Is DX superior to FX?

PB_PM

Camera equipment, the best weight loss program ever.

GreenFlash

The fact that the last two or three comments were about the qualities of beer does seem to indicate we have exhausted the subject.
So far the coolest thing I have gotten from this discussion is:from MickSlick:
http://www.michaelbrandtphotography.com/ca-coast-2014/#sthash.LWQ6fkOp.dpuf ... Taken with a dx camera, it's all the more impressive because a few of the shots are obviously low light situations.
I do really appreciate everyone's input because I personally have learned a lot about the situations in which each format may be better. Anyone reading the full discussion has to come away with a pretty good knowledge of the differences between the formats and the degree to which the added cost and weight of fx might be justified in their particular use.
Thanks everybody.

PB_PM

Tell me if I'm crazy...

Ok, you are crazy.

PB_PM

As for the issue you are having, it sounds like you are using the wrong lens for your style of shooting if you are always finding the focus points not where you want them. Not that I wouldn't mind if Nikon spread the points out (come on Nikon 51 AF points is so 2007), but even for portraits I've never found it so bad that I needed to heavily crop every shot to get what I wanted.

WestEndBoy

@PB_PM: yeah, you're prolly right.

You are not crazy. I run into the same issue when shooting portraits. It drives me crazy. I shoot in portrait mode, move the focus point to the very top, then waist 20 of the frame when I focus on the eyes.

At least the feet go to the bottom.......

WestEndBoy

Maybe Nikon doesn't think people focus outside of the centre. There is a logic to this given that lenses tend to be sharper in the centre.

PB_PM

There are other technical reasons as well. It allows them to make the AF sensor smaller, which reduces production costs.

SquamishPhoto

It's totally not a lens issue and I don't want focus points to dictate my style. If you want the head at the top of the frame... or worse, if you're shooting landscape using more or less the rule of thirds with the head at the top, you're basically screwed. The photo below is hard enough to frame in DX and basically impossible to frame with the D800. If shot wide open with focus on the eye on a D800, you're probably going to be left with a 10 megapixel file.

You may find using a manual focus lens in this situation often yields much better results. I know that the times I've taken my 85mm 1.4 with me and shot that way I missed many more shots than I would with the Zeiss.

WestEndBoy

There are other technical reasons as well. It allows them to make the AF sensor smaller, which reduces production costs.

This is a D800 that we are talking about, not a D610 or D7100 where serious compromises are required to contain cost.

PB_PM

The cost is not the technical reason. I do recall reading about it, but made no comment to the specifics, because I I don't have any links or specific data. If I recall correctly it had something to do with light fall off beyond the centre of the frame, and how that effects focus performance of phase detect systems. That would not effect DX cameras, since they only use the centre part of the lens.

Ade

I think you are all correct.

When talking about AF coverage, remember there are two dimensions -- height and width.

Let's assume a landscape orientation for a moment, as in @PitchBlack's image above and the D700 AF coverage illustration below:


(D700 coverage illustration from main blog)

In this orientation, the AF coverage height on a DSLR is largely determined by the geometry of the mirror box. There is actually a "sub-mirror" which reflects light to the AF sensor, and this sub-mirror can only be a certain height due to the clearances involved. So there is a physical limit on how high (or low) an AF point can be placed in the frame. It's simply not possible to cover the "rule of thirds" on an FX camera. On a DX camera, the same sized sub-mirror is proportionally larger vs. the sensor size, so the height (vertical) coverage is better.

The AF coverage width is not as constrained. I.e., you can make the sub-mirror as wide as the main mirror. This is why, as in the illustration above, there is more AF coverage horizontally vs. vertically. The limiting driver for horizontal coverage therefore is not geometry but cost.

In a mirrorless camera, we are no longer constrained by the sub-mirror geometry, so in theory full-frame AF coverage can be provided.

sevencrossing

. The only way to alleviate this is to back up and then crop generously. It's so wasteful..

Yes I sometimes do the same but I like the flexibly, cropping in post gives me
Most of my professional work, is for web sites and the webmaster likes some spare space round the subject, in case they want to add text or make a banner heading

For me, the very big advantage of FX is the ability to crop

Msmoto

Please allow me to chime in about my grumble regarding the four points and portraits. This will always be my reason why I sometimes manually focus as I can do the eyelash way outside the focus point area. Or, single servo, four and quickly reframe… With good light, manual seems to still be the best for me…. on the days my eyes are working…LOL

manhattanboy

Are you sure that it's FX that gives you a big advantage or the number of megapixels? You can have a higher resolution DX camera. And don't you think that the decision to leave space around a subject should be dictated by your creative decisions rather than the technical limitations of the camera? It's like the old joke that certain bugs in computer programs were called "features" by their developers.

