wayne_f1

<p>The SB-600 may be about 60 watt seconds, but I think the SB-800 is about 75 watt seconds. For one thing, the SB-800 meters about 1 stop less than 160 watt seconds (when both are compared in the same umbrella, at 24mm to fill it). For another, its 1400 uf capacitor and 325 volts computes 75 watt seconds of power. 300 watt seconds should be two stops stronger (in the same umbrella). </p>

<p>Cannot compare the reflectors. GN is about the reflector. Obviously the speedlight meters about 2 stops more at 105mm zoom than at 24 mm zoom, so we can only compare "power" when both lights cover about the same area.</p>

<p>>>Cleraly, the Photogenics unit put out more power than the Alienbees unit, unless I'm reading this wrong.</p>

<p>You are reading it wrong, real result is surely the opposite. The Photogenics say they come with a reflector that covers 35 degrees. Here: http://www.photogenic.com/item/23/314/pl7r-7&frac12-high-gain-reflector/</p>

<p>The Alienbees come with a reflector that covers 80 degrees, here: http://www.alienbees.com/7abr.html</p>

<p>If you have a camera speedlight, you know it zooms with the lens. Like 24mm to cover a wideange 24mm lens, and like 85mm to cover a telephoto 85 mm lens. It is much brighter at 85 mm, when concentrated to only cover a small spot on the wall (like a concentrated flashlight beam). It is much weaker at 24mm, but it probably covers the entire wall. If you metered these, you would conclude it has about 4x the power at 85mm, which is wrong, it is infact the same power, same speedlight. That is about the light meter reading inside that little spot, but it is meaningless if interested in "power". To be representative of power, you must meter them when both doing the same thing, illuminating the same size area. It requires much power to illuminate a large area. The area is about the reflector or light modifier, how that power is distributed, or diluted, so to speak.</p>

<p>In an umbrella, the AB will illuminate the entire umbrella, instead of just the center spot of it.</p>

<p>So instead, to equalize things, meter both of them with no reflector at all (how it is used in sofbox. At exactly same distance of course. Or with the reflector, set them both exactly 3 feet from a blank wall, and photograph that spot on the wall in the same way, so you can compare the area illuminated. Maybe tape a yardstick to the wall for that picture. Wider dilutes the power over a larger area... power per unit area, so to speak.</p>

<p>Effective watt seconds has no meaning at all, the AB B800 is rated 320 watt seconds.</p>

<p>Color varies with power level, and it may be different, but softer requires "large", like a softbox or umbrella. Soft is not about the little reflector.</p>

<p> </p>

<p>Yes, the Alienbees holds the umbrella. That is what the little hole in the AB reflector does. Rotate the reflector so that hole is at the top, to line up with the mounting hole on top of the AB case. Stick the the umbrella shaft through the hole in the reflector, into the hole on the top of the case, and clamp it down. Presto! The AB mount on the top of the stand allows you to tilt it to aim the light and umbrella.</p>

<p>If the light is a studio flash, that light will have means to hold the umbrella shaft, and means to tilt up and down to aim the light. All you need is the umbrella, stand, and studio light.</p>

<p>If the light is a camera speedlight, then you also need an umbrella mount, like this one: http://www.bhphotovideo.com/c/product/679112-REG/Impact_3117_UMBRELLA_SHOE_MOUNT_MULTI.html</p>

<p>This goes on top of the light stand, and holds the umbrella shaft, and tilts to aim it. The speedlight goes on a shoe on top of it (often not included). Note the hole for the umbrella shaft is normally tilted, so that the shaft inserted from the correct side will lift the umbrella higher, to be even with the taller speedlight head. Some pictures at http://www.scantips.com/lights/umbrellas.html</p>

<p>A 40-48 inch is large enough, a normal size. Normally close as "possible". Close and Large is good, the main property to create soft light, but you will need a lot of space for larger, larger can be awkward to try to work around in a small space. It likely will not actually be as large as the measurement, which is frequently the longer length over the curved top (dimension is the rib length, or fabric size). The actual straight across measurement likely is a bit less.<br /> Examples:<br /> Smith Victor white umbrella, 45 inch dimension is more like 40 inches across.<br /> Photogenic Eclipse, 60 inch dimension is more like 48 inches across.<br /> This is typical, but not without exception. Impact 32 inch is almost 30 inches across.</p>

