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Apr 01, 2016, 03:08 AM
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Thread OP
Question

What focal length is best?


Hi
I am just starting out in FPV. I'm building a Firstar EX2000 for it.

Question is, what camera focal length is best. I have two miniature board cameras, one is 2.1mm and the other 3.2mm. Obviously one has a wider view than the other.

Which is best? A wide view taking in everything, or a narrower view focusing on straight ahead. Or does it depend what sort of flying you are doing? Sport or leisurely. Or does it really make much difference at all?

cheers
Jack
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Apr 01, 2016, 03:37 AM
Wait...what?
gbmarsh's Avatar
Quote:
Originally Posted by Axle Jack
Hi
I am just starting out in FPV. I'm building a Firstar EX2000 for it.

Question is, what camera focal length is best. I have two miniature board cameras, one is 2.1mm and the other 3.2mm. Obviously one has a wider view than the other.

Which is best? A wide view taking in everything, or a narrower view focusing on straight ahead. Or does it depend what sort of flying you are doing? Sport or leisurely. Or does it really make much difference at all?


Cheers
Jack
Lenses for board cameras are as cheap as beans, buy several different focal lengths and find out which one you like the best.
That'll be the best one for YOU!
http://www.surveilzone.com/cctv-lens/mtv-lens
http://www.getfpv.com/fpv.html?cat=140
http://www.securitycamera2000.com/ca...TV-Mount-Lens/

Cheers,
Geoff
Last edited by gbmarsh; Apr 01, 2016 at 03:53 AM.
Apr 01, 2016, 08:48 AM
Registered User
and search. this question has been asked (and answered) numerous times.
Apr 01, 2016, 02:25 PM
Registered User
Thread OP
So... two replies...
One wont tell me anything cos I should find out for myself.
One wont tell me anything cos other people have already asked.

Useless.
Apr 01, 2016, 02:35 PM
Sent by Touch Typing
Heppy Ket's Avatar
Flying at some altitude, shall we say 60m or more, I prefer a narrower lens, even as far out as 6mm I find I use the camera pan lot more, for a more general purpose camera I prefer 2.8mm to 3.6mm, the lower numbers I find too wide, you can see lots, but no detail. this clip is 2.8mm. BTW the aircraft is a Firstar EX

7.035km flight Port Gawler (8 min 56 sec)


At the end of the day it comes down to personal preference.
Last edited by Heppy Ket; Apr 01, 2016 at 04:11 PM.
Apr 01, 2016, 02:51 PM
Wait...what?
gbmarsh's Avatar
Quote:
Originally Posted by Axle Jack
So... two replies...
One wont tell me anything cos I should find out for myself.
One wont tell me anything cos other people have already asked.

Useless.
You are welcome for the links I provided to various different useful lens options.
Nice attitude
Apr 01, 2016, 03:18 PM
A man with too many toys
Quote:
Originally Posted by Axle Jack
Hi
I am just starting out in FPV. I'm building a Firstar EX2000 for it.

Question is, what camera focal length is best. I have two miniature board cameras, one is 2.1mm and the other 3.2mm. Obviously one has a wider view than the other.

Which is best? A wide view taking in everything, or a narrower view focusing on straight ahead. Or does it depend what sort of flying you are doing? Sport or leisurely. Or does it really make much difference at all?

cheers
Jack

I also have a Firstar 2000 Ė love that airplane.

That all depends on how you fly. Thatís a long wing airplane so it may not be the best fly flying very low under trees. For low 2.8mm is good but you wonít be able to see very far. I like to cruise around at 200í and view the country side. I started with a 2.8 lens but ended up with a 6mm lens and a low cost pan and tilt mount from HK.

Lenses are inexpensive and easy to change. Make sure you get a CCD camera with WDR and takes standard lenses.

The HS1177 is by far the most popular camera (because itís the best FPV camera). You can select the lens and configuration that best fits your needs. http://www.surveilzone.com/DC5V-plas...m-lens-for-fpv

Some spare lenses:
http://www.surveilzone.com/cctv-lens/mtv-lens

.
Apr 09, 2016, 02:49 PM
Registered User
As you can see from this article, for 1/3" sensor used in a FPV camera, the "normal" is 6mm, will render exactly the same perspective as you see with your eyes.

But ! beware ! I meant what you see with a single, fixed eye !
No eye movement, no neck movement, not two eyes ! Try to drive a car looking straight forward, with one eye covered, no lateral mirrors !

Now you should understand why people needs the wider angle provided by the 2-3mm lenses, or a pan mechanism when using 6mm lens. To look around
Apr 09, 2016, 03:09 PM
Registered User
Thread OP
Hi Guys. Thanks for the input. Years ago I was keen on photography and on my cameras 50mm focal length was normal vision. So its interesting to see 6mm is normal for these ones. That gives me something to work from.

And I had not appreciated that longer lenses are better for higher altitude, but of course that makes complete sense.

How long before someone invents a servo operated zoom lens?
Apr 09, 2016, 03:15 PM
Registered User
Already exists, no need to be invented. 2-8mm is the most useful range, but nobody use them

And you think you can fly with only the field provided by optical viewfinder with a normal 50mm lens ?
Apr 09, 2016, 03:38 PM
Registered User
Thread OP
Quote:
Originally Posted by renatoa
And you think you can fly with only the field provided by optical viewfinder with a normal 50mm lens ?
No I don't. That's not what I said.
Apr 09, 2016, 04:16 PM
Registered User
I think that it was a rhetorical question. (I think)
Apr 10, 2016, 07:33 PM
Retired young, in R/C since 68
consumer61's Avatar
Quote:
Originally Posted by gbmarsh
Lenses for board cameras are as cheap as beans, buy several different focal lengths and find out which one you like the best.
That'll be the best one for YOU!
http://www.surveilzone.com/cctv-lens/mtv-lens
http://www.getfpv.com/fpv.html?cat=140
http://www.securitycamera2000.com/ca...TV-Mount-Lens/

Cheers,
Geoff
Excellent advice - not to say others haven't been more helpful and kind than they might be.

This is a subject totally up to personal opinion and this person gave you excellent neutral advice as did Heppy Ket. Try and find what works for you, as we are all individuals.

If he had just told you to buy a 2.8 lens, somebody else would say 2.1 lens, and you would be no further ahead, and wouldn't know who to believe. Then another person would tell you the lens depends on the size of the sensor so 2.8 on a 1/3" ccd is not the same as on a 1/4" ccd. Then you would be even more messed up.

I too am in the midst of learning this stuff after over 40 years of R/C, and you need to be prepared to read hundreds and hundreds of pages on your own - but of course that is Rule number 1 for ANY forum environment anywhere - search before asking as question, or risk getting chewed up and spit out for fish food. In fact on some forums, a post that has been answered before will simply be removed by moderators.

I have been reading almost 5 hours a day for over a month, and periodically before that for many months, and still haven't bought a thing (but getting close) because its taking that long to learn some of this.

I was in to photography 30+ years ago, and from best I can tell, take any comparison to what you know and throw it out the window compared to 35mm film. This is closer to digital photography, but using what were essentially designed as security cameras.

Best of luck!
Last edited by consumer61; Apr 10, 2016 at 07:39 PM.


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