50mm f/1.8 AF-S versus 50mm f/1.8 "D"

I am about to purchase a 50mm 1.8 lens and am looking at both the AF-S version and the older "D" version. Since I use the D90 either lens will work with my camera.

What are some recommendations between the two? The AF-S is a little more expensive used, new it is considerably more money.

I do not want any DX version, if it is out there, as I want the FX version which I think would be a better portrait lens on the crop sensor.

Actually, I just found this thread

http://nikonites.com/prime/12956-nikkor-af-s-50mm-f-1-8g-vs-nikkor-af-50mm-f-1-8d.html#axzz2qUyuj0te


I managed to fianlly get the whole video and it answered all of my questions.

So, disregard my request!!

Mike d90 said:

I am about to purchase a 50mm 1.8 lens and am looking at both the AF-S version and the older "D" version. Since I use the D90 either lens will work with my camera.

What are some recommendations between the two? The AF-S is a little more expensive used, new it is considerably more money.

I do not want any DX version, if it is out there, as I want the FX version which I think would be a better portrait lens on the crop sensor.

Click to expand...

Why would an FX lens be any better than any DX-version (if one did exist)?

With most lenses, the corners are not as sharp and typically suffer from light fall-off at wider apertures. An FX lens on a DX camera, you get the "center sweet spot".

The AF-S 50/1.8 lens uses Aspheric optics, which means less distortion associated with Fast/All-spherical optics.

I have the original series AF-Nikkor 50/1.4, had the AF-Nikkor 50/1.8 before that. The AF-S 50/1.8 is better.

Love my 50mm f/1.8G

480sparky said:

Why would an FX lens be any better than any DX-version (if one did exist)?

Click to expand...

I want the field of view of the FX lens. A 50mm FX lens on a DX camera should yield about 75mm field of view/crop image.

Unless, and here we go again, a DX lens is not a true 50mm filed of view on a DX camera. If you buy a 50mm DX lens to get a 50mm field of view/angle, then I think you should get a 50mm angle and field of view. Otherwise, why bother?

If I buy a DX lens I want an uncropped field of view to be the same as if I were using an FX lens on an FX camera.

Is this not the way it works?

Get the 50mm 1.8g new...($219)

ShootRaw said:

Get the 50mm 1.8g new...($219)

Click to expand...

That is the one I decided I wanted but I cannot afford it yet. Where did you see it for $219?

It is 216.95 at Amazon & B&H Photo

Pat in NH

They're ~$150 on the used market.

Mike d90 said:

I want the field of view of the FX lens. A 50mm FX lens on a DX camera should yield about 75mm field of view/crop image.

Unless, and here we go again, a DX lens is not a true 50mm filed of view on a DX camera. If you buy a 50mm DX lens to get a 50mm field of view/angle, then I think you should get a 50mm angle and field of view. Otherwise, why bother?

If I buy a DX lens I want an uncropped field of view to be the same as if I were using an FX lens on an FX camera.

Is this not the way it works?

Click to expand...

You will get exactly the same FOV. 50mm is 50mm is 50mm, day in, day out, all day long.

A 50mm DX lens and a 50mm FX lens will appear the same on a DX body.

480sparky said:

You will get exactly the same FOV. 50mm is 50mm is 50mm, day in, day out, all day long.

A 50mm DX lens and a 50mm FX lens will appear the same on a DX body.

Click to expand...

That just makes no sense though. I know what you are saying but how can you advertise a 50mm DX lens as a 50mm to someone who is expecting a 50mm field of view?

So the DX lenses do not reduce the entire image size to give the same FOV as an FX lens on a FX camera?

I love my POS $100 50 1.8D. from 2.5-4 its amazing.

But I have my eye on that new sigma 50 1.4 ART. and that 135mm 1.8. I dont think theyll deliver with the 135mm. I have a feeling it will be good but not stellar. like the 85mm 1.4 HSM. its a nice lens but not great. I think the 50 ART will be the one that will crush everyone though, except the otus.

