D500 confusion for sports

Welshy74

Welshy74

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A little confused with the release of the D500. I thought that with your camera you should look at great glass i.e FX lenses, meaning they are better than their DX equivalent. My question is that if you use FX lenses like I do 70-200 2.8 with my D7200 you arent getting the best out of the lens using a DX body. I will be in the future looking to upgrade to D750 or similar but as I shoot sports the higher fps is very appealing. Confused!!!!
 
You are getting the best from the lenses, in fact your camera is making the lenses work harder than if they were on an FX body as the DX sensor is applying a higher level of magnification (crop factor) through the glass from the start.

Probably best not to specifically think of them as FX lenses, they are lenses that work on both FX and DX.
 
But on the flip side, using FX glass on a DX body, you are using the best/sweetest part of the lens (the centre sections) as in most cases any IQ reduction occurs around the edges, which would show less on the smaller sensor DX body
 
rpsmith79 said:
But on the flip side, using FX glass on a DX body, you are using the best/sweetest part of the lens (the centre sections) as in most cases any IQ reduction occurs around the edges, which would show less on the smaller sensor DX body
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That can be a benefit of some lenses but I'm not sure how many super-telephoto togs are looking for edge to edge sharpness.

I think the mistake is to somehow think that FX lenses are intrinsically better than lenses for other sized sensors, that isn't necessarily the case.
 
Nawty said:
That can be a benefit of some lenses but I'm not sure how many super-telephoto togs are looking for edge to edge sharpness.

I think the mistake is to somehow think that FX lenses are intrinsically better than lenses for other sized sensors, that isn't necessarily the case.
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Yep, all depends what/which you're comparing. As rpsmith says though, if you have got really nice FX glass used on a DX body you are only using the best part of the 'best' glass so it's win win. Whilst I agree on telephotos edge to edge sharpness isn't critical, if you have it it's no bad thing :)
 
PERSONALLY, I've always had FF lenses and accepted the extra weight and redundancy of some of the image circle when used on Dx bodies. Mainly because I also used 35mm film for wider angles as well as the Dx bodies I had before FF was an affordable reality in DSLRs. I do have one Dx lens these days, an 18-200 which is on my V1 and FT1 adaptor and that has even more redundancy!

If there's any intention of upgrading to FF, IMO it's worth spending the extra on FF lenses and accepting the extra weight in order to avoid the added costs of upgrading lenses when the FF move comes along - the body cost is enough of a hit!
 
Nod said:
If there's any intention of upgrading to FF, IMO it's worth spending the extra on FF lenses and accepting the extra weight in order to avoid the added costs of upgrading lenses when the FF move comes along - the body cost is enough of a hit!
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I would disagree at the normal to wide end of the spectrum as the differences in size and weight (and useful FoV) are quite vast but the decision at the tele end is almost by default anyway if you want high quality lenses as the top of the line telephoto lenses are FF anyway.

But, each to their own :)
 
Nawty said:
I would disagree at the normal to wide end of the spectrum as the differences in size and weight (and useful FoV) are quite vast but the decision at the tele end is almost by default anyway if you want high quality lenses as the top of the line telephoto lenses are FF anyway.

But, each to their own :)
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I agree re the FOV. For example if I wanted a general walkabout lens I wouldn't want the 24-70 or 24-120 on a DX body as 36mm eq is not wide enough for me.
 
Welshy74 said:
Soooooo confusing
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Quite simple really, generally the worst part of a lens optically is the outer part so if you 'throw' this away then you would only be using the best part of the lens. This is essentially what you're doing by using an FX lens on a DX body as the image 'created' by an FX lens is bigger than the DX sensor so you are 'cropping' out the outer part of the image (hence the term crop body).
 
Nawty said:
I would disagree at the normal to wide end of the spectrum as the differences in size and weight (and useful FoV) are quite vast but the decision at the tele end is almost by default anyway if you want high quality lenses as the top of the line telephoto lenses are FF anyway.

But, each to their own :)
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snerkler said:
I agree re the FOV. For example if I wanted a general walkabout lens I wouldn't want the 24-70 or 24-120 on a DX body as 36mm eq is not wide enough for me.
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For me neither, which is why I have a 12-24 and an 8mm fisheye for FF.
For sports (as per the OP's OP), I wouldn't want a 24-? unless I was doing a paddock walk, although at our local hillclimb (Wiscombe Park), 120mm is long enough for frame filling pans (actually, 24mm is too on occasion).
 