Have you tried shooting the Nikon off of a cell phone? I know its crazy, but being able to two-finger enlarge and then touch an area for focus, all while being able to control the shutter and aperture easily may solve many of your focus problems. It slows down the work-flow as you'll need a tripod set-up, but spending more time with subjects like the one above is a problem I'd like to have!

sevencrossing

<=<i>Are you sure that it's FX that gives you a big advantage .

Yes, I have done real life comparisons, with my mates D7100

haroldp

To me there is also the question whether, when the pixels are made ever smaller, there is a point of dimishing returns. That is, is there a practical limit on pixel size on the sensors, below which sensor accuracy declines at more than a proportional pace?

I never dismiss the cleverness of new invention to blast through perceived barriers , but when pixel pitch gets to 1/2 wavelength of the longest red visible light (probably about .35 microns), things may get interesting. 1 micron gets us to about 320 mpx, for an FX sensor, that should hold us for awhile .

Lens grinders should get busy.

... H

Ade

@PitchBlack

Steve Jobs would never bother solving DSLR's AF coverage problem. That's a lot of wasted effort for a very incremental gain. Why bother? That's like trying to improve DOS.

What a Steve Jobs would do is declare the DSLR obsolete, throw out the legacy F-mount, and go mirrorless -- where there is no AF coverage limitations to begin with.

SquamishPhoto

I bet he would've looked at how to solve it, got some experts to show him how to do it quite easily and then he would've refused to do anything about it until its was too late. Oh, wait, thats his method for dealing with cancer, my bad.

donaldejose

Yes, we may see full area AF when the DSLR is replaced with a mirrorless body. Consider the latest AF on the Nikon 1 V3: 171 focus points.

manhattanboy

I'd love to spend more time with the lovely Ms. Chelsea, but I won't be crawling around on the floor shooting her if I'm tied to a tripod. Crawling around with her is the best part!

I could think of something else with her that is better, LOL

Yes, we may see full area AF when the DSLR is replaced with a mirrorless body. Consider the latest AF on the Nikon 1 V3: 171 focus points.

Some of the newer micro 4/3rds cameras have quite sophisticated face and eye auto-detect for focusing. This is definitely the future and I was watching this video
where basically the guy pits the top-of-the-line Nikon D4S against the mirrorless competition for autofocusing performance. The fact that the mirrorless even came close to the performance of the D4S should have Nikon management shaking in their boots (or more likely black shoes given the exec dress code in Japan).

sevencrossing

The fact that the mirrorless even came close to the performance of the D4S should have Nikon management shaking in their boots .

Coming close is not good enough

Digital took over from film, not when it was nearly as good but when it was an order of magnitude better

It remains to be seen who will bring out Mirrorless, that is an order of magnitude better than a DSLR but my money is on Nikon

The Nikon is not famous for producing the first SLR; it is famous for producing the best . Just compare an Exacta along side an Nikon F, to see what I mean . The Exacta had excellent specification, but it literally fell apart, even with only light studio use

haroldp

Coming close is not good enough

Digital took over from film, not when it was nearly as good but when it was an order of magnitude better

It remains to be seen who will bring out Mirrorless, that is an order of magnitude better than a DSLR but my money is on Nikon

The Nikon is not famous for producing the first SLR; it is famous for producing the best . Just compare an Exacta along side an Nikon F, to see what I mean . The Exacta had excellent specification, but it literally fell apart, even with only light studio use



Exacta was East German production, like Practica. While better than Russian production (try a Zorki sometimes), it was all crap, often built on prewar equipment.

Nikon 'f' did define the modern SLR and begin the trend because it was robust, and had great lenses for the time, some of which are still great lenses even in this time.

The modern trend in tech products is that more convenience will win if quality is 'good enough'.

While not up to D4s standards, mirrorless cameras incorporating phase detect elements on the sensor ( like fuji XT-1 ) are up to consumer / prosumer DSLR's in performance, and their DX lenses are better.

comparable DSLR's are much less expensive because of much higher production volumes, but the mirrorles is a less mechanically complex design with fewer parts and will ultimately be cheaper to produce.

... H

spraynpray

The fact that the mirrorless even came close to the performance of the D4S should have Nikon management shaking in their boots .

Coming close is not good enough

Oh yes it is. Don't forget what we are comparing in that vid. I'd like to have seen the mirrorless also compared to a DSLR of similar price bracket - then we would have seen how far along we really are.

sevencrossing

Sevencrossing Coming close is not good enough

S& P Oh yes it is

As in the past, we will have to agree to disagree

Mo Farah won the 10,000 m in the 2012 Olympics
The guy who came second, was close, very close, any one remember him name

Ade

But in many ways, mirrorless camera AF have already surpassed DSLRs.

See how Sony's AF works in this Gary Fong / Sony infomercial:



That kind of AF system is simply not practical in a DSLR. It's possible on mirrorless because the entire sensor area can be used for AF. I'd rather engineers innovate around this kind of advanced technology than fixing legacy AF coverage points.