<p> </p>

<p>>>If dpi has been the established term for scanner resolution for 3 decades; what purpose does injecting newbie terms do but inject confusion?</p>

<p>Exactly. Right on Kelly, thanks. Newbies dont always understand the real world, and just cause more confusion when they shout "Wrong" about 90% of what they see. Laughable, but sad too.</p>

<p>All scanners are rated dpi. There are no ink drops in scanners. dpi means pixels per inch.</p>

<p>JPEG specifications: http://www.w3.org/Graphics/JPEG/jfif3.pdf page 5 says "dpi".<br>

<br />TIFf specifications: http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf page 38 says resolution is "dots", per inch or centimeter</p>

<p>Always was dpi, probably always will be dpi. To have two meanings for dpi is not confusing. If the context is about images, it can only mean pixels per inch. If the context is about printers, it can only mean ink drops per inch. English words are like that.</p>

<p>The one thing that CAN be said to educate newbies is to tell them that we WILL see it both ways, and so it is good if we understand it both ways. Otherwise, we are ignorant, if we cannot understand what we read everywhere.</p>

<p> </p>

<p>>>My scanner says that its' maximum output resolution is 4000 pixels/inch. Why would I need that much resolution if all I want is to print up to 8 x 12 or send a picture in an email or post a picture on the web? Am I missing something here? Don't all I need is about 375 pixels and inch? That doesn't sound correct.</p>

<p>It is correct.<br>

4000 dpi is the "input" resolution, at the film size, about 1.4x0.9 inches. So this scan creates about<br>

(1.4 inches x 4000 dpi) x (0.9 inches x 4000 dpi) = 5600 x 3600 pixels of image size.<br>

<br />Those same exact unaltered 5600x4000 pixels, when scaled to be spaced 300 dpi printed on paper, will cover<br>

5600 pixels /300 dpi =18.6 inches<br>

3600 pixels /300 dpi = 12 inches. THIS is output size, 18x12 inches at 300 dpi. </p>

<p>This is called scaling, to specify a different dpi number to alter the number of inches that the SAME pixels will cover on paper.<br>

<br />The basics are that the ratio of (scanning dpi / printing dpi) = enlargement factor.</p>

<p>If you want to print the image 10 times larger than the film frame, then to have enough pixels do to that, you scan at scanning dpi = 10x the printing dpi.</p>

<p>10x dpi scan prints 10x larger, when at 1/10 the dpi (like 3000 dpi scan, 300 dpi print).</p>

 

<p>>>For example, when I place the bug on the middle exposure setting, the histogram is usually slightly to the left of the middle line. Brightening the exposure by a third of a stop will either center the on-camera histogram exactly or nudge it very slightly to the right past center</p>

<p>That was how this started for me. An 18% gray card ought to come out at 117, a bit below histogram center (everything about this is variable of course). But nothing about a gray card is related to histogram midpoint. 18% is 18% (linear).</p>

<p>After gamma, then the histogram should show:</p>

<p>One stop down: (0.5 ^ 1/2.2) = 0.73, x255 = 187 73% of 255 full scale</p>

<p>18%: (0.18 ^ 1/2.2) = 0.46, x255 = 117 46% of 255 full scale.</p>

<p>Kodak 18% gray card instructions say if we meter from a gray card, we should increase exposure 1/2 stop (to the 12% value claimed by others, including Sekonic).</p>

<p>Some recalibrate their meter to make the gray card be centered. This makes 18% read as if it were 22% (which should move to center, and the 50% center moved to 187). This is the opposite direction, and a bit of underexposure, but a small error, less than 1/3 stop (except for that 1/2 stop too). </p>

<p>The gray card was popularized by Ansel Adam's Zone System in 1940. There were no digital histograms and few quantitative tools at that time, and of course, negative film had more latitude of exposure. Still handy, though, for what it is.</p>

