Cheetahstand CL-360 and Canon 70d incompatible flash?

The CL360 spec states 360Ws, GN 80 (m ISO 100, with AD-S2 standard reflector). Turning that to a GN in feet, that is GN262 at ISO 100.

So at full power that light should result in f/11 at 24' distance from light to subject, at full power
at half power, f/8 at 24' (GN 185)
at quarter power, f/5.6 at 24' (GN 131)
at eighth power, f/4 at 24' (GN 92.7)

for shorter distance of 8.4' f/11 at eighth power, or 4.2' at f/22

Wilt wrote in post #18331181
The CL360 spec states 360Ws, GN 80 (m ISO 100, with AD-S2 standard reflector). Turning that to a GN in feet, that is GN262 at ISO 100.

So at full power that light should result in f/11 at 24' distance from light to subject, at full power
at half power, f/8 at 24' (GN 185)
at quarter power, f/5.6 at 24' (GN 131)
at eighth power, f/4 at 24' (GN 92.7)

for shorter distance of 8.4' f/11 at eighth power, or 4.2' at f/22

Wilt,
I'm intrigued by your fascination with guide numbers.

I have no idea how the guide number for the Godox 360 was determined. What I do know is that the real output of the light is closer to 300 Ws. Also, that I rarely use the light with its standard reflector.
Its much more useful for me to test the light in an often used modifier, as I described, then use that baseline for other modifiers.

When I was a young photographer guide numbers were all we had for the basic speedlites that were available. I suppose once, or twice, I started with the GN to determine the f stop I needed. Even then, it was much more a matter of how far off from the baseline distance and what I had to do to compensate by opening or closing the aperture. Film ISO wasn't variable, flash power wasn't variable. That made it a bit easier - just one thing to adjust considering distance.

With digital we are so far beyond those limitations.

Thanks everyone for your help. I set up my equipment on a tripod and was able to see the pictures. Now I have to work on it looking sharp instead of grainy.

Either ISO is too high, or shots are underexposed, and you are bringing the brightness after the fact? Share a raw file with us, and we can give you some pointers. Also take a shot of your layout and share that so we can get a visual of your setup.

dmward wrote in post #18331299
Wilt,
I'm intrigued by your fascination with guide numbers.

I have no idea how the guide number for the Godox 360 was determined. What I do know is that the real output of the light is closer to 300 Ws. Also, that I rarely use the light with its standard reflector.
Its much more useful for me to test the light in an often used modifier, as I described, then use that baseline for other modifiers.

When I was a young photographer guide numbers were all we had for the basic speedlites that were available. I suppose once, or twice, I started with the GN to determine the f stop I needed. Even then, it was much more a matter of how far off from the baseline distance and what I had to do to compensate by opening or closing the aperture. Film ISO wasn't variable, flash power wasn't variable. That made it a bit easier - just one thing to adjust considering distance.

With digital we are so far beyond those limitations.

I am not 'fascinated by' guide numbers. I fully appreciate the value of understanding the concept, and how it can be applied -- in advance -- to estimating the effect of using the lights in different circumstances. It avoids a whole lot of shot-in-the-dark trial and error testing, such as the testing suggest by several different responses in this thread already. Because you have a starting estimate, and in many cases that estimate proves to be true!

The Guide Nunber I used came from test reports on the Godox 360, and is apparently what the manufacturer (or Adorama) determined via testing of their own.

W-S rating never estimates light output, it only quantifies the amount of electricity stored in the power capacitors, and never factors in circuit losses or cable resistance losses nor reflector efficiency effects on the light coming out of the xenon tube. To illustrate that point, consider that decades ago Chimera published a catalog showing measured light output using one of their softboxes, with multiple brands and models of so-called '1000 w-s'. I distinctly remember that Dynalite 1000 w-s output was 1EV brighter than 1000 w-s output from another famous brand of professional studio strobe...w-s does NOT predict light output!

In the case of eTTL flash, the flash has a constant light output at full power which is limited by its power capacitor, yet the GN increases between 20mm FL angle coverage and 200mm FL angle coverage. Again proving my point about any so-called w-s equivalence...the GN changes although the power capacitor cannot change its full-power capacity.