Nod said:
For me neither, which is why I have a 12-24 and an 8mm fisheye for FF.
For sports (as per the OP's OP), I wouldn't want a 24-? unless I was doing a paddock walk, although at our local hillclimb (Wiscombe Park), 120mm is long enough for frame filling pans (actually, 24mm is too on occasion).
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I wasn't suggesting a 24-? for sports, just that it's not always best to go out and buy FF glass as there are other factors to consider, and used a walkabout lens as an example :p
 
snerkler said:
Quite simple really, generally the worst part of a lens optically is the outer part so if you 'throw' this away then you would only be using the best part of the lens. This is essentially what you're doing by using an FX lens on a DX body as the image 'created' by an FX lens is bigger than the DX sensor so you are 'cropping' out the outer part of the image (hence the term crop body).
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That sums it up nicely !
 
Nawty said:
It's simple really :)

To answer your question, yes you are getting the best from the 70-200 lens with the D7200.
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Apart from the effective focal length ;) I personally find the focal length absolutely spot on for a wide range of subjects, but for me the wide end is too long on a crop body. Only Sigma have attempted to deal with the issue by introducing APS-C specific zooms in that range.
 
snerkler said:
Quite simple really, generally the worst part of a lens optically is the outer part so if you 'throw' this away then you would only be using the best part of the lens. This is essentially what you're doing by using an FX lens on a DX body as the image 'created' by an FX lens is bigger than the DX sensor so you are 'cropping' out the outer part of the image (hence the term crop body).
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It doesn't really work like that though. You could equally argue that because the DX lens doesn't have to worry about a bigger image circle, it only uses the sweet spot anyway. In practise, there's evidence of that happening, but designers usually trade the substantial benefit of a smaller image circle against a number of things, not just sharpness - like wider zoom range, or faster aperture or lower cost. Plenty of examples of all those things in DX lenses. The answer really is, it depends.

What is certainly true though, as mentioned by Ned, is the higher resolution demands of DX. So if you put an FX lens on a DX camera, sharpness in the centre will always be lower. What happens towards the edges is less predictable (depends on how the various swings and roundabouts balance out) but on the whole FX wins that one, too.
 
HoppyUK said:
It doesn't really work like that though. You could equally argue that because the DX lens doesn't have to worry about a bigger image circle, it only uses the sweet spot anyway. In practise, there's evidence of that happening, but designers usually trade the substantial benefit of a smaller image circle against a number of things, not just sharpness - like wider zoom range, or faster aperture or lower cost. Plenty of examples of all those things in DX lenses. The answer really is, it depends.
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Not sure I agree with this, or we're talking about different things. Why would a DX lens only be using the sweet spot, it uses the full lens (near enough) just like FX on a FF body.
What is certainly true though, as mentioned by Ned, is the higher resolution demands of DX. So if you put an FX lens on a DX camera, sharpness in the centre will always be lower. What happens towards the edges is less predictable (depends on how the various swings and roundabouts balance out) but on the whole FX wins that one, too.
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now this is something that I'm struggling to get my head around. I understand that if you take an image and then crop it you're losing resolution and therefore sharpness, but what I don't understand is why crop sensors put more demands on a lens? I get that it's more 'zoomed' in but don't understand why this would affect resolution and sharpness?
(Not arguing here by the way, genuinely interested)
 
snerkler said:
I get that it's more 'zoomed' in but don't understand why this would affect resolution and sharpness?
(Not arguing here by the way, genuinely interested)
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Theres several factors. Pixel size is one and smaller pixels have higher resolution (potential) with lower contrast... think of it as a 500% pixel view. A single large pixel will stand out more than the same detail composed of numerous pixels. And our perception of "sharpness" is heavily biased by perceived contrast. Smaller sensors generally have smaller pixels.
The other primary factor is "stretching." A smaller sensor has to be physically enlarged more to generate the same size image. And a "detail" can only be enlarged to a certain extent before it stops looking sharp. That's why smaller sensors have a more restrictive COC standard.
 
sk66 said:
Theres several factors. Pixel size is one and smaller pixels have higher resolution (potential) with lower contrast... think of it as a 500% pixel view. A single large pixel will stand out more than the same detail composed of numerous pixels. And our perception of "sharpness" is heavily biased by perceived contrast. Smaller sensors generally have smaller pixels.
The other primary factor is "stretching." A smaller sensor has to be physically enlarged more to generate the same size image. And a "detail" can only be enlarged to a certain extent before it stops looking sharp. That's why smaller sensors have a more restrictive COC standard.
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Thanks. I get the stretching bit, but in the first paragraph you say that crop have smaller pixels and therefore better resolution capacity, but doesn't better resolution result in better perceived sharpness?
 
