The best lens for Bokeh for Canon EOS T5

[Jamesblond]

Greetings all, 

I have a Canon ESO T5 with the basic EF-S 18-55mm lens, which is great for a lot of things.

Now, I am trying to work on a project centering around bokeh --  but with a lowest aperture setting at 5.6, the standard lens is not going to work. Do any of you guys have thoughts about a Canon lens like the Canon EF 50mm f/1.8 STM Lens  —(https://www.amazon.com/Canon-Metal-Filter-Blower-Started/dp/B0792QSRB9/ref=cm_wl_huc_item)? This whole process is new to me, and all the bokeh lenses that I have found the best reviews for aren't compatible with the Canon. 

Would I be better off using a different camera + lens set-up entirely? I would rather do that than just get the Canon to work in a so-so way.

Any guidance appreciated. Thank you!

James

[TCampbell]

The amount of out-of-focus blur is based mostly on three things (there are some other factors that indirectly contribute to it)

#1  Subject distance:  Depth of field increases as the subject distance increases.  To maximize out of focus blur, you want a close subject and a distant background (don't put the subject up against the wall, etc. or the wall will appear to be in nearly as sharp focus as your intended subject.)

#2  Focal ratio:  Lower focal ratios mean the lens aperture is larger.  Due to the physics of how lens optics works, this results in  shallower depth of field ... meaning it's possible to use a low aperture to put the background out of focus.

#3  Focal length:  Long focal length lenses produce a shallower depth of field than short focal length (wide-angle) lenses.  For exmaple, I have a 14mm f/2.8 lens and I can adjust focus to about 3' and nearly the entire universe is in focus (that's an exaggeration of course... but even the most out of focus areas wont be very much out of focus.)

But it's ultimately the combination of all three factors that add up to create the result.

E.g. the 50mm f/1.8 (and in particular the EF 50mm f/1.8 STM version (avoid the non-STM version) can produce a bit of background blur IF the subject is also fairly close and the background is distant.  BUT... the 85mm f/1.8 does an even better job because it has a longer focal length.

I have a 135mm f/2 which is a bokeh cream machine... you can get diabetes just looking at these creamy photos.  And we can keep going... the 70-200mm f/2.8L is fantastic for portraits near the 200mm end.  This is actually a popular portrait lens because of this.

If you want bokeh on portraits... then these longer lenses end up being suitable for outdoor photos... but the focal lengths are a bit too long to use indoors unless you have a warehouse for a studio.

Keep in mind that when it comes to the 50mm ... there's also a 50mm f/1.4 and a 50mm f/1.2.  The same is true of the 85mm... there's a new f/1.4 version and an f/1.2 version (the 1.2 version has been out a while).  Those lower focal ratio versions produce even stronger background blur ... but they do cost more.

But... you can always rent the lens unless you think it's something you'll use enough to justify owning your own copy.

[ScottyP]

Everything Tim said is correct, though I'd comment on the 50mm f/1.8 that it CAN indeed deliver gobs of background blur and shallow depth of field. I had a crop camera and a nifty fifty (the older one) and I found that up close f/1.8 was very often unusable because of too shallow a depth of field.  I have images of my baby with only one of her eyes in focus and the other unintentionally (and thus irritatingly) OOF even though she was almost (but not quite) looking totally straight on at the camera.  And of course the rest of the face, ears, etc, was even more OOF.  Occasionally you want that look, but a little of that goes a very very long way and you generally want more than a photo of one eyeball.  

I also had and still have the 85mm f/1.8. It does indeed blur the background more readily and a bit more thoroughly but you may find 85mm to be too long for most shooting, particularly on a crop body where it has the angle of view of about a 135mm lens on full frame.  Mine sat in the closet a lot. Still does actually. 50mm would be more versatile while still delivering lots of shallow DOF for your projects. 

[kvbarkley]

Technical point:

Bokeh is the *quality* of the blur you get, not the amount. Any f/1.8 lens will get you the same amount of blur, but only a few have good bokeh.

While not its main selling point, the bokeh on my 150-600 sucks.

[TCampbell]

"Bokeh" does indeed refer to the quality and not the quantity.  The Canon EF 50mm f/1.8 II had a 5-blade aperture and it didn't use well-rounded blades.  This caused each point to blur into the shape of a pentagon.  That lens created a blur with a very strange quality ... it wasn't smooth or creamy (and wasn't highly regarded as desireable).

