Always limit of f4 for V1U?

[Ian Campbell]

Hello,
I know it's recommended to use a larger aperture such as F.4 when using small sensor cameras such as the V1U and Z1U, etc. Is there a time when using F.11, for example, would make sense?

I shot some video with my V1U the other day of the exterior of a large downtown hospital. I noticed a fair amount of fringing on the edge of the building against the blue / grey sky. I was shooting at 1/60th with the camera set to auto iris (using ND filter 1 or 2) with the camera iris limit set to F4. I wonder if on really bright days this is too big an opening when wanting to shoot at 1/60th?

Any thoughts on when one should / shouldn't go to F5.4, F11, etc.?

Thanks . . .

Ian

[Piotr Wozniacki]

Closing aperture too much will result not so much in fringing (attributable more to contrasty edges), but in diffraction demonstrating itself in image softening (lowering sharpness). Of course, in some circumstances (like extremely bright illumination, lack of additional ND filters, and priority of low shutter speed), you simply MUST close it beyond 5.6 (BTW it's 5.6 or 11, not 4, that you can limit it to in the menu for auto exposure operation).

I'm trying to never exceed 5.6, though - even at the cost of using shutter speeds as high as 1/300th, should need be. The adverse effect of such a fast shutter I checked to be much less serious than that of the iris closing far beyond 5.6 - the latter can make the image really soft!

PS. One of the reasons for closing aperture (apart form light limiting) has always been increasing DOF, but of course with such small chip cameras it's always deep enough - in fact, we're all trying to make it shallower, which again calls for aperture opening as much as possible...

[Simon Denny]

So if i was out shooting at the beach on a bright day and the camera called for f11 and ND filter 2, would i be better off increasing my shutter speed to open my iris to f4 -f5.6
Hope that makes sense.

Could you explain going soft a bit more with a high shutter speed?

Regards

[Piotr Wozniacki]

Simon,

The short answer to you first question (the bright beach) is yes. Engage ND2 and go up with the shutter speed as required, keeping aperture at mids (around 5.6).

Regarding the second question, I'm afraid you misunderstood: using high shutter speed does NOT cause image softening (closing aperture too much does). The only caveat of high shutter speed is the phenomenon called "strobing", but I really don't find it to spoil my shootings (it's more an aesthetic matter, a one of taste and picture "feel"). Yes, there are some who - due to the CMOS inherent 'rolling shutter" design - claim the 'rolling shutter effect" (slanted verticals with horizontal pans, if too fast) will occur with shutter speeds faster than 1/100th (I'm PAL, for NTSC it would be 1/120th); but again I haven't noticed it to be too pronounced (of course I'm trying to never pan too fast, for other obvious reasons).

Hope this helps.

[Simon Denny]

Thanks,
Will do some tests and check it out.

[Douglas Spotted Eagle]

Without going into all the maths, the upshot is that F4 is ideal for the imager size relationship. If you wanna have a little fun and education at the same time, set up a rez chart and while keeping exposure equal, adjust the iris. You'll see the image start to soften as the aperture closes

[Piotr Wozniacki]

Yep, F4 seems to be the "sweet spot" for the aperture on the V1.

[John Huebbe]

Originally Posted by Simon Ash

So if i was out shooting at the beach on a bright day and the camera called for f11 and ND filter 2, would i be better off increasing my shutter speed to open my iris to f4 -f5.6

Also, keep some screw on ND filters to add. They are not too expensive.