I think its going to have a heavy price tag

http://photorumors.com/2014/01/14/the-new-sigma-50mm-f1-4-dg-hsm-art-lens-should-be-crazy-good/

anything over the nikon and im out. ill stick with the POS $100. its fast as hell and sharp. no 50mm should be more than $300-500.

Mike d90 said:

That just makes no sense though. I know what you are saying but how can you advertise a 50mm DX lens as a 50mm to someone who is expecting a 50mm field of view?

So the DX lenses do not reduce the entire image size to give the same FOV as an FX lens on a FX camera?

Click to expand...

The only difference between an FX and DX lens is the size of the circle they project. FX lenses need to project a larger circle to cover the larger FX sensor. DX lenses project a smaller circle as they only need to cover a smaller area of the DX-format sensor.

Focal length has nothing to do with the size of the sensor of the camera... it's a matter of optics that determines to focal length. A 50mm lens is still 50mm, whether it's on a cell phone camera or an 8x10 view camera.

Mike d90 said:

That just makes no sense though. I know what you are saying but how can you advertise a 50mm DX lens as a 50mm to someone who is expecting a 50mm field of view?

So the DX lenses do not reduce the entire image size to give the same FOV as an FX lens on a FX camera?

Click to expand...

As 480sparky said a 50mm lens is a 50mm lens no matter what. The difference is that a 50mm lens on a DX body will have an equivalent FOV of a 75mm lens on an FX body. This doesn't have to do with focal length directly though. It has to do with how much of the image circle is "used" by the sensor. A lens designed for an FX body produces a larger image circle than a lens created specifically for a DX body. That is why people talk about the DX bodies using the "sweet spot" of the FX lens.

Let me try this angle:

The actual, physical size of the FX and DX sensors are different:





This is readily apparent if you look at an FX body next to a DX body, and can see the actual sensors when both are set to "Mirror Up for Cleaning":






So how does this translate into anything meaningful out in the 'real world'? Well, lets' pretend we're out there taking photos. And we come across this peaceful scene:







Now, an FX lens on an FX body has to project a large enough image to cover the larger FX sensor, so it will project an image into the camera that looks like this:





(Yeah, I know.... it's right-side-up. In reality, the image would be upside-down, but let's ignore that for the purpose here.)

The lens needs to create a large enough image to cover a sensor measuring 24x36mm (represented by the white rectangle):





So an FX lens/body will record the final image as:








Now let's take the same focal length lens, but only it's a DX-format lens. It will project a smaller circle:







Because it only needs to cover a sensor that measures 18x24mm:





So the same focal length lens, on a DX body, will record a final image as this:







Now, if we put the two final images (FX and DX) side by side, we end up with this:






Notice how the subjects in both images are exactly the same size? It's just that the DX sensor recorded a smaller portion of the scene because the sensor is physically smaller! This results in a narrower field of view.

So if you compare the sensor size:





with the above two images, you should be able to understand the 'crop sensor' effect on field of view.

Great illustrative explanation sparky. You can also think about it being no different than taking the FX image and cropping it down in pp. Same result. It is only when you try to make the final images the same size that the apparent size of objects in the images differ.

Steve B said:

Great illustrative explanation sparky. You can also think about it being no different than taking the FX image and cropping it down in pp. Same result. It is only when you try to make the final images the same size that the apparent size of objects in the images differ.

Click to expand...

I also use the analogy of taking an 8x10 print and cutting it down to a 5x7.... taking a pair of scissors to the print didn't change the focal length of the lens used to create the image.

You will still get less vignetting at wide-apertures and a sharper image over the recorded part of the frame using a lens with a larger image circle with the smaller sensor camera. The Nikkor 55/1.2 is a good example: this lens has better measured resolution over the center 2/3rds of the frame than the contemporary 50/1.4. Edges were a different matter. On a DX format camera, you get the sweet spot.

That post by Sparky above for the comparison should be a sticky on the forums. This always comes up and this was a great explanation.