2015 Roundup: High-end Interchangeable Lens Cameras $2000+

I do not really understand the question... The idea of a 200% crop is to show the detail achieved by a camera, or to check whether you focused well... If you use Adobe Bridge, it will also show you 200% enlargements if you click on a photo...

100% magnification displays a part of the image at a resolution that one pixel in the image matches one pixel on your screen. This is the maximum magnification that gives you any sensible information about sharpness. At 200% you already see individual pixels in your image, and there is no point to that. You cannot judge sharpness any better in a 200% crop compared to a 100% crop.

Cause there are lots of Nikon glass, excellent by the way, for Nikon. The Sony Zeiss glass has issues, in my experience, usability wise.

You mean the D4S and 1DX?

Close. I meant the 1Dx and the 5Ds

You're just right, Rishi.

2.8 zooms are not even necessary for wedding photographers anymore. I have 2 stops of low light flex with my a7s for weddings now vs even higher end bodies. Also at f4 i am able to grab group shots too.

So do you find that f4 lenses on the a7s work pretty well in low-light? I shoot mostly in low-light situations (concerts, mostly) and have been considering switching from the 5DMkiii to one of the Sonys, but I'm worried about the lack of 2.8 zooms, since I shoot almost exclusively wide open at 2.8 and that's often barely enough light.

@grock, i hear your pain. for indoor evening concerts, some are pretty well lit and AF with 2.8 are fine. for some of the indie w/ a few spot lights, f1.4 helps alot. what f1.4 got me was when subject is oof and it is dim, the af still hunt; lack of contrast. the lens suppose to render the beautiful bokeh tuns out to slow down my work in terms of getting the AF. That's when a little of manual focus guiding the camera save some of my shots. what really helps is the focus assist beams from the flash, but, i don't have a heart to interrupt the concert with my beam. happy shooting. :)

Constant f/4 is not consistent with consumer glass. Why? I think the reason is weight concern. Many attracted to mirrorless models are looking for a lighter bag. If filled with f/2.8 the Sony 1lb advantage becomes irrelevant.
I'm under the impression Canon f/2.8 glass works well with an adapter.

Currently SAR notes that the all-new fast 24-70/2.8 FE GM lens would be out next March. So 2.8 Zoom lovers would have their native FE lens...otherwise they could still use the excellent 24-70/2.8 L II, if money is not an issue to those who use it professional.

One could say equally that f2.8 lenses inhibit IQ compared to carrying a pair of bodies with lightweight, fast primes. No switching time required, sharper optics, and 1-2 stops lower ISO for the same shutter speed, with a total weight that is no greater than a single body with an f2.8 zoom.

Sounds like you've made a really strong argument for the fast primes, Teila.

Interestingly in Rishi's exhaustive test of the D750 during it's review, no mention was made of shutter shock, indeed they wax lyrical about it being one of the finest still cameras ever.
I have over 10000 shots on mine and have yet to notice this shutter shock. It's obviously there, hence the hardware update, but I certainly would not call it any kind of issue, either serious or minor.

@dM photography: the 200% crop is frighteningly sharp, in an admiring way. :)

@forpetessake, @ilza, I was replying to @RichRMA and I meant situations where everything else is equal, especially sensor size and brightness of the image. In that case, T-number (~F-number) determines the shutter speed (or brightness, if sensor size and shutter speeds are equal). I was trying to say exactly the same as ilza did. I'm glad that this was clarified.

@Jonathan thanks!! Yes frightening and with a consequence: having to use Photoshop in a more systematic way

People should stop trying to bend the laws of physics to fit their views on sensor size.

@RRMA:

The question is not as easy as this. There are many variables, and people are not aware of how to combine them — or omit important factors. For example, you yourself wrote

> A 100mm f/2.0 lens gathers more light than a 50mm f/1.4 lens

which is patently wrong as far as one discusses sensors of similar formfactors. (But this is correct if one compares sensors differing 2x in linear size — so the angles of view are the same.)

The fact that “f-number matters” is burned deep in people’s minds from the film time — when it WAS correct. Only few understand that NOW the only 2 things which matter are the angle of view, and the entry pupil. (Assuming optical quality is similar.)

Going back to 645: this and 35mm ARE very similar sensor formfactors. So, as far as I can see, the OP is correct.

