SB-700 Guide Number Details

The instruction manual of the SB-700 is available for download now from Nikon, and I could finally have a look at the guide number table. Before, all that was known was the GN at 35mm FX, and sadly that GN of 28 (m) is lower than the one of the SB-600 (GN30) it replaces.

But in contrast to the 600 there is sensor size detection available on the SB700 now, which means that it does not zoom to the 50mm reflector position when a 50mm lens is used with a DX camera like the D7000 or D90, but it zooms to around 70-75.

SB-700 Guide Number with FX Cameras

Click on the image to see a full size version of the guide number table showing the SB-600 next to the predecessor SB-600. Both flashes cover down to 14mm with the built in wide-panel for standard illumination. With the optional center weighted illumination, coverage extends to 12mm.

SB-700 GN Table FX

At the tele end, the SB-700 reflector ends at 120mm, whereas the SB-600 ends at 85mm already. However, the SB-600 is stronger by design and there is no focal length with an FX camera body where the SB-700 would be advantaged, neither at wide angle nor towards the tele end. SB-600 is always a stronger flash.

SB-700 GN Chart FX

SB-700 Guide Number with DX Cameras

With DX cameras the situation is different. Depending on the zoom setting the flash gains the ability to chose a more narrow zoom position. With the 50mm lens, the SB-600 will zoom its reflector to 50mm. The SB-700, however, will zoom to around 70mm reflector position and still cover the full frame while gaining a bit of power – or wasting less light.

Click on the table to see the details for different zoom settings and SB-600 versus SB-700 in DX zoom mode.

SB-700 GN Table DX

The following chart shows best the benefits of DX zoom on a speedlight, at least if you are using a camera with APS-C image sensor. From the 50mm lens setting on the old SB-600 is still advantaged, but at lens settings 35mm and lower the new SB-700 suddenly is the stronger flash of the two!

SB-700 GN Chart DX

Summary

I still don’t like the recent Nikon trend of making their latest speedlights weaker and lower in maximum output than the previous generation, and if you’re using an FX body like a D700 you just have less juice than before. At least, for DX shooters, the sensor size detection flash zoom feature helps mitigate the issue and can give you even an advantage.

And, overall, the SB-700 is a big improvement overall with much better ergonomics, an optical slave mode, the wireless master mode, and lots of other advanced features.

Further reading

Nikon SB-700 in-depth review page

Unboxing video of SB-700
Nikon SB-700 Compared to SB-600 and SB-900

Nikon SB-700 specs compared to SB-600 specs
Nikon SB-700 specs compared to SB-900 specs

Speedlight specs comparison page with data on all Nikon flash models from 1988 plus selected Canon, Metz, Nissin, Vivitar and Yongnuo flash units.

SB-700 available now in US!

Update from 12/16: A few Nikon SB-700 are available today on eBay and amazon has them in stock!

Check amazon, Adorama, B & H Photo and J & R for supplies – they will move fast.

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2 Responses to SB-700 Guide Number Details

  1. Gianluca says:

    I thought I got the point, but looking at the specs and the tables I do not understand why the 600 GN keeps increasing at 70mm and 85mm on DX format. I would have expected it to saturate at 85mm/1.5=57mm due to the 85mm zoom head limit and no FX/DX detection… Could you please explain?

  2. Gianluca says:

    Ok, in the meantime I thought again about it and the tables perfectly make sense, so no need for further explaination.

    However I still have a comments: the zoom head can be set manually on the SB-600, so it would be possible to “recover” the lack of FX/DX detection, though it would be surely a bit tricky.

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