bill_chiarchiaro

Andrew,

I might have misread your first posting, thinking that your were questioning the purpose of FV Lock. Page 7 of the booklet just shows an example in which FV Lock is useful.

I agree with you that simply flipping to manual focus shouldn't be a valid substitute for FV Lock.

--Bill

Andrew,

Take a look at page 7 of the booklet "A collection of example photos" that comes with the SB-800 and the SB-600.

--Bill

Lex,

"I've pored over every scrap of Nikon literature I can find in print and on the web and cannot find a single specific mention of whether iTTL wireless works via optical sensors or radio transmitters."

Nikon does bury this information. In the SB-800 manual, the only mentions that I recall are on page 74, "Speedlight and camera placement." That's where there are instructions to aim a remote flash unit's light sensor toward the master flash. Even this might further the confusion, because it doesn't state that the light sensor in question is the one for wireless remote, as opposed to the one for Non-TTL auto flash. By the way, there are similar instructions on page 151 of the D70 manual.

"some ... enthusiastic ... family member with a Rebel or N65 keeps triggering all of my flashes by popping away with her built in flash."

I expect that a regular flash would not trigger an SB-800 or SB-600 (assuming they're not in SU-4 mode). On the other hand, I imagine that a regular flash could prevent a remote SB-800/600 from firing. The light from a regular flash that's very close to the SB-800/600 might obliterate the remote-control light pulses from the master SB-800 (or a D70's built-in flash).

--Bill

"As far as I can tell the SB-800's AF assist lamp is disabled when connected via the SC-29."

It depends on how the SC-29's "AF-ILL" switch is set. If it's set to "OFF," then the SB-800's illuminator will operate; if it's set to "ON," then the SC-29's illuminator will operate.

--Bill

Hannu wrote:

"a Muscovy duck maybe?"

That was my guess.

--Bill

I've done one session of lightpainting with a Nikon D70, and I was pleased with these early results.

I was working indoors, photographing subjects about 8x8 feet in size, with no ambient light. The camera was set for ISO 200 and f/22. Exposures were in the range of 30 to 40 seconds. My light source was a 4-C-cell Maglite flashlight with an improvised snoot made of a sheet of 8.5x11 inch paper and some packing tape. I used the D70's wireless remote to open and close the shutter (press once to open, press again to close). I had my wristwatch on repeating countdown alarm (10 or 15 seconds) to help time the exposures. During an exposure, I'd keep the flashlight moving constantly. I used the camera's long exposure noise reduction, and none of the resulting photos showed hot pixels.

Good luck,

--Bill

The final two sentences of my previous response were superfluous. If the print size matches the image's dimensions in pixels divided by the display's PPI value, then the print and the display (running at 100%) will both be showing the same amount of detail per unit area (ignoring issues such as how crisply the display renders a pixel compared to the print, etc.).

--Bill

"the monitor DPI (72 for PC and 96 for Mac)"

72 or 96? Hmm... The computer I'm using to type this message has a display that measures 12 inches by 9 inches. It has a resolution of 1400x1050 pixels. That's 117 DPI (but it would be better to say 117 PPI --- Pixels Per Inch).

Arnab's correct about dividing the image dimensions in pixels by the display's DPI or PPI value to see how big the whole image would be, but there's an assumption that the image will be printed at that same DPI / PPI value. For example, at 100% (i.e. each pixel of the original image takes up exactly one pixel on the display) on my display, a 3008x2000 pixel image would have a virtual size of about 26 by 17 inches. But, if I go to print that image, then it would be 26 by 17 inches only if I print it at 117 PPI. If the printer is set to any other PPI value, then the print size is going to be different.

--Bill

Quite wet? Was it raining? Perhaps these spots are the very out of focus images of raindrops that were close to the lens and brightly lit by the flash.

--Bill

Paul wrote:

"In Capture, it takes a minute or so for things to settle down and then only 5-15 sec for raw adjustments. TO open it up in PS CS and take upwards of two minutes!"

Wow, that is painful. On my notebook that has a 1.5 GHz Pentium M with 768 MB of RAM, using the ufraw program, it takes less than 4 seconds to open a D2X NEF and display the preview image. Individual adjustments take less than 1 second each. Processing and saving the final image as a TIFF (8 or 16 bits per sample) takes about 26 seconds.

--Bill

Paul wrote:

"The only downside is the files are so large that processing them even with a gig of ram and a p 2.4 processor is a very slow procedure."

I assume that's with Nikon Capture 4.2. How many seconds does it take your machine to convert one image?

