Upgrading from Canon 750D (Rebel T6i)

The efs lens on a ef or ff body
There are so many different reasons stories put out there here are a few that I have been told
1 efs is to long on the back end and will get in the way of the mirror flip up
2 efs will not go onto ef body will not mate properly
3 image size will not cover a ff sensor
I don’t know the truth, I know that ef will fit and work on efs/crop sensor bodies provided they are of a certain age eg not to old the 1.3 crop

I regularly use l glass on my crop sensor canon 60d ,600d,1100d
Also worth noting that some sigma lenses are not compatible with canon camera, for more info on that there is a web site. Just did a quick search and a number of sites popped up

 

If I were you, I will look into getting better lenses to start with. As mentioned, a faster lens (wider max aperture) allow more light to the camera which help focusing in low light situation. On top of that, if you do not have a external flash yet, you may also consider getting one. Some of the external flash has focus assist beam which help camera focus in low light.

Personally, lenses upgrade had more impact on my photos than camera upgrade and lens investment last longer. The Tamron 17-50mm f/2.8 lens I bought used 10 years ago to replace the stock Canon standard zoom lens still works and products great image. It is still my go to lens with my 7D mk1 today. My 85mm f/1.8 lens still a great lens after all those years. I still like the creamy looking out of focus blur background it produces. (Same with the 70-200 f/4 I have). The recent gem I got is the Sigma 24-35 f/2 lens.

When I upgraded my first Canon XTi to 40D, the top display was the best upgrade feature. It is more or less a convenience upgrade. I no longer needed to go through the menu system to change the ISO, Shutter Speed, Aperture, Meter mode as well as Focus mode which sometimes was pain in the behind. Of course, this is just my personal preference. And the 2 wheels system really help changing the shutter speed and aperture during shooting. I guess that is what you meant by

"- hard to hold the camera steady while changing aperture settings in Manual(M) mode"

As for the camera body, it depends on your shooting. If you do a lot of wildlife or sports stuff, the 90D on your list maybe a better body. Otherwise, the 6D MK2 is my choice (lol that is what I have so I am kind of bias)

 

If I understand correctly, due to some quirks of how Canon approached the legal framework regarding EF and EFS, third-party lens makers are able to use the EF mount but are not yet able to use the differences that go with EFS. This means that third-party lens makers creating lenses for crop-sensor cameras will simply use the EF mount. The crop-sensor EF lens will still mount on a full-frame body, but it won't fill the sensor. Several of Christopher Frost's lens reviews on Youtube get into this. He has, from time to time, shown this issue by mounting such third-party lenses on his 6D to show this. When I corrected myself, I referred to his video covering the Tamron lens. I suppose I could've mounted my own copy of the lens on my old film camera and looked through the view finder, oh well.

Now, the advantage of the EFS lens for a crop-body is, as you pointed out, the reduced minimum clearance between the lens and the sensor, because the mirror is smaller and less clearance is required for it. This can help simplify lens design, since that large gap doesn't have to be so large. It's also why mirrorless is increasingly the future, since that gap can be incredibly small, only enough for the shutter depending on the necessary configuration for the desired optical characteristics, such that the lenses themselves can be much smaller and thus easier to carry more lenses in the same volume of space.

 

When I bought my body-only 77D I also bought the 24mm f/2.8, and it was better-enough at 24mm than my 18-55mm IS II that I tracked-down a used 17-55mm f/2.8. As a consequence the 24mm doesn't get a whole lot of use anymore (though I find it convenient when I don't want people to get their backs up when I'm taking pictures) but either way, going from ~f/4 to f/2.8 made a big difference in low light for a human subject. I've also enjoyed using the 50mm f/1.8 in the right situations, either low-light or to get that shallow depth-of-field.

Back before Christmas, one of my local pawn shops had one of those Tamron 17-50mm f/2.8 lenses for $100. The 50mm f/1.8 is also new only a tad more than that, and used can be had much less expensively. When I bought mine from that same pawn shop it was forty bucks with both caps and a rubber hood. It very well might be worth buying a cheap fast lens to try out first, before spending much more money on a new camera. The 50mm f/1.8 or a 40mm f/2.8 might both be good choices, as they're useful on both APS-C and full frame cameras, so even if the desire to upgrade remains, neither preclude any of the listed Canon options.

As far as speed to get a shot goes, for me it seems best if I set my camera to one-shot autofocus, with a single autofocus point, that point chosen based on what part of the subject I wish to focus on. When I shoot this way I usually pick a focus point near the top, centered or slightly off-center, such that the subject's face will end up at that point, and so I avoid accidentally focusing on something in the foreground. Obviously this doesn't work in all situations, and there are plenty of times when I let the camera figure it out, but if I'm trying to get a picture of my kid as she's running along, this seems to work best.

 

Wow ... that's a STEAL!!! GREAT price!!

 

Just to be clear, even if you could get an EF/S lens to mount on an EF body you run the risk of damage. A Canon lens rep told me there is a chance the mirror could hit the lens. I'm not going to test this assertion.

 

So you're saying I should go back and get it if it's still there?

 

Well, it is up to you since you already have the 17-55mm f/2.8 which I believe is a better lens. But $100 for the Tamron is a great price if it is in good shape.

 

I think brand new, the Tamron is a $300 lens, so $100 is a great price.
But if you already have a 17-55/2.8, the Tamron 17-50/2.8 is needless duplication, since it does not give you any more focal length in either direction. In which case it become a poor purchase.

 

If I understand correctly, due to some quirks of how Canon approached the legal framework regarding EF and EFS, third-party lens makers are able to use the EF mount but are not yet able to use the differences that go with EFS. This means that third-party lens makers creating lenses for crop-sensor cameras will simply use the EF mount.

The mount itself its the same on the EF and EF-S lenses.
I put our EF lenses on EF-S cameras all the time.​

The crop-sensor EF lens will still mount on a full-frame body, but it won't fill the sensor.

It may mount, but as was mentioned in other posts, the mirror may be damaged by the EF-S lens projecting too far into the mirror box for the larger FF mirror.
So the reverse of my statement above is not true. You may NOT be able to mount an EF-S lens on an EF camera.

Yes the image circle of an EF-S lens is smaller than an EF lens, so the image won't fill the sensor.​

 

The question was more in-jest. I probably will return to that pawn shop again at some point, they had a fair amount of stuff at the time. Can't remember what lens it was, but there was one camera+lens that I would have liked to buy the lens if not the camera, maybe see if they'd break them up.

I'm trying not to have too much duplication/overlap with my lenses. Some overlap is good since it may mean less lens-swapping, I'm already pretty heavy on lenses in that range. If I were to buy anything else it would either be that Sigma 18-35 f/1.8 or else some more primes.

 

Actually, if you plan things out, you can have a LOT of overlap of focal length, but not duplication of function.
Example a light 18-55/3.5-5.6 and a heavy fast 17-50/2.8.

The light 18-55 lens might be a daily carry/travel lens, and the heavy f/2.8 might be for shooting basketball in the dim gym.
The focal length is almost duplicated, but the lens functions are very different.​