Topic: A couple of easy Questions (Read 5661 times)

Joe Hardesty · « **on:** October 01, 2003, 11:55:42 am »

A general rule of thumb is that you can shoot handheld with a shutter speed of 1/focal length, with a minimum of 1/60th. So if your focal length is 85, you can shoot at 1/85th, or if it is 200, you can shoot 1/200th. With the 17-40, the minimum of 1/60th would aways apply.

Regarding highlights, you have to treat digital like shooting slide film and always expose for the hightlights. If you are having trouble with the 10D, set the meter so you are metering off of the smallest center area of the viewfinder, then set your exposures based on the lightest/brightest area of the subject.

Joe Hardesty · « **Reply #1 on:** October 01, 2003, 03:09:07 pm »

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So what are you saying is to set the metering to partial and get the readings from the the shadows and highlights and then set the camera to expose for the highlights. Is that correct?

Well...it gets a little more complicated than that, so I was trying to keep it simple by suggesting to expose for the highlights. Which is always a good rule of thumb, especially if the hightlights are in/on the main subject.

But you have to remember that digital (nor film for that matter) has the full dynamic range (range of f-stops) of our eyes, so sometimes you have to make compromises in the exposure. For example, in bright sunlight, it would be very difficult to get both highlight and shadow detail in a picture of a black dog standing next to a women in a white dress.

Since digital makes it real easy to experiment, I would suggest you take some time to find or setup various types of shots where you are trying to preserve the detail in certain area of the photo. It can often be very informative to bracket your shots by 1.5 stops to see how the whole scenario of exposure and metering plays out. Through all this, you are learning to see light the way the camera does--that is the goal.

Ray · « **Reply #2 on:** October 02, 2003, 11:30:43 am »

I recall discussing this issue a while back on this forum in relation to the cropping factor of the D60/10D etc. Does the reciprocal of focal length rule still apply?

I think the consensus was - it depends upon the degree of enlargement rather than the format of the camera. For example, a 1/100th sec should be adequate for a hand-held shot with a 100mm lens if the image is to be enlarged 8x, and 1/7th of a sec should also be adequate with a point & shoot 7mm lens provided the image is not to be enlarged more than 8x, which makes for a pretty small print of course.

Joe Hardesty · « **Reply #3 on:** October 02, 2003, 04:03:55 pm »

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Has anyone else had the overexposure problem with the 10D?

I have owned two 10Ds and neither of them exhibited any exposure problems whatsoever. If anything, I was always very impressed with how they even seem to get the tough situations right!

cheever · « **Reply #4 on:** October 02, 2003, 05:08:44 pm »

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Your 10D and mine are from the same litter. I almost always shoot 1/2 stop under. Makes a world of difference.

Dan

Yes it is crazy from -1/2 to -1 is where I get my best results. Other than that I love this camera and couldn't be happier. Jonathan Wienke I think posted something similar to what we are experiencing. Do I need to send it back in for a recalibration or something? Also thanks for all of the input about handholding and shutter speed. The max that I will be printing with my 10D would be 11X17 probably so I can just calculate for that.

Ray · « **Reply #5 on:** October 02, 2003, 09:39:01 pm »

On second thoughts, whilst one can't expect the camera to make esthetic decisions of it's own accord, Canon could perhaps give us a few more controls (yet more buttons and menu options

)

The inadequacy of the dynamic range of digital cameras and their tendency to sharply 'cut off' at the upper limit, has been well documented. Blown out highlights can be a nasty surprise for anyone used to negative film.

In light of a recent, lengthy discussion on 'exposing to the right of the histogram', on this forum, I think there might be a need for an additional metering option - one that guarantees that no more than 1% (for spectral highlights?) of the sensor area is clipped.

Such a system would ensure full exposure to the right of the histogram for maximum tonal gradation in all circumstances. What it would not do, however, is correctly expose a subject against a bright background, which is what the evaluative metering system is supposed to be able to work out, and the reason why it tends to blow highlights in contrasty situations.

russell a · « **Reply #6 on:** October 07, 2003, 04:59:15 pm »

My impression has been that some consumer cameras (I'm thinking of the Sony MVC-400 in particular) are calibrated to be more forgiving in the highlights (and less in the shadows) than prosumer cameras such as the Canon 1Ds. I assumed that the expectation of the engineering choices was that users of the higher end cameras would adjust accordingly. Initially with the 1Ds I was blowing highlights left and right, but soon learned to pay more attention. I have been impressed at the degree to which one can dig detail out of the shadows of 1Ds images without the noise that one would have expected. All this makes sense to me.

cheever · « **Reply #7 on:** October 01, 2003, 11:26:16 am »

First of all I know that this varies by focal length, but what is the lowest shutter that you can use without using a tripod? I primarily use my 17-40 F/4L. I searched for this using the search function but couldn't find anything on it so sorry about this question that has been asked a million times I'm sure.

Also I seem to be the blown highlights king on my 10D. It gets real frustrating because almost every shot I take I get the blown highlights warning on the screen when reviewing the pic. I have tested some of these shots with the camera's built in metering and the shots usually don't exceed more than 4 to 5 F stops from the darkest area to the lighest area of the photo. Another thing that I find funny with my 10D is that the metering of the camera seems to overexpose many of my shots. If I dial in a -2/3 manual exposure compensation the shot comes out right on the perfect exposure. Is this a defect with my camera? Any help would be appreciated.

