[Navmaxlp]

I've done a lot of searching through old forum posts about portrait lenses. I'm relatively set right now with a few lenses but I wanted to find some clarification on a few things. I'm confused about translation from FF to APSC. I am very aware that and APSC equivalent of FF is 1.5 times the focal length of the lens. So a 50mm lens is essentially a 75mm lens on an APSC camera. But that's kind of the problem. It seems to me that the information is correct but not applicable in this instance. Let me try to explain my confusion:

When we say a lens on APSC is 1.5 times the focal length, what we are talking about is the resulting size of the image. All the qualities of the image remain the same. It's like taking a picture with the lens on a FF camera and cropping to get the image 1.5 times closer. Again, the lens properties and distortion remain the same right?

Turning this then to the concept of a portrait lens, wouldn't the conversion be thrown out the window? I mean, in the film days the "accepted standard" for portrait lenses was what, between 50mm and 135mm? If I understand correctly, this was because of how the properties of those lenses rendered the image right? Slimming the talent etc. Wouldn't these same properties transcend the conversion? Nothing about an APSC camera alters the properties of the focal length. They simply crop the image in essence. So then wouldn't you be still looking for those same focal lengths to work with?

The one thing that does change here is working distance from the talent. I certainly don't want to be so far removed I feel disconnected. At the same time, I don't want to be right up in their face either. Definitely something that the conversion from FF to APSC changes.

Which brings me to my next question. Wouldn't, ideally for the APSC camera, the "ideal" portrait focal length then be between the 50mm and the 70/77mm? This would then give you the same lens properties while still keeping you in the working at the ideal working distance.

This is all guess work and an attempt to understand on my part. I've just started playing in the portrait area. My daughter is quickly tiring of sitting with daddy while he snaps pictures and flashes go off. I'm using a A 50 2.0 at this point but may want to branch out. I can use my 100 2.8 macro if needed but, I'm thinking of a 70 or 77 for my next purchase in addition to the DA50 1.8 to round it all out.

Am I wrong? Missing things? I'd love some feedback on this even if it's "you're an idiot. Of course that's not how this all works"

[Adam]

Wouldn't, ideally for the APSC camera, the "ideal" portrait focal length then be between the 50mm and the 70/77mm?

Indeed, and lots of users shoot with 50mm lenses, the DA* 55mm, DA 70mm or FA 77mm as a result.

[twilhelm]

All of my paid portraits were done with the FA77, from the K10D forward. The DA70 would make a great portrait lens also.

I think you have a good understanding of the “crop” factor. So yes, anything from 50 to 135 will work. While I loved using 135mm lenses on film (and again with the K1), they just put me too far from the subject with an aps-c body. I also prefer the 40, 43, 50 for portraits that are half to 3/4 body shots. YMMV

[dbs]

Hi Navmaxlp

I think you have the mechanics worked out, you just have to find the lenses to suit your vision,
. What there's only a few million to choose from...be it M42,ASPC or FF lenses.
Happy hunting.
What lenses that have already been mentioned is a good start.

Dave

[Docrwm]

50 was not a common portrait lens in film days. The oddball 77mm was but 85 was typically seen as the short end of portrait lenses and 150 the upper end. Longer lenses change the image in more than just the framing of the image. My advice is to shoot the same portrait with your 50mm and then with something in the 70-135 range (preferably 85-105) from a tripod with the same lighting. Most often people select the shots from the 85-105 length lenses even when the two are cropped to appear to be framed identically.

[Lowell Goudge]

forget everything posted up until now, and learn one simple formula

image size = subject size x focal length / distance,

or to re order this in terms of shooting distance

distance = subject size x focal length / image size.

for image size consider the format of your camera, APS C at 24 x 16 or full frame at 36 x 24, and whether this dimension is horizontal or vertical for your framing

for subject size, height of your subject, 30 Cm for head shot, 1 meter for Seated with torso and 2 meters for standing

with this info, think about the to have or can have based upon location, and work out what lens / focal length fills your frame appropriately.

there are no rules, or standard lenses. also consider longer lenses flatter the subject because there is less perspective distortion making nearer objects (like noses) appear bigger than they are, and longer lenses tend to produce nicer bokeh (out of focus detail) because the relative magnification of out of focus background appears larger than witl shorter lenses.

think about what you are going to do, and try out a few different lenses / focal lengths. decide for yourself the perspective and look you like

[AggieDad]

Why not play with a zoom until you find the focal length with which you are most comfortable, then get the prime for keeps.

