DX or FX Lenses?

[znelbok]

Hi All

I am keen for a lens at the moment and after doing a bit of reading I have a question that I need help understanding.

To start with, I am the type of person that likes to buy for now and the future. If I can spend a little more now for something that will offer flexibility in a few years then I have no issues with that as long as the money is not too much more.

Now, I am looking for a lens for my D80 and a prospective D7000 (or 7100 if it ever comes out). There are more and more cameras that are starting to use the full size sensor and I can see the level camera that we are looking at will start to get this size sensor within 5 years as manufacturing costs come down.

I do expect them to be high pixel counts and thus using a DX lens on them will still yield a great picture, just at a smaller one than if using an FX lens.

I don't know what the price difference is between the lenses yet, so this question my become null-and-void one I do that research. I am seeing people claim 2K for a 35mm f1.8 prime, but I am also seeing new Nikkor's DX lenses of the same spec that are <$200. If there is a price difference that great then the DX is the obvious choice.

So here is my delemma - do I buy a FX lens now for my DX cameras so that they are suitable for what I believe is the future or do I just stick with the DX lenses and deal with the issue as it come along.

Thanks

Mick

[ricktas]

If you are determined to go FF in future, get FX lenses now.

However, from you post, it would appear you are a Nikon shooter. Nikon has done something that Canon has not. You can use DX lenses on their FX bodies, albeit with a cropped result, but they attach and they work.

So if you buy one or two DX lenses then you can still use them on your FX body. The other thing is, that these cheap lenses can be sold in future. If you pay $200.00 for one now, and sell it for $100.00 in 5 years time, then you really have not lost a lot of money, and it gave you good use, for 5 years.

And why get rid of your D90, when you get an FX body? Keep it as a back-up, after all cameras do fail at times, and it is much better to have a D90 and use that, than have your camera fail, sent off to repair, and be without any camera for a few weeks. I shoot with a D3 mostly, but still have and use my D200. The D200 is good when I don't want to cart the weight of the D3 around.

[WhoDo]

My first question would be "what do you want to DO with the new lens"? The answer to that may make your choice easy.

I've developed a passion for bird photography, but the best lens I have is a kit 55mm-300mm zoom. I'd really love a 400mm f/4 prime but the cost is prohibitive at the moment.

I'm also keen to try macro with some decent kit, and I have my eye on a Tokina 100mm macro lens that is just about in my budget range. There are way better macro lens options out there, including nikkor and sigma, but again my budget is the limiting factor.

Camera bodies come and go while lenses can last a lifetime, so you are right to plan for future flexibility. That being the case, you should first consider WHAT you will be shooting rather than what you will be shooting it WITH. JMHO;)

[swifty]

Specifically in relation to the 35mm prime you mentioned, the FX version is a 35mm/1.4G whilst the DX version is a 35mm/1.8G.
There is a big price premium for the extra 2/3 EV max aperture as well as things like build, IQ, image circle covering full frame etc.
You almost always have to pay significantly more for the best but this isn't really a FX vs DX thing.
Eg. Both the 85mm 1.4G and 1.8G covers FX. Same with the 1.4G vs 1.8G versions of the 50mm lens. In both cases the 1.4G versions are disproportionately more expensive for the performance gains.
Incidentally even though the 35mm/1.8G is a DX lens, the image circle does cover FX but with some vignetting. It's well documented.

For a DX/FX discussion it's primarily the field of view that should be your concern.
A 24-70/2.8 will be great on both DX and FX but are you going to be happy with an effective 36mm at the wide end on DX caneras? If u have a dedicated wide angle for your DX then you can probably live with the trade off.
Secondly FX lenses will almost always be bigger and heavier (may or may not be an issue for you).
With the release of cameras like a D800, you essentially have both a DX and FX camera in 1. I would have no issues with eg. Using a 17-55/2.8 which is a DX lens, on a D800 in DX mode as my walk-around 'normal zoom'.

So there's no easy answer, some research will be required on specific lenses you're interested in.

[arthurking83]

If Nikon ever produces a lens such as a 35mm f/1.8 for full frame, it's cost wouldn't be great as the current 35/1.4 lens.

They recently announced a 28/1.8 for full frame, and the initial price is expected to be about $700, which is about par for a brand new design lens from Nikon at this level.
A 35mm at f/1.8 would(or should!!) come in just a touch cheaper again, but not by much .... say $500-600.

I'd recommend that you get the lenses that you can afford now, and worry about the Fx/Dx issue later. That is, if you can afford a 24-120 f/4 now as a general purpose lens for use on a D7000, then do it.

Otherwise go for an 18-135 Dx zoom lens(which is nearly $1K cheaper).

There are some good reason to go with an full frame capable lens, and that's when the lenses in question start to venture into the $1K plus region.

eg. why get a Nikon 12-14/4 for just over $1K, when you can get an almost equal focal length 14-24/2.8 for not really all that much more .. I've seen them in the $1.9K price range.

While $900 is a lot of money, if you know at some point that you will hop onto the full frame bandwagon, then it make less sense to go with an inherently much less wide 12-24Dx lens, than to lose that 2mm for as long as you have the Dx camera for .. knowing that at some point in the future you will eventually get it all back(and more) when moving up to a FF body.