<p> </p>

<p>Thanks guys. I think it must be the camera making adjustments. I know Adobe ACR does a S-curve, but I was speaking of the camera LCD. Was speaking of a Nikon D300, but I just tried a D70S, and one stop down is just above 75%, more in agreement to the expected 73% (there is some error at my 255 end). But a D300 is more like 7/8 or 88% at one stop down. <br /><br />Thom's D300 guide has some info related to this. However, it seems more confused than I am though, not sure what it is saying. Page 67 (edition 2) shows a chart of values within stops, which says theoretically assumes the camera has exactly 7 stops of range. It starts at the 0 end, and it puts the center 4th stop centered on 128 (says 111 to 146). So that is not a linear assumption. I think it is not gamma either. It says this imaginary top 7th stop is 220 to 255. However, this chart obviously only divides 255 into 7 equal spans (36, 73, 110, 146, 183, 219, 255) , which I think does not represent stops, but he calls it stops.<br /><br />Page 69 shows a response curve said to be plotted from photographing a Kodak step chart. No units or coordinates to get hold of, but I doubt this can be linear, and it does in fact look similar to a gamma chart (a curve with midpoint boosted substantially). Says a bit unexpected that it is not perfectly flat as on previous Nikons ? I don't get much from that. No content containing detail. The words imply a boosted gamma curve however, and that is what I am seeing, on the D300, but not on the D70S.</p>

<p><br />Technical question about gamma in histogram, and one stop exposure difference.<br /><br />We know camera sensors are linear (RAW data).<br /><br />We know that one stop underexposure is 1/2 of the light intensity.<br /><br />So we know one stop underexposure will move any data represented by 255, down to be at midpoint, or half scale, which is at 128 (in linear RAW data).<br /><br />We know we never see linear, all RGB images and histograms are gamma encoded. So this gamma encoding shifts linear midpoint 128 at 50% to be shown at<br />(0.5 ^ 1/2.2) = 0.73, x255 = 187, or 73% of 255 full scale <br /><br />So the conclusion is that one stop down from 255 should be at 187, or 73% on histogram.<br /><br />I would never question any of that, it seems true by definition, but yet.... it does not happen. One stop underexposure (Nikon D300) does not move a white peak at right edge at 255 to be anywhere near 187 at the 3/4 point. One stop under full scale shifts no more than half of that much, if that. Crudely, perhaps to 88% or 90% instead of 73%.<br /><br />I cannot account for why not? There are additional things happening, like White Balance, but I would not expect any other effect nearly this large...<br /><br />Any insights to resolve this would be appreciated.</p>

<p>>>Assuming that we are using GN at the same ISO, output at full power, etc. Guide Number (GN) seems to be <strong>proportional</strong> to the square root of Output Energy in joules = watts-seconds (WS), in the sense that, everything being equal, a flash with GN = 64 will have twice the WS than a flash with GN = 45.</p>

<p>Simply No... Forget it.</p>

<p>A speedlight (at full power setting) has one computed power level in watt seconds, but it has numerous guide numbers, a different one at every zoom level. The GN zoomed long may be as much as four timese the GN zoomed wide - and 4x GN is 4x distance range, which is 16x equivalent power. Yet the actual power level at the capacitor is still exactly the same electrical power. </p>

<p>Which one of these guide numbers do you wish to convert to watt seconds? All of the guide numbers at all of the zooms have the same watt seconds input power.</p>

<p>Zoomed long, maybe we illuminate a small spot on the wall. Zoomed wide, maybe we illuminate the entire wall. The concentrated small spot will be much brighter than the lighting the full wall. It requires much greater power to illuminate a large area. Power per unit area, so to speak.</p>

<p>The GN is as much or more about the reflector (the angle of light coverage) than it is about the power. You are not taking that into account. GN is about illumination result with some one reflector. Watt seconds is about input electrical power.</p>

<p>The watt second number is the electrical input power to the capacitor, theoretically all dissipated in the flash tube when triggered (not quite so). There are also efficiency factors affecting the degree of light output. Then we can use some specific reflector to spread or concentrate that light in different ways, over different size areas, for different results.</p>

<p>Simply very different factors. More GN in equal situations does act a little like more power acts, but effect of 4x GN compares to 16x more power. You cannot numerically convert GN to watt seconds. </p>

<p>GN is largely about the reflector and the angle of light coverage.</p>

<p> </p>

<p>You doubt you could stay in the same room with a 1200 wattsecond monolight. :) Probably the 2000 watt seconds was a power pack, to be shared by 4 or 5 lights (and all of them turned way down). If you use an old view camera with lens at f/32, you may need that.</p>