[hcc]

+1 for the FA77mm Ltd. I use it on my K7 and K3 (APS-C cameras). I love the colour rendering of the FA77mm, especially for portraiture.

Hope that the comment may help.

[Sandy Hancock]

Nothing about an APSC camera alters the properties of the focal length. They simply crop the image in essence. So then wouldn't you be still looking for those same focal lengths to work with?

The one thing that does change here is working distance from the talent. I certainly don't want to be so far removed I feel disconnected. At the same time, I don't want to be right up in their face either.

This is the most important point, which I think you are slightly misunderstanding.

As I understand it, "distance from the talent" is the only determinant of perspective and all that implies. That is exactly why a lens behaves longer on a crop camera. The only downside is you lose a stop of ultimately shallow depth of field, if that is important to your portraiture.

Pick a good quality, fast lens with the focal length which gives you an appropriate camera to subject distance for the perspective you want. That is why the DA*55 (=86mm on FF) and FA77 (=116mm on FF) are so popular.

[Just1MoreDave]

Why not play with a zoom until you find the focal length with which you are most comfortable, then get the prime for keeps.

I was wondering if the DA 18-135 had a lot of focus breathing. That would mean setting the zoom ring to 70mm gives you something wider than 70mm at close distances. A casual comparison with the DA 70 seems to give me the same frame with either lens. It's one thing to check before using the zoom, because some zoom ring focal lengths are only accurate at infinity.

[sutherland]

I'm not sure what is ideal when it comes to portraiture. Some like 28mm for more scenic portraits, others like 85mm. There really isn't one magical focal length, more so, it's what you are most comfortable using and if the results are what you are expecting. I love using telephotos for portraits as it provides wonderful background compression.

One important thing worth noting is the facial distortion that different focal lengths can give. If known, it's a great little trick photographers use to create satisfying and appealing images for their clients.

[Dartmoor Dave]

One important thing worth noting is the facial distortion that different focal lengths can give.

Just a slightly finicky point for the sake of clarity: different focal lengths don't cause facial distortions. Different focal lengths force shooting at different distances to get the framing you want, and it's the different distances that cause the distortions. I know you knew that already, but I just wanted it to be made clear in the thread.

Shoot from too close with too wide a lens and people will look like their heads have been inflated with air hoses.

Shoot from too far away with too long a lens and people will look like their faces have been ironed flat.

So if your subject has got a big round head and a long nose and bulgy-out eyes (like me), shooting from further away with a longer lens will be more flattering. If your subject has got flat features and a button nose, going in closer and a bit wider might suit them better. Choose a shooting distance by eye, without even looking through your viewfinder, that makes your subject's particular individual features look good, then use a focal length that lets you shoot from that distance.

[Fogel70]

I've done a lot of searching through old forum posts about portrait lenses. I'm relatively set right now with a few lenses but I wanted to find some clarification on a few things. I'm confused about translation from FF to APSC. I am very aware that and APSC equivalent of FF is 1.5 times the focal length of the lens. So a 50mm lens is essentially a 75mm lens on an APSC camera. But that's kind of the problem. It seems to me that the information is correct but not applicable in this instance. Let me try to explain my confusion:

When we say a lens on APSC is 1.5 times the focal length, what we are talking about is the resulting size of the image. All the qualities of the image remain the same. It's like taking a picture with the lens on a FF camera and cropping to get the image 1.5 times closer. Again, the lens properties and distortion remain the same right?

