Posted by David Schoen on October 16, 2017 at 11:34 AM
I think I have a relatively good knowledge of how to use fill flash in avian photography but I have some questions about the operations of the flash itself. I currently have a Nikon SB 800. This flash utilizes 4 AA batteries and a 5th AA battery to decrease the recycle speed to 1 second or less. It can be used with or without the 5th AA battery but I always use it with. My camera is always set to high speed synchronize which in the case of the D500 and D850 is 250th. I believe the D800E was 320th. So if I shoot with fresh batteries, the flash seems to keep up with the shutter when I shoot in height speed bursts of 7 to 10 frames per second but only 25% of the images show signs of flash illumination. Is this reciprocity failure or equipment failure? Even if I am shooting at 250th or below, it doesn't seem to make a difference. Only 25% roughly of the images show signs of illumination. I am considering the purchase of another flash unit. Is there anything to gain with the SB5000 at $600 as opposed to the SB 700 at half the price?
Posted by Nate Chappell on October 16, 2017 at 11:55 AM
Hi David, I can't speak to the Nikon particulars, but what I am pretty sure is happening here is the flash is not recycling fast enough to work on most of these images. This is very typical, even with the higher end Canon flashes, I only usually get 2 images with flash during a burst, after which time the flash needs to recycle. A higher end flash might help a little but probably not much. If you want more flash images in a row you need to buy a power pack for the flash unit. This will shorten recycling time and let you get more exposures, but you still won't get 7 in a row. There are more expensive after market options like the Quantum battery packs that will get you even more flashes as well. Here is a link to the current Nikon one, but I imagine if you search around you can find one compatible with the SB-800. https://www.bhphotovideo.com/c/product/570528-REG/Nikon_4952_SD_9_Battery_Pack.html
I have the Canon equivalent and I have hardly used it because it is just one more thing to weight me down that needs a connection.
Posted by David Schoen on October 16, 2017 at 12:09 PM
Nate:
That's what I suspected. To the untrained eye, the flash appears to keep up, but in fact, it is not synchronizing with the shutter when is open. The flash occurs before or after the shutter opens and only when the shutter opens about 25 to 30% of the time. So that makes sense. With a battery pack one gets much faster recycle time so the advantage of the SB5000 and probably the high end Canon equivalent is the built in cooling system to prevent flash meltdown. I certainly hear you about the weight issue. But for shooting around my home it is less of a deal. The cost of the battery pack is another matter altogether. Don't you use a battery pack or packs with your hummingbird flash setups?
Posted by Nate Chappell on October 16, 2017 at 12:20 PM
David, for the hummingbird photography, most of the work is done by slave flashes which are set to 1/16 power and my main flash which triggers them is set to 1/64. At these low powers they recycle much faster so there is no need for a battery pack.
Posted by Jim Zablotny on October 18, 2017 at 9:04 PM
Hi David,
Your flash cannot keep up with the burst mode. I run into the same issue with my flash equipment and get more shots with fill when the batteries are fresh. I get fairly fast refresh rates when doing hummingbirds with my jury rigged flash system with power set at 1/16th. ...........................Jim
Posted by David Schoen on October 19, 2017 at 8:36 PM
So I understand that fresh batteries make a difference. The external battery packs utilize four or eight AA batteries. In addition to the four or five AA batteries that are in the SB 800 flash unit. The Nikon flash unit is $199, but there are third-party units for much less, and according to people who own them, they work just as well as the Nikon unit. The third-party units also use four or eight AA batteries.
The SB 800 was the only flash unit made by Nikon that utilized, a 5th battery in order to decrease the recycling time. It could be used either way with four or five AA batteries. The following chart indicates the recycling times with different batteries for the SB 800. See the above chart
So with five NIMH 2000 mA batteries, this chart implies, one should get 150 flashes in 2.9 seconds if I’m reading this correctly. If the camera can shoot 10 frames per second. It should easily be able keep up with 29 flashes in 2.9 seconds and all the images should have equal flash exposure.
In fact, today, when I was shooting hummingbirds with the D 500 and the SB 800, it seemed that all the images have equal light exposure from the flash of 10 that I shot. However, when I shot the other day with the D850, which only shoots at seven frames per second, only two or three of the frames out of 10 that I shot were illuminated. Both cameras were set too high speed sync at 250th.
The flash is clearly going off more than one time every 2.9 seconds so the number of flashes and the recycling time are different creatures. The flash may go off numerous times between recycling episodes. I’m also aware there is a stroboscopic setting for these on camera flashes but one has to be careful that the flash doesn’t overheat and melt down.