When Canon replaced the lens with the "STM" version, the arrangement and shape of the glass elements didn't change at all (the EF 50mm f/1.8 II and the EF 50mm f/1.8 STM have IDENTICAL optics) but Canon did change the aperture blades and the STM lens now has a 7-blade aperture and it produces a significantly improved quality to the out of focus blur.

Also, the spherical nature of each lens can be thought of as having two directions ... and think of a bicycle tire.  The direction that runs from the center toward the outer edge (think of the direction of the "spokes" of the tire) can have a different amount of blur than the direction that runs circularly (think of the direction of the tire itself).   The technical terms are "sagital" vs "meridonal".  But lenses that blur more in the direction going around the center axis of the lens (the direction of the tire... not the direction of the spokes) can create a "swirled" nature to the out of focus blur.

Though that "swirl" is technically an imbalance between the amount of sagital vs. meridonal blur (technically it's an optical imperfection) the result can actually be desireable (sometimes the lens that doesn't score the best on an MTF chart may actually produce the results that you feel are more appealing.)

[TCampbell]

One last point...

This one can be a bit confusing but... I may as well adress it because you're bound to run into this.

You'll occasionally find either an article or a person who will say that the size of the sensor also contributes to the amount of blur.

This is "sort of" true.  

Technically in absolute terms, its not true... but there's a side-effect.  When a camera has a larger sensor (the dimensions of the digital sensor are larger in one camera than in another) then that camera will technically have a wider "angle of view" as compared to when that same lens is used on a camera with a smaller sensor.  

But photographers have a composition in mind for how they want to frame a subject.  And since the angle of view is wider, it means they can get closer to the subject to still get the framing they want.  

BECAUSE they are closer... they've decreased the depth of field and increased the amount of background blur.

The reverse... using a camera with a smaller sensor to frame a subject, means they'll need to take a few steps back to get the equivalent compositon ... thereby increasing the focused distance to the subject.  That increase distance also increases the depth of field and decreases the amount of background blur.

So the physics of the lens are that the focal length is the focal length is the focal length ... and the amount of blur you get from a lens of a given focal length and a given focal ratio at a given focused distance DOES NOT CHANGE just because you changed the size of the camera sensor.   But it WILL change the angle of view.

But thre reality is... the photographer will now behave differently because the angle of view changed (by standing either nearer or farhter) and that DISTANCE change will alter the depth of field.

Consequently, you'll hear that cameras with larger sensors produce shallower depth of field and stronger background blur.  Strictly speaking it isn't the sensor size... but the fact that the photographer is able to position the camera closer to the subject which causes that change.  

But the net-effect is ... yeah... you'll get more blur shooting with a full frame camerra (because when you used the crop-frame camera you didn't have the option to position the camera closer without cutting out some of what you wanted to capture.)

[RobertTheFat]

---

@kvbarkley wrote:

Technical point:

Bokeh is the *quality* of the blur you get, not the amount. Any f/1.8 lens will get you the same amount of blur, but only a few have good bokeh.

While not its main selling point, the bokeh on my 150-600 sucks.

---

The EF-S 60mm f/2.8 macro lens has good bokeh, isn't ridiculously expensive, and should be a very satisfactory portrait lens on a T5.

[kvbarkley]

I agree that the EF-S 60 mm has nice bokeh

[Jamesblond]

Thank you for all this — really comprehensive and exactly what I was hoping to learn. Thank you so much.

One follow-up: one key part of what I am trying to achieve (which I should have been more clear about) is bokeh at dusk and night — and the distant lights turning into the translucent/opaque circles.

Would you alter your opinion at all to achieve this effect? 

Again thanks for your input. 

[RobertTheFat]

---

@Jamesblond wrote:

Thank you for all this — really comprehensive and exactly what I was hoping to learn. Thank you so much.

One follow-up: one key part of what I am trying to achieve (which I should have been more clear about) is bokeh at dusk and night — and the distant lights turning into the translucent/opaque circles.

Would you alter your opinion at all to achieve this effect? 

 ...

---

I don't think so. In general, what one looks for in judging bokeh is a lens that displays an out-of-focus point source as a circle, rather than as an oval, a polygon, a crescent, or some other distracting figure. It shouldn't matter much what the source is or whether it's light or dark; a good lens should treat them pretty much the same.