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Forums > Back > D7000 lens tests? Implications of high MP density sensor on lens choices?
#1
A few related things I'm wondering about:

[size="2"](particularly since Marcus posting yesterday that you'd "like the D7000 to have a bit less resolution, as some lenses struggle near the borders...")[/size]



  1. If there are any plans to start testing on the D7000? (I noticed you've been testing at 15MP on Canon APS-C for quite a while.)



  2. What would be the effect on resolution figures from a given lens tested on two different APS-C sensors?



  3. What are the implications for D7000 owners re lens choices? Other than "buy the best you can afford", is there a sort of 'cut-off' point in resolution below which it's not worth buying, because the image quality probably won't be acceptable to most people (who've bought the camera), although I appreciate that's subjective.

    How applicable are the test results from one (APS-C) sensor to another?

    I thought I could use both the Nikon D200 and the Canon 15MP (for third-party lenses) APS-C tests for choosing lenses, weighted on the basis of optical quality.

    Now, I'm a bit confused (again...!) <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />






I haven't worked out how all the variables interact, though I think I almost understand some of Wim's post a while back..! <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/huh.gif' class='bbc_emoticon' alt='Huh' />



[quote name='wim' timestamp='1287530403' post='3699']

...

1) Lens quality.

The best lenses out there, generally are diffraction limited by about F/4. Think the best Zeiss glass, Canon L primes, the Nikon professional range, the better Sony (Zeiss) glass. This means that these lenses will resolve right to the physical limit possible, which is about 400 lp/mm (line pairs per mm) at F/4, and the criterion being the Rayleigh criterion, which states that this is at 9% contrast, IOW, much less than the 50% MTFs we are looking at from manufacturers, but resulting in higher resolution than on those 50% charts. Do note that "lesser" lenses may not be diffraction limited, but modern prosumer lenses are often close anyway. 250 lp/mm is considered to be excellent.



2) Sensor, or medium (film, sensor, whatever) resolution.

The higher the number of pixels or silver halide crystals or photon counters, or whatever per square unit of area, the higher the resolution...

Do note that final negative or RAW resolution is inversely proportional to the inverse individual resolutions of sensor and glass, or if said in a different way, 1 / total recorded resolution equals the sum of 1 / lens resolution at a specific f-stop + 1 / maximum recording resolution. You can express this in pixels per image height, as is done on this site, or in lines / mm, or as we used to do in the past, lp/mm, as one needs a minimum of 2 lines in order to depict an edge or line.



Due to the nature of the above formula, it follows that in order to get out the maximum of the one element in that formula, resolution needs to be infinite for the other component...

...Note that for a 200 lp/mm end result, we need both the lens and sensor being capable of resolving 400 lp/mm, as follows from the formula above. If you work it out, we are talking here about a ~550 MP sensor in that case. Since we are still rather far from such resolutions, I do think we stil have along way ahead before we even get close.



...Finally, at these resolutions it becomes increasingly impossible to get the ultimate sharpness from the negative, whether RAW or film, for the simple reason that the smallest of vibrations or of deviation from perfect focus WILL influence the end result much more than an increase in resolutions, as is already being experienced by medium format shooters at 50 and 60 MP. You'll need heavy tripods, MLU, remote switches, etc. to get the most out of the system.



...

HTH, kind regards, Wim

[/quote]
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#2
[quote name='IanCD' timestamp='1299877494' post='6681']

A few related things I'm wondering about:

[size="2"](particularly since Marcus posting yesterday that you'd "like the D7000 to have a bit less resolution, as some lenses struggle near the borders...")[/size]

[/quote]

I like new sports cars to have a slightly lower top speed because most roads aren't good enough for those kinds of speeds.



GTW
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#3
As you can see (from the Canon EOS 350D 8mp and Canon EOS 50D 15mp tests, There will not be a big difference how lenses perform on a D7000 and on a D200. Only when resolving power on the D200 is very low you will start to see a bigger impact with the higher res. D7000.





And that is only when you pixel peep, for printed images on a similar size there will be no difference at all.



So, don't worry in any way about choosing lenses for a 16mp D7000 or whatever, you can use the D200 tests to determine if a lens offers what you think is important. And you can even use the 350D and 50D tests where it is a 3rd party lens, the crop factor difference is very small.
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#4
[quote name='genotypewriter' timestamp='1299897457' post='6682']

I like new sports cars to have a slightly lower top speed because most roads aren't good enough for those kinds of speeds.

[/quote]



There is probably more truth in that comparison than you intended. If I was looking for a sports car, than the thing that would be least important to me is top speed. I'd care more about acceleration and traction, curve speed, response, etc.



-- Markus
Editor
opticallimits.com

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#5
[quote name='Genotypewriter']

12 March 2011 - 02:37 AM

I like new sports cars to have a slightly lower top speed because most roads aren't good enough for those kinds of speeds.

[/quote]

[quote name='mst']

There is probably more truth in that comparison than you intended. If I was looking for a sports car, than the thing that would be least important to me is top speed. I'd care more about acceleration and traction, curve speed, response, etc.

-- Markus

[/quote]

Ok, now that little exchange isn't very helpful... I always have struggled with analogies..!! <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='Wink' /> <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />



So, are there any plans for D7000 tests, Markus?



BC: Thanks.

So where a lens is showing low resolution, eg at corners, on the D200 (or on the Canon APS-C tests), I'm going to see a bigger impact on the D7000.



