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I thought pixcels relates to sensor size but sensor size of Nikon D7000 and D7100 is the same but their pixcels are very much different. On the other hand, D610's pixcels is the same as D7100 but sensor size of D610 is much larger than that of D7100. Could anyone shed light on what the pixcels and the sensor size of DSLR camera are?

Well there is a ton of variables that go into deciding which camera shoots better pictures.

But between the D7100 and the D610, the D610 wins.

Pixel counts have reached such absurdly large numbers that it is not the limiting factor in deciding picture quality. The larger the sensor, the more light it can sense, hence less noise and faster shutters and exposures are possible.

Think of pixels (Please, please spell it right! ) as the number of tiles in the bathroom floor.
Depending on the tile size, you can fit a few or a great many onto a given floor.

Sensor size is the actual size of the bathroom floor. Again, this can be bigger or smaller.

Among currently available cameras, the size of the tiles varies somewhat, but is not wildly so. In general, a larger sensor will have more pixels, but there are exceptions.

Absolute pixel count doesn't matter nearly as much as the Marketing Monkeys would have you believe. I'd suggest you try various cameras and pick the one in your price range that you find easiest to use. Ergonomic controls, a big bright viewfinder, easy-to-use menus, etc. are all more far important that how many megapickles the thing has.

Based on the replies so far, my understanding is as follows:

For a given number of pixels, larger the sensor size larger the individual light sensing pixel size. If this is correct the pixel size of D7100 is smaller than that of D7000, which means D7100 is inferior to D7000 in this respect.

Is the above correct?

churin wrote:

Based on the replies so far, my understanding is as follows:

For a given number of pixels, larger the sensor size larger the individual light sensing pixel size. If this is correct the pixel size of D7100 is smaller than that of D7000, which means D7100 is inferior to D7000 in this respect.

Is the above correct?

That's mostly the idea.
When it comes to pixel size, generally, the larger the better, since it can detect light better.
This is why cheap cameras and phones have terrible low light and noise performance.
Their pixel sizes are 1.4µm or 1.1µm for backside illuminated sensors.
Compare that to the ~4-5µm for larger DSLRs
This also explains why smartphone sensors can cram 8MP into their 1/3.2" sensors as opposed to DSLRs that have sensors larger than 1".

chµck wrote:

churin wrote:

Based on the replies so far, my understanding is as follows:

For a given number of pixels, larger the sensor size larger the individual light sensing pixel size. If this is correct the pixel size of D7100 is smaller than that of D7000, which means D7100 is inferior to D7000 in this respect.

Is the above correct?

That's mostly the idea.
When it comes to pixel size, generally, the larger the better, since it can detect light better.
This is why cheap cameras and phones have terrible low light and noise performance.
Their pixel sizes are 1.4µm or 1.1µm for backside illuminated sensors.
Compare that to the ~4-5µm for larger DSLRs
This also explains why smartphone sensors can cram 8MP into their 1/3.2" sensors as opposed to DSLRs that have sensors larger than 1".

One of the spec changes from D7000 to D7100 is the pixel size: It got smaller for D7100 which is negative factor, and as a result total pixel counts went greater which is positive factor. Did Nikon do this because the change is net positive?

churin wrote:

One of the spec changes from D7000 to D7100 is the pixel size: It got smaller for D7100 which is negative factor, and as a result total pixel counts went greater which is positive factor. Did Nikon do this because the change is net positive?

With the same sensor size, a higher pixel count means that when light is plentiful and the optics are sharp, the sensor can capture more detail. In bad light however, the resulting image might have more pixels, but the individual pixels have more variance and the resulting image will have more noise. With appropriate noise filtering, both cameras will produce similar low light images though. So, all else being equal, a sensor with the same size but more pixels (more sample points) will produce images of equal or higher quality.

However, all else is not always equal because of the way that the sensor works on the level of individual pixels. I don't know how the sensors work exactly (can somebody explain?) but I do know that there's always a bit of light wasted in between the pixels. That is, you might assume that on a sensor of 1 megapixel, each pixel would get about 1 millionth of the light to work with, but in practice this is less because of the way that the light is collected into the individual sensors that make up each pixel. Each of these sensors are tiny electrical components that have to be manufactured in a way not dissimilar to how CPUs and GPUs are made, and when cramming more of these tiny sensors in the same space, they have to make compromises.

Please, correct me where I'm wrong and elaborate where you can!

