dx only lenses

jamiebonline

jamiebonline

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Jamie
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Hi

I am curious about how many of you out there have experience with dx lenses. I don't mean the kit lenses. I am referring to faster zoom lenses designed for dx cameras. I think they are highly useful since I have a dx camera and very much like the fact that 50mm on the lens, for example, is a true 50mm and I don't have to convert it. I also saw a video on YouTube from Tony Northup about fx lenses not being particularly sharp on dx bodies. Well, I am not sure about that but I have a Sigma 17-50 2.8 and I am really happy with it. I am actually looking for something as sharp and as fast but more in the 24-70 range. Not sure if such a dx lens exists... Interested in your dx lens experiences :)


J
 
Not sure what you mean by a true 50mm ... a 50mm lens on any format is a 50mm lens - it is a property of the lens and has absolutely nothing to do with the size of the sensor or film.

Some dx specific options would be the Nikon 16-85mm VR, Sigma 17-70mm and almost any of the 18-xxx lenses with the later 18-140 probably being the best of them.
 
PaulButler said:
Not sure what you mean by a true 50mm ... a 50mm lens on any format is a 50mm lens - it is a property of the lens and has absolutely nothing to do with the size of the sensor or film.

Some dx specific options would be the Nikon 16-85mm VR, Sigma 17-70mm and almost any of the 18-xxx lenses with the later 18-140 probably being the best of them.
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I mean, 50mm on dx does not give the same field of view as on fx. The full frame produces 50mm and the crop produces something close to 80mm on Nikon bodies, no? So when people talk about lenses that are good for portraits and mention 85, one must factor in the very different results on the dx.

Thanks for the tip on lenses :) I am looking into the 17-70. It could be very good to have.
 
jamiebonline said:
I mean, 50mm on dx does not give the same field of view as on fx. The full frame produces 50mm and the crop produces something close to 80mm on Nikon bodies, no? So when people talk about lenses that are good for portraits and mention 85, one must factor in the very different results on the dx.
....
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That is not correct. The thing that changes is the effective field of view (FoV). The focal length of a lens is a physical property of the lens so if you use it on DX it is a 50mm lens with an effective FoV in fx (or 35mm) terms of approx. 75mm, if the same lens was used on a micro four thirds it would give an effective FoV of approx. 100mm, if it was then used on a medium format camera it would give an effective FoV of approx. 30mm. BUT the focal length opf the lens has remained the same.

APS-C camera are referred to as crop cameras because the image is the same as if you had cropped it from a full frame camera. To demonstrate this I've taken a couple of images using the same 50mm lens but one is on a full frame camera (D600) the other on a DX or cropped camera (D70). The images were taken on a tripod so the position is the same. The third image is a crop of the D600 image taken at the same size as the DX sensor which is 24mmx16mm vs the fx sensor of 36x24mm. Note how the FoV changes, remember the physical position of the camera was the same and I used the exact same lens. Then note how the crop looks identical to the DX image.

Full size D600 image
Crop_Demo_D600-0179 by PabloRosso, on Flickr

Full size D70 image
Crop_Demo_D70-4286 by PabloRosso, on Flickr

Crop to DX format from D600 image
Crop_Demo_D600-0179_cropped by PabloRosso, on Flickr

Hope that explains it better :)
 
Hi again, yes I understand even though I explained it wrong. Thanks for the demo anyway.
 
Nothing wrong with DX only lenses. When I had the d7000, I used the sigma 17-50mm f/2.8 OS, and the sigma 50-150mm f/2.8 OS. However, I don't think they make the 50-150 any more?
 
Nikkor 17-55 f2.8 is a cracking DX lens, used around £500, quick to focus and sharp
 
yeah they stopped the 50 150 production awhile ago which is a shame, im guessing more people went with 70-200

i think 16-50 f2.8, 60mm f2 macro, and 70-200 2.8 makes a nice, if bit heavy kit and covers alot of potential :)
 
Are you people reading the same topic o_O, the OP already has a 17-50, but wants something in the range of 24-70 but DX Specific

AFAIK there will be no DX specific 24-70 as that is the realm of FX, but there is absolutely no reason an FX 24-70 won't perform very well on DX body
 
rpsmith79 said:
Are you people reading the same topic o_O, the OP already has a 17-50, but wants something in the range of 24-70 but DX Specific
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Oops, clearly not!

In which case I would seriously question the rational of making that switch. 70mm isn't really much of a gain vs 50mm but 24mm is a lot narrower that 18mm.

Modern FX lenses are fine on DX bodies as they are designed for high resolution sensors.

If th OP really wants a different lens and is prepared to sacrifice a fast aperture then a Nikon 18-140 would work quite well.
 
Am I missing something? A 17-50 on DX gives pretty much the same field of view as a 24-70 on FX doesn't it?

I think the OP is wrong, DX lenses are designed for DX cameras and optimised for the smaller sensor. But a 50mm DX lens on a DX camera still has a field of view of that of a 75mm lens on FX.
 