Ok so far...

Not at print sizes, though? I was wondering where the cutoff is... e.g., the 35mm 1.8G DX has a score of 1545 at f1.8 at the corners.

I've bought a couple of fast primes for low-light (gigs). It's likely that if I added this, I'd often be using it wide open. And I might sometimes want to crop or print at A3.



So, I was trying to get a feel for a potential 'cutoff' point on the D7000 (given Markus's point)... and also trying to understand a bit better the relationship between lens and sensor resolution, sensor size, the 'sweet spot' effect of using FF lenses on DX sensors... and other factors that impact... for my crash course in this field..!

Ian
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#6
[quote name='IanCD' timestamp='1299952802' post='6697']

Ok, now that little exchange isn't very helpful... I always have struggled with analogies..!! <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='Wink' /> <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' /> [/quote]



Sorry <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='Wink' />



[quote name='IanCD' timestamp='1299952802' post='6697']

So, are there any plans for D7000 tests, Markus?

[/quote]



Yes, there are. I'm currently spending most of my time in the lab, measuring, mostly with the D7000.



I'll try to get some reviews written, soon.



-- Markus
Editor
opticallimits.com

  Reply
#7
[quote name='mst' timestamp='1299955519' post='6698']

Yes, there are. I'm currently spending most of my time in the lab, measuring, mostly with the D7000.



I'll try to get some reviews written, soon.



-- Markus

[/quote]

Great! Thanks, Markus <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />



Following up on the 'cutoff' issue... It seemed like a good plan to stick to lenses which get 4* or more for optical quality...

The Nikon 35mm 1.8G DX makes that, but the extreme borders have lower resolution, and I wondered if that would be the sort of performance which you'd seen struggle on the D7000?

(I just checked out the Sigma 30mm which clearly doesn't make it at all..!)

Ian
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#8
[quote name='mst' timestamp='1299955519' post='6698']

Sorry <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='Wink' />







Yes, there are. I'm currently spending most of my time in the lab, measuring, mostly with the D7000.



I'll try to get some reviews written, soon.



-- Markus

[/quote]



And, what are you seeing? Any lenses which were lemons on the D200 performing exceptionally on the D7000? Sorry to be cynic here, but I think that is the key question. Are there any severe repositionings? I assume not. Lenses which performed great on the D200 will continue to do so, and those being lemons on the D200 will not shine on the D7000.



Upgrading your equipment from the D200 to the D7000 seems worthwhile, though I expect there is little point in reassessing much of what has been measured on the D200 in the past years with the D7000.



You have any dead/hot pixels on your D7000?



Greetings J.
enjoy
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#9
[quote name='IanCD' timestamp='1299955863' post='6699']

Great! Thanks, Markus <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />



Following up on the 'cutoff' issue... It seemed like a good plan to stick to lenses which get 4* or more for optical quality...

The Nikon 35mm 1.8G DX makes that, but the extreme borders have lower resolution, and I wondered if that would be the sort of performance which you'd seen struggle on the D7000?

(I just checked out the Sigma 30mm which clearly doesn't make it at all..!)

Ian

[/quote]

Corners for a prime wide open are not very important at all. The DOF will be so shallow that you almost never will look for "sharp corners".



Corner sharpness tends to be more important with landscape stuff, with bigger DOF and with wide angle. With shallow DOF, you almost never are dealing with a flat subject. And unless the subject is strangely in the corner, you simply will not have a soft corner problem.



Personally, I have no high opinion of the 35mm f1.8 Dx at all, when used with any shallow DOF... I find its bokeh to be the least attractive of lenses I can think of right now. To me, that is more important than "sharpness in corners". Also contrast is important, but not often tested (color foto, german magazine, tests for it).



The Sigma 30mm f1.4 happens to have nice bokeh, for the focal length. There are some people that don't like it, due to focus consistency (mainly on Canon DSLR bodies from a ferw generations ago), and there are big fans of the lens (also for its bokeh).



Like mentioned above... it does not matter whether a lens is tested on a D200 or something else. If it is a good lens on a D200, it is a good lens on a D7000.
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#10
[quote name='IanCD' timestamp='1299952802' post='6697']



So, I was trying to get a feel for a potential 'cutoff' point on the D7000 (given Markus's point)... and also trying to understand a bit better the relationship between lens and sensor resolution, sensor size, the 'sweet spot' effect of using FF lenses on DX sensors... and other factors that impact... for my crash course in this field..!

Ian

[/quote]



Regarding the resolution of lenses vs. sensors (APS-C or FF), you can stick to the statement that the resolution of the system is limited by the sensor not by the lens. Of course (at least in theory) there can be exceptions but very rarely:



A tack-sharp lens with 200lp/mm resolution (24mm) mounted on a D700 will give more system resolution than D3x and a 80lp/mm lens combo (if we simply ignore the AA filter and NEF handling differences). But frankly, I think this D3x and 80lp/mm lens combo is not realistic at all.



If you have a DX body and you think that you will possibly upgrade to FX in someday, then better collect FF compatible lenses. Yes they might be heavier/bulkier than DX versions but among other arguable advantages, at least one thing is for sure that you almost get no visible vignetting/light falloff (the image circles of FX lenses are larger than the DX sensor requires). And of course, it's a good investment for the future FX body.



Serkan
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