Shallow DOF with the HMC40

[Cranky]

Per Barry's calculations, there is less than one f-stop difference between 1/4-inch and 1/3-inch to achieve the same DOF. He calculated 3/4 of f-stop, let's say it is an even stop, for simplicity.

So, if one wants as shallow DOF as possible, the HMC40 is a loser? Not necessarily. The HMC40 stays at F2.8 for 2 and 1/2 of additional stops of light. Then the iris closes up, but how close it can be without an external ND filter in a bright day at say 1/60 shutter speed? Compared to the HMC150, can the HMC150 stay at F4 with full ND engaged in a bright day? Comparing to the XH-A1, I've read that it has quite insufficient ND filter, so in a bright day even with the ND fully engaged, its iris can be as small as F9.5, this is 2-1/2 stops smaller than F4, which is equal to the HMC40's F2.8. I mean, one can open the Canon wider, but with an external filter.

The consumer Canons engage ND filter at F4, not at F2.8, and this filter absorbs up to 4 stops. On a good side, you almost always get F4 on a consumer Canon camcorder in bright light, which is equal to the HMC40's F2.8 DOF-wise. On another hand, if you want wider iris, you have to defeat these 4 stops with an external filter plus you have to defeat additional light if the Canon shows f-number higher than F4. For all practical purposes, one cannot go wider than F4 in good light. This means, that the HMC40 matches, say, the HV40.

So, in real-life conditions, when one does not have time to fiddle with filters, which camera will have shallower DOF? The HMC40 seems to be pretty well designed for conditions with good light, and is able to pull as much of shallow DOF as possible from its tiny chips. Well, not as much, the consumer Canons can soak up up 4 stops of light, so Panasonic still has a way to go. Presently, whenever you see f-number pegging above F6.4, you can screw on a 0.6ND filter and get back to F2.8 shallow DOF zone.

 

[Barry_Green]

So, if one wants as shallow DOF as possible, the HMC40 is a loser? Not necessarily. The HMC40 stays at F2.8 for 2 and 1/2 of additional stops of light. Then the iris closes up, but how close it can be without an external ND filter in a bright day at say 1/60 shutter speed? Compared to the HMC150, can the HMC150 stay at F4 with full ND engaged in a bright day?

Easily.

Comparing to the XH-A1, I've read that it has quite insufficient ND filter

Nonsense. The HMC150 has three two-stop filters, so you have your choice of 2, 4, or 6 stops of ND. The XHA1 has two filters, each 2.5 stops, for a grand total of five stops of filtration. The HMC150 beats the XHA1 in ND filtration handily.

This means, that the HMC40 matches, say, the HV40.

The HMC40 is about the same speed, maybe half a stop slower, than the HV40. But the HMC40 only has two stops of ND filtration total. In bright daylight you're not going to be at f/2.8 on an HMC40, you'll be more like f/11. If you want to keep the HMC40's iris open outdoors, you're going to need external ND filtration.

 

[David Saraceno]

Barry, have you used a Variable Neutral Density Filter on a video cam? Philip Bloom has tested one with the 7D, but I was wondering how one might work with a video cam.

 

[Cranky]

Nonsense. The HMC150 has three two-stop filters, so you have your choice of 2, 4, or 6 stops of ND. The XHA1 has two filters, each 2.5 stops, for a grand total of five stops of filtration. The HMC150 beats the XHA1 in ND filtration handily.

How your statement that the HMC150 beats the XHA1 in ND filtration disproves the statement that the HX-A1 has the ND filter insufficient to stay open in a bright day? Now I see that my original statement was worded incorrectly. I meant the xh-a1.

The HMC40 is about the same speed, maybe half a stop slower, than the HV40.

I was not talking about the speed, I was talking the most usual f-number the camera selects with shutter speed manually locked to 1/60. The HV40 will likely stay at F4 because of its powerful 4-stop ND filter, but I have to double check.

EDIT: Actually, Canon uses f/5.6 as the "base camp" on the HV, not f/4.0. So the HV will stick at f/5.6 even in bright day. Canon uses f/4.0 for other cams, like the DC50 or the current crop of AVCHD cams.

But the HMC40 only has two stops of ND filtration total.

2 and 1/2 stops?

In bright daylight you're not going to be at f/2.8 on an HMC40, you'll be more like f/11. If you want to keep the HMC40's iris open outdoors, you're going to need external ND filtration.

Virtual f/11? So it is about f/4.8? Not that bad, but the camera obviously need a more powerful filter if it is to stay at real f/2.8 even on a bright day.

 

[Cranky]

I used VariND on the HDC-SD100 and on the HDC-SD1. Works well, though yesterday I noticed quite a loss of sharpness. I was trying to clean the filter with isopropanol and a cheap lens cleaning paper, but was getting foggy residue, which I could not get rid of.