KitsuneAndy said:
Am I missing something? A 17-50 on DX gives pretty much the same field of view as a 24-70 on FX doesn't it?

I think the OP is wrong, DX lenses are designed for DX cameras and optimised for the smaller sensor. But a 50mm DX lens on a DX camera still has a field of view of that of a 75mm lens on FX.
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Yes i think you are missing something, the OP wants a 24-70mm FoV on a DX body, but is asking if there are any DX specific 24-70's.............. which AFAIK there is not as that is the usual starting point for a general purpose FX (Full Frame) lens
 
As for the OP question about DX only lenses, it is generally only the case at the wider end of the scale anyway as that is where the biggest difference in lens construction lies, at the wide end

For example a ultra wide on DX is around 10-12mm, an ultra wide angle on FX is around 14-16mm i believe (i stand to be corrected though)

At the other end of the scale (telephoto) i don't think there are really any DX/FX specific lenses as the lens construction is the same no matter the sensor size, but the advantage on the DX crop factor means you get the effective extra reach
 
rpsmith79 said:
Yes i think you are missing something, the OP wants a 24-70mm FoV on a DX body, but is asking if there are any DX specific 24-70's.............. which AFAIK there is not as that is the usual starting point for a general purpose FX (Full Frame) lens
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He already has that though, as his 17-50 has a FOV equiv of 25.5-75. I think the OP is wrong when he thinks that a 50mm DX lens gives a 50mm FOV on a DX Camera.
 
Sorry, i shouldn't have said FoV, i should have said he wants a 24-70 lens on his crop body but a DX specific one

He obviously wants a bit more reach than what he has with the 17-50
 
rpsmith79 said:
He obviously wants a bit more reach than what he has with the 17-50
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That may be, but his assertion is still wrong in the first post, and it depends on his reason for wanting a 24-70. If it's because it's generally recommended to have that range, especially for weddings, then he already has it and just thinks he doesn't.

Although, if he already has a 17-50, I'd look at getting something starting closer to 50, rather than overlap the existing focal range.

I'd also question the fact that FX lenses aren't as sharp on DX bodies. You're effectively cropping the image on DX to the centre of the FX lens, which is the sharper part of the image.
 
KitsuneAndy said:
That may be, but his assertion is still wrong in the first post, and it depends on his reason for wanting a 24-70. If it's because it's generally recommended to have that range, especially for weddings, then he already has it and just thinks he doesn't.

Although, if he already has a 17-50, I'd look at getting something starting closer to 50, rather than overlap the existing focal range.

I'd also question the fact that FX lenses aren't as sharp on DX bodies. You're effectively cropping the image on DX to the centre of the FX lens, which is the sharper part of the image.
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I think the waters have been muddied by all the talk about 50mm being 50mm etc

But i think your last comment is what the OP was really wanting to hear, the fact the FX lenses will be fine used on DX bodies
 
Hi all,

So it got confused with the issue of 50mm on dx or fx. I have a Sigma 17-50 which is a fantastic lens for my dx camera. It is a dx lens. I wondered if there was another dx lens (not an fx lens) that you might recommend. An fx lens like the 24-70 2.8 ones are SO much more expensive than my dx lens. That is a factor. The price. Maybe companies don't want to expand their dx only selection because it might stop consumers moving up to the fx cameras and they would be essentially competing with themselves!

I plan to do events as well as couples portraits. I have a 17-50 2.8 and I am getting a 50 1.8 and an 85 1.8. None of these break the bank and it seems like an OK set up, yes?

More thoughts and ideas very welcome :)
 
The reason the DX lens is 17-50 is because it gives more or less the same field of view on a DX camera as a 24-70 does on an FX camera. This is intentional - it is no coincidence that the DX lens is designed to give the same field of view as an FX system - it just works.

The whole reason for DX is that the lenses are cheaper and smaller - not much point on slapping a massive expensive lens on there if you don't have to.
 
Any particular reason why you are getting a 50mm f1.8 when you already have the focal length covered with the 17-50 ?
 
OK I must be wrong then...

This is what I thought: My 17-50 is giving me the same fov on my dx body as a 17-50 would on an fx camera. (because it is a dx lens not an fx lens on a dx body :p )

And I thought my 50mm prime would give me an fov of close to 80mm on my dx body

Help :)
 
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Focal lengths remain the same, it can help to simply think that the focal length is the distance from the back to the front of the lens (which isn't that far from the truth - this is why telephoto lenses are long). Focal length is focal length.

All 50mm lenses are FX so lets not sue that as an example.

A 35mm FX lens on a DX body gives the same image as a 35mm DX lens on a DX body but the FX lens will be bigger and more expensive. See here:

http://www.wexphotographic.com/buy-nikon-35mm-f1-8-g-af-s-dx-lens/p1030389

http://www.wexphotographic.com/buy-nikon-35mm-f1-8-g-ed-af-s-nikkor-lens/p1547266

By putting a 35mm lens on an FX body you reduce the magnification compared to DX (because the sensor is bigger) and therefore the field of view changes - it becomes wider.
 
