What’s the Difference: Kit vs 50mm

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[Let me preface this post noting that the following information is based on the use of my Canon Rebel XT and it’s kit lens (18-55mm f/3.5-5.6).  I understand that there may be some difference between brands, body models and even kit lenses may differ, but just work with me here.  It’s relative.]

Thanks to Facebook, I get to keep up with the very busy lives of my friends in the form of stalking.  But I’ve also been able to reconnect with people I haven’t spoken to in years.  Not because I don’t like them, but because our lives took us in different directions.  And many of the conversations I end up having with long, lost pals is about photography.  So recently, when sharing some juicy photog tips I was asked “What’s your favorite lens?”

Uh… I’m guessing this gal doesn’t read silly mud putty.  So I replied with “My 50mm prime – I use it 85% of the time.”  My pal then asked, “Well doesn’t my kit lens do the same thing, since it’s a 18-55mm lens?”  Hmmm… yes.  And no no no.

On the kit lens (18-55mm, that is), you can adjust the focal length to 50mm.  If you can find the darn thing.  I say that because I thought I had but sadly I missed the mark and had every photo come in at 49mm.  But yes, your kit lens can be set to 50mm.  The kicker is, since you have your zoom in play, your aperture is limited and the lowest stop you can go is f/5.6.  Thus the f/3.5-5.6 setting on the lens; at your shortest focal length (18mm) your aperture opens all the way to f/3.5.  When you zoom in to 50mm-55mm, you can only open to f/5.6.

And here lies the difference between the kit and the 50mm prime:

  1. The 50mm prime does not zoom.  It’s a fixed position lens meaning that it only has one focal length: 50mm.  I like this because if forces you to work with your subject, step in and step out, and understand how the light actual helps or hurts you.  I really believe it makes me more creative with my composition.
  2. The 50mm primes that are available have wider apertures than most kit lens.  I said “most” because I really don’t know what kit lens come with cameras so I’m pretty much just CYA here.  But this is what we’re going to talk about: aperture.

I own the Canon 50mm f/1.8.  They make others that offer f/1.4 and even f/1.2 [but those are rather pricey compared to the $100 price tag of the f/1.8].  In case you missed it, I SAID F/1.8!!! That right there is a big big big difference between the 50mm prime and the kit.  OK, let’s do some math, shall we?

Progression of f/ stops

I hate fractions so just know doing this sucked.  And I most definitely checked my work via the interweb.  Thank you, Google.

Here we go: the f/stop identifies the size of the aperture and the depth of field.  There are full stops, half stops and with the ever-so-clever digital SLR cameras, third stops.  We know the kit lens only opens to f/5.6 at 50mm.  And we know the 50mm prime opens to f/1.8.  The difference between 5.6 and 1.8 is 3 1/3 stops. May not seem like a lot when we’re just looking at the number value but each time you increase one full stop (opening the aperture), you double the amount of light that reaches the sensor.  That’s a lot of light, my friends.  Just imagine what you can do in low light with the 50mm prime.

Also, by having a larger aperture, the depth of field becomes more narrow.  I like a narrow depth of field for particular subjects; I like creating a story with a photograph and I love the look of bokeh.  The 50mm prime is my go-to lens when I’m photographing people and animals because capturing the eyes and knocking out the background knocks my socks off.  I love it.  But I’m not one to just talk about how something works – I took some flower photos to show you how the two lenses compare.

[Note: It was very, very windy the day I took these photos.  And I was swapping out lenses at record speeds by myself.  So if you aren’t satisfied that they aren’t exactly the same, bite me.  It’s relative.]

I made sure to list my camera settings so that not only can you see the different apertures (I took two photos with the 50mm at different f/stops) but so you can also see how the shutter speed is affected.  But we are not talking about shutter speed today.  I didn’t even mess with it because I was shooting in the Aperture Priority mode.  All photographs are SOOC (straight out of camera) and were taken at ISO 100.