Also, since some lenses grossly vignette leaving the edges of the image sometimes two stops darker this impacts overall light gathering as well.

I think this is the answer:

The total amount of light captured by the sensor is proportional to the sensor area multiplied by the shutter duration and then divided by the F-number. FF sensor area is 860mm2, 645Z sensor area is 1452mm2.

Here are two other interesting formulas:

Effective focal length = Physical focal length x Crop factor

Effective F-number = Physical F-number x Crop factor

The effective F-number is only relevant for determining the depth-of-field. FF crop factor is 1, APS-C crop factor is 1.5 or 1.6, 645Z crop factor is 0.78

Correction:
The total amount of light captured by the sensor is proportional to the sensor area multiplied by the shutter duration and then divided by THE SQUARE of the F-number. FF sensor area is 860mm2, 645Z sensor area is 1452mm2.

Does this make sense?

There are two different situations to look at when looking at the light-gathering ability of a camera system:
(1) The light (or rather shutter speed)-constrained situation. There, sensor diagonal times maximum f-stop (for a given AOV) matters and the Pentax looses out to FF with f/1.4 (or even faster lenses).
(2) A situation without shutter speed constraints. There, the sensor diagonal divided by the square root of the ratio of the base ISO values.

If you can expose as long as you want because you have a static subject (or if the shutter speed at base ISO and the desired DOF/f-stop is short enough to not result in any noticeable blur), the maximum f-stop of the lens doesn't matter anymore. Only the sensor size, its base ISO value and of course the sensor performance in terms of QE and read noise.

But even here, the ISO 64 of the D810 might cause it to match the 645Z. And if you have a static subject and a tripod, you can also merge multiple exposures to simulate a lower base ISO.

@IDM:

> Effective F-number = Physical F-number x Crop factor
> The effective F-number is only relevant for determining the depth-of-field.

This is tricky — again! Dof ALSO depends on the field of view. (And distance to the subject.)

Moreover, your “effective” is better written as “35mm equivalent”.

Ilya

@Richard:

> 35mm F2 lens on FF is equivalent to approx. a 45mm F2.8 lens on Pentax

Make it “F2.5 lens on Pentax”.

My math came out to 2.6 and I did say *approximately*.

To take this back to photographically-relevant terms, our point was that when you can give the camera the extra light, for example in landscape or studio scenarios where you can control the exposure typically to your heart's content, the 645Z will allow for more total light capture. This leads to higher total signal:noise ratio, yielding better images generally. The only real exception being the stellar Nikon D810 and its ISO 64 ability that effectively allows it to capture more total light than any other full frame DSLR.

@Rishi: you may think that 645Z dynamic range would be much better than any FF camera, but it isn't. According to DR measurements the Pentax is just ~0.15 stop better than Sony A7R or Nikon D810.

Phrases like 'give the camera the extra light' do not help anyone.

@forpetessake
It's true, the Pentax 645Z does not offer a better dynamic Range than D810 or A7RII but more resolution. The Canon 5DS/5DS R offers a similar resolution but sacrifying the dynamic range.

Dynamic range essentially tells how much noise you have in the shadows (with a lot of caveats). But two cameras could have the same shadow noise while one of them has a higher SNR in medium tones. And I think that is the case here with the 645Z (and the D810 due to its lower base ISO). But the A7r II is also doing something fancy here, reaching about the same SNR for 18% grey (as of DxO) at its higher base ISO as achieved by the D810; maybe BSI has something to do with it.

@fence sitter
It's not true that way, because the sensor of the 645Z is much bigger then a simple "FF" 36x24mm Sensor...so it does capture much more photons then a FF sensor, the MF sensor inside the 645Z, and you can't compare the cropfactor too, FF is x1.0, whileas the 645 Pentax DSLR is x0.78 "Crop".
(Sensor size: 33x44mm, which is much larger then 36x24 FF.)
by laws of physics, that sensor gathers anyway much more photons because of sensor-surface area, and doesn't need that faster glas like FF, because it is bigger anyway, capturing more light into the same time.

This is interesting. There seems to be different discussions going on and points made.

