ART Good fixed-length lens for portraits?

Alt+F4

official OT hockey stud
Dec 13, 2001
3,786
Manchester, NH
I'm hoping to purchase a Nikon D70S and the kit 18-70 soon. It's my second DSLR, but it's been a few years since I've used one. Also a few years since my last photography course (a throwaway undergrad one).

I'm buying this camera to take pics of my twins, due in April. As with my son, this'll be both for putzing around the house snapping away, as well as more organized shots like christmas cards and whatnot. This question is regarding the latter.

I need to be educated on what the difference is between something like a 35mm 1.8 and a 50mm 1.8. I realize it's simply the focal length, but what does this mean if I'm trying to line up my kids to take a portrait. Does the 35mm simply allow me to stand closer, or to include more people in the image?

Also, for either focal length, what is a good F stop for portraits? 1.8 is nice and all, but that's a very shallow depth of field. What's common?

Thanks all. I realize these are noob questions, but I'm just trying to "remember" what I knew a few years ago.

For your troubles...a couple of my favorites. My son back in 2007.

border_Untitled-2.jpg

D70, 50mm F2.5

600wide_DSC_6945.jpg

D70, 50mm F1.8
 
TS
TS
Alt+F4

Alt+F4

official OT hockey stud
Dec 13, 2001
3,786
Manchester, NH
Sorry, not really asking for lens opinions. Rather, trying to understand the difference. My thread title is misleading, sorry about that.

Money is a factor, so I'd just like to know why one is better than the other. Also, why is the 50mm 1.8 so much cheaper than the 35 1.8 and 85 1.8?
 

Steef

New Member
Oct 26, 2004
2,355
WA
Sorry, not really asking for lens opinions. Rather, trying to understand the difference.

Money is a factor, so I'd just like to know why one is better than the other.

Ah, okay. Well longer focal length = shallower DoF = more bokeh = more focus on the subject. This is just my opinion though. I'm sure there are plenty of other factors to consider to take it as you will :)
 

Steef

New Member
Oct 26, 2004
2,355
WA
The longer the focal length, the more shallow DoF you get without having to jump to a really low f-stop. For example, a 90mm 2.8 will give you a much more shallow DoF than a 50mm 2.8.
 

dmora

Sorry, not really asking for lens opinions. Rather, trying to understand the difference. My thread title is misleading, sorry about that.

Money is a factor, so I'd just like to know why one is better than the other. Also, why is the 50mm 1.8 so much cheaper than the 35 1.8 and 85 1.8?
because its a piece of junk.
 

Marix

OT Supporter
May 23, 2006
27,969
Depth of field is a function is distance from subject and aperture. If you want ultimate tiny depth of field you want a long lens with a wide aperture, like a 135mm 1.8 or similar.

On a crop sensor body a 50mm 1.8 or 85mm would be a good portrait lens - especially headshots and 1/2 body shots

Even a 35mm 1.7 or 1.8 would be a good portrait lens for longer body shots (like 3/4 length shots)




Personally I use the 35mm for portraits in environments like in the house or across the table in a restaurant. 50mm is great outside when you have a bit more room. I really want a 135mm for bokehlicious outdoor headshots now :cool:
 

GlobeGuy

New Member
Jun 14, 2004
2,888
I read somewhere that 50mm focal length is technically the easiest to design and manufacture all else equal. That's probably why 50mm focal length is cheap.
 

Kappa00

Pizza
Nov 25, 2008
370
I need to be educated on what the difference is between something like a 35mm 1.8 and a 50mm 1.8. I realize it's simply the focal length, but what does this mean if I'm trying to line up my kids to take a portrait. Does the 35mm simply allow me to stand closer, or to include more people in the image?
With the 35mm on a D70S, it will be like a 50mm on a full frame camera or film slr.
The lower the mm the wider view the camera gets.
The lower the max aperture, the faster the lens.
Depth of field is determined by focal length and aperture.
If you keep aperture constant and increase focal length, depth of field decreases.
If you keep focal length constant and lower aperture, depth of field decreases.
On a D70S, around 6mm gives you a view of 180 degrees.
Generally, longer lenses are preferred for portraits because people look less distorted when compared to a really wide lens.
Also, for either focal length, what is a good F stop for portraits? 1.8 is nice and all, but that's a very shallow depth of field. What's common?
f/4 is a good place to start for multiple people in the shot.
 

FryingPan

Certified Thread Killer
May 19, 2000
51,123
Raleigh, NC
Longer lenses give the scene more compression- making the subject look more natural and proportionate. The use of long lenses for portraiture has more to do with this and less to do with obtaining a shallow DOF.
 

wrong1

Member
Sep 12, 2004
1,355
socal
Longer lenses give the scene more compression- making the subject look more natural and proportionate. The use of long lenses for portraiture has more to do with this and less to do with obtaining a shallow DOF.

:werd: when talking serious portraits 50mm is ok for full body shots, I use 85 or my 105f2 for waist up and 105 to 200mm for headshots.
 
Last edited:

Marix

OT Supporter
May 23, 2006
27,969
It's not *too* bad if you're doing a headshot at 200mm.

But if you were doing waist up or full length you'd need a megaphone to yell instructions to the model
 

wrong1

Member
Sep 12, 2004
1,355
socal
200mm give you a waist up shot at about 15 feet on a FF sensor... not an unreasonable working distance.
 

wrong1

Member
Sep 12, 2004
1,355
socal
Here is a series of shots at different focal lengths. 50/85/105/200 (d700)

50 1.4
5378888926_ebc4bd6f42_o.jpg


85 f2
5378889028_5b0647c48c_o.jpg


105 f2
5378889118_36d7018c06_o.jpg


200 2.8
5378289247_71c920b792_o.jpg



Notice how things change as you increase the distance from your subject. For example his nose shrunk significantly from 50mm to 200mm.
 
Last edited:

Marix

OT Supporter
May 23, 2006
27,969
Also caused by turning his head straight rather than side-on, but I see your point :p
 

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