How does any of this help Nicole, who seems to be having issues with just the basics of exposure in general? Just providing some starting points on where to place the flash, and some ISO/shutter/aperture settings would be beneficial, but guide numbers? Probably not the most helpful thing at this point....

TeamSpeed wrote in post #18331717
How does any of this help Nicole, who seems to be having issues with just the basics of exposure in general? Just providing some starting points on where to place the flash, and some ISO/shutter/aperture settings would be beneficial, but guide numbers? Probably not the most helpful thing at this point....

I gave her a starting estimate of the f/stop to use, assuming a given distance from light-to-subject.

at distance of 8.4' f/11 at eighth power, or 4.2' at f/22

...that helps Nicole get reasonable exposure!

Everyone else merely suggested "make the aperture smaller and take a shot, adjust, try it again...adjust, try again..." with zero idea of what was 'in the ballpark' for an f/stop to use.

dmward already gave some starting specs to start with. Also if this is a setup for future portraits, f11 and f22 are not apertures one has a tendency to use, so there will have to be some trial and error here of setting apertures more wide open and reducing power, or distance of flash. We both have these flash units and are trying to be helpful using our experiences with these units, and not use advertised specs.

As there seems to be confusion on basic exposure, let's see if we can pic of the scene and a sample file.

dmward gave a very nice description of a trial and error approach.

This approach has everything near the middle of its range. Make the first test exposure. If its too dark, increase power 2 EV and try again. If its too bright reduce power 1 EV and try again. Fine tune until you have the power setting for a good exposure.

If you have zero idea where to start, that procedure is appropriately described.
I gave specific settings and distances to start with.

at distance of 8.4' f/11 at eighth power, or 4.2' at f/22

...I believe that is helpful to Nicole by reducing trial and error to a succesful shot most rapidly.

I guess we will let Nicole see?

I use 2 of these for each portraiture session, about 8-9' ft away, but I don't remember the power settings. I feel your theoretical settings will be too dark. I might pull mine out tomorrow and see, but I never use guide numbers when setting this up. It takes about 5-10 minutes to get the lights laid out, and initial settings to do test shots, then a few tweaks later, we are ready to go.

The problems I fight are 2 catchlights in the eyes, so this next round, I am going to have to mix things up a bit. Also, we use black backgrounds, and I want no spillage on those if possible, so I have moved the subjects away from the backdrop a bit to blur it out, as well as play with light placement and power to reduce any exposure on those curtains. Low ceilings don't help any either.

TeamSpeed wrote in post #18331734
I guess we will let Nicole see?

I use 2 of these for each portraiture session, about 8-9' ft away, but I don't remember the power settings. I feel your theoretical settings will be too dark. I might pull mine out tomorrow and see, but I never use guide numbers when setting this up. It takes about 5-10 minutes to get the lights laid out, and initial settings to do test shots, then a few tweaks later, we are ready to go.

Just as comparison, my Dynalite 500 w-s pack with a single head has in the past measured f/12 at 4' at 1/8 power
vs. the suggested start of f/22 at 4.2'. So your instinct could well be right, and the claimed Guide Number (80m/262ft) published at full power is overstated

Interesting article, perhaps some info to help also.

http://jerryphpics.blo​gspot.com/2015/08/ad-360-review.html

Wilt wrote in post #18331738
Just as comparison, my Dynalite 500 w-s pack with a single head has in the past measured f/12 at 4' at 1/8 power
vs. the suggested start of f/22 at 4.2'. So your instinct could well be right, and the claimed Guide Number (80m/262ft) published at full power is overstated

Since Adorama sells the Godox 360 as the Streaklight 360WS, I went to Adorama web site and find that THEY list a Guide Number for that unit of 56m or 182', (vs. the previous spec of 80m/262' for the Godox 360.

In that case,

• full power GN 182
  
• half power GN 116
  
• quarter power GN 91
  
• eighth power GN64
  

It would be nice to know what Nicole plans on shooting long-term. 4' during family portraits isn't feasible...
Senior portraits? Then yes, you can have more flexibility where you run these lights for effect and mood on a single person.
Product shots? The sky's the limit there, whatever it takes to accentuate the details or point of interest.

Thanks all, I will upload a few raw files tonight. I plan to do portraits. I like taking pictures of people and candids.