The differences between sensors are illustrated here nicely:

http://www.digicamdb.com/compare/nikon_d7100-vs-nikon_d7000/

http://www.digicamdb.com/compare/nikon_d7100-vs-nikon_d610/

A part of each pitzel's area is "wasted" as it doesn't collect photons, and manufacturers are trying to minimize this wasted area. It's basically what's shown here, in the second animation:

http://www.nikon.com/about/technology/rd/core/optics/cmos/index.htm

This is one of the reasons that a newer sensor will likely perform a little better - or, in case of D7100 vs. D7000, not (much) worse, despite smaller pitzels. You can see the results here:

http://www.dpreview.com/reviews/nikon-d7100/13

Note that these are 100% crops here - one screen pixel corresponds to one pixel on the sensor, without scaling.

The basic understanding is correct, but you also have to consider advancement in sensor design. The D7100 (and D3200 and D5300) have the best APS-C sensor available in a DSLR. While the D7100 may have smaller pixels (rather, photo sites) than the D7000, it also has a more advanced sensor and better processors/firmware/software to back it up.

Also note that there's a whole lot more to a sensor than just the abstract 'noise' moniker. Noise is going to vary from non-existent at lower ISO speeds to overbearing at higher ISO speeds, as well as from good light to very low light, from sensor to sensor.

Firestarter wrote:

So, all else being equal, a sensor with the same size but more pixels (more sample points) will produce images of equal or higher quality.

All else being equal, both should produce images of very similar quality. The amount of light captured by the sensor, and the amount of noise generated in it, would be the same, just the noise would be more fine-grained in the sensor with more pixels. It's only in low light, of course, where signal-to-noise ratio becomes an issue and any differences become visible.
But everything else isn't equal, and so the D800 is known to be better at high ISO than D700 when both are downsampled to the same resolution. (I'd be extremely happy if I could have a week with both of them and come to the conclusion myself).

Note that there's a pretty big difference between an ancient Nikon sensor and a far newer Sony sensor, a la D700 vs. D600/D800. Down-sample a shot from two of the latter to the same resolution with the same processing, and you'll find the newer bodies will have a noticeable edge.

Thank all responding my question.
I own D7000 and am planning to upgrade it to D610. A friend of mine interested in buying my D7000 who does not know about DSLR. I let him know about an alternative model of D7100 but he did not understand what the pixel counts difference between D7000 and D7100 means. It appeared to me that there is pro and con since the sensor size is the same.
Thanks again. I myself learned a lot about DSLR through this thread.

churin wrote:

Thank all responding my question.
I own D7000 and am planning to upgrade it to D610. A friend of mine interested in buying my D7000 who does not know about DSLR. I let him know about an alternative model of D7100 but he did not understand what the pixel counts difference between D7000 and D7100 means. It appeared to me that there is pro and con since the sensor size is the same.
Thanks again. I myself learned a lot about DSLR through this thread.

If you're new to photography, think very hard before jumping onto full frame and all it entails. Do you already have an assortment of full frame lenses? What are your photographic needs? Have you tried carrying around a full frame kit on your typical photo shoots and are you comfortable with the weight and bulk? What exactly are you after by going full frame? More dynamic range? Less depth of field? Better low light performance? Weather sealing? Pro lenses?

Voldenuit wrote:

If you're new to photography, think very hard before jumping onto full frame and all it entails. Do you already have an assortment of full frame lenses? What are your photographic needs? Have you tried carrying around a full frame kit on your typical photo shoots and are you comfortable with the weight and bulk? What exactly are you after by going full frame? More dynamic range? Less depth of field? Better low light performance? Weather sealing? Pro lenses?

Note that the FF camera in question is about the same size and weight as the semi-pro D7000- same for the Canon side with the 6D vs. 60D/70D. And with respect to lenses, the biggest difference is in zooms given that there are very few primes designed only for the crop cameras.

You are upgrading from a D7000 to a D610? Wow! I've really got to upgrade. I'm still rocking a D80. I've spent far too much $ on lenses. Hopefully a D7100 by the summer or I wait it out for its successor.

Airmantharp wrote:

Voldenuit wrote:

If you're new to photography, think very hard before jumping onto full frame and all it entails. Do you already have an assortment of full frame lenses? What are your photographic needs? Have you tried carrying around a full frame kit on your typical photo shoots and are you comfortable with the weight and bulk? What exactly are you after by going full frame? More dynamic range? Less depth of field? Better low light performance? Weather sealing? Pro lenses?

Note that the FF camera in question is about the same size and weight as the semi-pro D7000- same for the Canon side with the 6D vs. 60D/70D. And with respect to lenses, the biggest difference is in zooms given that there are very few primes designed only for the crop cameras.

