which lens should I get on my EOS 90d? 24-105mm f/4 IS USM 'L' len,EF Zoom 24-105mm or other lens?

[Jaden]

I saw many articles saying that both lenses are pretty good for all general purposes. so it struggles me a lot because I don't know what should I get. or if there's another option for me and I used this camera mainly for taking photos for the yearbook and portraits.

[Tronhard · Accepted solution]

Hi Jaden and welcome to the forum:
As always some idea of budget is helpful as well as some idea of the lighting setup you will be working with - e.g. available light, simple single flash or strobe, or a more sophisticated setup. 

What the output is has significance. If you are creating images for a yearbook, then the likelihood is that your images are not going to be massive prints, but may be published on social media or digital devices. That takes some pressure of the quality of the optics, but nevertheless you want to create as good an image as possible.  Since there is an interrelationship between Aperture, Shutter speed and ISO, for publication you likely want to keep your ISO low, to avoid noise, but you will have a fairly low f/stop value - so f/4 or below.  The shutter speed will then follow - hopefully, you are able to use a tripod to get the maximum stability.

Generally, one wants something in the mild to middle telephoto range to give a more flattering look - wide angle lenses tend to make faces look distorted if one tries to fill the frame.  For the 90D, which has a crop sensor, a lens with a focal length of about 35mm is considered 'normal', so a 50mm lens is actually in that category of telephoto.  If you want explore this, read the following article: Equivalence v3.pdf.

The longer the focal length the further from your subject you will be to get their face in, and thus the better the lighting as light intensity drops off as an inverse square of the distance to subject.

So, you could look for something like a 50mm f/1.8 or f/1.4 prime lens.  It has the advantage of being a good general-purpose focal length, a reasonably low f/stop value and a small investment.

If you want more flexibility for focal length with a zoom, then the 24-105L f/4 would be a good option, as would a 24-70L - the latter is available in several variants and the later ones are, logically, the better optics. I would suggest staying away from a zoom lens that has a variable aperture as one zooms out - having a constant aperture costs more but is generally a better solution.

[Jaden]

The budget is around 1000 or below ( it can go over a little)and I don't have a lightning set up but I use  Speedlie el-100 as my flashlight 

[Tronhard]

You need to figure the lighting out, and if your budget is $1000 then that need to include gear like flash, tripod etc.  Don't skimp on a cheap tripod, get something that you can carry but is solid.

If you are not experienced in this kind of photography, I suggest watching some videos on taking portraits with a simple light setup.  I suggest watching a few of these:
(5) single light portraits - YouTube

As regards  optics, I will stick with my suggestions - the lenses I have referred to will all fit within your budget and leave you some funds left over for the other gear.

[Tronhard]

Amongst the videos I referred to, I particularly suggest this one:
Shooting Portraits with One Speedlight - YouTube  You can learn a lot from Sean, he is an amazing portrait photographer.

[Jaden]

thanks for the help, 

[Jaden]

I also want to know if the photos I will be taking most likely going to be outside for example taking some sport teams photos, prom photos, and school events like rallies,do u think I should get ef 24-105l or ef 24-70l, I'm struggling to think which one to buy. 

[Tronhard]

The 24-70 is regarded as the classic for portraiture, but doesn't have the focal flexibility of the 24-105.  I have shot with the latter and it's a good lens, particularly the MkII version, but either works.
As an example, the following images were all taken in available light at an academic symposium, and involved a group shot outside, plus a series of internal shots of presenters and the audiance.

EOS 5DMkIII, 24-105@ 32mm, f/7.0, 1/160sec, ISO-6405DIII< 24-105@24mm, f/7.1, 1/25sec, ISO-16005DIII, 24-105@65mm, 1/80sec, f/4.5, ISO-1600,

[Tronhard]

I found one more image at the maximum FL of the 24-105.  Again hand-held available light.

5DIII, 24-105@105mm, f/5.6, 1/30sec, ISO-2000

One thing you should remember that what your 90D will capture is not the same as my 5DIII.  That is a full-frame camera, so the focal lengths of the lenses it uses will match what is written on the lens, however the 90D is a APS-C crop sensor camera, along with the same 24-105 will actually render a Field of View equivalent to a 38-168mm lens.  If you don't get that read the article on Equivalence that I referenced in a previous post in this thread.