D2000 or Z-240?

[bvanant]

First, the Inon strobes like most are rated with a surface GN.

Second, to convert to an underwater GN you need to divide by about a factor of 3.

Third, the equation for your exposure is:

GN / Distance = f stop

or

f stop = GN / Distance

Now you only need to realize that the D2000 with a surface GN of 20 underwater is a GN of 6.6 and the Z240 with a surface GN of 24 underwater only GN 8.0.

Fourth, now plug those numbers and f stops and distances into the equation above and tell me if you really want to spend 150 more dollars for the Z240. You are talking inches of difference in working distance. You would be better off to spend the money on two S2000 or two D2000 than a single Z240. BTW, doubling your strobes only increases the area of coverage, not the effective distance.

N

I am really confused now. The numbers I quoted for the DS-200 (Ikelite) and the Z-240 (Inon) were BOTH surface GN in meters at ISO 100. Both strobes claim surface GN of 24 meters and both claim UW guide numbers of 12. Also, the DS-200 is about $350 MORE than the Z240 not less. I am well aware of the fact that more strobes means more coverage not more distance or smaller fstops, that is why I carry 3 S-2000 strobes although for wide angle stuff, I use the 240s
Bill

 

[HerraduraDivers]

You are right,
i overseen that Ikelite post the GN as well and it's 24 as for the Z-240.
So both manufacturer claim GN24 what may be true, may be false...
Now i am also confused as i just discovered that Ikelite claims:
DS-200 GN 24 and 200 watt/seconds
DS-160 GN 24 and 160 watt/seconds
DS-51 GN 17 and 50 watt/seconds
So having the same GN the power output must be the same???
I feel that my DS-125 is ways more powerful than my D-2000,
but i may be fooled by the different size of the strobes.

Now i am confused too....

Chris


I agree 100% that battery packs are a PITA and i would prefer that the Ikelite uses
rechargable AA/AAA style batterys too.

 

[Nemrod]

All I can say is if you think you are confused, I am 2X more confused than you. I am talking about the Inon D2000 vs the Inon Z240. I think.

Yes, some people claim the underwater guide number is surface GN/2 and others claim it is surface GN/3. I tend to go with the later just based on my old Nikonos III where I actually had to figure this stuff.

I think Ikelite may actually be providing a corrected GN? Their big strobes do have a lot of punch, they ought to being they are as big as a submarine.

N

 

[bvanant]

That's because you were answering the original question that compared the z240 with the Inon D2000. Later someone suggested that the OP should buy a real strobe the DS200 from Ike and suggested that the Ike was a lot more powerful. I think everyone agrees that the Z240 has more photons than the D2000. Beyond that I think we are all just woofing. In the real world, it seems clear from testing that there is less than 1/2 stop difference between the Inon and the Ike and the rest is personal preference.

Bill

 

[Nemrod]

That's because you were answering the original question that compared the z240 with the Inon D2000. ----------I think everyone agrees that the Z240 has more photons than the D2000. Beyond that I think we are all just woofing. -----------Bill

Well, y'all are woofing, , I am calculating and I calculate about a half a foot difference in effective range between a D2000 and a Z240. The Ikelite stuff, I know nothing, nothing ------.

N

 

[bvanant]

My measurements (I can't calculate this stuff, too many adjustable parameters in the model) suggest that half a foot is about right; I get the same exposure within a 1/4 stop with them both and the Ike as well. You did it the smart way, I often tell the kids in my lab that 6 months in the lab can easily save 1 hour in the library.

Dive Safe

Bill