Yeah, the D610 is very small for a full frame DSLR, but lenses will still be bigger. And you can mount FX lenses on DX bodies and retain all functions, as long as it's not an older screw-drive lens.

I'm just pointing out that going full frame is not a panacea for photographic issues. While FF cameras have larger sensors and pixels, corner to corner sharpness and vignetting can be an issue compared to crop bodies with smaller image circles. And there are situations where increased DoF is actually beneficial (closeups/macro, landscapes, etc). I'm actually curious as to what application the OP is finding his D7000 inadequate, because that's already "a lotta camera".

Don't get me wrong, a FF body/system is the precisely the right tool for some people and jobs. Just be sure it's the right tool for you before you buy it.

Voldenuit wrote:

I'm actually curious as to what application the OP is finding his D7000 inadequate, because that's already "a lotta camera".

I'm also interested in which lenses the OP is using on the D7000.

End User wrote:

Voldenuit wrote:

I'm actually curious as to what application the OP is finding his D7000 inadequate, because that's already "a lotta camera".

I'm also interested in which lenses the OP is using on the D7000.

Hard to imagine that that there'd be a large selection of DX lenses other than 'kit' zooms/superzooms. There are exactly four DX primes available, and on the Canon side, exactly three EF-S primes, counting third-party lenses. So unless the OP is using a nicer DX zoom like a 16-85 or 17-55/2.8, there's very little reason to worry.

Thanks for lot more posts since.
The lenses I use with D7000 are 18-105mm f/3.5-5.6G ED VR AF-S DX and 50mm f/1.4G AF-S. I take pictures of portraits, people, flowers, landscape, etc.
Why I want to replace D7000 with D610? Because I want to see how much better picture I can take using D610. The weight being about the same as D7000 is very important factor in deciding on D610.

Taking this opportunity let me ask for suggestion as to what lense(s) is recommended to go with D610. One of the lenses I will be using is the above prime lens I already own. So question is what zoom lens I should get. Presently, I am considering 28-300mm f/3.5-5.6G ED VR AF-S. Is it correct that this lens does not allow as much close-up as the above DX lens?

If you want close focus, get a Micro (macro) lens; and if you want a good zoom, a superzoom isn't it. A 28-300 ~11x zoom is one giant compromise.

Your 50mm lens is great, better than what we can get for Canon. For your listed subjects, I'd get the D610 kit with the 24-85, then add a Samyang/Rokinon/Bower 14/2.8 lens if you really need wider for landscapes, and add a 100mm+ macro lens for portrait isolation and close-ups.

churin wrote:

Presently, I am considering 28-300mm f/3.5-5.6G ED VR AF-S.

No. Dear God, just... no.

Please don't spend a lot of money (even though the D610 is fairly inexpensive for a FF body) on a camera body just to put a **** lens in front of it.

For portraits: Nikkor AF-S 85mm f/1.8 G

For macros:
AF-S Micro-NIKKOR 60mm f/2.8G ED or
AF-S VR Micro-NIKKOR 105mm f/2.8G IF-ED
These would also be good for portraits, depending on the look you're after and the working distance you have available. If you already have the 50/1.4, you may consider getting the 105/2.8 and skipping the 85/1.8 as the 105 can double nicely as a portrait lens.

For landscapes:
Nikkor AF-S 18-35mm f/3.5-4.5 G ED or
Tokina AF 17-35mm f/4 AT-X Pro FX
Note that you'll have to stop down to get acceptable corner sharpness on both these lenses. See below.

General walk-around lens:
Nikkor AF-S 24-70mm f/2.8G ED
Bear in mind that the corners will be slightly soft wide open with this lens. This is one of the tradeoffs of moving to full frame.

Airmantharp wrote:

For your listed subjects, I'd get the D610 kit with the 24-85, then add a Samyang/Rokinon/Bower 14/2.8 lens if you really need wider for landscapes, and add a 100mm+ macro lens for portrait isolation and close-ups.

All good solid options, except for the 24-85, which is pretty lousy in the corners EDIT: Correction, just realized that I linked to the 24-84/2.8-4, whereas the kit lens is probably the 24-85/3.4-4, which is somewhat better behaved, but still not stellar in corners.

The sad fact is that most full frame lenses (especially zooms) will suffer from vignetting and corner softness. Primes tend to fare better than zooms, but for best results, you will rarely want to shoot wide open (except in subject isolation shots such as portraits where the corners are unimportant).

I meant to try to keep the budget under control, not spend more on a standard zoom than the camera .