Choose quality lenses, choose wisely.

As Swifty said: " .. There's no easy answer.. "

[rodw]

If your next camera is ging to be DX, stick with DX lenses where you can, as you will save some cash. As far as 35 mm goes, grab the DX cheapie or even a second hand one as I am sure you will love it.

If you wanted to hedge your bets for FX and tick off the 35mm focal length, maybe look at the 16-35 or the 17-35 which I have. I find it an incredibly useful lens and it lives on my DX body most of the time. The 24-70 won't really be wide enough on DX.

[Tannin]

Hi Mick,

I'm afraid that it simply does not make sense to answer your question in all-purpose generic terms. This is why you are seeing diametrically opposed answers in the replies above. In cricket, should you play a square cut? Or is it better to play a forward defensive stroke? The answer, of course, depends on whether you are facing a fast yorker or a floater a bit short of a length. There is no one-size-fits-all answer.

The same applies here with lenses. Think it through this way:

Obviously, it is better to get an FX lens than a DX lens if all else is equal. But all else hardly ever is equal, so we need to go a bit further in our thinking.

Some lens types are much the same performance-wise. They provide similar focal length range, speed, and quality and the weight isn't too far apart. This makes FX very attractive provided only that you can live with the extra cost. Look for this type of situation in:


normal-length prime lenses (say 35mm through to 85mm)
shorter macro lenses (say 35mm to 70mm)
mid-range telephoto zooms (50ish to 300ish)


With these types of lens, there is often an even choice between FX and DX: either lens will do what you need today, and be a little different but nevertheless still good for purpose another year on FX. To my mind, you have to look at spending the extra if you possibly can - but be aware of cost all the same. You may find that the FX lens is overpriced and just too dear for what it is. It wouldn't be the first overpriced lens ever sold, nor the last. In that case, it might be best to consider another product and leave your FX needs for another day when you might get better value. Just the same, most of the time an FX product will be the best option. (And in fact the manufacturers recognise this: in the categories just mentioned, several major manufacturers don't even bother making a DX product. Canon don't make DX primes, for example, and there are only two or three DX macros of any brand on the market.)

Some lens types are always made in FX-only because it makes no sense to make them in a DX form. This is particularly so with long lenses - the cost and weight saving in, say, a 400mm f/5.6 prime made in DX instead of FX might be a few grammes and $50 or at most $100 in a $2000 lens. What would be the point? So there are no DX super-teles, and there are hardly any DX macros over 60mm. All the 100mm-class macro lenses, for example, are FX lenses. Even in the 70-300 class, DX lenses are the exception rather than the rule.

Some lens types cannot be replicated in a non-native format. There is no such thing as a true ultra-wide on DX in an FX lens. Given the constraints of cost and weight and practicality, you just can't make an FX lens that's wide enough on DX to be seriously wide. Well, you can get out to 12mm (just), but 12mm isn't all that wide on DX, and the only 12mm wide FX lens on the market (the Sigma 12-24) is quite expensive and not very sharp. The specialised DX-only ultra-wides (such as Canon 10-22, Nikkor 10-24, Sigma 10-20, Tokina 11-16) are all sharper and wider and cheaper. (Well, the Tamron DX-only 10-24 isn't sharper, but that one seems to be a bit of a dud. Doubtless they will replace it with a better effort before too long.)

There are some very sharp ultra-wide FX lenses, but they are only ultra-wide on FX. The excellent Canon 16-35, the well-regarded Tokina 16-28, and even the legendary Nikkor 14-24 are only wide, not ultra-wide when you put them on a DX body. So if you want ultra-wide on DX, you have no choice: you must buy a DX lens. Perhaps your least expensive option would be to get a Sigma 10-20 'cause it's cheap and decent. Then again, the Nikkor 10-24 or the Canon 10-22 or the Tokina 11-16 would all have better resale value. In the end you spend the money now and weep later.

Another must-have-DX category is the general-purpose zoom. The widest general-purpose FX lenses start at 24mm. 24mm on DX is way too long to be good for walkaround and general use. There are any number of truly excellent 24-something FX lenses, some of them are even half-way reasonable in price, but none of them is really up to scratch as a walkaround lens on DX. Your only other FX option for a DX walkaround is to mis-use an FX ultrawide as a DX normal. Over in Canonland, people often try this with the Canon 17-40/4L. It doesn't really work all that well. It's only modestly wide at 17mm, and way, way too short at 40mm. It's an OK solution, I guess, but not great. The 16-35 is even shorter, and costs a bomb. Similar comments apply to the Nikkor FX wides.

In short, for a DX camera, you need a DX standard lens, something like a 16-85 or a 17-55/2.8. And you need a DX ultra-wide. But everything else you buy should be in FX mount unless you have a very good reason why not.

[rodw]

I think Tony has summed it up pretty well. If you try to build a collection of FX lenses for DX they will not be the right focal length so stick to DX lenses.

[znelbok]

Thanks for all the detailed replies.

I have read it once and will re-read it again later after what I have read the first time has sunk in a bit.

I really appreciate the input.

Mick