FX-DX format question

[Wander]

Excuse the question but I'm not familiar with the FX format details other than it is essentially 35mm in size and is the hot tend in DSLR's

My question is related to lenses and compatabilty. It was mentioned in another thread that DX lenses will not work on FX bodies due to the cropping aspect of the DX format. I was reading about the Nikon D700 and it can be shot in either FX or DX format so does that also mean that DX lenses will work (the brochure indicates this) and is there something lost in the function of the lens?

I am curious as I need a new lens for my D70s but I am also interested in the FX format but I doubt I can swing a whole new kit right now. The FX lenses I have checked out would give up the wide aspect on my DX format body and a DX lens I am intersted in is the Nikor 16-85. Would I be throwing that money away because it won't work on a FX body later?

 

[Lost Canadian]

Excuse the question but I'm not familiar with the FX format details other than it is essentially 35mm in size and is the hot tend in DSLR's

My question is related to lenses and compatabilty. It was mentioned in another thread that DX lenses will not work on FX bodies due to the cropping aspect of the DX format. I was reading about the Nikon D700 and it can be shot in either FX or DX format so does that also mean that DX lenses will work (the brochure indicates this) and is there something lost in the function of the lens?

I am curious as I need a new lens for my D70s but I am also interested in the FX format but I doubt I can swing a whole new kit right now. The FX lenses I have checked out would give up the wide aspect on my DX format body and a DX lens I am intersted in is the Nikor 16-85. Would I be throwing that money away because it won't work on a FX body later?

They work, but when they are mounted to the camera it recognizes this and the camera automatically crops the image down, basically turning that 12 megapixel sensor into a 5 megapixel sensor. The reason it does this is because the image projected by a DX lens isn't large enough to cover the larger FX sensor and you end up with a very heavy black vignette around all of your images without the auto cropping.

Edit: So yes while using a DX lens on a Nikon FX camera is possible by virtue of the cameras electronic wizardry, in doing so you are in essence throwing away half of the sensor making it a bit of a waste.

 

[Wander]

Thanks Trevor, that makes more cense now. I can see that camera gods are just pushing me to buy an FX kit- and the no interest for a year offer I got from Amazon today is not helping the temptation at all.

 

[off-roader]

Matt,

It's not as simple as that though...

There are some very inherent benefits to having a DX sensor over an FX sensor and that's directly related to the DX crop.

With a DX sensor the lens inherently has a 1.5x additional magnification due to this crop. For a wildlife or sports photographer this can be a big benefit because instead of buying a 600mm lens you can get away with only buying a 400mm lens.

It's a key reason I have no interest in buying an FX body at this time.:ylsmoke:

 

[HB 4X4]

I touched a bit on this in one of our other discussions, so i'll just elaborate a little bit more.

Almost all DX lenses will behave as mentioned above when placed on to a FX sensor. There is an exception or two out there, although I only know of one. The 35mm 1.8 is supposed to work perfectly fine on a FX body without cropping or vignetting for some reason, but I have yet to personally test it. I have heard this from multiple unrelated sources but I am unsure of its validity.

If you plan on going to a FX body later, then I would advise against buying any DX lenses now. If you don't have a need for FX then stick with DX and buy the lenses that fit your needs. In the long run it's cheaper to not have to re-buy all of your lenses.

The only area that will limit you dramatically with a DX body is the wide angle. Like you said, a 16mm isn't all that wide on a DX body. I use a 12-24 for this reason, and when I get a FX body I'll get the 16-35 which will be 2mm wider than 12mm on my DX sensor. You can always get the 14-24 which is still pretty wide on a DX body, but it does not take filters (that's why I am getting the 16-35, which is actually turning out to possibly be considerably sharper).

Generally speaking, FX lenses will be considerably sharper. Ideally you want your collection to be f/2.8 or lower. I am making an exception for my wide angle with the 16-35 which is f/4.

 

[DiploStrat]

Getting Technical!

OK, now we are getting technical.

Trevor gave you the practical, hands on answer. If you want to understand the "why?" then this link will help:

http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

In grossest terms, the larger the sensor and the lower the photosite density, the better the quality. See also: "Why Megapixels don't Matter."

But at around the 10 MP and lower you probably aren't going to see a difference. And within a certain range, a smaller sensor can have advantages if you are looking for effective length in a lens or, as in the 4/3 system, a physically smaller package.

Me? I'm lusting after an FX body. Size matters! :wings:

Enjoy!

 

[Lost Canadian]

...and when I get a FX body I'll get the 16-35 which will be 2mm wider than 12mm on my DX sensor. You can always get the 14-24 which is still pretty wide on a DX body, but it does not take filters (that's why I am getting the 16-35, which is actually turning out to possibly be considerably sharper).

Generally speaking, FX lenses will be considerably sharper. Ideally you want your collection to be f/2.8 or lower. I am making an exception for my wide angle with the 16-35 which is f/4.

Sorry HB, I'm going to have to challenge a couple points here. FX vs DX doesn't really have anything to do with how sharp an image is. There are some razor sharp as a razor DX lens and some dull as wood FX lenses. A bigger sensor doesn't equate to sharper. Generally speaking there are two main factors that play into how much detail can be extracted, one is megapixels, and the other is the lenses resolving power. Of course things like diffraction, noise etc play into how much detail can be resolved pixel for pixel but these are arguments of a much more technical nature. Simply speaking though an optimized 12 megapixel DX sensor will match an optimized 12 megapixel FX.

