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Old Jan 08, 2010, 10:37 PM
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Craig9080's Avatar
United States, GA, Butler
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What lense do you use? (FOV?)

Hey everyone,
I just finally got my whole setup running and i notice that i have quite the "bubble" effect from the wide-angle lens that came with my KX171 HQ. It is a 3.6mm mini lens with a 90 degree FOV. I was wondering what you guys where using on your cameras and if you had particular reason to favor a particular FOV.
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Old Jan 08, 2010, 10:52 PM
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North vancouver, B.C. Canada
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3.6 or to 4.3
unless you have two cameras
on the same plane hehehe

don't forget to refocuss the lense
before you fly
factory settings
are not the best
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Old Jan 08, 2010, 11:26 PM
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United States, GA, Butler
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Good point on the refocus. for reference, here is the video i made today.

Radian FPV on a snowy day in New England (7 min 27 sec)


Any tips on the refocus as far as "bench" refocusing. I live in the city and my radian is just a little too big for me to feel comfortable to fly at the soccer field here at WPI so i go just outside Worcester into Shrewsbury to fly (take off) at thier public fields.
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Old Jan 08, 2010, 11:29 PM
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David22 and others - How do you focus your camera for the best focus when flying. If I were flying high, to get the best picture would it best to set the focus on more distant objects then an object close up on?
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Old Jan 08, 2010, 11:37 PM
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kason's Avatar
Taiwan
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A. 2.9 ~ 9 mm vari-focal
B. 3.6 mm
C. 230x auto focus vari-focal camera heavy!
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Old Jan 09, 2010, 03:20 AM
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S. Wales
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After experimenting with a variety of lenses I found that a 6mm suits me best. The field of view is narrower but the resolution is correspondingly higher so more detail. Also, no curved horizon distortion. Haven't tried an 8mm yet but I did get hold of a 16mm which was a nightmare. No way to fly with this. The narrow FOV made it impossible to "keep up" with what was on the display. Seemed like the plane was lurching all over the place. I thought a head tracker would smoothe out the fast changing scenary but no chance.
As for focussing; choose a point about 100m away to focus the lense at infinity. Fixing the lense at this setting can be surprisingly difficult. A fixing screw tends to change the focus as it is tightened. Using PTFE tape and a spring works well and stops the lense from vibrating out of focus during flights.
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Old Jan 09, 2010, 03:41 AM
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Romania, Dolj, Craiova
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I second 6mm. And here the reason why:
http://en.wikipedia.org/wiki/Normal_lens#Digital_still
Beware: it is important to specify the sensor size !
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Old Jan 09, 2010, 03:52 AM
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Quote:
Originally Posted by Craig9080 View Post

......Any tips on the refocus as far as "bench" refocusing.
Yeah, for my professional video production company, we all use these

http://www.rondexter.com/focus_pattern.pdf

(although we buy A3 laminated ones) but print that out it will work fine..

It is very effective on our small little CCD cameras we use for FPV..

Print it out, put it over the other side of the room and you'll be amazed when you see how easy it is...

Cheers

Andy
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Old Jan 09, 2010, 09:03 AM
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I printed off the cool poster andology posted

will try that

but have been, when i am not lazy, to just look out the window at an object that is about 100 feet away or further

I am only guessing but imagine these camaeras are adjusted for close up video taking when they come out of the box

I have tried the 6mm on the 201 camera, but would rather not try that again

the 3.6 and 4 mm IMHO look exactly the same

2.8 I found to be not real enough of a fpv experience

the 6mm was too real of an experience, looked to me to be almost the exact depth perception with the 6 mm,



Quote:
Originally Posted by man2000me View Post
David22 and others - How do you focus your camera for the best focus when flying. If I were flying high, to get the best picture would it best to set the focus on more distant objects then an object close up on?
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Old Jan 09, 2010, 09:25 AM
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Quote:
Originally Posted by David22 View Post
I printed off the cool poster andology posted

will try that

but have been, when i am not lazy, to just look out the window at an object that is about 100 feet away or further

I am only guessing but imagine these camaeras are adjusted for close up video taking when they come out of the box

I have tried the 6mm on the 201 camera, but would rather not try that again

the 3.6 and 4 mm IMHO look exactly the same

2.8 I found to be not real enough of a fpv experience

the 6mm was too real of an experience, looked to me to be almost the exact depth perception with the 6 mm,

Let us know how you get on with the focus pattern David..

So are you saying you like to run 6mm then?

Cheers

Andy
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Old Jan 09, 2010, 09:33 AM
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no 6mm for me, everything goes by so fast and orienteering close to the ground is very hard.

up high , above 400 feet or so would be good with 6mm

I printed the patern off, my guess the idea is to see it clearly from the other side of the room.?

funky patern man thanks
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Old Jan 09, 2010, 09:47 AM
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you'll see when you try focusing, the blur will slowly dissapear from the outside inwards until the blur starts going from the inside of the circle outwards again (going back the other way on the focus).. easy to get very exact focus, and because of the high f rating of the lens, the depth of field is very deep vs shallow so even if you are doing this at 10ft, that's pretty good for 1000ft.

Hmm, not tried full FPV yet so still wondering what lens i'll feel more comfortable with, but have the 3.6mm on my DX201 but i've got a 2.97mm and an 8 and a 12 (but those are for the antenna tracking calibration screen since the 12mm FOV is identical to the Yagi i intend on using, assuming the antenna tracker can keep the plane / heli in view, i know the yagi will be pointing within the optimum gain pattern (at least that's the plan! )

Cheers

Andy
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Old Jan 09, 2010, 09:56 AM
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More resources, but from a surveillance point of view, not FPV:

http://www.promaxusa.com/cctv-lens-chart.php#visual
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Old Jan 09, 2010, 10:30 AM
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North vancouver, B.C. Canada
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for a maiden fpv experience I would suggest the 2.97
or stock 3.6

not 6 or 8 mm

the 6mm does really make you feel like you are in the plane

everything is at basically the exact distance away while you fly
sounds easier, but not so
but will give really good video quality



Quote:
Originally Posted by Andology View Post
you'll see when you try focusing, the blur will slowly dissapear from the outside inwards until the blur starts going from the inside of the circle outwards again (going back the other way on the focus).. easy to get very exact focus, and because of the high f rating of the lens, the depth of field is very deep vs shallow so even if you are doing this at 10ft, that's pretty good for 1000ft.

Hmm, not tried full FPV yet so still wondering what lens i'll feel more comfortable with, but have the 3.6mm on my DX201 but i've got a 2.97mm and an 8 and a 12 (but those are for the antenna tracking calibration screen since the 12mm FOV is identical to the Yagi i intend on using, assuming the antenna tracker can keep the plane / heli in view, i know the yagi will be pointing within the optimum gain pattern (at least that's the plan! )

Cheers

Andy
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Old Jan 09, 2010, 10:49 AM
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ok, cool, i'll have to pick up a 6mm one next time i'm ordering something then, just so i can give it a go when i'm ready..

Cheers

Andy
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