Strobe for Macro

[mawyatt]

If anyone is considering strobes rather than a Speedlights for macro work, take a look at the Adoroma Flashpoint Studio 300 Monolight with Built-in R2 2.4GHz Radio Remote System - Bowens Mount (SK300II). These might be worthwhile to consider.

I switched to strobes from Speedlights long ago for studio work, especially for large stacking sessions where the batteries could give out in one session with speed lights (and the longer recycle time), or the speeddlights would overheat. The first strobes I used were cheap ones from Neewer and I had a few actually blow up!! This was due to the abuse I was administering to the strobes asking for 500 successive close to full power flashes with only a few seconds between!! The failure was the voltage doubler capacitors, which I replaced. Then I got some Interfit strobes in a kit, these held up well, but I did have a couple of the fans fail and the output seemed inconsistent sometimes. I started using the Adorama Flashpoint brand a couple years ago with good success except getting all the strobe to consistently fire at once (which I eventually solved by using both RF and Optical triggers). I have two setups now, one using 5 strobes and the other 3 strobes, this is for uniform subject (chips) illumination. These strobes (320M and DG600) have been worked hard and held up pretty well IMO.

Adorama has taken on the Godox as a rebrand with the AD600, Rapid 600, and SK300II (and SK400II). All these strobes have common R2 RF wireless, and use the popular Bowen mount while the previous Flashpoint strobes used the proprietary Flashpoint mount.

I just received a couple of the SK300II at $120 each. These are 300WS, R2 RF wireless power control, S1 and S2 optical trigger and a 150W controllable modeling light. After checking the operation out, I disassembled one. This is a very well designed & built strobe, as good as I've seen. The circuit boards are nice and clean, with connectors. Even the flash tube assembly is on a nice circuit board that plugs into the main board where the big caps are located.

The first thing I checked was the energy storage capacitors, 12 at 330uF each rated at 400 volts. This gives (1/2 C*V^2) a potential of 316.8 Joules (WS), so the rating of 300 seems reasonable. The electronic design appears to be based upon a AC to DC conversion by way of full wave rectification, then DC to DC conversion, rather than the usual AC to DC voltage doubler in cheap strobes. Potentially this means a tighter control of the optical power with a regulated DC to DC conversion. The electronic components seem of good quality, at least from just looking at them.

I checked out the operation and the recycle time is good, the R2 RF Trigger and Power Control works as does the Optical Sensor (S1). Modeling light is nicely proportional controlled. Adorama states that this strobe line holds it's output within 2% at the same setting, which would point to a regulated control as I mentioned above.

Only time will tell if they hold up, but certainly look good from the start!!

Update, the only things I find issues with so far is the modeling lamp protrudes slightly beyond the refector front, which is a smaller 6" rather than 7" reflector, and the power range is only 4 stops (16 to 1). The reflector issue can easily be solved with a Bowens type 7" reflector which I just tried. This will allow honeycomb grids which can't be used with the supplied reflector.

Best,

Mike

[Deanimator]

I still have to build my permanent studio macro rig after I get back to work, so this is very useful information.

Thanks.

[concon]

Interesting, I look forward to seeing how this setup works out for you. I use two Yongnuo IV speedlights at around 1/64-1/32+7 power and my camera at 50iso. I haven't experienced the same issues with batteries dying (unless I'm not diligent and forget to change them) or my flashes overheating; however, my max stack has only been around 425 shots. with about a 2s delay in-between.

I just had a friend switch to a studio flash for his work as well (a Godox I believe), but the last I heard he was having consistency issues. What benefits are achieved (beyond the batteries) between a studio flash and a few speedlights?

[mawyatt]

I've seen output uniformity issues with both speed lights and strobes. One reason I'm looking at these new Flashpoint strobes which claim a uniformity of 2% at the same output setting.

Ive used Yongnuo speed lights and they were very good, but did show variation and overheating issues. The subject chips I image, especially ones with solder balls, require extreme diffusion, in many cases up to 4 levels, which requires lots of optical power to start with...too much for regular speed lights which are ~60WS while the strobes are often over 300WS. Recycle time is better on strobes too.

The speed lights are much faster but only at the lower power levels and get really slow near full output....about the same as the older design strobes. Some of the new designed strobes like the Flashpoint (or Godox) Rapid 600 are very quick, much quicker at a specific output power level than a speed light, and use the IGBT same technology. These new strobes also have most of the features a speed light has, such a TTL, Rear Curtain Sync, High Speed Sync, Optical Slave and so on including battery powered (Flashpoint or Godox AD600), so a speedlight on steroids so to speak. They are more expensive though, around $450 and up. The main drawback is the size and weight of course.

