topic Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body in Gear Guide

Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

Kashifr — Tue, 01 Apr 2025 23:50:47 GMT

Hello,

I am debating between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body.

I have 18-55, 55-250 and 50 f1.8.I mostly shoot while traveling and this time I want to level up and take some more attractive and sharp pictures and also like to carry less lens. I like to do portraits with blur and all in focus. I shoot landscapes, cities, and nature, indoor and outdoor. I am debating between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4. I am mostly leaning towards Canon Canon EF 24-105 f4 L but wondering if I can shoot portraits with or without a blurred background. Sometimes I like all in focus as to capture nice background and popular background.

My other question is about crop factor. I understand that my camera has 1.6 cf. I experimented with my 18-55 on 24 and 36 mm and figured out that I only have to move only a few feet back to get a 24mm, please correct me if I am wrong.

Lastly I am wondering why Canon EF 24-105 f4 is so expensive when it has only f4 and can I change the aperture to 5.6 and higher.

Canon 15-85 f3.5-5.6 got my attention, but feel two on the top is better.

Thank you for your time.

Thank you

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

deebatman316 — Wed, 02 Apr 2025 00:29:04 GMT

The EF 24-105mm F/4L IS USM lens lineup is a professional grade lens. That's why it is much more expensive regardless of the aperture. Also constant aperture lenses are more expensive to make because it must maintain that large maximum aperture. The lens doesn't have a fixed F/4 aperture that's why it can be stopped down to for instance F/11. Now the image sensor causes the crop. NOT the lens so regardless of the lens mounted there's always a 1.6x crop applied. The EF-S 17-55 f2.8 IS USM lens is the best lens available for APS-C shooters. That lens provides nearly the same angle of view as the 24-105mm. Canon hasn't made a lens with a fixed aperture in the EF Mount. Therefore the aperture can be changed. Full Frame lenses may not provide ideal focal lengths on APS-C cameras. Unless you plan to move to Full Frame then stick with the 17-55mm lens. None of the lenses you mentioned have a fixed aperture. They can be set to different apertures. The F/4 in the name is just the maximum aperture. The smaller the number the wider the aperture and more light can enter the lens.

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

Kashifr — Wed, 02 Apr 2025 01:45:06 GMT

@deebatman316 wrote:

so regardless of the lens mounted there's always a 1.6x crop applied.

So I understand that image will always cropped even if i use EF-S lens on cropped body.

I am still confuse which lens to pick.

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

March411 — Wed, 02 Apr 2025 02:43:06 GMT

Kashifr, the T3i DSLR has an 18MP CMOS (APS-C) sensor and you can pair it with any Canon EF and EF-S lenses. And no it will not be cropped but it will change your field of view. What you see in the viewfinder is essentially what you will capture.

With the EF 24-105 f4 L you can absolutely capture portraits with or without a blurred background. At f4 you will achieve a blurred background. The further the background is from the subject the more blur you will achieve. The minimum aperture of the lens is f22. As you use the larger numbered f stop the the iris of the lens closes and sharpness will improve. The illustration deebatman316 posted above is a great example.

f4 blurred
f8 sharper
f16 even sharper
f22 the sharpest the lens will acheive

The other positive of the EF 24-105 f4 L is that you will have range so you can photograph full length or head shots by simply using the zoom. Be aware that on a 1.6x APS-C camera body, which your camera is, the field of view is around that of a 40–168mm lens.

Wider aperture (smaller f-stop) allows more light to enter the camera, which is helpful in low-light situations and also creates a shallower depth of field resulting in a narrow range of the scene is in focus. A narrower aperture (larger f-stop) allows less light in, which results in a greater depth of field which results in more of the scene being in focus. You will always have a higher price tag on a fasted fix focal length lens. Just look at the jump between an f4 and an f2.8 or an f2.

Regarding your question on zoom lens and using your Canon 15-85 f3.5-5.6. As you zoom out to 85mm your aperture will change impacting your exposure settings. On the 24-105, a fixed aperture as you zoom your aperture remains consistent. You kind of pay for that luxury because the design and build of fixed lenses are more expensive.

I hope I answered your questions and that I didn't tell you something you already knew, my intention was to assist.

