Whats my option for a prime 50mm with a DX sensor Camera?

Paul Lange

I've had a look around but I cant see an option for a fast 50mm prime lens for a DX camera. The AF-S f1.4 is a FX sensor lens so effective focal length for me would be 75mm. The 35mm FX lens that would give me approx 50mm is f2 and I'm hoping for something a little faster.

Have I missed something or does there seem to be a hole in the lens line up.
Nikon has an f/1.8 35mm DX at a quite reasonable price. The f/1.8 50mm is an extremely useful lens at 75mm equivalent and superior to the much more expensive f/1.4 up to f/5.6 where they become equal. Very fast primes were a great asset when ISO400 film was considered super-fast. They also helped in focusing accurately in low light and could occasionally be used wide-open if content was far more important than image quality.

I shot with an f/1.2 for years back then, but only used the speed as a focusing aid. It really was not usable for photography below f/2.8 unless there was no other way to get the shot. Since I was working for a morning paper, most of my photography was available darkness. Now I would be delighted if all my lenses were no faster than f/4.0. Even an entry-level camera will produce acceptable results at ISO1600 and my D700 at ISO25,600 is about equivalent to old Tri-X at ISO800.
I often have a look through those as well although I tend to use Reid Reviews on-line (it's a pay site but well worth it as Sean is very thorough). Other than that, I find the reviews in BJP pretty good as are the ones in Profi-Foto. Funnily enough the reviews in Amateur Photographer in the UK are some of the most in-depth you will find (and cover everything from budget optics to the latest and greatest).

Most of my modern '35mm' glass is either Nikon (14-24, 24-70 and the new 70-200 plus their range of shift/tilt lenses and the odd macro lens) or Zeiss (many of the ZF primes are very good indeed). My medium format gear is either Hassleblad (V and H) or Mamiya (7II) so there is little to quibble about with quality there (and not much choice!). Large format is either Rodenstock (mostly), Schneider or Cooke although I do have a series of Nikon LF lenses that are sharp and high contrast and, more importantly, relatively light that I use on an Ebony field camera. I have recently bought a Fujinon 450 f12.5 but have not shot anything with it yet. There's not a lot of information out there about this lens but everything I have read has been positive. It is very small and light although you need a top-hat to get it to focus on a field camera as it is not a telephoto design.
I saw the Nikon 35mm for DX sensors and it looked interesting. I have an 85mm Macro which is a great portrait lens so using the 50mm for a FX sensor to give 75mm effective focal length would be too close to this although it would be a lot faster than the 85mm.

The sigma lens 30mm is a DC lens so would still 30mm on my camera however I did spot the Sigma 28mm f1.4 DG lens which would give me 46mm effective focal length. It was late when I spotted this one so haven't looked into it.

Does anyone know if using a full frame lens on a smaller frame digital offers any advantages in terms of better quality of the optical performance. I heard that grinding the center of the lenses is far more easier to do accurately that the edges and you would only be using the center of the lens on a DX SLR?
Sorry, I didn't realise the Sigma was quoted in that format.

Yes, using a FF lens on a small sensor can give an improvement in quality as the image circle required is smaller than the lens is designed for. Thus a mediocre FF lens can prove to be significantly better when mounted on a camera which has a smaller sensor. It is not so much to do with the grinding of the elements than the actual design as the more extreme diffraction that occurs at the edges of elements is more prone to various form of aberration than in the more central area and thus more difficult (and expensive) to correct.
28 x 1.53(nikon crop factor) = 42.84
A normal lens for a 35mm camera is technically 43.3mm
So if you get a 28mm 1.4 you will have a more "normal" lens than even those people who have sort out the more rare 45mm lenses for their 35mm cameras!
28mm on dx is a nice focal length!

Your 85mm makes such a good portrait lens because it's 127 equiv ... Wheni sell my d300 I am going to miss the effect of my 85 1.4 on it!
Yeah, that's a dam good bit of advice... I stopes buying dx lenses (apart from the 17-55 2.8 nikon which was a must) as soon as I heard of full frame nikon ...
Another reason to go for the 28 1.4 :)
For me, the D700 is the camera I have been waiting for all my life. However, for many a DX camera is a far better choice. For someone doing sports or wild-life photography it is like having a built-in 1.5× teleconverter with none of the downside. For those not accustomed to being a beast of burden, lenses for the DX sensors are lighter, more compact and cheaper. For those who shoot mainly in daylight or with flash as the primary light source, the extraordinary high ISO performance of the sensor is not needed, thus the DX sensor is a money-saver.