Earlier I had dealt with the output variability by using many (up to 12) separate strobes, all highly diffused, to help "average" out any individual strobe output change. This worked OK but required a large footprint for the setup. I have been forced into a much smaller space now and recently tried to get by with 4 of the older design strobes (320M and DG600) and a smaller light tent (I used dual light tents before one inside the other). This produce some banding in the final stacked images, I've traced most of the banding to different optical "waveforms" not aligning themselves over each other, and surmised this was due to the different RF trigger delays in each strobe (I did some experiments a few years back that showed some RF delays on speed lights and strobes). By engaging the optical triggers (S1) and the RF Triggers simultaneously I thought the Optical trigger would help align the optical outputs better and was able to significantly reduce the banding I was seeing. I declared Victory (not a wise decision) and Murphy must have been listening!! After a recent stack I noticed some very slight banding again, with the RF and Optical Triggers engaged.

After reading about the new low end Flashpoint (and Godox) SK300II ($120) and 400II ($150) having a 2% output variation I decided to pre order from Adorama (could always return if they didn't work out). I just received 2 SK300II and did a quick test which looked pretty good for starters. So I decided to investigate the design (I'm an EE with a pretty broad background). After disassembling the strobe (which I have done on many strobes and speed lights) I was impressed with the overall construction and PCBs as well as the components. The actual electrical design appears to be very well done with a regulated DC to DC converter after a full wave AC rectification, which coincides with the claimed 2% output variability. A simple voltage doubler design that's used in most low cost strobes should have much more variability, but this design is at a much higher level.

I'm somewhat convinced that I just ordered a couple more. I'll be out of town for a major chip design review for the next week, so won't be able to get back to this for awhile.

Anyway, this is an extraordinary designed and constructed strobe for the cost IMO, for whatever that's worth?

Best,

Mike

[mawyatt]

A little study of these strobes operation revels that in the voltage doubler designs, as most low cost strobes are based upon, the optical output variation is twice the input supply voltage (AC power) variation (for you scientific types, the partial of energy output with respect to voltage is CV, or the delta in output energy is 2*E*delta V). So for example, a small 3% variation in AC line voltage shows up as a 6% variation in optical output. Where I live the AC line voltage easily varies much more than 3% over a short time, probably more like 8%, especially if the air conditioner compressor turns on or off during the stack.

After realizing how sensitive my stack subjects are, and how much my local AC voltage varies, then seeing this claimed 2% exposure control which implies a 1% voltage regulation....well I had to give it a try.

Best,

Mike

[mjkzz]

Mike,

I use SK400II, along with 433Mhz trigger system (I think it is illegal to use 433Mhz frequency in US). I do not think it has the claimed 1% variation, but so far so good with SK400II, so I recommend that. But with this system, you can change power outputs from the transmitter on your camera.

A little study of these strobes operation revels that in the voltage doubler designs, as most low cost strobes are based upon, the optical output variation is twice the input supply voltage (AC power) variation (for you scientific types, the partial of energy output with respect to voltage is CV, or the delta in output energy is 2*E*delta V). So for example, a small 3% variation in AC line voltage shows up as a 6% variation in optical output. Where I live the AC line voltage easily varies much more than 3% over a short time, probably more like 8%, especially if the air conditioner compressor turns on or off during the stack.

Formaula for energy stored in caps is 1/2*Q*V*V where Q is the capacitance and V is the final voltage at terminals of the caps.

So dE/dV = QV, so 3% AC voltage diff means 6% energy output diff if the strobe works the way you think.

However, for a precision strobe, usually a reference voltage is used (such as a zener diode) and voltage at terminals of cap are measured against that, so it could be independent of your AC voltage. I did not open up my SK400II as it works well, so I do not know.

Just some thoughts.

Regards
Peter

[mawyatt]

Mike,

I use SK400II, along with 433Mhz trigger system (I think it is illegal to use 433Mhz frequency in US). I do not think it has the claimed 1% variation, but so far so good with SK400II, so I recommend that. But with this system, you can change power outputs from the transmitter on your camera.

A little study of these strobes operation revels that in the voltage doubler designs, as most low cost strobes are based upon, the optical output variation is twice the input supply voltage (AC power) variation (for you scientific types, the partial of energy output with respect to voltage is CV, or the delta in output energy is 2*E*delta V). So for example, a small 3% variation in AC line voltage shows up as a 6% variation in optical output. Where I live the AC line voltage easily varies much more than 3% over a short time, probably more like 8%, especially if the air conditioner compressor turns on or off during the stack.

Formaula for energy stored in caps is 1/2*Q*V*V where Q is the capacitance and V is the final voltage at terminals of the caps.

So dE/dV = QV, so 3% AC voltage diff means 6% energy output diff if the strobe works the way you think.