Turning this then to the concept of a portrait lens, wouldn't the conversion be thrown out the window? I mean, in the film days the "accepted standard" for portrait lenses was what, between 50mm and 135mm? If I understand correctly, this was because of how the properties of those lenses rendered the image right? Slimming the talent etc. Wouldn't these same properties transcend the conversion? Nothing about an APSC camera alters the properties of the focal length. They simply crop the image in essence. So then wouldn't you be still looking for those same focal lengths to work with?

One of the most important aspect of photography is perspective, and perspective change with distance to subject.
A lens with tighter FOV need longer distance to subject to capture the same frame. So using the same lens on different sized sensors gives different images, either a different framing or a different perspective (or a combination of both)

To give the same framing and perspective as a 50mm lens on APS-C, you need a 75mm lens on FF. Which is why we say a 50mm lens on APS-C is like a 75mm lens on FF.

[Lowell Goudge]

I was wondering if the DA 18-135 had a lot of focus breathing. That would mean setting the zoom ring to 70mm gives you something wider than 70mm at close distances. A casual comparison with the DA 70 seems to give me the same frame with either lens. It's one thing to check before using the zoom, because some zoom ring focal lengths are only accurate at infinity.

This is a function / behaviour that exists to some extent in all internally focused lenses , but zooms exhibit the greatest amount.

Sadly no lens review ever reports on this so users are left to figure it out by themselves

[Navmaxlp]

Just a slightly finicky point for the sake of clarity: different focal lengths don't cause facial distortions. Different focal lengths force shooting at different distances to get the framing you want, and it's the different distances that cause the distortions. I know you knew that already, but I just wanted it to be made clear in the thread.

Shoot from too close with too wide a lens and people will look like their heads have been inflated with air hoses.

Shoot from too far away with too long a lens and people will look like their faces have been ironed flat.

So if your subject has got a big round head and a long nose and bulgy-out eyes (like me), shooting from further away with a longer lens will be more flattering. If your subject has got flat features and a button nose, going in closer and a bit wider might suit them better. Choose a shooting distance by eye, without even looking through your viewfinder, that makes your subject's particular individual features look good, then use a focal length that lets you shoot from that distance.

One of the most important aspect of photography is perspective, and perspective change with distance to subject.
A lens with tighter FOV need longer distance to subject to capture the same frame. So using the same lens on different sized sensors gives different images, either a different framing or a different perspective (or a combination of both)

To give the same framing and perspective as a 50mm lens on APS-C, you need a 75mm lens on FF. Which is why we say a 50mm lens on APS-C is like a 75mm lens on FF.

So, I think this is what I was thinking originally but I want to make sure I understand. It seems like the conversion from FF to APSC has to do with multiple things. The main difference is image size on the sensor for the same picture. Meaning, the smaller APSC will capture a smaller portion of what comes through the lens. In order to stand in the same spot and achieve the same sized image on the sensor, you would need a lens with a wider field of view. 1.5 times wider to be exact. If you wanted to use the same lens on APSC as on FF for it's distortion properties, you would have to move further away from the subject. The only problem with that is, moving away from the subject creates additional distortion in the image that may or may not be desired. Is that all correct?

Basically, what I'm getting from this is; stop trying to figure out which lens is "best" and figure out what I want to accomplish within the photo. Then use the lens and distance that best captures what I'm looking for. Is that right? Like I said earlier, right now, I've got an A 50mm 2.0 and a 100mm 2.8 Macro. It seems like these may be fine for certain portraits I'm looking for but not for others. Would you all say adding a DA 70 (because there's no way I can afford the FA 77) would kind of round things out for me? It will certainly be some time before I can pick it up (months to years) but I like knowing where I'm going so I can plan for it. In the mean time, I can also use my 18-135mm for anything needed between the two primes. The DA 50 1.8 might be in the future as well but it will depend on how the manual focus of the 50 2.0 goes. I know it's not a highly regarded lens but, for me, I think it will do fine.

Thanks for all the feedback. I love nerding out on a lot of this stuff. It definitely helps me to understand how it all works.