So once again, my real question is once again, why do some images lack lighting from the flash. Is it a timing issue with the shutter? Is it reciprocity failure, or is there something potentially wrong with the equipment? And I say that because according to the chart if one is using fresh batteries, one should be able to achieve 150 flashes in 2.9 seconds and that is without a battery pack.
Posted by Keith Bauer on October 20, 2017 at 7:33 AM
one should be able to achieve 150 flashes in 2.9 seconds and that is without a battery pack.
I don't think that is what the chart says. I can't imagine a flash being able to fire 150 flashes in 2.9 seconds. The chart says with fresh batteries at full manual power of 1/1, one could expect 150 flashes with recycling time of 2.9 to 30 seconds.
I believe the answer to your question is pretty simple. The flash is not keeping up with the burst rate you are shooting at. You mentioned reciprocity failure? That has absolutely nothing to do with it. That is an issue with the relationship between exposure doubling in time yet the media (film) did not receive twice the exposure. It was an issue to be noted when dealing with long exposures with film. Rarely is a digital sensor exposed for the durations of time that reciprocity failure came into play with film because of the issue with noise.
Posted by David Schoen on October 20, 2017 at 3:39 PM
The information about reciprocity failure came from the e-book: Secrets of Digital Bird Photography from W. H. Majoros from his chapter on flash. It's a rather complicated discussion. I just want to know if there's anything I can do to improve my success rate when using my flash. If the flash is only working 30% of the time, what can I do to improve that rate, other than using fresh batteries every time I use the flash. And if I recharge the batteries every time I use them only once, won't that have a negative effect on the batteries? There may not be just one good answer for this conundrum. Yes, there appear to be risks using a battery pack such as overheating. The newer and more expensive flashes seem to have algorithms to prevent overheating. So far, other readers have reported having similar experiences with approximately the same flash success ratio as I am getting. I'm just once again curious to see if that can be approved upon. One never knows when they will have a missed opportunity created by a missed flash synchronization.
Discussion
7 repliesI have the Canon equivalent and I have hardly used it because it is just one more thing to weight me down that needs a connection.
That's what I suspected. To the untrained eye, the flash appears to keep up, but in fact, it is not synchronizing with the shutter when is open. The flash occurs before or after the shutter opens and only when the shutter opens about 25 to 30% of the time. So that makes sense. With a battery pack one gets much faster recycle time so the advantage of the SB5000 and probably the high end Canon equivalent is the built in cooling system to prevent flash meltdown. I certainly hear you about the weight issue. But for shooting around my home it is less of a deal. The cost of the battery pack is another matter altogether. Don't you use a battery pack or packs with your hummingbird flash setups?
Your flash cannot keep up with the burst mode. I run into the same issue with my flash equipment and get more shots with fill when the batteries are fresh. I get fairly fast refresh rates when doing hummingbirds with my jury rigged flash system with power set at 1/16th. ...........................Jim
The SB 800 was the only flash unit made by Nikon that utilized, a 5th battery in order to decrease the recycling time. It could be used either way with four or five AA batteries. The following chart indicates the recycling times with different batteries for the SB 800.
See the above chart
So with five NIMH 2000 mA batteries, this chart implies, one should get 150 flashes in 2.9 seconds if I’m reading this correctly. If the camera can shoot 10 frames per second. It should easily be able keep up with 29 flashes in 2.9 seconds and all the images should have equal flash exposure.
In fact, today, when I was shooting hummingbirds with the D 500 and the SB 800, it seemed that all the images have equal light exposure from the flash of 10 that I shot. However, when I shot the other day with the D850, which only shoots at seven frames per second, only two or three of the frames out of 10 that I shot were illuminated. Both cameras were set too high speed sync at 250th.
The flash is clearly going off more than one time every 2.9 seconds so the number of flashes and the recycling time are different creatures. The flash may go off numerous times between recycling episodes. I’m also aware there is a stroboscopic setting for these on camera flashes but one has to be careful that the flash doesn’t overheat and melt down.
So once again, my real question is once again, why do some images lack lighting from the flash. Is it a timing issue with the shutter? Is it reciprocity failure, or is there something potentially wrong with the equipment? And I say that because according to the chart if one is using fresh batteries, one should be able to achieve 150 flashes in 2.9 seconds and that is without a battery pack.
I believe the answer to your question is pretty simple. The flash is not keeping up with the burst rate you are shooting at. You mentioned reciprocity failure? That has absolutely nothing to do with it. That is an issue with the relationship between exposure doubling in time yet the media (film) did not receive twice the exposure. It was an issue to be noted when dealing with long exposures with film. Rarely is a digital sensor exposed for the durations of time that reciprocity failure came into play with film because of the issue with noise.