Unable to focus

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CoachAP
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Joined: 10.11.2018 14:14

Unable to focus

Post by CoachAP » 10.11.2018 14:41

I have been using the Helicon FB Tube successfully for a few months now. But today I have a problem getting the camera to focus. I focal range is only over a few centimetres. I cannot focus on anything beyond about 300mm distance. I have just updated to IOS 12.1 and wondered if that could be the issue. Or, it may be that I have just done a rookie error and missed something. I have followed the set-up process a couple of times now, just to check. I'm sure I've been able to focus at a greater distance before.
(Nikon D810 - Nikkor 24-70mm f2.8G & Nikkor 105 f2.8Macro)

CoachAP

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Stas Yatsenko
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Re: Unable to focus

Post by Stas Yatsenko » 12.11.2018 11:28

Mobile device is only used to transmit the data about the necessary step size and/or shooting direction to the tube, so iOS version cannot influence the ability of the lens to focus. Indeed, Helicon FB Tube, just as any macro extension tube, does change the properties of the optical system bringing the nearest focusing point much closer and making it impossible to focus at infinity. We’ve done tests on some of the lenses to show the changes in the focusing range when using an extension tube: http://www.heliconsoft.com/helicon-fb-tube-focusing-distances/

As you can see, for instance, for Nikon 24-70 @f8, @70mm, the nearest focusing point is being shifted from 0.38 m to 0.11m, and from 0.3 to 0.14 m for Nikkor 105 mm @f8. But please note that the farthest focusing point on your 24-70 mm lens depends a lot on the focal length you shoot at: while the max focusing distance for this lens @70mm with the tube is 0.4m, it’s 0.02m for the same lens @24mm. Maybe this is what you meant saying you used to be able to focus at a greater distance.

CoachAP
Posts: 2
Joined: 10.11.2018 14:14

Re: Unable to focus

Post by CoachAP » 12.11.2018 16:02

Thank you.

Makes sense now.

Regards

CoachAP

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