To help better clarify what is being describe on "light gathering", effective F stop and etc.
Is it possible, we would agree on one simple thing.
For natural light photography, if a calibrated light meter read the following settings for proper exposure:
ISO 100, shutter speed 1/100 sec, aperture F16.
the aps-s camera, the FF, the 645, the 6x7, and the 8x10 film will use the same setting across the different medium size regardless of the focal length, say on a 28mm FF to 150mm FF.
If not, why not?

If so, how does the field of view, effective f stop, and light gathering/cm square come into the place? Or what was the point from the dear readers?

BTW, I do notice my a 80mmF2.8 on a 6x6 MF has a slightly shallower DOF than a 50mm F2.8 in a FF. But both format use the same setting as from the light meter to get proper exposure.

Thanks in advance for clarifying the points discussed.

@Jonathan Lee: Just two points to help with your confusion: 1) ISO is not part of the exposure; 2) equivalent lenses with FL*cf, Fstop*cf, and therefore the same physical aperture (where cf is crop factor) produce the same DOF, FOV, photon noise on any format. That's why people commented on the fact that slow lenses on 645Z make it lag the modern FF cameras in everything but 0.15 stops of DR and possibly resolution.

This place isn't really suitable for discussions or arguments, but doing a little web search should provide you with plenty of references.

@forpetessake
I agree on what you mention regarding FL*cf and Fstop*cf calculations (same DOF and FOV), but photon noise should be lower with a larger sensor, or not?
The 645Z lenses are comparatively slow because they were designed for film cameras as well (60mm x 45mm) and in my opinion Pentax will produce in the future a medium format camera with that sensor's dimension, so 80% larger than the current sensor that is 70% larger than FF. With such a larger sensor the crop factor would be 0.57 and the Effective F-ratio (or 35mm equivalent F-ratio) would be 1.6, almost 1.4 which is standard in FF.

@Jonathen Lee
It's the same when you compare DoF with APS-C/DX and FF cameras, the DoF on FF is more shallow than onto (here) there smaller APS-C/DX size sensor.

@Rishi:

when shown that the argument in the review does not make sense (the photon-capturing ability of the LENSES is NOT better for Pentax 645), you just change the subject (and consider the photon-capturing ability of the SENSOR). AND: what you write does not NECESSARILY make sense either.

For a sensor, the photon- (or, what makes more sense, electron-) capturing ability is the total full well of all the sensels. Indeed, WITH SIMILAR DESIGN of sensels, this may be better for larger sensor. However, this is not NECESSARILY so, since the full well depends very strongly on the design, and it is easier to have a more advanced design on a smaller sensor.

Which boils down to: do you KNOW the total full well of FF and 645 sensors?

Ilya

Well, I'd say it's a pretty good bet the full well capacity of pixels in a much larger sensor are going to be...larger with the same pixel count, right?

And I am discussing the fact that for all we know, the 645Z very likely has a higher saturation capacity than (almost) all FF cameras. All the evidence we have (from PDR over sensor age and make to qualitative reports by serious people) is consistent with that assumption and there is no evidence that would indicate the opposite.

And it is worth discussing because that 'higher saturation capacity' was the original point of contention. Settle that and all other discussions become moot.

@ marc petzold. You know it is an interesting comparison of

a) DOF between *different* focal length 80mm@f2.8 (on one step larger format) vs. 50mm@f2.8 (FF) and

b) DOF of a same focal length of 50mmf2.8 on a FF vs APS-C.

does anyone have some visuals to show both cases?

this is getting fun. lol

Have at it:

http://www.dofmaster.com/dofjs.html

@RichRMA thanks for the linky.

it says for a
Film - 35mm @ 50mm, f2.8, 2ft subject camera distance, the DOF has a total .08 ft

Film - APS with the same focal length, apt, distance, the total DOF is .06 ft, which is narrower.

the smaller senor using the 50mm is getting shallower DOF by that website. will ppl flockin back to APSC cam, now?

hum... i am in a circle of confusion by the numbers and need a drink.

nite.

@Jonathan Lee. The reason behind the shallower DOF for APS-C is that you need to magnify the image more to get the same print size. Personally I have never understood the physics behind this, and IMHO the "equivalence" used e.g. here in DPreview is against this. There is a Wikipedia article about this and the equations are there, but it does not explain the phenomena.

Edit.: I suspect that those DOF-calculators and the Wikipedia are wrong. There are 1000 threads about equivalence on DPR, I have read maybe 15, but I'm still pretty clueless.

