Question for Great Bustard

Started 2 months ago | Discussions thread
Richard Butler
Richard Butler dpreview Admin • Posts: 2,463
Re: look it up in the dictionary

nigelht wrote:

What's stopping you using faster shutter speeds? If you can shoot at F2.8 and 1/500th on a small sensor, what's stopping you shooting F15.5 and 1/500th on a proportionately larger sensor?

The lack of a longer lens at f16 or otherwise.

Sure. But again equivalence lets you know what that lens would be. It doesn't assume that the lens exists, that it's practical or that you can afford it. But it lets you assess that.

The lack of ISO on the FF camera. It does end and not everyone has extended range past 51200.

No, but the circumstance in which you'd need to shoot ISO 51200 with the same depth-of-field settings as an F2.8 on 1/2.3" sensor would require you to be shooting as ISO 1600 on the smaller camera, which is unlikely to look any better.

If the crop camera is made with the same generation sensor as the FF and tops out at the same native ISO then at F15.5 the crop camera can be near the end of the "okay" native ISO while the FF will be in the middle of the "not so okay" marketing ISO.

That's an arbitrary line. If ISO 1600 is acceptable on a small camera, ISO 51200 is likely to be similarly acceptable from the large camera. Or, if you can live with shallower depth-of-field, there's an opportunity to open up the lens on the larger camera, use a lower ISO and get better image quality.

No one is saying you have to stifle every camera to limit it to the performance of the other, they're merely pointing out where they'd behave in the same manner so that you know the extent to which you can then improve upon the other (for all that additional weight, size and cost).

Is the assumption that modern sensors no longer has a knee in the noise curve?

This is a term I've not heard before.

But for many people, WIDER DOF is preferable anyway.

A wider DOF cannot, so I say the overall advantage goes to the wider DOF.

As Great Bustard explains, what are the situations in which you see this wider depth-of-field? What's to stop you stopping-down a larger sensor camera?

Situations are when shooting sports and you want a wider DoF so more of the player is in focus and also have a little wiggle room when the AF is a little off.

What stops you from stopping down on a larger sensor camera is the desire to maintain shutter speed and a reasonable ISO.

Again, at equivalent settings, the ISO that is reasonable on one is highly likely to be a good match for the setting on the other, since they're both trying to turn the same number of photons into an image.

And also not buying a $8-12K lens vs a $2-4K lens.

Nothing about equivalence suggests you should pay for capability you don't need/can't benefit from.

If you get the same total light (and hence very similar image quality at the same viewing/printing size), what's the advantage of one approach over the other?

Richard -

If there are no advantages why doesn't sports photographers shoot at f5.6 and simply push ISO a couple more stops?

You'd have to ask them. There's a risk they're looking at their images at 100% and assuming that the larger image is noisier, which it may not be when printed/viewed at the same size.

Richard -

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