IQ of 7d w 15-85mm Vs 6d w 24-105mm?

Started Mar 8, 2013 | Questions thread
MAC
MAC
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Re: 24-105mm rated 50% better than 15-85 at dxo
In reply to ultimitsu, Mar 12, 2013

ultimitsu wrote:

MAC wrote:

When one buys a 5d2, don't they expect 21 MPix?

Only with perfect lens. When you buy Porsche you do not expect to be able to drive 280kph on all roads do you? only on very smooth roads or race tracks.

They get perfect 21 when they use $6800 300 f2.8 IS.

They get 12 on a 5dii -- which sucks -- when they use $800 24-105

And then DXO moves crop camera sensors farther away -- which is invalid -- and they assign lower numbers to crop cameras -- which is invalid.

The distance needs to be the same when comparing across formats.

Fundamental Principle -- a photographer cannot be in two places at the same time -- particularly in pj shooting scenarios.  Measurement comparisons across formats need to have the photographer standing in the same position photographing the target at the same distance.

It is intuitive.  Moving further away -- in general, takes a better, more expensive optic to display the same resolution.  The 7d sensor doesn't magnify anything.  Lenses magnify.  Why would we allow the sensors to be placed further away across different formats to compare.  We do that for the same format to get the same AOV on the resolution chart -- but it is unfair to do this for the crop sensor -- because the crop sensor does not magnify -- it is simply a sensor -- not a magnifying device

dxo is really going to confuse buyers of the 5d2/6d/5d3 on that one

Only people who have no idea how things work. Molst people who bother to read DXO have sufficient intelligence to get it, especially after reading DXO's explanation.

and you can describe for use their method and the validity of testing resolution of systems across platforms at different distances?  Give us a break please.

well, I've found when I process my 60d images properly, the sharpness is really nice. And if you read TDP, you'll find out that my T4i RAW images are tuned to 1dx sharpness level right out of the camera -- in RAW.

I own 60D and 70-200 F4 IS and 17-55, both considered to be Canon's finest. for 17-55 at F2.8 it loses a lot of resolution.

sure, it is on a high pixel density sensor -- just a a 46 mpxl 5d4 would lose a lot -- but in the end, be better than the older technology -- but carry unnecessary mpxl and file size overhead for much of the intended use

How did DXO test MPix? We don't know 1) how they tested?

Converted from MTF

Like photozone said -- you can't compare across formats

2) what 1 number means?

Explained very well by their article and was linked by us many times.

One number-- you got to be kidding right?

I think they made a mistake with the crop, and sent it to farther distant places -- an error in testing

That is exactly how it should be done.

no its not.  read GB's equivalence.  distance must be the same.  GB had it right to be able to compare -- but for resolution -- it becomes very difficult to compare because zooms differ across the zoom and you'd have to use a different prime in a prime comparison.

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