Upgrade from D300 for a poor college student?

Started Apr 7, 2013 | Discussions thread
ultimitsu
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Re: Upgrade from D300 for a poor college student?
In reply to Ray Ritchie, Apr 9, 2013

Ray Ritchie wrote:

I believe DxO is the first to use the notion of "megapixels" as a measure of sharpness. There was a lot of discussion here about what it meant when they started using that metric, and as I recall, a lot of people here, myself included, did not really understand what it meant. Perhaps you could post a separate thread giving your interpretation as an aid to those of us who are having trouble with the concept.

I would note that most reviews of lenses previously used measures like line pairs of resolution and MTF, both of which have been used for a long time and are pretty well understood. Attaching the notion of a number of megapixels less than the actual megapixel count of a given sensor to the resolution of a lens is much less well quantified, in my opinion.

I am not sure why it is a difficult concept to wrap one's head around. If I could use the analogy of horsepower in automobiles. Generally there is a figure representing horsepower at engine. That is how much power the engine is capable of producing. Because no transmission is fraction-less, there is some powerless in the drivetrain, we then have another figure representing horsepower at the wheel. That is the amount of horsepower ended up available at the wheel. Two cars sharing the same engine may not have the same drivetrain therefore wouldhave different amount of horsepower at the wheel.

Same concept here. The sensor has a particular resolving capacity. that capacity would be fully utilised if there was a perfect lens. But since the perfect lens do no exist some resolution capability is lost.  The more imperfect the lens the more loss to the resolving capability of the sensor.

There are so many parameters other than pixel count that determine the IQ of a camera/ lens combination that I can't quite wrap my brain around what that specific number may mean.

Pmp does not attempt to represent other IQ metric - such as Dr or color depth, it only concerns with resolution.

But to return to my previous comment, I do believe you can see a distinct improvement in image quality going from a D300 to a D600 with the same lens. I even believe you can get significant improvement with the D600 using a less expensive lens than you use on the D300.

We are in agreement here.

Going from D300 to D700 with the same lens, however, the improvement may be noticeable under some shooting conditions, but up to ISO 800, I think it's pretty usually pretty hard to see.

From base ISO D700 has better colour depth, at ISO 800 it maintains over 11bit DR while D300 drops below 9.5.

I would be very interested if you can show me an image shot on a D700 with 24-85VR lens which is better in IQ than the same image shot with the D300 and 17-55. I've never seen that comparison, and doubt that it can be done.

I understand 17-55 is a better built lens with more exortic elements than 24-85. it has slightly less distortion and less CA. But I do not think these will be significant in real life. On the other hand 24-85 has a 2 stop VR, that is very significant when photographing static subjects in less than optimal light.

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