The 17-50mm is exactly that. 17-50mm. Factor in the 1.5 crop of your DX sensor and it will not give you the same as a 17-50mm on a fx camera. Compare the sigma 17-50mm on your DX camera to, let's say, the 17-40mm canon on a fx canon, at the wide end, the image will not look the same.

The 50mm on your DX will give around 75mm. On an fx camera, that same 50mm lens will give 50mm.

That's why the others have suggested that if you have the sigma 17-50mm 2.8, there's no point getting the 50mm 1.8 as essentially, at the long end of the sigma, it will give the same perceived length.

"17-50" on a DX lens does not state that it has already taken in to account the crop factor of the DX sensor. It just means that the lens is built/optimised to be used with DX sized sensors. Basically, when you buy a DX lens, you will still have to factor in that 1.5 crop yourself to get an idea of the equivalent fov its going to give you.

17x1.5=25.5, 50x1.5=75. Therefore the 17-50mm 2.8 is the DX equivalent to the fx 24-70mm 2.8 lens.
 
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jamiebonline said:
OK I must be wrong then...

This is what I thought: My 17-50 is giving me the same fov on my dx body as a 17-50 would on an fx camera. (because it is a dx lens not an fx lens on a dx body :p )

And I thought my 50mm prime would give me an fov of close to 80mm on my dx body

Help :)
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I thought that was the case ... you need to carefully read my previous posts re focal length. You would have found that the results produced by the 50mm lens and the 17-50mm when zoomed to 50mm would have been identical. The focal length of the lens is a physical property of the lens and has nothing to do with the size of the sensor it is used on.

Look again at the images I posted. Sorry for repeating but I used the exact same lens on two bodies, one FX and one DX. The field of view has changed it is wider on the FX than DX body. Now look at the last pic, that was cropped from the first one using photoshop. I set the image size to be 24x16 which is the same size sensor as in the D70 (the DX camera I used) - the cropped image and the D70 image are to all intents and purposes the same in terms of field of view. Remember the exact same lens was used. The reason DX and other APS-C sized cameras are called crop cameras is because the image produced is as though you cropped it from a larger sensor i.e. full frame.

I could have produced the same results by using a DX specific lens like your 17-50mm - it may have vignette on the FX body, but the field of view @ 50mm would have been identical to the images I've posted.
 
Is it me, or is not everyone on this thread saying the same thing? I think not.

Pity I sold the 50mm 1.8 or I would test it right now because I was convinced that 50 (on my Sigma 17-50 dx lens) was wider than what I got with the 50mm 1.8 on the same camera.

so.. I understand crop factor though it looks like I don't. I know the physical properties of the lens don't change. It comes down to one simple question

... what exactly is a DX lens???
 
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jamiebonline said:
Is it me, or is not everyone on this thread saying the same thing? I think not.

Pity I sold the 50mm 1.8 or I would test it right now because I was convinced that 50 (on my Sigma 17-50 dx lens) was wider than what I got with the 50mm 1.8 on the same camera.
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The 50mm prime and the 17-50 zoom at 50mm will be exactly the same. The only way it might not be is if the 17-50 has been rounded up at the long end, does happen sometime.
 
R.Y.K. LEE said:
"17-50" on a DX lens does not state that it has already taken in to account the crop factor of the DX sensor. It just means that the lens is built/optimised to be used with DX sized sensors. Basically, when you buy a DX lens, you will still have to factor in that 1.5 crop yourself to get an idea of the equivalent fov its going to give you.
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Yes. This is exactly what I wanted to know. This was my confusion. Thanks. And thanks to all the others for patience :)
 
Basically, a DX lens will not work on an FX body, you will end up with very heavy vignetting, but all FX lenses will work on a DX body

Generally speaking FX lenses are built to a higher standard than DX lenses as they use more of the available glass in the lens to focus the image onto a larger sensor size, so are usually larger and more complex in design

I'm sure someone will be along soon to give a better explaination, but as stated, just because a lens is stated as DX only it doesn't take into account the crop factor as you could also fit this lens to a camera with a smaller sensor (using adaptors) and it would still have the same focal length
 
All I can say is the sigma 17-50mm f2.8 is a very affordable lens, with excellent results, I see you have a 17-50 and an 85 mm prime, so have this focal length almost covered. It is my always on lens when walking around.
 
My experience with DX lenses is that it is a PIA when/if you move to full frame.

I also think an FX lens on a APSc camera generally gives a better IQ as you are only using the centre part of the lens, which is usually sharper.
 
To answer the question posed in the last line of post #27, a Dx lens is a lens designed to give an image on a smaller-than-35mm film sensor, commonly known as an APS-C, in a Nikon body. They CAN be used on Nikon FF DSLRs but will either give heavy vignetting or put the FF body into Dx mode. The vignetting in the shot below is actually from a Sigma DC lens rather than a Nikkor Dx one but displays the vignette.

GPN_3119 by gpn63, on Flickr
 
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