Kit lens [that I tried to set at 50mm but failed]:

Lens Discussion: 50mm vs Kit
Aperture: f/5.6
Exposure:   1/640 sec
Focal length: 49mm

50mm prime lens:

Lens Discussion: 50mm vs Kit
Aperture: f/3.2
Exposure: 1/1600 sec
Focal length: 50mm

Lens Discussion: 50mm vs Kit
Aperture: f/1.8
Exposure:   1/4000 sec
Focal length: 50mm

Kit lens [that I tried to set at 50mm but failed]:

Lens Discussion: 50mm vs Kit
Aperture: f/5.6
Exposure:   1/500 sec
Focal length: 49mm

50mm prime lens:

Lens Discussion: 50mm vs Kit
Aperture: f/3.2
Exposure:   1/1250 sec
Focal length: 50mm

Lens Discussion: 50mm vs Kit
Aperture: f/1.8
Exposure:   1/4000 sec
Focal length: 50mm

Kit lens [that I tried to set at 50mm but failed]:

Lens Discussion: 50mm vs Kit
Aperture: f/5.6
Exposure:   1/400 sec
Focal length: 49mm

50mm prime lens:

Lens Discussion: 50mm vs Kit
Aperture: f/3.5
Exposure:   1/800 sec
Focal length: 50mm

Lens Discussion: 50mm vs Kit
Aperture: f/1.8
Exposure:   1/3200 sec
Focal length: 50mm

You can see how being able to open the aperture even to f/3.2, the background becomes blurry and all the focus is on the selected flower.  These aren’t the best examples by any means but it does show us how different the 50mm prime is compared to the kit lens that only opens to f/5.6.  Hell, that purple flower shot taken by the kit lens looks like a bunch of weeds; you can’t see the flower at all.  Opening the aperture narrowed the depth of field, let more light into the lens and the focus was all on the flower.

I’ve been working with my 50mm prime for almost a year now.  Like I said before, I use 85% of the time.  I leave it on my camera body and only switch it out if I know I’m needing to zoom or want to use the ultra wide-angle or if I just need to spice it up a bit.  The 50mm prime is not a good walking lens; the fixed position makes it difficult to compose photographs of random crap when you’re on a walkabout but I love to use it indoors, in small friendly settings and when I know I want the narrow DOF.  And portraits.  Love it for portraits.

Here are some photographs I’ve snagged over the last year with the 50mm prime.  For a $100 lens, I’m impressed. I honestly feel that I couldn’t have taken the same photo with the kit lens [but that could be total rubbish].  I don’t know – you be the judge.

Week 4: Red

Lives in my Backyard

Blackeyed Susans

The Chasey Bear

Surprising Kelly

Bev Knitting


I heart my 50mm.  And this pup.

[It’s relative.]

To learn more about Brooke and see her recent work, visit her new site at brookemurphyphoto.com. Follow Brooke on Facebook or Twitter.

April 8, 2010 - 9:58 am

katie o. - boo- this might be your best blog post yet! a)i’m incredibly impressed with your knowledge and b) your mad skills.
Oh and the photo of the black eyed susan will forever remind me of you and this blog.
Oh. I heart my 50mm too. (thanks to you!)

April 8, 2010 - 10:45 am

courtney - Loooooove this! Why are you not doing this professionally already???? :)

April 8, 2010 - 10:46 am

shutterboo - Pshhh! You so funny!

April 8, 2010 - 10:47 am

shutterboo - Thanks yo! I love the black eyed susans too… they make me smile.
50mms unite!

April 8, 2010 - 11:11 am

Victoria - Thanks for the info!
I have a Nikon and have been looking into other lenses.
This helps make a decision… kinda.
Nikon’s lens of the same runs about $120. And then like you said the price goes up at f/1.4.
So, a question… If a person had the funds should they invest in the bigger aperture?
I’m thinkin’ I probably won’t regret settling for the cheaper one. According to Amazon it’s rated pretty good.

