GN #'s are starting to piss me off!

[Netskimmer]

I'm trying to research flashes but I can't nail down the GN #'s. I know there is much more to a flash than just the GN number but it is an important factor so I would like to at least like to be able to compare them reliably. I can compare Nissin and Vivitar because they give their numbers at 105mm and 100 ISO but Nikon gives the sb-700 and sb-900 at 35mm and when I try to search for their numbers at 105 and get different numbers from different places and none of them make sense. The Nissins and Vivitar I looked at are between 140 and 200 at 105mm and the SB-900 and 700 are between 28 and 50 at 105mm (as far as I can tell) are they really that much less powerful? I know that GN numbers are approximate and manufactures smudge their specs but that is a big difference in power. I am assuming that I'm just reading the figures wrong, could someone clear the waters up a bit for me?

 

[kundalini]

You may want to try downloading the user manual for those units that don't give you a straight number in the specs section. For instance, the SB800 has a nice GN chart up to 105mm on page 42 and the SB600 on page 35 up to 85mm.

 

[Big Mike]

Make sure that you are differentiating between Guide Numbers in feet and Guide numbers in meters.

Outside the US, most countries use the metric system, so it's natural that the GN be listed in meters...but it's often converted to feet for the American consumer.

 

[Netskimmer]

Make sure that you are differentiating between Guide Numbers in feet and Guide numbers in meters.

Outside the US, most countries use the metric system, so it's natural that the GN be listed in meters...but it's often converted to feet for the American consumer.

Didn't think about that, will make sure they are consistent.

You may want to try downloading the user manual for those units that don't give you a straight number in the specs section. For instance, the SB800 has a nice GN chart up to 105mm on page 42 and the SB600 on page 35 up to 85mm.

Will DL manuals and get the specs from them. I guess it always good to RTFM, even before you buy.

 

[Derrel]

"...SB-900 and 700 are between 28 and 50 at 105mm (as far as I can tell) are they really that much less powerful?"

Those specs are in Meters. Multiply the Meters GN by 3.25 and you'll arrive at the GN in Feet.

 

[cnutco]

Just buy a couple SB-900's and forget about the GN...

You will not regret your purchase!

 

[Netskimmer]

"...SB-900 and 700 are between 28 and 50 at 105mm (as far as I can tell) are they really that much less powerful?"

Those specs are in Meters. Multiply the Meters GN by 3.25 and you'll arrive at the GN in Feet.

Thanks, I knew those numbers didn't look right.

Just buy a couple SB-900's and forget about the GN...

You will not regret your purchase!

If I had that kind of money to throw around I probably would (and if that is what is necessary, I will), I would like to consider a more frugal approach first.

Here are the factors I am considering:

GN(ft)@105mm
GN(ft)@35mm
recycle time
price

Here are the models I have looked at:

Nissin Di866
Nissin Di622
Vivitar 285HV
sb-900
sb-700

I don't intend to mess with TTL because I've read that it's overly complex and consistently inconsistent. What other factors should I be considering? Are there any other flashes that I should look at?

 

[Derrel]

The single biggest problem with the Vivitar 285HV is that is only bounces, and does not swivel, and so when used in the hotshoe, it isn't usable for vertically-framed bounce flash shots, which necessitates using a 285HV either held in-hand with a remote connector cord, or mounted on a rotating type flash bracket. I own three 285's from the 1980's--these things were built like tractors...and the 4-color (4/f-stop) AUTO modes work splendidly, and the flash has a simply ingenious rotating ANALOG calculator dial that shows MORE information at one glance than an LCD display is capable of. The calculator dial also has a button for the "nightlight" function. In terms of POWER-to-PRICE ratio, and durability, simplicity, the 285HV is a real winner. It has a PC outlet built in. It can be ganged together with cheap, reliably 7-inch PC connecvtor cords, or with 1 meter, 5, 10, or 20-foot PC cords, and multiple remotes can be triggered with just ONE optical slave unit, and the other flashes hard-wired together with cheap PC cords. The 285HV is easy to rubber-band 2 units back-to back, dial the power to half or quarter power, and run 2 units off of Quantum Battery 1 pack, and have ultra-fast recycle times, 1,200 flash capability, and the ability to light up a large area, cheaply.

SB-900 units, and other Nikon flashes, have FOCUS-ASSIST capability, which the Vivitars, and many other flash units lack...they have TTL metering capability, and both bounce AND swivel, meaning that they are usable for on-camera bounce flash work without a bracket, and they can rotate and swivel pretty much in ANY direction, which is not the case with the Vivitars. The Nikon speedlights have a lot of high-tech features that other flash units lack.

As far as TTL being consistent/inconsistent: I think that is overstated quite a bit, mostly by non-Nikon users, or by casual users who are really not all that skilled at using their equipment, or who do not really understand exactly how Nikon's color-aware TTL light metering wants to meter various types of scenes. OTOH, old-school 285HV users often understand the simple 4-f/stop AUTO color modes and manual fractional power modes of the old Vivitars, and know how to get the most out of them. The thing about using a NON-TTL flash is that the user is in a strong position of control, and since most NON-TTL flash units do not communicate with the camera's metering system, there is no relaying of exposure or ISO information between the camera, or the flash, which allows a smart NON-TTL flash user to set the flash in X, or Y, or Z configuration (adjusting 1-AUTO or Manual power output and 2-ISO in use and 3-fractional power level and 4-zoom head position) and then take a test shot or light meter reading. If the flash stays in the same location and orientation, the simple NON-TTL flash unit's electric eye sensor will produce very consistent flash exposures, and then the camera's setting can be adjusted, INDEPENDENTLY, to get the perfect exposure. OR, conversely, the flash unit's controls can be minutely tweaked, such as adjusting the ISO on the flash up or downward in 1/3 stop clicks, or switching AUTO f/stops, or lowering the power level in either AUTO-flash or Manual modes. So, with the better old-technology Vivitar, Metz, Sunpak flash units that are NON-dedicated, the camera and the flash are pretty much independednt contractors...each knows its role and does its job...the shooter is the foreman, with God-like authority.

With dedicated, Nikon TTL flash units, you can slap on a flash, turn it on, and shoot a TTL flash shot at virtually ANY f/stop, from closest range to 20 feet, and be pretty confident of a decent exposure, even if you've done something incredibly stupid, like set the shutter to 1/800 second and the lens was left at f/11...you can also get accurate autofocus IN THE DARK with the AF assist beam enabled...or in a wedding ballroom or a campfire situation where its very dark...

So, those are the factors: simplicity and good power and low price for the 285HV, plus PC outlets, easy multi-flash with cords or slaves or triggers, but not good for vertical bounce flash shots without a bracket. And, no backward bounce capability. The Sb 900 and 700 are much more high-tech, and much more expensive. Sigma has some flashes in the middle, but they only have one flash unit (I think) that will offer the kind of control options I would want to have; their upper-middle lower-end model did not impress me with its specs the last time I compared it with their more expensive model.

 

[Netskimmer]

Wow, thanks for taking the time to write such a lengthy response. I had concerns about the 285HV not being able to swivel and the slow recycle rate when using it on a hotshoe. It sounds like the 285HV's would be excillent for studio work and complex field setups as well as a good beginner flash. I will probably buy at least one of them and if I decide I need more I can get a Nissin or SB-900 and use the 285HV as a secondary.