--Bill

Arnab,

Maybe we should give it a few hours, to see if anyone finds a problem with my analysis! We hear so much about the crop factor that's it's easy to assume it affects just about everything. Let's see, ISO 800 on the D70 must be equivalent to ISO 1200 on a 35mm film camera...

--Bill

Magnification does not depend upon the size of the sensor or film (but field of view does).

The 6T has a power of 2.9 diopters, meaning its focal length is 345 mm (1000 / 2.9). So, if the camera lens behind it is set to infinity, then the working distance of the combination will be 345 mm from the 6T. This is regardless of the focal length of the camera lens. The diverging light rays from an object at 345 mm will be made parallel by the 6T. The camera lens will take those parallel rays and bring them to focus on the sensor or film.

Indeed, one formula for magnification is (image distance) / (object distance). Or, reproduction ratio is 1 : (object distance) / (image distance). In this example, the reproduction ratio would be 1 : 345 / 210, or 1:1.64.

The D70's sensor is 23.7 mm wide, so at that reproduction ratio, an object 38.9 mm would fill the width of the frame (23.7 * 1.64).

Note that the D70's "1.5x crop factor" didn't enter into this.

Also note again that the working distance mentioned above is measured from the 6T, in other words essentially from the front of the camera lens. On the other hand, the distances on the lens's focusing ring are measured from the sensor or film plane. You need to add the 345 mm to the distance between the sensor or film plane and the front of the camera lens (ignoring the thickness of the 6T to keep it simple) to make the distances comparable.

--Bill

When I look at http://www.naturfotograf.com, I see the following about the 50 mm f/1.4 SC [non-AI]:

"Wide open there is some softening in the corners"

and about the 50mm f/1.4 AF-D:

"It delivers crisp and sharp images even set wide open"

and about the 50 mm f/1.8 AIS/AF (and presumably AF-D):

"Wide open there is a trace of softness into the corners"

This sounds like the f/1.4 AF-D does well wide-open, compared to the other two.

--Bill

"Nikon RAW format from the new D2X is already different from the RAW file produced by Nikon D70."

<p>But, it seems the difference is minor. I've already processed D2X NEF files (from other people's cameras) through the dcraw and ufraw raw converter programs. These programs (note that ufraw is based on dcraw) don't yet know anything specific about the D2X. However, the only problem I've noticed is that they don't use the D2X's white balance setting. This is not a surprise, because the programs do contain camera-specific details about white balance. Dave Coffin, the author of dcraw, has been pointed to sample D2X NEF files, so this issue will probably be rectified soon. In any case, the user still has the choice of manually setting the white balance, using spot WB from the image, or letting the programs automatically determine the WB.

<p>I suspect that with other programs, such as Nikon Capture, each version has a list of which camera models were in existence at the time the version was released, and they refuse to work at all on files produced by other models.

<p>dcraw and ufraw are open-source programs, so no matter how computer hardware or software evolve, it will always be possible to use them. These programs were primarily developed for use on Unix computers, but pre-built dcraw executables are available for MS Windows computers. See:

<p><a href="http://www.cybercom.net/~dcoffin/dcraw">dcraw Web site</a>

<p><a href="http://ufraw.sourceforge.net">ufraw Web site</a>

<p>The ufraw Web site has links to sites for MS Windows executables.

<p>--Bill

Online copies of the D2X user's manual became available today at

www.nikonusa.com. There are two version: a printable one which

requires a valid North American D2X serial number, and a non-printable

one.

--Bill

Ilkka wrote:

"Notice the Capture requirement of >1 GB RAM to process D2X files."

For a comparison, I ran ufraw (based on dcraw; see http://ufraw.sourceforge.net) on a 12-megapixel D2X NEF file, saving the result as 16-bit TIFF. The size of the process was only 196 MB. This was on a Unix computer.

--Bill

For whatever it's worth, I had never been bothered by the low-light AF behavior of my 50mm f/1.4 D on the D70. That's the only lens I have that's faster than f/2.8. It's a small, lightweight lens, so it might be easy for the D70's AF motor to drive, as compared to other non-AF-S lenses.

Last night, I tried some experiments with this lens and body in a dimly lit room. I tried AF on a variety of objects at distances from about 60cm to 2.5m. I used the center AF sensor, single-servo mode, and no AF assist illuminator. For each object, I tried AF with the lens preset to infinity, minimum focus, and somewhere close to the object distance. I set the lens to f/1.4 and the body to aperture priority, ISO 1600, and matrix metering. The objects in the AF sensor tended to be dark with low contrast; the overall scenes were more or less average in reflectance.