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

Kashifr — Wed, 02 Apr 2025 05:40:58 GMT

Hello Mr. Marc,

Thank you very much for your detail reply and yes I learned something new specially about how f4 works on this lens. Demetrius reply is also very helpful but still I cannot decide what to get. You and Demetrius both gave me a good new information, but it is just me how cannot pick one. I am thinking about other factors like how good is 24-105 for traveling, do I have to move myself way back to capture image equaling to 24mm or less, do this lens is easy enough to operate like my kit lenses.

Thank you,

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

deebatman316 — Wed, 02 Apr 2025 13:57:42 GMT

The best general purpose lens for your camera is the EF-S 17-55mm F/2.8 IS USM lens. The 24-105mm lens while a great lens. Has a focal length that isn’t ideal for APS-C cameras. You have to move back to capture an image at 24mm. You’re zooming 1.6x because of the sensor size. For instance the EF 50mm F/1.8 STM lens. On my EOS 5D Mark IV it has a crop factor of 1x. So the focal length remains 50mm. But on my EOS 40D has a crop factor of 1.6x just like your EOS Rebel T3i. The angle of view the EF 50mm F/1.8 STM lens would provide an 80mm angle of view when compared to Full Frame.

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

Kashifr — Thu, 03 Apr 2025 15:36:51 GMT

Thank you for useful information. Meanwhile, I am also trying to find peoples experience with these two lenses with a crop camera, and their recommendation.

Thank you.

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

deebatman316 — Thu, 03 Apr 2025 16:03:25 GMT

From my experience using a standard zoom Full Frame lens on an APS-C camera can be difficult. It’s simply not wide enough. Now I own the EF 24-70mm F/2.8L II USM lens. It’s a similar focal length to the 24-105mm lens. Starting out at 24mm will provide an angle of view of 40mm on APS-C. This will make it difficult to use on your camera. I found the 16-35mm to be a much better choice on APS-C as a standard zoom lens. Even though it’s a wide angle zoom lens designed for Full Frame camera. But it still will work on an APS-C camera. I shoot with Full Frame lenses on APS-C. I don’t own any APS-C lenses anymore. The 24-70mm wouldn’t be my first choice for an APS-C camera.

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

Kashifr — Thu, 03 Apr 2025 17:04:18 GMT

Thank you very much. I am really learning from you guys and getting closer to make a decision.

I just pulled the data from my last trip and see that I shoot most picture with 18mm focal length. Below is the data.

Lens	Focal Length	Quantity	%
50mm	50	127	9.62%
18-55	18	250	18.93%
18-55	20-53	501	37.94%
18-55	55	144	10.90%
55-250	55	78.5	5.94%
55-250	60-84	42	3.18%
55-250	90-250	178	13.48%
	Total	1320.5	100.00%

So based on the data above and the lens quality and capabilities which lens should I choose

17-55 f2.8 EF-S

15-85 f3.5-5.6 EF-S

Thank you.

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

deebatman316 — Thu, 03 Apr 2025 17:26:23 GMT

The EF-S 17-55mm F/2.8 IS USM lens is the best option for your camera. Also Canon still supports repairs for this lens. The other lens I believe is no longer supported by Canon and it had a problem with internal flex cable failing.

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

LeeP — Thu, 03 Apr 2025 18:41:34 GMT

I have owned the EF 24-105 f4 L for an inordinately long time and it is my only EF lens that has not been replaced by an equivalent RF. I will have to admit that my attachment to it may be more sentimental than objective, but it is a tremendously versatile lens. When I passed my DSLRs to a friend who wanted to take his first steps in photography, I grabbed a duplicate for cheap for him on Ebay. Knock on wood; mine is operating flawlessly, but if it stops, I will now know why because of you. Thanks.

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

deebatman316 — Thu, 03 Apr 2025 19:12:51 GMT

I was talking about the 15-85mm not the 24-105mm. I don’t know if that lens had a flex cable issue like the old 24-70mm F/2.8 lens.

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

LeeP — Thu, 03 Apr 2025 19:18:13 GMT

Love the graphic. It's a keeper!

Re: Selecting between Canon EF-S17-55 f2.8 or Canon EF 24-105 f4 L with T3i body

deebatman316 — Thu, 03 Apr 2025 19:46:03 GMT

I did not make it but I found it on Google.