TampaRalph wrote:
....is the bokeh nice and creamy? I’m interested in using whichever I buy for portraits....
I agree with an earlier response... either the 35mm or the 40mm is a bit short focal length for portraiture.
But I don't quite agree with the focal length they suggested instead.
On an APS-C camera, anything in the 50mm to 85mm range falls within the "Goldilocks portrait focal length range".... not too long, not too short.
Nikkor AF-S 50mm f/1.8G would likely be your best bet, in that it's close to the price of those other lenses. It sells for just over $200 new. The AF-S 50mm f/1.4G would be even better, but is over twice as expensive. AF-S 85mm f/1.8G is priced similarly. The 85mm may be too long if shooting indoors in tighter spaces, but can give you more stand off from your subject when there's plenty of room to work. The longer focal length also has more potential to blur down subjects.
Another lens you might consider is the Tamron SP 60mm f/2.0 Macro/Portrait... right in the middle of the "ideal" portrait focal lengths, plus an unusually large aperture for a macro lens. It's more dual purpose since it can also do full 1:1 macro, if that interests you. This lens is a bit slower focusing (as are most macro lenses by design), but it's more than adequate for most portraiture and macro shooting. It's a "crop only" lens... while all the Nikkors above are FX capable. It is reasonably compact and internal focusing, but a bit more expensive... maybe that's justifiable if it serves the roll of several lenses (I carry it when I opt to leave my 50mm and 85mm "portrait" lenses and 100mm macro lens at home.... one lens taking the place of three.)
A zoom can be handy for some types of portraiture... such as active kids and pets. My preferred portrait zoom on a crop camera is a 24-70mm f/2.8. I actually don't like it (a little too short) for portraiture on full frame and switch to a 70-200mm instead. The problem is, these lenses are rather large and intrusive.... kids and pets will ignore you as soon as something else distracts them, but with other subjects the large lens makes candid shots rather difficult. Of course, these lenses are also pretty pricey.
This is not to say that sometimes shorter and longer focal lengths can't be used for portraiture. They can.... On crop cameras I've used as wide as 24mm or even 20mm and as long as 300mm and even 500mm. However, those are more specialized uses... Shorter focal lengths have to be used very carefully, for full length portraits, couples, small groups, not too close and keeping the subjects well away from the edges of the images to avoid various distortions and perspective exaggerations that are inherent with wider lenses. With longer lenses it's the opposite...you have no choice but to work from much greater distance and the telephotos tend to compress perspective, but it's easy to completely obliterate backgrounds with strong blur effects. The ability to really isolate the subject can be useful when working on location, where you have little control over whatever is behind your subject or simply want them to stand out sharply in the image.
Some examples for focal length (since I shoot with Canon gear), all done with APS-C crop cameras:
50mm f/1.4 (at f/2.0)...
85mm f/1.8 (at f/2.0, note the slight blur of the wine bottle and hand)...
24-70mm lens at 58mm (f/11 to include background)...
70-200mm at 93mm (f/4)...
28-135mm at 117mm (f/7.1)...
70-200mm at 160mm (f/5.6)...
300mm (at f/4)...
500mm + 1.4X teleconverter = 700mm (f/5.6)
Here's what happens when you get too close with too wide a lens. It can be humorous.... but not very flattering! In this case it's a 24-70mm at 58mm on a full frame camera, which is roughly equivalent to that 40mm lens on your camera. Of course, the 35mm lens would have even stronger effect....
CatMarley wrote:
....The effective aperture on a DX at 2.8 is F/4. So if I were getting a portrait lens I would be looking at a 50 - 80 at f/1.2....
I cringe a little every time I read or hear that statement. It just confuses people. Actually, f/2.8 is still f/2.8... ESPECIALLY when it comes to exposure. The difference occurs in Depth of Field. But it's not directly due to ue to the aperture OR the sensor format. In fact, if you were to use the same lens with the same aperture from the same distance on FX and DX cameras, the Depth of Field is virtually the same... there's no effect to speak of at all. However, if you did that, due to the change in sensor format the image shot with the DX camera will be cropped much tighter. In order to frame the subject the same way, it's necessary to either use a different (shorter) focal length on the DX camera or to move farther from the subject... or a little of both. And when you change distance or focal length.... THAT changes Depth of Field and makes the smaller format DX camera
seem to render deeper DoF.
I doubt that someone shopping for one lens in the $250 range is going to want to consider f/1.2 lenses, since they typically cost between $1200 and $1800. Plus... AFAIK... Nikon only offers a legacy, manual focus 50mm f/1.2 for around $700. There's also a manual focus Mitakon Zhongyi 85mm f/1.2 offered in F-mount for $800 (Canon has both 50mm f/1.2 and 85mm f/1.2.. rather difficult to work with, but very popular with wedding photographers in particular). Stronger background blurs can be gotten by using a longer focal length, too. That's probably more practical than looking for an f/1.2 lens.