full frame dof advantage/disadvantage

[william_bray1]

I gave this some more thought today the 5dmkii has older technology,

we're not just comparing FF vs cropped, you're also comparing 2 years old tech against the latest Canon has to offer.For me its not a case of shall I

get FF I think now is not the time with the 5dmkii getting on a bit

especially when you're talking about parting with a lot of money.

[george_mcc1]

<blockquote>

<p>Hi I needed to get my head around the dof issue. As far as I'm aware a full frame sensor like the 5d mkii doesn't actually give less DOF because l a lenses focal length doesn't change, whether you use it on a FF or cropped camera. It's just that you have to physically move closer to the subject with a FF so as to have the same field of view as a cropped camera. And when you move closer you naturally get less DOF. So that being the case when you use a FF camera you have to increase the the aperture, thus losing more light, and increasing the threat of diffraction. I know that FF camera operate better at high iso but if more DOF is required eg, macro or landscapes doesn't it make this a mute point. Please could you let me know if I'm right about this assumption or I'm barking up the wrong tree. Thanks.</p>

</blockquote>

<p>You forget that full frame cameras have on average two stops iso advantage over apsc. When needing a smaller aperture, you stop down the lens and you increase iso.</p>

<p>However, when you need shallow dof, you cannot open up the aperture past its maximum on small sensor. With shallow dof, full frame has almost two stops advantage over cropped. For deep dof it's a toss up between full and cropped frame.</p>

<p>So you're never worse off with full frame, at least not for dof.</p>

<p>PS: there's no such thing as "increasing" an aperture. Increasing would actually mean "to open up".</p>

 

[g dan mitchell]

<p>A simple way to think about it is that you can get any DOF value from a full frame body that you can get from a cropped sensor body by using a smaller aperture at the expense of higher ISO or longer exposure. </p>

<p>You'll gave a greater range of control over DOF with full frame since you can generally stop down roughly two stops more on the FF body before diffraction blur might become an issue. For example, if you feel that f/8 is about as far as you would stop down on crop, you'll get roughly the same level of diffraction blur (expressed as a percent of frame width) at f/16 on FF. Thus you get two additional useful apertures on FF.</p>

<p>Disclaimer: I am not claiming that FF is "better" than crop, just pointing out one difference that might or might not be relevant to a particular photographer.</p>

<p>Dan</p>