Thanks

cheever · « **Reply #8 on:** October 01, 2003, 02:51:23 pm »

Ah thanks for that little rule of thumb I didn't know about that. So what are you saying is to set the metering to partial and get the readings from the the shadows and highlights and then set the camera to expose for the highlights. Is that correct?

BJL · « **Reply #9 on:** October 01, 2003, 05:26:42 pm »

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A general rule of thumb is that you can shoot handheld with a shutter speed of 1/focal length, with a minimum of 1/60th.

The "speed of at least focal length" rule is traditional for 35mm photography; maybe it works also for larger format on the basis that you are still aiming for the same resolution (lp/mm on the film) and hence more total detail.

But maybe it needs to be updated for DSLR's, for two reasons:

a) smaller sensor means more enlargement and so an image taken with a given focal length will be more blurred by camera movement; that might suggest revising to rule to use the "35mm equivalent focal length".

if your sensor's resolution is significantly more than envisioned in that rule of thumb, due to small pixels, you might want to be more cautious. I suspect that the rule is old enough to be based on only "adequate" rather than excellent resolution, like the "1000 line pairs per picture height" that floats around with depth of field reckoning. So maybe this needs to be adjusted to account for pixel size, which roughly sets the resolution you would like to achieve.

Let me float a version, based on the thinking that DSLR's with sensors 2000 pixels high roughly match the traditionally envisioned sharpness of 35mm film: replace focal length by something like

(focal length in mm)*12/(pixel pitch in microns)

Example: the Nikon D100 has pixel pitch 8 microns, so maximum exposure duration of 1/(1.5*focal length).

This matches tradition for a 35mm format sensor of resolution 2000x3000, because that has pixel pitch of 12 microns, but the actual value of the constant factor 12 is probably something one should adjust personally. That was an experiment we did early in my first photography course: take a sequence of photographs of something with fine detail like writing at various speeds, and examine the slides carefully for sharpness.

I have not heard the "minimum of 1/60" part; would that number apply equally for other formats?

cheever · « **Reply #10 on:** October 02, 2003, 12:22:47 pm »

Has anyone else had the overexposure problem with the 10D?

BJL · « **Reply #11 on:** October 02, 2003, 04:40:49 pm »

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I recall discussing this issue a while back on this forum in relation to the cropping factor of the D60/10D etc. Does the reciprocal of focal length rule still apply?

I think the consensus was - it depends upon the degree of enlargement rather than the format of the camera.

Thanks; that gives another, simpler rule of thumb, for a slightly different purpose. The original 1/f was probably based on what looks good at a certain standard print size, and I will assume it was 10"x8" but it might have been smaller. So
a) if you want a sharp 10"x8", adjust the 1/(focal length) rule by the "crop factor", because that is how much extra magnification you need for the same print size.
if you also want a different print size, adjust again: if you want 20"x16" and think your sensor has enough resolution for that, double the speed needed because you are doubling the magnification.

So with a 1.5x crop factor and hoping for a sharp 20"x16" print you might want three times the traditional speed: 1/150 with a 50mm lens. But you might be pushing beyond the sharpness that the sensor can give.

My alternative was based on the different objective of getting the ultimate resolution of the sensor. Either way, probably the best way to go is to experiment and "calibrate your hands" by studying prints at the largest size that you like to make.

dbarthel · « **Reply #12 on:** October 02, 2003, 04:43:25 pm »

Your 10D and mine are from the same litter. I almost always shoot 1/2 stop under. Makes a world of difference.

Dan

Ray · « **Reply #13 on:** October 02, 2003, 07:41:20 pm »

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My alternative was based on the different objective of getting the ultimate resolution of the sensor. Either way, probably the best way to go is to experiment and "calibrate your hands" by studying prints at the largest size that you like to make.

Of course, rules of thumb are just that - rough guides only. How steady you can hold that camera will depend on lots of other factors including individual techniques like leaning against a tree or breathing out prior to pressing the shutter, and so on.

On the issue of 10D overexposure, this was one of the first mistakes I made with my D60 and evaluative metering. So many shots from that first batch (and it was a big batch because I was travelling and away from my computer) had blown highlights. I wasn't paying enough attention to the flashing 'blown highlight' indicator. But I soon learned to underexpose or use AEB.

There's probably a good reason for the adjustment of the camera's metering system so that it overexposes in contrasty situations. The nature of digital cameras is such that for maximum tonal gradation it is recommended one expose fully so that the histogram reaches the right. The apparent overexposure is not really overexposure. It only happens when the dynamic range of the scene is beyond the capabilities of the camera. One can't expect the electronics in the camera to make the esthetic judgement that, in a particular shot, shadow detail should be sacrificed in order to preserve highlight detail.

BJL · « **Reply #14 on:** October 07, 2003, 12:27:45 pm »

For "manual metering", tools like the histogram and flashing on blown highlights seem to be serving well, but for more automated metering, I get the feeling that no camera maker has yet modified the algorithms of their multi-zone metering systems to better fit the peculiarities of digital cameras, like limited highlight headroom.

Has any camera maker made such metering changes? If not, would it make sense, for example, to pay more attention to keeping the brightest zone within range? (I think that this means keeping within about three stops of the declared 18% gray point for JPEG output, maybe a bit more for RAW). Should the chosen exposure level differ according to whether RAW or JPEG output has been selected, if RAW can accomodate more headroom?

Author Topic: A couple of easy Questions (Read 5661 times)