It's the reduced contrast of the smaller pixels that reduces the perceived sharpness... Basically, just think of it as the available contrast (of a detail) divided by the number of pixels resolving it.
 
snerkler said:
Not sure I agree with this, or we're talking about different things. Why would a DX lens only be using the sweet spot, it uses the full lens (near enough) just like FX on a FF body.
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Simply this: yes, lenses are always less sharp towards the edges of the field, and the larger the format, the greater the fall-off (very generally). With DX lenses, the designer doesn't have to worry about the extra coverage outside the APS-C image area, but the higher sharpness closer to the centre is still there. The best DX lenses are very sharp, with less fall-off across the frame, even more so with some M4/3 lenses.

now this is something that I'm struggling to get my head around. I understand that if you take an image and then crop it you're losing resolution and therefore sharpness, but what I don't understand is why crop sensors put more demands on a lens? I get that it's more 'zoomed' in but don't understand why this would affect resolution and sharpness?
(Not arguing here by the way, genuinely interested)
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Contrary to popular belief, pixels are not a major factor here (within reason). 'Sharpness' is about the relationship between resolution (the fineness of detail) and contrast (how clearly those details are rendered). Of the two, it is contrast that plays the bigger part in our visual perception of sharpness. Resolution and contrast are the two axes of an MTF graph (Modulation Transfer Function - your link) and there's one fundamental fact of physics at play: as resolution goes up, so contrast goes down. See any MTF graph where performance at different resolutions is shown.

It's like a car that accelerates from 0-60 in six seconds, but takes a heck of a lot longer to get from 60-120. The more you want, the harder it gets.

With full-frame vs APS-C (FX vs DX), FF has to be enlarged less for a given size output/print. The difference is the crop factor, and in resolution terms, it means that to achieve the same standard of sharpness the APS-C lens has to deliver the same level of contrast at, say, 36-lines-per-mm as the FF lens does at 24-lpmm (24x1.5=36). That doesn't happen, and that's why FF is sharper than APS-C, which is sharper than M4/3, which is sharper than smaller formats etc etc.
 
More simplistic evidence of this is that if you look at the sharpening tool in any PP software, it doesn't somehow magically make your lens resolve finer detail, it increases contrast at edges.
 
Nod said:
If there's any intention of upgrading to FF, IMO it's worth spending the extra on FF lenses and accepting the extra weight in order to avoid the added costs of upgrading lenses when the FF move comes along - the body cost is enough of a hit!
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There are no long telephoto lenses that are DX / crop only. It's mainly just the short / mid zooms and UWA lenses.

You'll find anything over 250mm will be a full frame lens anyway!
 
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Welshy74 said:
Thanks all. Think I will upgrade to the D500 this year once its been used for a couple of months. Interesting though that a D810 is now selling at the same price. New D810 maybe????
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The crop mode of the D810 is what? 16mp and the D500 is 20mp? so not really anything in them in terms of resolution so it depends if the other features suit your needs.
 
HoppyUK said:
Contrary to popular belief, pixels are not a major factor here (within reason).
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Confusing statement (at least to me). Pixels *are* a major factor as smaller is higher resolution with lower contrast... which is what the rest says.

Unless you meant that *increased resolution* (above a reasonable minimum ~12MP) isn't a big factor in increasing sharpness... I would agree with that.
 
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Nawty said:
The crop mode of the D810 is what? 16mp and the D500 is 20mp? so not really anything in them in terms of resolution so it depends if the other features suit your needs.
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I wouldn't say that a 25% increase isn't anything... The real issue is that you will almost never be able to take advantage of it when photographing wildlife.
 
sk66 said:
I wouldn't say that a 25% increase isn't anything... The real issue is that you will almost never be able to take advantage of it when photographing wildlife.
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That's total image area though so the actual image size only increases by 15% or so, not something I would be overly concerned about to be honest, the difference in other features would be far more of a deciding factor.
 
Nawty said:
More simplistic evidence of this is that if you look at the sharpening tool in any PP software, it doesn't somehow magically make your lens resolve finer detail, it increases contrast at edges.
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Yes, and when pushed right up, it actually draws a line around the edges. You see that a lot in TV pictures.

And then there's 'contrast-detect' AF that doesn't look for fine detail, but simply looks for the focus point where the dark tones are darkest and the lighter tones are brightest - that's the position of maximum contrast and maximum sharpness.
 
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sk66 said:
Confusing statement (at least to me). Pixels *are* a major factor as smaller is higher resolution with lower contrast... which is what the rest says.

Unless you meant that *increased resolution* (above a reasonable minimum ~12MP) isn't a big factor in increasing sharpness... I would agree with that.
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Yes, as per your second sentence. I said, "pixels are not a major factor here (within reason)."

The point about pixels is not that they don't matter, but they're not the most significant contributor to sharpness, as many people believe. The main driver is the improved lens MTF performance that is the direct result of a larger sensor format. Bigger is better* and always has been in terms of image quality. We didn't have any problem with that concept when shooting film, and digital hasn't changed that, even when the smaller sensor has the same number of pixels (or sometimes more!).

*with improved ISO performance and dynamic range, too - both also derived from the larger sensor area.
 
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