<p>I use Alienbees B400 (160 watt seconds) at about 1/8 power in Large softbox for close portraits at about f/10. ISO 200. Softbox may be at about 30 inches, and a fill umbrella maybe at 5 feet. </p>

<p>At full power, one B400 160 watt second monolight will do f/8 in a white umbrella, fabric at ten feet for groups (ISO 200 again). Indoors, how much more power do you need? I also have two B800 (320 watt seconds) which have to be at 1/16 power for close portraits above, so I relegate them to background and hair light use, where I can put grids on them to knock them down some.</p>

<p>If you have a ISO 200 camera, look for about 150-160 watt seconds. More than plenty for the living room. You will have to turn it way down.<br>

If you have a ISO 100 camera, maybe look at 320 watt seconds (to be the same).</p>

<p>ISO 200 160 watt seconds is exactly equivalent situation as ISO 100 320 watt seconds.</p>

<p> </p>

<p>The Sekonic L-308 is spec'd with a 40 degree angle for reflected. That is what I have, and I like it, and would replace with same thing if necessary, but I use it for flash (incident). Simple to use and more than plenty. However outdoors, it has no Aperture Preferred setting, it is only Shutter Preferred. Which is perfect for flash, but is awkward to me outdoors.</p>

<p>>>I was under the assumption, though it seems possibly mistakenly, that when using a PC cord shutter speed can be set at whatever. How do people like Lois Greenfield stop motion as majestically as she does? Then there's Nikon's FP High Speed Sync</p>

<p>There are several things to be learned about this subject.<br>

1. The focal plane shutter will simply not sync faster than 1/250 second. Period. Yes, in Manual mode, it allows setting shutter to any speed, but it will still only sync at 1/250 second. That means if you set the shutter to say 1/2000 second, you will get a wide black unexposed strip at the top of your frame. Unusable. It only works right when shutter is at max sync speed, or less.</p>

<p>2. The flash is typically much faster than the shutter. High Speed photography uses the flash duration speed, not the shutter speed. Flash does not care what the shutter speed is, it is faster than the shutter speed. See http://www.scantips.com/speed.html for an example.</p>

<p>3. FP HSS converts the flash to be continuous light (continuous like sunlight, to simply eliminate the sync speed issue- but at lower power level), but which is the slowest possible "speed". HSS is merely high speed sync, NOT high speed flash. It is the opposite of high speed flash, because the shutter is typically slower than the flash.</p>

<p>Just use the PC sync to one studio light, and then all the others will be triggered by their optical slave triggers.</p>

 

<p>No. Simply different systems. The SB-800 has backwards compatibility with older cameras, but the CLS cameras have none (and the SB-900 has none). Assuming a CLS camera, then the SB-80DX will have no iTTL and no wireless communication with the commander. </p>

<p>If all flashes involved are in real Manual mode, it should still do it Manual mode and Auto mode, either on hot shoe or as a SU-4 remote slave.</p>

<p>>> YES I tried new batteries.</p>

<p>If the Nikon flash, when in Remote mode, does not show the Ready LED on, and if its LCD changes to show Standby status (Remote mode flashes never otherwise go into Standby), then that is a clear symptom that the batteries are dead.</p>

<p>My question is more specifically about these "new" batteries... Have you tried recharging the rechargables? New rechargables from the store may not be charged enough to work. Or have you tried (non-rechargable) new alkaline batteries? Try your friends SB-800 working batteries in one of your flashes. If new or properly recharged batteries does not fix it, then it sounds like repair is necessary. But two flashes developing same problem at same time seems extremely unlikely, not reasonable.. it instead sure does sound like a battery situation.</p>

<p> </p>

<p>A SB-800 is closer to 75 watt seconds. It has a 1400 microfarad capacitor at 325 volts, and 1/2 CV² computes 75 watt seconds. Metered individually in the same umbrella, it meters 1 stop down from a 160 watt second Alienbees B400, suggesting same level is correct. However, its slower recycle does make it seem less powerful, full power is not pleasant.</p>

