I just got back from visiting the DPPreview forum after reading one of its posts.
The post stated, that when it comes to sports photography, with the lens mm. being equal, the camera with the cropped sensor has the advantage over the full frame camera because of its greater reach.
I know what my opinion is regarding this but I am very interested in hearing from you and what you have to say. The 'Yays" go to one side of the room and the "Nays" go to the other side.
John in NH
Yes and no. It's not as simple as that.
The cropped frame sensor doesn't have 'greater reach'. What it does is give you a tighter crop on the image give the appearance of greater reach.
That said, which is better comes down to pixel count. A Nikon D700 is a 12MP camera. It can shoot in FX and DX modes. In DX mode it's only a 5MP camera. So you can't do as much with that image as one from, say, a 12MP camera. You could do the same crop in post and you'd still have the same 5MP end result. Now, a D800 is a 36MP camera. In DX mode it's a 16MP camera. In that case, you could do more with that image than the 12MP camera referenced earlier but not as much as one of the new 20+MP APS-C sensored cameras.
None of that takes into account the other factors that play into the 'which is better' argument, such as dynamic range and noise. On those fronts the FX camera will be, generally, superior.
DPReview is good if you like long, drawn out shouting matches that play out along the lines of the old Miller Lite 'less filling, tastes great' commercials, or if you want über-fanboy type goings on, but not so good if you want actual information and fact; although in the rare instance you can find that there.
Almost the same could be said about full-frame vs half-frame 35mm film
formats. The half-frame format failed miserably, and thus it is surprising the
DX/APS digital is doing so well. But are two digital formats really needed?
Chan Tran, the resolution, i.e., sensor pixel density, does not depend on sensor
size: the same number of pixels squeezed per square millimeter on a DX
sensor may be put on an FX/APS-one. But the more you squeeze them, the
tinier, and noisier, they get and there's your choice.
I think that DX is a legacy format, a remnant of the early days of digital photography
when large sensors were too expensive to fabricate; in the mean time, as
'real photogs' craved 35mm film format and detested the nonsensical 'equivalent focal
lengths' gobbledygook, technology advance gave them a hand and nowadays they are
getting a prim and increasingly affordable 36x24mm.
And "full frame" sensors are still much more expensive to produce than DX sized sensors. Both sized sensors are cut out of the same sized wafer. So, if the wafer cost is constant, and I can get twice as many DX sensors out of a wafer than "Full Frame" sensors, then DX will always be less expensive. The question is when does the price point become acceptable to the masses. Right now, with the 6D at $2,000, I don't know if the common enthusiast is going to think full frame first when the T3i can be had for $500.
Also, the focal length issue is only an issue for folks on message boards yearning for an argument. No one cares anymore. You look through the viewfinder, compose your shot and snap the shutter. Even during my film days, I never thought about focal lengths in absolutes. It was always relative. I knew my 28mm was wider than my 50mm, but I never looked at a shot and thought "I need to set my zoom to 29.78mm to get the perfect composition.
Unless there is another revolution in photography, the DX format will be around long after both of us are dead and gone.
It's not the same as it was a few years ago though, Tom. Sensor makers have been able to increase pixel density and improve noise performance as well as dynamic range over previous models. They still don't perform, generally, as well as full frame sensors but the performance doesn't degrade the way we used to expect. The D7000 confounded those expectations.
As far as whether there's a need for both in the market; there are more than 2 sensor factors available in the interchangeable lens market and none seem likely to go away any time soon.
In response to the OP's original question, cropped or full frame sensor seems like a moot point to me.
Considering where most sports photos end up, either in printed magazines or newspapers or online, there is no real advantage from either.
Unless you are going to print large posters, the size of images in the aforementioned media aren't large enough to show much noticeable difference in resolution.
What seems most important to me is focus speed and frame rate, to be able to get the shots that capture the action and tell the story.
There are two pips in a beaut,
four beauts in a lulu,
eight lulus in doozy,
and sixteen doozies in a humdinger.
Nobody knows how many humdingers are in a lollapalooza.
I think that there will be a market for DX as long as it is significantly less expensive than FX. DX meets the needs of a large majority of amateurs, and for us there is no need to spend more for FX.