…sigh… decisions, decisions. And to think, I was worried about what to make for dinner just moments ago :)

Great post! Thanks!

April 8, 2010 - 11:13 am

Victoria - p.s.
Love the shot of the knitter’s hands. Love, love, love , love it!
Thanks for letting me get that out… whew.

April 8, 2010 - 11:17 am

shutterboo - Um, I’d say it’s a personal preference. The f/1.8 does an amazing job for the price. If we did the unit pricing on my 50mm f/1.8, we’d see that I’ve got it down to pennies. And I’m not as worried about hurting it because if I ever needed to replace it [I can’t believe I even typed that] it was only a $100 investment and I can save that up quickly to get another one [if I ever needed to, like I would ever intentionally hurt my sacred 50mm].
The Nikkor is pricier – most Nikkor lenses do cost more than Canon. But the f/1.8: low on investment, high on fun times.

April 8, 2010 - 11:25 am

Victoria - Okay, according to some data: the cheaper lens would not auto focus on my camera.
Is that the same for the Canon?
I’m not sure if I should sacrifice that feature for the cost.

April 8, 2010 - 11:32 am

shutterboo - Ah, I forgot about this [not a Nikon user]. My friend eMohn had mentioned this to me before.
There are certain Nikon cameras the Nikkor 50mm f/1.8 lens will not utilize AF. The D40 and D60 come to mind. You may want to do a Google search to confirm.
If you like the AF feature, then maybe try to find another lens that would work for you. Also, the 50mm has a slight zoom; if you want something a little more wide, maybe check out the 35mm prime. The Canon 50mm f/1.8 is a gem because of the results and the price. But if price is being sacrificed, then you’re opening up the options. :)

April 8, 2010 - 2:47 pm

splendidsweets - I have a Nikon D80 and mine will AF. I have the 50mm 1.8 and I love it, it is definately worth the money. Brooke is right if you google it you can find which models will not autofocus.

April 8, 2010 - 3:52 pm

Joan Nova - I’m not going to pretend I understand what you wrote (or that I even really read it – sorry) but I must say that the photos took my breath away.

April 8, 2010 - 4:59 pm

What's the Difference: Kit vs 50mm « shutterboo | Prime Lenses - […] the original post:  What's the Difference: Kit vs 50mm « shutterboo Tags: because-if-forces, does-not, fixed-position, light, light-actual, one-focal, subject, […]

April 8, 2010 - 5:12 pm

Susan the Pod-Mate - Fantastic post! You have a way of making all of these crazy numbers make sense. Plus, I appreciate the effort you took to change your lenses in that crazy wind. You rock, Shutterboo!

April 8, 2010 - 6:52 pm

Dawn - I have that same lens and I sort of want to make out with it. I use it just about all the time as well – the images are fantastic and I love love love the wider aperature range. I haven’t done a side-by-side like you did, but it’s pretty amazing to see the difference.

April 8, 2010 - 7:54 pm

shutterboo - Ha! Anybody that has one [and knows it’s quirks] can get some kickass shots. The hubs’ friend has refered to it as “cheating”. Bah – don’t buy that but it does buy my love. *hugs 50mm*

April 8, 2010 - 7:54 pm

shutterboo - No – you rock! That lens changing thing blew; I should have coaxed you out on my walk with a Subway cookie.

April 8, 2010 - 7:55 pm

shutterboo - Thank you… and thank you for being honest. :)

April 8, 2010 - 7:56 pm

shutterboo - I love that you love it. I wish I had nickle for every single 50mm I recommended. I’d be rich!

April 9, 2010 - 12:37 pm

Melissa - I LOVED this post. I am interested in a fixed lense. I have a d40. So I am up a creek without $500 to spend on one that will AF. But you did send me on a goose hunt that made me think and learn a little more about what I want in my next lens. My camera is new to me, so the kit lens is fine for now. I am learnin.