<p>There are many tougher situations than mine, such as f/22, or overpowering the sun, or lighting the basketball court, but for my ISO 200 camera, 160 watt seconds is more than plenty for anything you can do indoors at home. More power would be a distinct problem, always shooting at minimum power is no fun either. I replaced 320 watt second B800s with 160 watt second B400s for that reason of practicality. I shoot close portraits with 160 watt second Alienbees B400 in at 1/8 power in Large softbox at ISO 200 f/10. Full power in umbrellas will do groups at ten feet at f/8 (ISO 200). How much more is needed?<br>

My point is that 160 watt seconds at ISO 200 is exactly the same situation as 320 watt seconds at ISO 100. So also inquire about ISO when people state you need more.</p>

<p>The speedlight is really about enough power in very many cases, but the slow recycle and the AA batteries are a real drag, and other than umbrellas, it does not fit the modifiers.</p>

 

<p>Here is the manual for the SU-4:<br>

http://www.nikonusa.com/pdf/manuals/Speedlights/SU4.pdf</p>

<p>The SB-28 cannot be in TTL mode, it must be in Manual mode. But the SU-4 (in its Auto mode) can "follow" a TTL flash to simulate multilple flash TTL (follow implying starting with the triggering flash, and ending with the triggering flash). The SU-4 is designed for film TTL, whereas digital TTL has the preflash. All references to TTL in the manual refer to film TTL, digital TTL was unknown at that time. The digital preflash will trigger it too, before the shutter opens, but it is fast, and if the triggered flash is not at full power, it probably can trigger again. The digital cameras TTL cannot control this SB-28, but it will follow the controlled triggering flash duration. Possibly may be "close enough".</p>

<p>Another SB-600 used with the Nikon Commander is Nikons way to do digital multiflash TTL, and that is the way to plan for digital TTL, but try it, this SB-28 with SU-4 may work for you.</p>

<p>Of those, for sure get the White Lightning X1600, because it is smaller (and larger) than the X800. It has the switch to convert it between a 660 watt second huge light, or to be a 160 watt second flash, a true small fast unit. Then it is NOT just a big slow flash turned down even slower, it is a true 160 watt second fast smaller light (which is all you can use in your room, and then some). It has a 7 stop range, in the good way. This is a mighty big feature, in situations like you mention.</p><p><br></p>

<p>>>>According to Nikon these bodies sync at 1/500, but is that only with the SB800? Is there a Nikon body that syncs faster?</p>

<p>These bodies with CCD and electronic shutters, those with the 1/500 maximum sync speed (these are all CCD models, the CMOS models cannot do that) will sync at any faster shutter speed, so long as the camera does not know the flash is present. If you put the speedlight on the hot shoe, the camera knows flash is present, and will limit maximum sync speed to the 1/500 second. Take the flash off camera, on a PC sync cord (which has no communication with the camera), or a remote optical trigger, then it will sync at any faster shutter speed. </p>

<p>If and buts. If the shutter is faster, like 1/2000 second, it will be faster than the flash (studio lights, and except for speedlights at power level lower than maximum power), therefore it truncates the flash duration, and therefore you lose substantial power. Many radio triggers do not even do 1/500 second, so they may not work either.</p>

<p>The higher end cameras (with CMOS sensors and focal plane shutters) which have the 1/200 or 1/250 second sync speed, CANNOT sync faster than that. Period. However, most of them do provide the HSS "Auto FP" mode which converts the so-designed speedlight flash (SB-600, SB-800, SB-900) to be continuous lights (repeated sequential series of lower powered flashes), so there is no concept of sync speed, so they work at any higher shutter speed (just like sunlight works but truncates at fast shutter speeds). This FP mode will reduce the flash power to something less than 1/4 maximum power, something more than 2 stops loss.</p>

 

<p>Nikons Exif "flash did not fire" message simply means "TTL flash" was not active, and there was no TTL metered light detected. Any camera's metering systems otherwise have no knowledge if any manual flash was present or not.</p>

 

<p>I have four Alienbees, and think they are a great buy, quality, price, service, if assuming use in the USA. But maybe not for on other side of world... Sure, you need something more designed for your local situation of voltage and local service.</p>

<p>The Interfit lights are rather minimal, low end. Some things to look for:</p>

<p>Venus 150 watt seconds vs Alienbees 160 watt seconds - same - probably no noticeable difference (if marketing is honest - never guaranteed). This is plenty of power for portraits or small groups indoors. Not sufficient for great distances or to match the sun outdoors.</p>