As for the 16-35 possibly being "considerably sharper" than the 14-24, my lustful desire to own the 14-24 compels me to point out that resolution tests show that this is simply not the case. Below are the resolution figures for both lenses, both shot using a 24 megapixel D3x. The 14-24 is simply out of this world in terms of its resolving power, even into the far reaches of the corners. The 16-35 isn't even close in this respect. You're right about the filters though, however Lee now has a system designed just for the 14-24 but it uses giant 150mm filters.:Wow1:
Link to a video of the system.

 

[off-roader]

What I've been reading through various sources and hearing on the This Week In Photography podcasts is... in addition to the lens sharpness the image processing (both sensor and processing engine/chip) have a large part to contribute to the overall sharpness of your image and some chipsets are far better than others. They were primarily discussing P&S's so I'm not sure how much applies to DSLR's but I'm sure there's some level that applies to it.

 

[Ryanmb21]

Might be offtopic but I'll state anyway:

Why does everybody have plans to switch to FX soon or in the future?

Sure right now absolute picture quality is better right now (but the next gen DX sensors might be as good). But aren't the conditions where the differences show up quite a bit extreme? Correct me if I'm wrong but on a good DX camera (e.g. D90) you can shoot basically up to ISO 1600 without noise. Do you really need more than that? (wedding photographers I understand). How big do you have to print shots before you need the extra resolution? What benefits are there other than better extreme high ISO performance?

What about the size of the f/2.8 zooms that most seem to use with FX? Is it worth carrying those around?

I'm not trying argue DX v FX, I'm just curious if the benefits outweigh the significant price and weight costs?

 

[cnynrat]

The nature of electronics is that any technical advancement that applied to the DX sensor to increase it's performance could and would be applied to FX sensors, so the theoretical advantage of the sensor with the larger photosites will always exist. Whether that matters or is visible in your photography is another question.

People often talk about the fact the a DX sensor increases the effective focal length and hold that out as an advantage. True enough if you are doing a lot of sports or wildlife photography where you want a long telephoto/zoom. For me though, I find that it's challenging to get wide enough with a DX sensor. There aren't a lot of lenses in that range, and the good ones are expensive and bulky.

 

[DiploStrat]

I shoot mostly tele, so I am well aware of the DX "advantages." That said, like most folks, I tend to shoot between 35mm and 300mm, so FX has some real appeal. (Even in the 35mm slide days, I found that 35mm was as wide as I wanted to go.)

Off topic, but I love this quote:

"A venturesome minority will always be eager to set off on their own, and no obstacles should be placed in their path; let them take risks, for godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free citizen."

I would add:

"But let them do it within their own country, so I don't have to try to clean up the mess!"

-- The prayer of Consular Officers of every nation! :wings:

 

[dzzz]

Trevor, I go to the trouble of using the Nikon 14-24 on Canon because it is so good.

As is sorta pointed out, it's not sensor size but pixel density that counts. Whether the crop is in camera, like the DX, or later in photoshop with the FX, it doesn't matter.

IMO, the reason to shoot full frame is extensive use of ultra wide angle and/or to get the maximum print size possible. If either are not important, it's probably not worth the extra money. All better cameras from all brands are now pretty darn good.

As a landscape shooter I shoot full frame with Canon, but I also have a 1.3 crop camera for critters.

 

[dzzz]

I would add:

"But let them do it within their own country, so I don't have to try to clean up the mess!"

-- The prayer of Consular Officers of every nation! :wings:

We just hate it when our dying interferes with you guys having tea.

 

[DrMoab]

Might be offtopic but I'll state anyway:

Why does everybody have plans to switch to FX soon or in the future?

Sure right now absolute picture quality is better right now (but the next gen DX sensors might be as good). But aren't the conditions where the differences show up quite a bit extreme? Correct me if I'm wrong but on a good DX camera (e.g. D90) you can shoot basically up to ISO 1600 without noise. Do you really need more than that? (wedding photographers I understand). How big do you have to print shots before you need the extra resolution? What benefits are there other than better extreme high ISO performance?

For me the desire to switch from a small sensor camera to a large has nothing to do with image sharpness. Its all about the low light capability. With Canon and Nikon both shooting at 12K ISO or higher with hardly any noise on their bigger sensor the difference is obvious.

 

[HB 4X4]

Lost Canadian,
I am not referring to the sensor when I refer to DX vs. FX lenses. I am referring to the glass itself, more specifically the main pro lenses. I do not even consider the lower end FX lenses when I speak of high end glass, because they aren't even worth mentioning. Aside from primes, FX lenses will generally be sharper since they are pro quality. The 17-55 is a sharp lens for a DX, however the 24-70 is still sharper. Then we have the 14-24 and 16-35 compared to lenses such as the 12-24. While the 12-24 is a great lens, it does not compare. The 70-200 is much sharper than any DX lens in it's range, and there is absolutely no competition there. Same goes for 200-400, etc.

You can't even get started on Macro's because the 105mm Nikkor is sharper than any 3rd party lens, let alone a DX lens equivalent.

The 35mm 1.8 DX lens is sharper than any 50mm 1.8, FX or otherwise. The 50mm 1.4 however is sharper than the 35mm.

Like I said, there are exceptions, but as a general blanket statement you can easily justify saying FX lenses are sharper than DX lenses.