First, look at a narrow (laser?) ray entering the eye — where would it LOOK coming from? ANSWER: from the point P where this ray intersects “the plane at distance 3.5m”. (The ray would light one point on the retina — the image of the piont P.)

Now put a point source S at distance 4m. Which light rays from it enter the eye? A whole cone of rays connecting the source with the entry pupil (of diameter 2mm). Where these rays intersect “the plane at distance 3.5m”? In a circle of radius 0.25mm = 2mm * 0.5m/4m. THIS IS THE CIRCLE OF CONFUSION!

In other words: the image (bokeh!) of the point S is exactly the same as the image of the circle of radius 0.25mm on the focus plane.      AND: to find this, ALL we needed was the entry pupil!

ToBeConted…

So: when we focus at 3.5m, and subject is at 4m, the defocus circle of confusion is 0.25mm (at distance of 3.5m). One needs to move the subject to 8m to grow the defocus circle of confusion up to 1mm — the size of the diffraction circle of confusion.

Likewise, same happens when one moves the subject to distance 2.33m. So depth of focus is 2.3m–8m (with the best COMBINED [diffraction+defocus] circle of confusion 1mm, worst about 1.5mm — both mapped to distance 3.5m).

    Above, “mapped” means: the same angular size
    as “this circle” “at this distance”.

ilza described Circle of Confusion very well. here is the illustrated version : https://www.youtube.com/watch?v=Pdq65lEYFOM

and DOF: https://www.youtube.com/watch?v=mFf6zhbhI8Y

I think i've had posted this some months or years ago, cambridge in colour is a way good ressource to this, and also to explain the CIC (circle of confusion, airy disk) together with what diffraction is, here:

http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

thank you, marc!

@ilza, What are the metrics of entry pupil? How it is defined?

@shadowfax Without any specific complaints it's difficult to see where you're coming from, but many people regard the D810 as a huge step up from the D800 despite the modest on-paper differences.

Certainly, placing the deeply flawed D610 above the D810 leaves me scratching my head.

He listed the D800 not the D810. Ranking the D6x0/D750 above the D800 he was dissatisfied with isn't so strange. The D800 was built for resolution and compromised quite a bit to obtain it. The D610 makes some compromises to cut costs, but is still - I agree with the above - a "very capable" camera for the price.

um... you still haven't told us what it is about the D800 you don't like.

I hope sony read the user comments and try to improve on next products. or if possible start by firmware upgrade first

@neatpicture
Something is wrong with your a7rII or your adapter is causing problems. I'm using all native lenses and the camera has yet to freeze on me.
With 5DIII, 5DII and 6D, it would freeze on several occasions even with L lenses. Of course removing the battery did the trick, but I don't believe that Sony is any worse.

@ JLim22
1) Sony needs to rebuilt card database every so often
2) My A7RII has problems on writing to card when I push it in fast paced shoots and filling the buffer
Most Canon errors are caused from poor lens/camera connection most of the time because the electrical connections are not clean. Also, my 2 months old A7RII is already showing more wear than my 2 years old 1DX.

@ PVCdroid
if you want to do pro work Sony hardly offers adequate lens selection.

It's a phenomenon that was highlighted with the new high resolution cameras. They only started testing for this recently so they probably didn't test for this on the D610.

Since they've put the D750 in the same category as the hogh res cameras they had to mention it so you can compare them in this regard although D750 doesn't suffer from it that much because of the lower resolution.

Ok so link me to your article about a7rii and leica lenses please.

@EthanP99
You can do go search yourself. Iit is not a secret it is a widely known fact. Even in the site you pointed out that he refers to a standard lens 35mm as wide and that there are no issues. Except that he forgets to really mention wide lenses.....

So you have no proof in a7rii and leica wide lenses. Ok got it.

Because it´s not about "doing photography" - it´s about talking about photography, battling opinions about photography etc. I bet that many people don´t actually own and use the cameras they are talking about on the internet and even if they buy a camera, they don´t really "shoot and enjoy" it - what they do is reading and talking about it and trying to confirm that their buying decision was right and that they made the best use of their money. They identify somehow with the camera and brand and group and oh... I feel sick, sorry - have to stop or I´ll puke.

After six high end bodies it was about a damn time. Wait, it's not even announced yet:-(
(Sony a7 shooter here)