Best aperture?
 

Hi folks

Damn these tiny chips! I'm shooting wide angle (with the Sony .8 adapter) a lot at the moment and I'm trying to avoid picking up the inevitable dust and other crap that always seems to adhere to the filter/front element no matter how careful one is about cleaning. I like to shoot against the light sometimes for effect and specks and stuff show up horrible when a bit of sunlight gets on the lens/filter. I would like to shoot with the widest aperture to minimise the DoF but I'm scared I'm going to loose resolution. At what aperture does the Z1 lens perform best? Is it safe to cotrol the light for the widest aperture?

Best

Michael

You are going to get best image quality from f.1.8-f.4 . I wouldn't be too scared of closing it down so that you have a deeper dof and don't see the dust as your not going to film I assume :-)

Thanks Ainslie. I'm not going to film but I am shooting HDV and even though it will be output to SD DVD in the first instance, the project has such a shelf life that I will inevetably be publishing to Blu-Ray, HD-DVD - whatever - the dust etc. most definitely is an issue when the Dof extends back to the front element.

I am fascinated that you can recommend f1.8. My understanding of lenses has always been that wide aperture = lost resolution. Is your confidence based on personal experience or is there data out there that I should know about? I would be a happy bunny to be able to use f1.8 without worrying.

I say this beacause i'm pretty much always down at f.1.6-f.2.6 (depending on zoom) for a shallow DOF. I have seen a few of my 10x zoom f2.6 shots on the big screen and they look great. Thinking about it, I don't know if i'm ever below 2.6 unless it's low light. I'm pretty sure that the best aperture is f4 on this camera. From 1.6 all the way to 11, it will be hard to pick results on a 32-42" LCD at 720p which is what most people seem to view "HD" on.

Michael, don't be afraid to use wide apertures. Modern zoom lenses are built to incredibly fine tolerances and diffraction losses are much more of a resolution robber than wide apertures are. Diffraction has little or nothing to do with how well the lens is designed or made BTW, it's simply loss of resolution due to the laws of optics and the way light bends when it meets sharp edges.

I'd be much happier shooting wide at f/1.6 than I ever would be shooting at f/8 or f/11, and the Z1's book warns you about this. Use those NDs even before they're called for.

The Z1's lens vignettes at the widest two apertures and the zebras will show you this quite easily. But unless you're shooting test charts it's very difficult to spot in normal footage.

So remove any filters if you've got the 0.8x fitted as DOF will mean dust and imperfections cause those nasty flare spots when you shoot into the light. Also use a 16:9 hood and shade that front element whenever possible.

I use a 0.5x converter on my Z1, so my focal length is an incredible 2.2 mm. At these focal lengths and feeding tiny 1/3" chips, make sure f/4 is the smallest aperture you use.

tom.

Tom - many thanks for that - most helpfull.

My only regret is that I love to use a polarising filter in such instances as well. However, as long as there isn't any camera movement in the shot I can usually get away with it. Yes, I do use a Vocas mattebox with 16:9 shade and flag. But most reassuring about use of wide apertures to minimise the effect.

Thanks.

My observation is that f4 resolves the most detail at wider angles, but distant shots of the landscape will be sharper at the borders at f5.6 when zoomed to 12x. The difference is slight.

F1.8 is definitely softer in my view, and I avoid anything below f4 that needs to show the maximum detail, depth of field considerations the exception.

If I'm shooting a film or a dramatic video along those lines, I try to stick with a more "fixed" aperature no higher than F3.4 or so. Of course, I notice it's a little different on other DV and HDV cameras, ie, the amount of light going into lens. Plus, the more open the aperature, the shallower the depth of field.

heath