July 18, 2014

Sunwayfoto DDH-03i Panning Clamp Reduced Torque Capacity

Sunwayfoto DDH-03i Panning Clamp overview
A few days ago I received an email from a reader asking for my opinion (thanks Ray) on an issue he was experiencing with a recently acquired DDH-03i panning clamp.
The clamp did not seem to be able to withstand the load of a Nikon D600 + 70-200mm f:2.8 (approx 2.5 kg) set out by 18cm from the center of the clamp.

Therefore, I had to order a DDH-03i clamp and verify the panning lock strength before running into any conclusions.

To be honest, since there are not any visually detectable differences in the design of the newer Sunwayfoto DDH-03i panning lock mechanism versus the older DDH-03 version, I didn't expect that any notable differences in torque capacity would exist between the two versions.

Sunwayfoto DDH-03 and DDH-03i Panning Clamps side by side
Older Sunwayfoto DDH-03 on the left and the newer DDH-03i Panning Clamps on the right.
And since the DDH-03i is considered an improved version, I actually expected that it would be stronger.

In the original Sunwayfoto DDH-03 Panning Clamp Review I performed a simple torque test where the clamp was attached on top of the Sunwyafoto XB-44 Low Profile Ball Head, mounted on the Triopo GX-1328 Carbon Fiber Classic Tripod as shown below. Then a 10" long rail was clamped between the DDH-03 jaws, this rail offered me a handy decimal scale and then one of my counter-balance weight bags was hang on the rail. By moving slowly the bag outwards I reached the maximum point before the clamp started losing its inert status.

Sunwayfoto DDH-03 PC w/ rail + sandbag - closeup
At that time the test was monitored by an electronic protractor / inclinometer. At the moment the inclinometer started to show a minor deviation from zero degrees then the maximum distance was reached. It was quite a delicate task but it was worthwhile. The photo above shows a deviation of 3 hundredths of a degree in a rightmost slope.
A weight of approx 5,5 Kg (12.1 lb) hanging at an offset position of 13 cm is translated to a Torque of ~71.50 KgF*cm by which number the DDH-03 outperformed the much larger and heavier Benro PC-0 (45.05 kgF*cm)!

Now, using the same setup as above I repeated the test on the DDH-03i and by comparing the results to the ones of the original DDH-03, I had to regretfully agree with Ray. My copy of the DDH-03i could not withstand more than 38,5 kgF*cm initially .

Sunwayfoto DDH-03i PC w/ rail + sandbag - closeup
After some endeavor the clamp managed to lock with a the load at 7,5 cm distance from the center which translates to a Torque ~41,25 KgF*cm.

Somehow, I fiddled a little more with the pan-lock knob by increasing the lock force (tightening the knob) using pliers and exercising a lot more torque rotating a full 360° the locked panning base by hand. After this stress test the clamp seems to have a more a affirmative lock, slightly better than before but cannot equal the older DDH-03.
Nevertheless, no end user is supposed to use pliers or break a finger trying to make the pan lock to operate as expected.
What I think is that in this batch of DDH clamps the pan-lock knob tip is inadequately finished, which results in exercising less pressure on the panning base.

Of course I contacted Sunwayfoto about the issue, conferring my findings. After a few days, I received a confirmation, where their tests also proved that the latest DDH-03i Panning Clamps are not as strong as the older DDH-03. Further, their engineers stated that DDH-03 and DDH-03i locking structures are different. Most important though, is that they are working on a solution by redesigning the locking mechanism.

Let me discriminate one thing though. The maximum torque is required when the DDH-03i panning clamp is used in a vertical orientation and the camera / lens combo is hanging at an offset position mounted on a Nodal Slide as is the case of a Multi Row Panorama Head like the Sunwayfoto Pano-3.

Otherwise, if the clamp is used in a horizontal orientation there is no need for excess locking force in order to lock the panning clamp. So it can be used without problem.

Sunwayfoto DDH-03i PC on XB-44 LP ball head
Sunwayfoto DDH-03i Panning Clamp attached directly on the XB-44 Low Profile ball head.
Needless to say that as soon as I receive any further notice from Sunwayfoto, I shall update accordingly.

This review and test was run on a single product sample, using the specifically described methods. Independent of the favorable or unfavorable results of any test, a test on a single product can not be used as a rule, unless more samples of the same product are tested. Furthermore, similar comparison tests should be run with comparative capabilities products so as to reach a solid conclusion.

Update Oct 2014
Sunwayfoto Revised 2014 version DDH-03i Panning Clamp Review

I hope you found the information useful, thank you for viewing.
All Photos © 2013-14 S.C.Vlachos

Update Jun 2017
After the known US patent infringement issues Sunwayfoto DDH clamps are only available outside US from eBay and from Amazon.de

Referenced Articles:

Sunwayfoto DDH-03 Panning Clamp Preview

Sunwayfoto DDH-03 Panning Clamp Review

Sunwayfoto XB-44 Low Profile Ball Head Review

Triopo GX-1328 Carbon Fiber Classic Tripod Review

Relevant Articles:

New Improved Sunwayfoto DDH-02i & DDH-03i Panning Clamps Preview

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