Reversed Lens DOF Ponderings...

Austin Greene

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Hey everyone,

I'm just trying to wrap my head around this. I recently picked up a reversal ring which I'll be using along with a nifty fifty and some extension tubes for macro purposes. I've been wondering, and I'm quite sure my intuitions are correct, but doesn't the aperture retain its same function when reversed?

As in if I do the DOF Preview trick to set my aperture (before reverse mounting the lens) to say f/8, would it not increase my DOF over its normal wide-open reversed setting (f/1.8)? I mean, the aperture is still limiting the light entering the sensor, so thats all that should matter in terms of DOF, but I just want to make sure.


Am I correct in my suspicions that regardless of the lens being reversed, if it looks and smells like an f/stop, it still acts like an f/stop?

Thanks

Toga
 
It's possible, but keep in mind that increased magnification of the subject will decrease DOF. In macro/close ups, the magnification is very large so the DOF will be very small, even at smaller apertures.

Of course, if you're shooting digital, it's basically free to try various settings and see what you get.
 
I know with my reversed 28, it's tack sharp at f/8. f/11 is marginal and the IQ drops off the face of the earth below that. So stopping down for more DOF is a double-edged sword.
 
It's possible, but keep in mind that increased magnification of the subject will decrease DOF. In macro/close ups, the magnification is very large so the DOF will be very small, even at smaller apertures.

Of course, if you're shooting digital, it's basically free to try various settings and see what you get.

Good reminder. I'm definitely well aware, my working DOF right now at about f/8 is roughly 1-3mm.

I know with my reversed 28, it's tack sharp at f/8. f/11 is marginal and the IQ drops off the face of the earth below that. So stopping down for more DOF is a double-edged sword.

Thats what I noticed with my reversed 50. Wide open it appears to be "ok" but not where I want it to be. At f/22 its god-awful. Right about f/8 seems to be the sweet spot, though I still need to check a few other settings.


Thanks for the input, I appreciate the fact that I no longer suspect I'm losing my mind :)
 

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