Going FX, my bag grew dramatically from a 12-24mm and 18-200mm plus D300 body to a D700 plus 14-24mm huge, heavy and expensive lens, plus the 24-120mm walkin'-'round, shootin'-stuff lens and the wonderful 70-300mm tele-zoom. For me it was worth it, but I rarely carry the whole arsenal, taking only what I think I will need for the shoot. All too often the 14-24mm stays home, and to a lesser extent the 70-300mm. If only the 14-24mm were an f/4.5-5.6 weighing a third of what it does, small and discrete. It is an awesome gold-ring lens, but I would trade it in a second for a smaller, slower lens of equal quality.

I also have a number of AI-S lenses of very high quality that work perfectly but are only used for contemplative photography, which is a small percentage of what I do. As much as I am in awe of what the D700 does, I would hesitate to suggest that FX is the future of digital photography. For me, it has opened up the night and many other things and it is my ideal camera. I would not be so arrogant as to say it is the ideal camera for everyone. DX and µ4/3 certainly have their place and for many, they may be the ideal.

If you are looking for a new camera, don't listen to us. Instead, clearly define your photographic - not cameras as jewelery -goals and consider all the largess that is being announced during the run-up to Photokina plus the wealth of cameras and lenses now on the shelves. Fit the cameras and lenses to your budget and image-making goals, not the quest for the ultimate camera that may be totally wrong for your goals as a photographer.
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Seems like some wise words Larry. Hindsight from one becomes foresight to another!

Hamish, I rashly thought my 85mm was a DX lens! I must have missed that one!

Yeah, The Sigma 28mm seems like the one, just a shame it hasn't got an internal motor but for what I want it for it would mostly be used in manual focus anyway.

Now then, what about flash guns?? Does anyone know if the Sigma Macro Flash Gun could be used for normal flash photography as well as macro? The website says it compatible for Nikon iTTL but is there any unspoken caveats?
It is a dx lens ... But focal lengths always remain the same... It is still an 85 mm lens, it wouldn't work on a fx body... But it's equiv focal length on a dx camera is (actually now i work it out) 130mm
Focal length is a constant, and is always stated as so.. the effect you get from the focal length is down to the size of the light sensitive surface
I agree Paul, Larry - wise advice indeed. We all have reasons for what we buy and like you, for me the arrival of the FF Nikons was what I'd been waiting for in digital. Of course we also often buy things that we thought we needed but didn't. For me I guess it is the 14-24. A great lens but I really don't use it often. On the D3 for technical stuff it is usually one of the S/T lenses, however, for general photography I tend you use the 24-70 the most although quite often I will stick an old 135 f2.8 pre-ai (but ai converted) lens on - I love the focal length and the look of the images it presents (and the discipline that a prime imposes). So I can see the appeal of the 85 on the DX body.
Hamish, Have I got this right a 85mm DX lens does not give effective 85mm focal length on a DX body, but instead 130mm?

I had a quick Google and the consensus is that it doesn't matter what lens you have Nikon DX, FX or Sigma DG or DC if you have a DX body you multiply the lenses focal length by approx 1.5.

Have I got this right as then it would seem that I can use the Nikon 30mm AF-S 1.4 lens to have effective 45mm ish FL?
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Hi Paul,

Basically yes. The sensor is smaller and so only receives a fraction of the total image circle cast by the lens. This means the image that is captured by a 85 mm lens mounted on a DX body is effectively the same as would be captured by a 130 mm lens on a FX body. There are some DX only lenses of course but the focal lengths they are given are also FX lengths even though they will only give a cropped image on a FX sensor.
Since there is usually a fall-off in sharpness as one gets to the edge of a lens's image circle, there can be a sharpness advantage to using a DX camera, since it only employs the centre area of the circle where fall-off is minimal.
Ahhhh, OK so there's not a hole in the Nikon lens line up only lenses with focal lengths that are not the effective focal lengths even though they're designed for the sensor.

Its all simple and straight forward when you think about it. I wanted an apple but they sold me a pear but its OK as its all fruit at the end of the day.