade in all your gear for a Canon SLR with a zoom lens, but you might consider (some day) "upgrading" to a full-frame mirrorless, like the Sony A7Riii with a 42MP sensor, 5-stop In-Body-Image-Stabilization (IBIS—which would work for even adapted lenses), and amazing dynamic range. Of course that $3K camera would pair nicely with the $2K 24–70mm G-Master zoom lens, other zooms, or a number of nice primes, either from Sony or adapted. One nice thing about the Sony mirrorless cameras (and possibly other cameras with EVF) is that adapted manual-focus lenses, stopped down, can still be focused; indeed, you can still use the focus magnifier to fine-tune your focus. I use a number of Carl Zeiss T* lenses made for Contax (Kyocera’s bodies from the 70s to 90s) with a simple adapter to use them on the original Sony A7R (but you can tell I have serious GAS for the A7Riii ;-) )

All that said, your Fujifilm X-T2 is a great camera and I don't want to take away from your enjoyment of it, nor the lenses you already have. You’re really fine to stick with what you have and I certainly wouldn’t bother with SLRs in this day and age. Mirrorless has way too many pros for me to ever want to go back to an SLR.

Normally, I'd write this as a comment, but I think it's important enough to stand on its own as an answer. I'm surprised I don't see it already mentioned. (Perhaps it's in an easy to miss comment somewhere). You wrote (emphasis added):

... I love the 90mm lens... I love my gear, ... and I don't just want to sell it. It's light and small, good for videos too and I like the bokeh and I like the film simulation (classic chrome <3).

That answers your real question: Should you sell all of your current gear and "upgrade" to a full-frame Canon camera?

As for comparing a FujiFilm body with a complete set of lenses against a Canon full-frame body with a single, super-expensive zoom lens, seems like it's pretty much already thoroughly discussed.

OK. Slightly opinionated answer follows, which I still consider valid.

"If I sell all my gear, I might be able to afford it..." kind of means you cannot afford it.

Equipment crucial to doing either a serious hobby or a job is truly affordable if you could afford to replace it if necessary (lost, stolen, damaged, impounded)- if you buy these two pieces of equipment, let's assume they are both equally priced, you still end up with two monolithic pieces you couldn't afford replacing.