April 9, 2010 - 5:34 pm

shutterboo - One thing I didn’t think of is maybe there’s another brand that will fit a Nikon that has a smaller price tag. Like Sigma. The interweb is chocked full of info. (Glad you LOVED it. I LOVE you for saying so. :))

April 13, 2010 - 9:47 am

David Horan - Hey Brooke, it’s David Horan, I tried to leave this on your facebook, but it’s being a pain, so I thought I’d leave it here.

Here’s a photography challenge put on by a tech site (that does cameras as well as other gadgets) I thought you might appreciate some of the shots.


April 13, 2010 - 9:57 am

shutterboo - Those are pretty fly – I’m a fan of photographing flowers myself so I like to see what others cook up. Thanks for the link, Davy!

April 16, 2010 - 9:27 am

Love Is - I absolutely agree with you. I bought the 50mm for my Canon XSi kit and after using it, I almost never take out the kit lens. It just doesn’t do my photos any justice. Most of the photos on my page are taken with my 50mm.

Great post and thanks for sharing!

April 16, 2010 - 9:41 am

shutterboo - Thanks. I find that most who get the 50mm are very happy. It’s a lot of fun to shoot with!

April 17, 2010 - 10:49 am

Nancy - the 50 f/1.8 is most definitely my favorite lens. i use it 90 percent of the time. (excellent post by the way) i would love to have the f/1.2 (can’t afford it) you’re right, you can’t beat the price tag on the 50 f/1.8. as you know, i just purchased the 85mm f/1.8. i got it for portraits, which i don’t do a whole lot of, but i would like to start doing more. it allows you to get a close enough shot without having to stand right on top of someone, and it’s really light. beautiful blog and your photographs are fabulous.

April 17, 2010 - 11:30 am

shutterboo - Thanks – I’m excited to see what you capture with the 85mm… it still seems like a lot of zoom to me. :)

July 15, 2010 - 8:28 pm

emily gooch - Thank you so much for the info. I just ordered a Nikon 50mm prime f/1.8 yesterday. It should be here next week. Your post was perfect timing.

July 20, 2010 - 9:35 am

Becky Sue - I love my 50mm 1.4 prime lens and it’s on my camera 90% of the time. Every once in a while I go back to the kit lens for landscapes or when I need a bit of zoom and I’m always sorely disappointed. I do feel that my 50mm limits me when taking landscape shots and I’m in the market for a wide angle lens but I just can’t decide which way to go.

And good for you explaining the fractions, my eyes crossed and my brain got all squirrely so I’ll just have to take your word for it. The pictures speak for themselves.

July 20, 2010 - 9:57 am

Brooke - @Becky Sue I’d drool over a f/1.4. But I have to say, the f/1.8 does a mighty fine job for being so inexpensive (in the world of lenses). I’m finding myself going back to the kit for upclose shots now… maybe a phase I’m going through. But that 50… we share a common bond with our stubby lenses. :)

July 22, 2010 - 12:18 pm

Jonathan Fleming - Thanks for your comment on my blog. =)
Really like your write up here! It very clearly explains some of the differences between variable aperture zooms and fast primes like the nifty fifty. Good job, and nice shots!

August 3, 2010 - 4:24 pm

Jan Smith - That’s funny…I shoot with a Canon Rebel XT and I bought a 50mm lens last year to photograph a baby. I broke that one on the day of the shoot. My camera fell, but the lens saved the camera. I just bought another one and I hardly ever put it on the camera. After reading this I’m going to start shooting with it more and see what I get. Thanks for the post. Of course, I’ve never taken a photography class and I’m not good at math so that part of the post when shwooshing over my head. :) LOVE THE PHOTOS!

September 4, 2010 - 5:51 pm

Brittany Norris - Hey! This blog post was extremely helpful!!! Thanks for the clarification on the differences of these two lenses. I just invested in a nice 50mm in part due to this post. I’ve been wanting one, but was never fully sure of how it expanded my options more than my kit lens. Thanks again!

October 27, 2010 - 8:22 pm

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