I didn't really want the 24-105 in my kit, either- same reasons- but as you say, primes are better for vignetting and corner sharpness, whether wide-open or stopped down, and they're definitely cheaper.

Airmantharp wrote:

I meant to try to keep the budget under control, not spend more on a standard zoom than the camera .

Hehe, it's easy to get carried away with spendiness on camera gear.

But in general, the lenses are what you should be spending the money on, not the body (within reason).

My best advice for the OP is to stick with the D7000 and spend money on better lenses instead of buying a better body but not having any good lenses to attach to it. Keeping in mind the caveat that the 'Pro' lenses are almost all FX, but still usable on DX bodies as long as you get a usable focal length range post-crop factor.

Also (and I can't stress this enough): Stay away from superzooms (anything with 5-10x+ zoom range)! There's a reason most pro lenses are 3-4x zoom at the most - it's because you start having to compromise the optics to get longer zoom ranges in.

churin wrote:

I take pictures of portraits, people, flowers, landscape, etc.
Why I want to replace D7000 with D610? Because I want to see how much better picture I can take using D610.

Based upon your subject matter I really don't think you'll see a drastic difference. I'd rent a D610 before buying one.

End User wrote:

churin wrote:

I take pictures of portraits, people, flowers, landscape, etc.
Why I want to replace D7000 with D610? Because I want to see how much better picture I can take using D610.

Based upon your subject matter I really don't think you'll see a drastic difference. I'd rent a D610 before buying one.

I agree with End User here- one nice thing about Nikon's crop sensors is that they don't seem to have the same low-light noise issues that Canons run into. It's almost comical that Canon rules the top-end low-light and sports/action/wildlife scenes, while Nikon takes the landscape scene due to better performance at low ISOs, and rules the crop IQ scene. In particular, the D7100 holds a lot of interest in that regard with the combination of of IQ, nice AF, and good build quality and handling for the price.

Sensor size versus pixel number is a dark art. Larger sensors with equivalent pixel counts do better in several areas but with the advances in sensor tech things are changing fast.

I would recommend the Fuji X stuff as X Trans seems to be better than all the other APS-C sensors. I am very pleased with mine and if I did not need more pixels for printing I would not be making any changes. Both the camera and the XF lenses kill. There is little to compare to them to except FF cameras, and they do well in that comparison as well.

All I expect from the Sony a7R I am about to buy is about twice as many pixels.

What makes an interchangeable lens camera great is mostly the selection of lenses that you can mount. Therefore, we have Canon and Nikon at the top, traiiled by Sony. The other brands are fringe players.

Voldenuit wrote:

churin wrote:

Presently, I am considering 28-300mm f/3.5-5.6G ED VR AF-S.

No. Dear God, just... no.

Please don't spend a lot of money (even though the D610 is fairly inexpensive for a FF body) on a camera body just to put a **** lens in front of it.

That bad? It is 5 star rated by 96 reviwers at Nikon website.

For portraits: Nikkor AF-S 85mm f/1.8 G

What is wrong with AF-S 50mm f/1.4G I own for portrait?

For macros:
AF-S Micro-NIKKOR 60mm f/2.8G ED or
AF-S VR Micro-NIKKOR 105mm f/2.8G IF-ED
These would also be good for portraits, depending on the look you're after and the working distance you have available. If you already have the 50/1.4, you may consider getting the 105/2.8 and skipping the 85/1.8 as the 105 can double nicely as a portrait lens.

For landscapes:
Nikkor AF-S 18-35mm f/3.5-4.5 G ED or
Tokina AF 17-35mm f/4 AT-X Pro FX
Note that you'll have to stop down to get acceptable corner sharpness on both these lenses. See below.

General walk-around lens:
Nikkor AF-S 24-70mm f/2.8G ED
Bear in mind that the corners will be slightly soft wide open with this lens. This is one of the tradeoffs of moving to full frame.

I think what you are saying is that the zoom lens having a large range should be avoided and a proper lens should be picked for each shooting situation - portrait, closeup, landscape, etc.
I want to start with 50/1.4 plus one more lens which I have to decide on. My budget for that lens is not much more than $1000. What lens could be the best compromise?

churin wrote:

That bad? It is 5 star rated by 96 reviwers at Nikon website.

And who are the reviewers? What did they use that lens for? On what camera?

churin wrote:

What is wrong with AF-S 50mm f/1.4G I own for portrait?

Absolutely nothing, although on a full-frame body it's not really a portrait lens anymore.

churin wrote:

What lens could be the best compromise?

Only you can decide that for yourself!