Auto or Manual Focus?

For the camera buffs.

Auto or Manual Focus?

Postby Michael D » Sun Sep 08, 2013 8:35 pm

Hey guys,

Just wondering what some of the better photographers on here use - auto or manual focus? I usually use manual but occasionally get out of focus shots that are really annoying.

Using a D3100 with Nikon 18-55mm and Sigma 70-300mm.

Thanks,
User avatar
Michael D
Member
Member
 
Posts: 336
Joined: Wed Oct 24, 2012 7:24 pm
Location: Melbourne, Australia

Re: Auto or Manual Focus?

Postby Brock L » Sun Sep 08, 2013 9:23 pm

Better to use auto especially when shooting fast-moving objects (e.g. aircraft). I usually always use auto, and it does the job. If it's a static object then it's no worries at all with which setting you use really.
Photos

JetPhotos.net (1024 Photos)

Next Flights

30 Nov: JQ239 OOL-AKL (A320)
10 Dec: JQ238 AKL-OOL (A320)
User avatar
Brock L
Senior Member
Senior Member
 
Posts: 914
Joined: Sat Jul 17, 2010 10:38 am
Location: Gold Coast

Re: Auto or Manual Focus?

Postby Ian Gains » Mon Sep 09, 2013 7:37 am

Hi Michael,

I guarantee that the camera will focus faster than you can. I've only had my 1st DSLR for just over a year, & the feature I like best over my old film SLR is the awesome focusing, especially over 300mm focal length.

I've also set the camera up to give a short 3 frame burst, which I've found helpful for long tele subjects. The camera pulls focus well but, with a moving subject, occasionally the 1st frame can be a little soft - this way, the subsequent frames are spot on.

Read up on your lenses to find the aperture that they perform optically best at - normally around f/8. Try & use this if possible as it is the sweet spot of the lens, & it gives you reasonable depth of field to help ensure that all of the aircraft is acceptably sharp.

And always use IS if you have it. Unless you are trying to blur the background, IS lets you get away with a slower shutter speed than conventional wisdom suggests. In the old days, it was always a good idea to use a speed that was a reciprocal of the focal length of the lens that you were using if hand holding. ie 300mm lens = 1/300 sec, so use 1/500 sec. Most IS systems will give you around 3 stops improvement. Personally, I wouldn't drop below 1/250 sec using the 300mm example.
User avatar
Ian Gains
Prolific Member
Prolific Member
 
Posts: 2543
Joined: Fri Sep 21, 2007 7:10 pm
Location: Melbourne, Australia

Re: Auto or Manual Focus?

Postby Michael D » Sat Sep 14, 2013 11:22 am

Wow, autofocus is so much better at least on the Nikon lens. Really came in handy for spotting at LAX today. The Sigma lens seems to be slower at focusing though.
User avatar
Michael D
Member
Member
 
Posts: 336
Joined: Wed Oct 24, 2012 7:24 pm
Location: Melbourne, Australia

Re: Auto or Manual Focus?

Postby Ian Gains » Sat Sep 14, 2013 2:00 pm

Spotting at LAX - lucky bugger ! I checked the specs for your camera & the D3100 doesn't have an in-body autofocus motor, so focusing is entirely lens dependant ! I'm not disparaging the Sigma lens as I don't know much about it optically or mechanically, but this explains the focusing speed difference you have noticed. The same lens would probably work better on a different model body which does have an in-body autofocus motor.

Have a great trip.
User avatar
Ian Gains
Prolific Member
Prolific Member
 
Posts: 2543
Joined: Fri Sep 21, 2007 7:10 pm
Location: Melbourne, Australia

Re: Auto or Manual Focus?

Postby Michael D » Sat Sep 14, 2013 3:38 pm

Thanks once again Ian - very helpful!
User avatar
Michael D
Member
Member
 
Posts: 336
Joined: Wed Oct 24, 2012 7:24 pm
Location: Melbourne, Australia

Re: Auto or Manual Focus?

Postby nfarmer » Sat Sep 14, 2013 5:35 pm

I agree with previous posters that autofocus is both faster and more accurate than trying to do it manually. With the later DSLRs there are also questions about AF settings. Once the green square 'camera does everything in JPEGs' is changed to Tv or Av or M there are also many options to improve the AF.
In full auto the camera generally picks the closest object that any AF point sees. This might not be the aircraft. If the centre AF point is chosen (this is usually the most accurate) then that has to be placed on the aircraft when focussing takes place. If AF servo is also selected the camera will also track the aircraft as it flies closer allowing the shutter to be fully pressed at the best time for composition. Alternatively if the shot can be pre composed (by a trial exposure) then a different, but more suitable AF point can be selected allowing for better composition.
Most DSLRs allow the AF to be separated from the shutter button and be activated by a button on the back. This allows focus and recompose to be done. By following the aircraft and pressing the back focussing button the lens is focussed, the shot can then be quickly recomposed and the shot taken.
Having said all that, I find it easy to just pre focus using 'one shot' with the back button on a point where I want to take the shot. That gets focussing out of the way and I press the shutter where I want the shot, sometimes a second press of the back button will quickly refocus if the aircraft has moved too close for the previous setting.
Like all things photographic there will be some who swear by one procedure and setting, others will be equally sure a different method is best. Trial and error is the best teacher, use what works best for you.
If people think aircraft are difficult subjects to focus on they should try BIF (birds in flight) as a subject.
nfarmer
Member
Member
 
Posts: 30
Joined: Sat Jan 19, 2013 9:32 pm


Return to Aviation Photography

Who is online

Users browsing this forum: No registered users and 1 guest


cron