Forum: General F-16 forum

I have a silly question.

you know our eyes focus. if the object near to me is in focus then the object in background which is out of focus will give me double image. put your finger few inches from your eyes and see anything on your desk, your finger will be out of ficus and will give u double image.

Now my question is that if are watching/reading/aiming through your HUD and at the same time u have a lock on on enemy aircraft, wont u have a double image of the enemy. and if u focus on enemy aircraft wont u see double image of HUD, if its true then how do u aim effectively.

same thing can happen in landing too if u r on visual approach and can see runway threshold form couple of miles away, if you concentrate on your HUD, you will see double image of runway.

I can be totally wrong in my assumption.

real pilots please answer.

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Not a pilot, so no comment on the HUD, but seemingly similar situation. "Wing shooting" with a shotgun, and competitive handgun, you sight and shoot with both eyes open. May seem difficult or even impossible at first, but with practice and dicipline you find that you can clearly see both the sights up close and the target at range.

no problem the HUD is focused to eternity (or whatever the word is in English) i think the furthest optical focus for humans is 6-10 meters..thats it everything further then that is the same focus..and thats what the HUD is Focused to...

The light in the HUD is collimated, i.e. it comes out the the black box through lenses that forces all the "light beams" of HUD symbols parallel to each others which is basically how objects at infinity will appear. Therefore, if you try and focus up close on the HUD, in theory it should actually appear out of focus. Me, I was always in the PIT where the HUD was projected on an MFD and it was all flat anyway so I can't speak to that

Roscoe wrote:

Therefore, if you try and focus up close on the HUD, in theory it should actually appear out of focus.

Correct; if you focus on the combining glass itself, you'll se that you'll get two sets of HUD symbology out of focus.

thanks Roscoe

and you too tieu, i was thinking the same thing which u explained very well that ig u focus the HUD glass u will see two sets of HUD readings (sumbology)

Forum: General F-16 forum

Focus - HUD