Alternative to YS-250 Pro?

[stuartv]

Thanks, all, for the comments. I had never looked into rapid shooting before. I always just assumed u/w photos (with my "prosumer" gear) just wouldn't support rapid shots with a strobe. Yesterday and today have been very educational.

You're pretty battery savvy. Which NiMh are you using? You want something with low resistance that will support higher current draw.

I am using Loopacell high capacity NiMH.

https://www.amazon.com/gp/product/B01HDRM5LE/

They test well for capacity. They claim to be low internal resistance. But, how do I test that? What should I be looking for? $7 for for batteries is a lot better than $36 for 8 x Eneloop Pros .... unless they don't actually do what I want. Then they'll be good for my other AA-powered gadgets...

Should I just set up my rig, put a strobe in a sinkful of water and start firing away?

Do not be mesmerized by half power rapid fire. All (most, many) strobes can deliver multiple flashes per second at half power. My ys110s can easily keep up with my G16's 12fps at half power. Full power, not so much.

Do you need raw power or rapid cycle? Or both?

Thank you for that. I WAS HYP-MOTIZED by that video. Now I see that many, including the strobes I have, will do the same thing.

What do I need? Well, raw power and rapid cycle together, of course! But, I don't think I need it to do rapid fire, high powered flashes for long periods of time. 3 - 5 seconds, at most, I would think.

2 years ago was my first Wreck Shark Shootout. I had my GoPro 3 Black. :-| Last year, I went back and it was my first real outing with my Oly OM-D E-M10 and 2 x Inon Z240s. I got a decent number of photos that I am pretty happy with. I posted some here. But, I can still see plenty of room for improvement.

Now, I am starting to prep for WSS 2018. One of the things I have learned that I would like to have in my bag o' tricks is the ability to shoot rapid fire at a shark that is swimming past. And maybe further away than what I was really trying to shoot last year. And with an f/stop that is a stop or too smaller for better depth of field.

After what I've learned in the last 24 hours, I am considering getting new strobes. Possibly the new Inon Z330s, the Ikelite DS161s, or the YS-D2s. Those all look like they would give me another 2 or 3 feet of distance for the same illumination of my subject.

And I will be going to do some preparatory diving just to focus (ha ha!) on dialing in my ability to shoot rapid fire sequences. I also need to work on my ambient light shooting. I think I'll do that when I go to Coz (hopefully) in April.

 

[stuartv]

So, how do you sort out shooting rapid fire with strobes?

I shoot with optical cables and run my camera internal flash on 1/64th. How do I go about setting it up so that it will auto-fire (with strobe) as rapidly as possible?

I would like to not have to divert my eyes to the backs of my strobes to see if the Ready light is on before every shot.

 

[stuartv]

They test well for capacity. They claim to be low internal resistance. But, how do I test that?

I found this answer:

How to Measure the Internal Resistance of a Battery?

It appears to be:

- measure battery voltage
- measure resistor resistance
- put resistor in parallel with battery and measure voltage again
- do some arithmetic to calculate battery internal resistance

If anyone knows a better or easier way, please let me know. Otherwise, I guess I'll have to go look for a local source of suitable resistors.

 

[fmerkel]

I can almost guarantee you those Loopacell are a BIG part of your problem. Extremely high capacity NiMh are a 'come on'. Compromises in chemical reactivity have to be made to do that, at the expense of capacity. Those really bad Ansmann I mentioned were cousins.

Get some Eneloops. IMO, the stock 2000mA are as good for your application as the higher capacity Pros. Imedion and Fujitsu are all good. MUST BE MADE IN JAPAN.
I've got 10 year old Eneloops that work fine. I've got other cheaper batteries that started showing extreme aging in 2 years (high resistance, capacity going down). So, they seem cheaper, but they don't last long. It's like buying a really cheap car with no reliability.

The method you found for IR measuring is the most accurate, and the most cumbersome. Just get a Zanflare C4 4-bay charger. It'll do NiMh and Lithium, do cycle tests, AND internal resistance. It's easy. It's not as accurate but you can easily tell the difference between a good battery and one that is going to hell.

The Opus BT - C3100 V2.2 is a bit more versatile but has some other issues people don't like. Too much to go into here but I can point you in the right direction if you want to try that. A well loved and decent charger is the Liitokala-500 Engineer. Works great, BUT the IR function is worthless.

 

[stuartv]

The Xtar VP4 Dragon Plus charger tests battery internal resistance. I have been looking for an excuse, so I just ordered one.

From other reading, I gather that a "good" low resistance AA will have about 20 mOhms or less of IR and the low discharge/high resistance cells might be 100 or more mOhms?

Anybody know what the IR is on a typical Eneloop Pro?

 

[stuartv]

The Opus BT - C3100 V2.2 is a bit more versatile

I have an Opus BT-C3400. But, it doesn't do an IR test.

I've had the Loopacells for almost 1 year now. It will be interesting to see how they test now, for both capacity and IR. I will post an update after I test them. If they aren't good for my strobes, I have plenty of other uses for them where they'll be just fine.

The Xtar charger had free same day delivery, so I should get it tonight!

 

[stuartv]

I can almost guarantee you those Loopacell are a BIG part of your problem.

ps. I don't know (yet) whether I have any problem at all. I have never tried shooting my strobes rapid fire. And I have not had an issue with feeling like they were cycling too slowly in single shot mode. But, I certainly grant that it's likely that I WOULD have problems if I did try to use the Loopacells for rapid-fire strobe shots.

 

[fmerkel]

Xtar VP4 Dragon Plus should be excellent! Didn't know you were willing to spend that much. So.....excellent chargers, cheap out on NiMh, eh? I know you shop Li-on carefully.

IR is a function of cell size (larger cells are lower) state of charge (lower charge is higher), temperature (cold is higher), age of cell (goes up over time), and of course...quality.
New Eneloop AA will be 40-60....ON MY CHARGER READING. This is not an absolute number when using the chargers IR function. I think the Dragon may be more accurate and reliable than what I have. What I do is mark new cells; capacity and IR. Then I can start tracking them, using the same measuring tool over time.

When you start measuring 200, 300, 500, and higher on a AA, you know it's going to hell and time to move it to low draw duty. I'll bet the Loops are like 500. You'll have 'fun' with the new tool.

 

[bvanant]

I wouldn't be in a rush to get rid of the Z240s to move to the Z330s. The GN of the 240 is 24 and the GN of the 330 is 33 (no coincidence in the names, I am sure). What does this mean practically. As we know GN = distance x Fstop.

Suppose you want to shoot at f16 for good depth of field. That means with the 240 you can shoot a subject at 1.5 meters (5 feet) while with the z240 you can shoot the same subject at a little over 2 meters (6.5 feet). Similarly if you want to shoot something at 2 meters your f-stop with the 330 will be 16, with the 240 it will be a half stop less or f12.
Most of the time I shoot my strobes at 1/2 power or less trying to be in the sweet spot for sharpness (f11 to f16). The only real advantage to higher power strobes will be if you are trying to shoot into a sunball then you will need the power.

As for high speed, remember that if you are using the camera flash for triggering, that will be the bottleneck to your speed of shooting. The YS250 was most likely triggered by electric sync not fiber so that makes a huge difference.

Cheers
Bill

 

[Chris Ross]

You say you want to shoot faster and stopped down and further away, all placing more demand on your strobe. What settings (f stop and ISO) are you using on your rig, is it still the EM-10?

The Oly flash can be set at 1/64th power and works fine there to trigger the Z-240 and I suspect can rapid fire longer than the Z-240.