I found that at indicated shutter speeds down to 1/25 sec, the AF action was always fast with no overshoot or hunting. At 1/20 sec, the lens would quickly get very close to final focus, but then jitter for a small fraction of a second before locking. At 1/15 sec, when starting from infinity or minimum focus, the lens would overshoot and then hunt; quick shots would be difficult. At 1/8 sec, the AF action hunted a lot and was annoyingly sluggish.

So, this particular lens and this particular body gave good AF performance, with the center sensor, in lighting down to 1/20 sec or 1/25 sec at f/1.4 and ISO 1600. There might be unit-to-unit variations within one model of lens that result in AF difficulty with some models of bodies, and I expect some models of lenses are generally more difficult to focus than others.

--Bill

Ilkka,

Your comments in this and another thread have piqued my curiosity. Are you experiencing your problems with f/2.8 lenses? f/1.4 lenses?

How low does the light have to be (scene illuminance or subject luminance, or camera meter reading) for the problems to occur?

Thanks,

--Bill

Mike asked:

<p>"I know what APS is, but is APS-C? That is, what does the "C" mean?"

<p>As Godfrey indicated, APS is not just one format, but rather a family of formats. When people say simply "APS" they usually mean "APS-C." See, for example, <a href="http://www.answers.com/main/ntquery;jsessionid=2vh09qg623bht?method=4&dsid=2222&dekey=Advanced+Photo+System&gwp=8&curtab=2222_1&sbid=lc04b">Answers.com</a> for a brief explanation of the APS formats.

<p>--Bill

Vivek: Thanks! I appreciate the compliment.

Luis: Don't feel bad. The first time I read the title of this thread, I thought it was about a training course ("workshop") for wedding photography!

--Bill

Godfrey wrote:

'"16x24mm" vs "24x36mm" is much more understandable'

That's for sure the way I think of them!

--Bill

Godfrey,

The sensors used in the Four Thirds systems do have a 4:3 aspect ratio, but they are named for their 4/3-inch size, not their aspect ratio.

Visit the link I posted above to see an explanation of what 4/3-inch, 2/3-inch, 1/1.8-inch, etc. mean.

--Bill

Ken,

<p>You're confusing aspect ratios, such as the 3:2 of 35mm film and APS-C sensors, or the 4:3 of compact digicams, with the archaic naming convention for sensor sizes. You're not alone in this. See <a href="http://www.dpreview.com/learn/?/Glossary/Camera_System/Sensor_Sizes_01.htm">dpreview's explanation of sensor sizes.</a>

<p>The name of the "Four Thirds" system is a reference to size, not aspect ratio.

<p>--Bill

Keith,

If the shooting session won't be under severe time limits, then take advantage of the fact that you have a digital SLR --- experiment with different settings and lenses during the shoot, review the results, and adjust.

Some hints:

There will be a huge lighting ratio in the scene. Take advantage of spot metering to base the exposure on an area that's not right next to the welding arc or flame (if you're using a lens that gives a wide view), and let the arc or flame be overexposed. Or, again take advantage of your DSLR, use manual exposure, and quickly try a range of exposures. Using a lens with a narrower view can reduce the lighting ratio by restricting the scene to areas close to the arc or flame.

Ghosting and perhaps flare could be problems. Some lenses are better than others in this regard. You might want to remove any filters from your lenses. If you're using a lens that tends to produce ghosts or flare, try to use as small an aperture as possible.

Do test shots with a white or grey card, or identify a neutral object in the scene, for setting white balance. Shooting in raw mode is probably a good idea.

Think about how you want to depict motion. If there's enough ambient light, or if you've narrowed your view, you could use a fast shutter speed to freeze the shower of sparks. Or, you might want to use a slower speed to get blurring to indicate motion or to make the shower look more full.

Give some consideration to using flash to bring up the level of ambient lighting; a welding scene can be similar to a backlit scene in sunlight.

I was recently shooting in an aircraft restoration workshop. I came around a corner and saw a mechanic using an electric arc welder; I had only a few seconds to shoot before he stopped. A matrix-metered exposure was very underexposed. Shown here is my favorite shot (still not a wonderful photo), which was spot metered on the frame of the vehicle being welded. The lens was the 12-24mm DX at 24mm, with a Nikon L37c filter; the exposure was ISO 800, 1/160 sec, f/4. This was raw mode, with spot white balance during conversion from NEF. With more time, I would have used a lower ISO setting, but I was set up for low-available-light shooting. At 1/160 sec, there was some elongation of the sparks, but a slower shutter speed would have been better for accentuating the shower. There were no ghosts or flare.

--Bill<div></div>