<p>Venus recycle speed 1.5 seconds - Alienbees 0.5 seconds. This is the time you must wait between shots. This is full power, operating them at 1/8 power will be faster.</p>

<p>Venus duration 1 to 3 milliseconds (1/1000 to 1/333 seconds) - Alienbees 1/3000 to 1/6000 seconds.</p>

<p>Venus Power range - Full to 1/8 power (4 stops) - Alienbees Full to 1/32 power (6 stops)</p>

<p>Venus modeling lights 50 watts, can use 100 watts - Alienbees 100 watts, can use 150 watt halogens.</p>

<p> </p>

<p>It is probably safe. Search Google for<br>

portaflash 336VM voltage<br>

and one guy says he measured his and it was 9 volts, which is safe. Not that internet info is to be trusted, but this sounds valid.<br>

The Nikon DSLR are rated for 250 volts (D80 page 119), so it can stand a lot.<br>

Some old flashes might measure 200 volts on the sync cord (connected to the camera). You can measure it yourself with a DC voltmeter, flash turned on but not connected. I doubt this one is that old. Normal on todays gear is 4 to 6 volts, but 9 volts or 20 volts is no issue at all.<br>

Other choices are to use it remotely with a optical or radio trigger, and then those items are all that is at risk, no longer the camera.</p>

<p> </p>

<p>>>Sure enough, the White Lightning strobes <a rel="nofollow" href="http://www.white-lightning.com/x1600.html" target="_blank">http://www.white-lightning.com/x1600.html</a> <br /> seem to have some unusual circuitry which means that a 1/32 power flash could have a longer duration than one at full power, while a 1/4 power flash is much shorter.</p>

<p>Pretty mainstream actually. Flash units only have about four ways to output lower power (there is no one answer).</p>

<p>1. Reduce the voltage on the capacitors for low power. Watt seconds = 1/2 CV², C is farads, V is volts. The flash duration will become longer at low voltage and power, perhaps 2x longer duration from maximum to minimum power. Those flashes which are affordable are generally of this type, White Lighting and Alienbees, Elinchrom D-lite, etc. These units become more red at low power.</p>

<p>2. Switch out most of the capacitance. A subclass of 1 actually, still voltage controlled. The White Lighting X1600 mentioned switches in 4 capacitors for 660 watt seconds, or switches in only one capacitor for 1/4 power at 160 watt seconds. Watt seconds = 1/2 CV², C is farads, V is volts. This becomes a true low power flash which is very fast duration, instead of merely a large flash turned down, which is very slow. Two flashes in one. In both modes, full or 1/4 power, each still has six stops of voltage control from Full to 1/32 power.</p>

<p>3. Thyristor control, which always recycles to full voltage, but it interrupts the flash tube current to stop the flash sooner. Thyristor is an old term, the modern semiconductor that do this today are called IGBT. Camera speedlights are of this type (Nikon, Canon, Metz, Vivitar, etc), and it is why they are called speedlights. A few studio lights (Photogenic StudioMax III is one), but these larger ones tend to be slow at full power (1/120 second t.5). But camera speedlight duration is incredibly fast at lower power, like 1/20,000 or 1/30,000 second is very possible at low power (used up close in dim rooms) - used for high speed photography like milk drops or hummingbird wings - fast simply because they are interrupted very quickly for less power. No RC decay, t.5 and t.1 are equal except at full power. These units become more blue at low power. http://www.scantips.com/speed.html shows examples of these speeds.</p>

<p>4. The high end (expensive) units may combine methods of thyristor with lower voltage. These offsetting color shifts makes the color more stable between min and max power, but it is not inexpensive.</p>

<p> </p>

<p>>> " if the IR system from the SU800 is more reliable than the in camera set up?" -yes.<br>

>> It has twice longer operating distance.</p>

<p>People who have actually tested this report fully the opposite.<br>

For example, http://www.nikoncafe.com/vforums/showthread.php?t=161433</p>

<p>Here is a good to-the-point summary of the procedure by Nikon:<br>

http://www.nikonusa.com/Assets/Common-Assets/PDF/FastTrack_To_WirelessSpeedlights.pdf</p>

<p> </p>