However, for a precision strobe, usually a reference voltage is used (such as a zener diode) and voltage at terminals of cap are measured against that, so it could be independent of your AC voltage. I did not open up my SK400II as it works well, so I do not know.

Just some thoughts.

Regards
Peter

Peter,

Yes, pretty much what I said. I don't know if these strobes are as good as absolute 1% voltage control, although a 1% variation is relatively easy to achieve.

The Adorama version is 2.4GHz, which is compatible with the R2 transmitter which allows remote power control.

Believe me I have seen lots of very cheap stuff, and these strobes are very well built, and the electronic design looks good too. My main interest in these is the apparent design based upon a regulated DC to DC converter (similar to a higher end Speedlight) rather than a voltage doubler.

From the little testing I've done , they seem to work very well and provide a uniform output over a long stacking session.

Best,

Mike

[johnsankey]

I've a Nikon D700, with M-series objectives 5,10,20x, simple LED lighting, Stackshot and Zerene stacker (http://johnsankey.ca/closeup.html#MO). Even with mirror-up mode, the shutter vibration lasts 100ms or so, so I have to use 1/8s or more to get adequate bite; I'd really like to get better (http://johnsankey.ca/gardenbugs.html)

Assuming I move to strobe rear-curtain synch, I don't need modelling lights, remote triggers, or other fancy stuff, just high enough speed to kill vibration after the 100ms. I can put the flash within 10cm of the subject and use a white reflector the other side so don't need huge power either. 110V is within inches.

It sounds as though the Adorama line is the way to go, but I'd greatly appreciate any suggestions as to the most reliable firing method and strobe unit options for this next step.

[mawyatt]

John,

I think the Adorama line or Godox line of strobes is good and you have a lot of selections, from simple manual, very high speed, to complex TTL and battery powered. They have standardized on a 2.4GHz RF trigger system across the new Speedlight and Strobe line.

I have an number of the older Adorama 320M and DG600, which have held up well but I was seeing some small variation in output. The new SK300 and SK400 claim to be uniform at a given output within 2%, so I order a couple and waited (they were new backordered). A few weeks later they were delivered and I've done a couple 100~200 stack session and they seem really good and the output seems uniform from shot to shot. So I ordered a couple more and plan on these being my main go too strobes for macro.

Another nice feature is they have the R2 radio system which allows remote power control in 1/3 stops with the proper transmitter, and are compatible with the older RF trigger system that allows 0.1 stop control (you need a separate trigger receiver though). The only weakness I've found is the control range is only 16 to 1, but you can always move the strobe (square-law effect) for more range

As mentioned they are very well electrically designed and constructed, and very good value at $120 and $150 respectively.

I'm using 3 SK300 now about a foot away at 120 degrees apart illuminating a foam cup as a diffuser on a WeMacro Vertical Stand. This gives good illumination for my subjects (chips) which don't have solder balls, for which I use a more complex light tent structure on a horizontal optical bench.

BTW these are not IGBT devices, so optical speed is specified as 1/800 to 1/2000 second. IGBT base strobes like the Flashpoint Rapid 600 are ~1/1300 to 1/20,000 second but cost $430, or the battery powered AD600 1/220 to 1/10,000 second and $550.

So far so good with the SK300II.

https://www.adorama.com/fplfs300b.html


Best,

Mike

[johnsankey]

That's the kind of experience-centered encouragement I was hoping for. I'll get one SK300II to start, then start the inevitable experimenting to work out how to get the best out of what I've got.

[mawyatt]

John,

Be sure and get the R2 Trigger for your Nikon. This will allow remote trigger, power adjustment, as well as iTTL, HSS and so on if later you get more advanced Adorama or Godox strobes.


Another nice feature is these are Bowens mount, so you can get all sorts of light modifiers for very reasonable prices. Things like shoots with grids and colored gels, bigger 7" reflectors with grids (they come with 6" reflectors), soft boxes and so on.

Best,

Mike

https://www.adorama.com/fprrr2tn.html#s ... uctOptions

[mawyatt]

For you folks that have studio strobes or thinking about them I've found some LED Corn Type bulbs that replace the normal modeling bulbs.

My older Adorama Flashpoint 320M and newer Adorama Studio 300 AC strobes use a thin incandescent modeling bulb. These are E26 mounts in US and ~32mm diameter so they don't block the flash output, and being incandescent can be dimmed. These bulbs tend to get really hot when used anywhere above minimum output.

If found a 18W LED bulb with 31mm diameter, E26 mount that is dimmable and works well with my strobes mentioned, doesn't attenuate the flash output and are dimmable. They may be bright enough for continuous lighting, but my need is more for getting things aligned and setup, rather than continuous lighting use.

https://www.ebay.com/itm/Dimmable-E26-E ... 2749.l2649





Flashpoint 320M on left, Studio 300 AC on right
Best,

Mike