Camera lens advice

TLH · Nov 5, 2017

I love taking family photos with the blurred background. I'm wondering if I should invest in getting a 50mm camera lens or keep my 55mm lens and just get a photo editing software? I'm really just a novice so I'm not sure what my next step should be.

480sparky · Nov 5, 2017

A little clarification, please.

1. What 55mm lens do you have?
2. On what camera?
3. What 50mm lens are you thinking of?
4. Why do you think a 50mm lens will improve your backgrounds favorably over a 55mm?

Keep in mind it's a bazillion times easier and faster to create a blurred background in-camera than it is in post.

TLH · Nov 5, 2017

480sparky said:
A little clarification, please.

1. What 55mm lens do you have?
2. On what camera?
3. What 50mm lens are you thinking of?
4. Why do you think a 50mm lens will improve your backgrounds favorably over a 55mm?

Keep in mind it's a bazillion times easier and faster to create a blurred background in-camera than it is in post.

TLH · Nov 5, 2017

I have a the 55mm lense that came with my Canon EOS Rebel T5. It only has an aperture of 4.5. Canon EF 50mm f/1.8 STM Lens is the one I'm interested in buying.

TLH · Nov 5, 2017

The f1.8 looks like it would take sharper photos and have a way better blurred background.

480sparky · Nov 5, 2017

Why not up to a longer lens? 85mm. 100mm. 135mm.

TLH · Nov 5, 2017

Why would you go longer? (I'm sorry...i just started learning the "science" of photography). I really just want a shallower depth.

480sparky · Nov 5, 2017

Longer lenses 'compress' the subject. In order to maintain the same image, you are forced to move back. This moves the focus distance further from you, thus changing how the background is blurred.

This this. Lock the FOV once you get your parameters inputted, then change the focal length.

fmw · Nov 6, 2017

TLH do some reading on the internet about depth of field. That may answer some questions for you. The three characteristics that affect it are lens focal length, lens aperture and camera to subject distance. The longer the lens the more shallow the depth of field. The larger the aperture, the more shallow the depth of field. The closer the camera is to the subject, the more shallow the depth of field. You should be able to plenty of tutorials on the subject. No point in writing a book here.

TCampbell · Nov 6, 2017

To capture a sharp subject with blurred background you want three things:

1) Close focusing distance to the subject & distant background
2) Low focal ratio
3) Long focal length lens

Taking these one at a time...

#1 If the subject and background are both at nearly the same difference then you wont see much difference in focus quality. Placing subjects up against a wall, etc. means the wall wont be very blurred. You want the background the camera lens to adjust for a close focusing distance and this throws the distant background out of focus.

#2 What qualifies as a "low" focal ratio really depends on the focal length of the lens. For typically lenses this means f/2.8 or lower (e.g. f/2, f/1.4). But with long lenses you can get away with higher focal ratios. I often shoot at f/4 using a 200mm lens and the background has a nice amount of blur -- but that only works because it's a long focal length. You wouldn't get much blur using f/4 at say... 50mm.

#3 Long focal lengths really help a lot. I have a 14mm f/2.8 lens and with that lens, I can basically focus to about 3' and the whole world is focused -- even at f/2.8. This is because short focal lengths create much larger depth of field and prevent you from creating anything which is substantially out of focus.

If you want strong out of focus blur... then an 85mm f/1.8 lens would be a great choice. I have a 135mm f/2 which is fantastic for blur... but the caveat is that 135mm is long enough that you'll need a fair bit of distance between you and the subject to fit them into the frame (not a good choice for indoor shots.)

One other caveat is that when you use thin depth of field, you'll need to be careful not to be TOO thin. You can find yourself in the situation where if you're shooting a couple (instead of a single person) that it becomes difficult to get both people in sharp focus.

beagle100 · Nov 9, 2017

TCampbell said:
To capture a sharp subject with blurred background you want three things:

1) Close focusing distance to the subject & distant background
2) Low focal ratio
3) Long focal length lens

Taking these one at a time...

#1 If the subject and background are both at nearly the same difference then you wont see much difference in focus quality. Placing subjects up against a wall, etc. means the wall wont be very blurred. You want the background the camera lens to adjust for a close focusing distance and this throws the distant background out of focus.

#2 What qualifies as a "low" focal ratio really depends on the focal length of the lens. For typically lenses this means f/2.8 or lower (e.g. f/2, f/1.4). But with long lenses you can get away with higher focal ratios. I often shoot at f/4 using a 200mm lens and the background has a nice amount of blur -- but that only works because it's a long focal length. You wouldn't get much blur using f/4 at say... 50mm.

#3 Long focal lengths really help a lot. I have a 14mm f/2.8 lens and with that lens, I can basically focus to about 3' and the whole world is focused -- even at f/2.8. This is because short focal lengths create much larger depth of field and prevent you from creating anything which is substantially out of focus.

If you want strong out of focus blur... then an 85mm f/1.8 lens would be a great choice. I have a 135mm f/2 which is fantastic for blur... but the caveat is that 135mm is long enough that you'll need a fair bit of distance between you and the subject to fit them into the frame (not a good choice for indoor shots.)

One other caveat is that when you use thin depth of field, you'll need to be careful not to be TOO thin. You can find yourself in the situation where if you're shooting a couple (instead of a single person) that it becomes difficult to get both people in sharp focus.