Question for Great Bustard

Started 5 months ago | Discussions thread
nigelht Senior Member • Posts: 1,549
Re: Disingenuous posting

Richard Butler wrote:

nigelht wrote:

The entire issue IS semantics. When you say that a 50mm f/1.8 lens on APS-C is equivalent to a 75mm f/2.4 lens on FF that's what people remember and the nuance that f/2.4 applies only to DoF is forgotten/misunderstood/etc.

It doesn't apply only to DoF. It tells you just as much about the total amount of light available to make up the image as the actual f-number tells you about light per unit area. Cameras shot at equivalent settings produce images that are more similar than those shot at the same exposures.

Okay, DoF and noise.  I do understand it impacts both but "and noise" adds two works and 9 characters.

Nowhere do I see it said that a A7RIII is equivalent to a 10.5MP m4/3 camera and it should be said and understood when folks are trying to determine whether they want a FF, APS-C or m43 system.

Er, no.

Er no what?  There is a thread in the Nikon forum whether getting a D850 gives you D500 capability...albeit at a higher price point.

If the general purpose of the equivalence concept is to provide readers with the ability to evaluate different camera systems with difference sensor sizes then crop equivalence matters.

These two camera systems are identical from an equivalence perspective:

A7RIII vs GH5 w/Sigma 30mm f/1.4

If you're only using a Four Thirds-sized chunk of the sensor then the cameras aren't equivalent, they're the same.

No, they aren't the same because the A7RIII doesn't have enough resolution to be the same as the GH5.

BUT if you can live with the final resolution of the m43 crop they are close...aka equivalent but not equal.

If you are always cropping your m43 images (like say for BIFs) then it won't work out that well for you even all the other features were equal.

Most manufacturers make lenses designed to provide equivalent fields of view, presumably on the assumption that most people won't pay extra for a larger sensor and then decide not to use the extra area. Instead they'll use an equivalent focal length to access the potential benefits of the larger sensor, rather than always shooting a cropped field-of-view.

Given infinite resources (and personal stamina) yes you will buy a 600mm f4 to fill the frame of a FF.

However, if you are shooting BIFs or sports with less than a 5 figure lens budget you will be cropping a lot.

I would argue that equivalence matters a lot more to folks shooting at the edges of performance (reach, shutter speed, light) than folks that don't because the costs skyrocket beyond a certain point.

And this have been short changed in the articles and discussions to date.  It would be helpful if you added this perspective to your equivalance article since it is referred to quite a bit.

What part of the equivalence formula is important to sports and wildlife shooters?  I would argue it is not DoF and noise as much as reach and speed.

Name your settings on a Micro Four Thirds camera and I can tell you what settings will let a full frame camera take a near-identical image. At which point, you can work out whether either camera can then be set to access more light (which usually means a better image)/

Sure, the math is easy...especially for m43.  It's just the exposure triangle.

What's hard is being able to do that with a lens within your budget or would be willing to carry using the equivalence formula provided.

Using crop equivalence the math is also easy but the cost and weight stays the same as long as the resolution is viable after the crop on the FF.

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