For some reason the SB-25 from Nikon is much less known as a strobist flash than its precursor SB-24 or the later SB-28 model. Compared to the SB-24, the Nikon SB-25 has 2 clear advantages: first, its manual mode goes down to 1/64, which means it has 2 stops more than its precursor with a minimum power setting of 1/16. Second, the SB-25 has a built in wide angle diffuser that allows 20mm coverage. SB-24 is missing this feature, its coverage starts at 24mm. The later SB-28 has only a 0.5 sec recycle time advantage at full power (6.5 vs. 7 sec), 18mm coverage and a somewhat more compact design to offer. The Nikon SB-25 is an excellent strobist flash, and therefore prices on eBay reflect that point today.
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Like all Nikon flash units in the professional line, the Nikon SB-25 has a male PC port for triggering, and it certainly can also be triggered via the standard compliant Nikon flash foot. The flash uses a low trigger voltage of 4V, so usage with modern cameras or low voltage triggers is no issue. It does not feature any optical triggering sensor (this addition was introduced with the SB-26, and then left out in the SB-28 again).
There have been some reports about triggering issues, but there seems to be no systematic problem or incompatibility, apart from an inability to fire with high synch voltage triggers on their hot shoes, e.g. the Cactus V2 version designed for high voltage flash. Even in that scenario, you should be fine using the PC port, though. It might not be the best idea anyway to put a heavy unit like the Nikon SB-25 on the flimsy V2s hot shoe. Just go with a low voltage trigger like RF-602 or also Cactus V4 and you should be fine.
The unit has a dedicated mode switch which makes it fast and easy to set the “M” mode (the other settings are “A” for automatic mode, “TTL” for the non-i-TTL mode, and a setting for stroboscopic mode). If set to “M”, there is also an “M” symbol lighting up on the display. A big improvement over the SB-24 is the 7 (instead of 5) stop manual power range with all full stops from 1/1 down to 1/64 to choose from. Repeated pushing on the dedicated “M” button underneath the display toggles through all manual output levels in full stops.
Standby does not become an issue with this unit. There is a dedicated on/off switch with 3 settings: “on”, “off”, and “standby”. Just switch to “on” for off camera flash, and the only thing you have to pay attention to is to switch it off when you’re finished, but you won’t miss any shots due to a sleeping flash unit.
The Nikon SB-25 offers the usual pro-grade Nikon swivel and tilt features. Vertical adjustment of the beam is possible between -7 to +90 degrees angle. The flash head’s tilting mechanism locks in the 0 as well as the 90 degrees position. Swivel goes from -90 to +180 degrees. There is a built in wide angle diffuser which gives coverage down to 20mm, as well as a reflector card. For manual zooming, keep pressing the dedicated “zoom’ button underneath the LCD display to cycle through the 24 – 28 – 35 – 50 – 70 – 85mm settings. No journey through the menu system needed, excellent! There is also an AF assist beam lamp, but no 2nd reflector or optical sensor on the flash head.
The guide number is specified as 36 (m) at 35mm and ISO 100. At 20mm with the wide angle diffuser, guide number is still at 20 (m), and it reaches 50 at the 85mm setting of the zoom reflector. Flash duration at full power is 1/1000 seconds and it goes down to 1/23000 sec at 1/64. Recycle time with AA alkaline batteries is specified as 7 seconds, which is not overly fast. It can be assumed that it recharges considerably faster with NiMH batteries however. And even the much newer SB-800 still needs 6 seconds if operated without the 5th battery.
Apart from usage with 4 AA size cells (the handbook states both 1.5v and 1.2V versions), the Nikon SB-25 can be powered via external battery packs. Recycle times with the optional SD-7 or SD-8 battery packs are greatly reduced, they go down indeed to a mere 1.6 sec (specified with NiCD batteries).
i-TTL / E-TTL
The Nikon SB-25 is a pre-digital flash, so there is no modern i-TTL mode available. It has TTL, but this is the old analog version which is useless with modern digital cameras. There is also an auto mode which some photographers like to use even today, although certainly not in the strobist scenario but rather on camera.
The Nikon SB-25 flash unit was introduced in 1992 together with the F90 (N90 in US) camera, 4 years after the SB-24. Only 2 years later, the SB-26 was launched as its successor with the integration of optical triggering sensors and a little bit more wide angle coverage. It is mainly the short production time that makes the Nikon SB-25 an often overlooked strobist flash, in terms of features there is really nothing to sneeze at.
Full Tech Specs
Despite the great reputation of Nikon’s pro level flash units, it is worth noting that production of this specific unit ended in 1994, so these SB-25 units have some years on their backs. However, there seem to be only 2 weak spots to look at closer when buying used:
- Ask the seller to test all power levels. One of the seemingly more typical problems is that some of the old SB-25 always fire at full power, even when set to partial output. If set to 1/64 and the recycle time is still around 7 seconds, it means that the actual output was 1/1 rather than the minimum setting.
- Also, ask the seller or check yourself if the zoom motor still works. If the wide angle diffuser is not broken off and folded in and the zoom setting shows “–” on the display and there is no sound when changing focal length, the zoom motor is defective or burnt out. You might be willing to live with a zoom stuck in the 24mm setting, but it will be a bigger handicap if it is at 85.