Am I correct...

[Reschsmooth]

My new camera has an exposure factor of 20x, which means, for example, a film ISO of 400 has an effective EI of 20. This equates to about 4 1/3 stop reduction in light hitting the film plane.

Now, I am planning a still life shoot at the camera's sync speed of 1/60th at an aperture of 5.6. I expect to use Tri-X, which, for the sake of my maths, has an ISO of 400. The only variable, therefore, will by light output.

Following discussion had last week betwix Matt, Gary and myself, I will be using the D200 to make test shots. If I want to make the exposure consistent between the two cameras, am I correct that the shutter speed of the D200 will need to be set at about 1/1300th or so (or whatever is closest settable speed)?

One of my alternatives is to pick up sheet Polaroid film at about $10 per shot! I would rather avoid that.

[biggerry]

yes....no....maybe..
alright, i have no fing idea but thought i would just burn a few electrons.

[surenj]

I am getting around 1/960 forgetting the 1/3 stop.

The only variable, therefore, will by light output.

Do you mean ambient light?

i would just burn a few electrons.

Yeah same here.

[Reschsmooth]

I am getting around 1/960 forgetting the 1/3 stop.

The only variable, therefore, will by light output.

Do you mean ambient light?

No, I mean strobe.

My workings are as follows:

Shutter speed on F is 1/60th.

Difference is 4 1/3 stops.

1/60th - 1/125 - 1/250 - 1/500 - 1/1,000 = 1/1,300 (or so)

[Matt. K]

I'm confused about what you mean by an exposure factor of 20X....but when it comes to strobes then the shutter speed, as long as it is in synch range, is not a factor.
If you set both cameras to ISO 400...the Nikon F to 1/60 at f5.6 and your digital camera to the same setting then they should both give the same result??? Or am I missing your point?

[PiroStitch]

Can you elaborate more about the definition of the exposure factor? I'm reading it more as the dynamic range.

I do find a slight difference between film and digital, but it's really negligible (i.e., probably not worth thinking about since it's highly unlikely to result in a hugely overexposed image).

[Reschsmooth]

Matt, what I am saying is, based on what I have read, is that the F with the 4x5 back, will let in about 4 1/3 stops less light, for a given ISO, shutter speed and aperture as the F with the 35 mm film back. Therefore, the F with 4x5 back, loaded with ISO 400 film, at 5.6 and 1/60th, is the same as the D200 at ISO 400 at 5.6 at something like 1/1,300th. In other words, the ISO 400 film exposes liken ISO 20 film.

My question was about whether my calculation of the 1/1,300 shutter speed was correct.

Think of it as a 4 1/3 ND filter.

[Matt. K]

OH..I missed the 4 x 5 back bit. Got it now. I think you are on the right track.

[surenj]

Patrick, the math is looking sound. Although you will need to figure out the strobe power using the D200 and then translate back. I doubt you could use the 1/1300 to calibrate the strobe.

[ATJ]

If you're shooting with a strobe, the shutter speed of the camera is irrelevant for the exposure (other than for the effect of the ambient light). For example, if you took a photograph in a dark room with a strobe, you'd end up with the same exposure with the camera at 1/60s as you would at 30s.

[Reschsmooth]

If you're shooting with a strobe, the shutter speed of the camera is irrelevant for the exposure (other than for the effect of the ambient light). For example, if you took a photograph in a dark room with a strobe, you'd end up with the same exposure with the camera at 1/60s as you would at 30s.

Good point: this will be in a dark room with only strobe light for illumination. I guess I need to adjust the ISO and aperture of the D200 to equalise. So, ISO 20 equivalent at 5.6 will be like ISO 200 at f/16 or thereabouts or ISO 100 at f/11.

[ATJ]

So, ISO 20 equivalent at 5.6 will be like ISO 200 at f/16 or thereabouts or ISO 100 at f/11.

ISO f/stop
20 f/5.6
40 f/8
80 f/11
160 f/16

[phillipb]

Would it make more sense to adjust the ISO on the D200 by 4 1/3 stops instead of the shutter speed? that way you can use the same combination of shutter speed and aperture on both cameras.

[Reschsmooth]

Would it make more sense to adjust the ISO on the D200 by 4 1/3 stops instead of the shutter speed? that way you can use the same combination of shutter speed and aperture on both cameras.

Perhaps, except the D200 ISOonly ges down to 100, compared to the effective ISO of Tri-X of 16.