Author Topic: 70-400G not auto focussing  (Read 5040 times)

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Offline Chris82

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70-400G not auto focussing
« on: November 29, 2015, 09:56:12 AM »
 My 70-400G is not auto focussing on either of my cameras (A99 & A7II). I was out early today looking for a telephoto shot of Stirling castle. It began raining when i had setup so i covered the camera, snapped a few shots and put the camera back in its bag once i dried it off (only a few spots). When i got home i opened my bag to let it air and dry thoroughly. After brekkie and a look at my pics on computer i thought i will take a few shots out my window as the images didn't seem as sharp as i have come to expect from the lens. After a few shots the AF stopped working.

It was not very wet and never got soaked before hand

Trying to change focussing modes it says "not available with this lens" on both cameras

Any ideas

Offline Chris82

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Re: 70-400G not auto focussing
« Reply #1 on: November 29, 2015, 10:39:15 AM »
 Scare over. It appears it may have been damp or cold that has caused the issue. I cleaned all the connections and gave it a good old blast with a rocket blower. It appears to be working again, at least for the time being.

Offline CHOLLY

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Re: 70-400G not auto focussing
« Reply #2 on: November 29, 2015, 07:47:42 PM »
Whew!

Good luck to you Chris....
There are people who actually think LENS stabilization is better than sensor shifting!

Offline Chris82

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Re: 70-400G not auto focussing
« Reply #3 on: November 29, 2015, 08:55:08 PM »
I'm wondering if there is a slight glitch with the switch on the lens. I had switched it to manual focus to see if i could achieve a sharper shot myself and when i switched it back to AF, nothing. Thankfully it works just now and i'll keep an eye on it and not switch to manual focus on the lens again just incase.

Offline chappo1

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Re: 70-400G not auto focussing
« Reply #4 on: November 29, 2015, 09:31:55 PM »
Chris,
Sometimes I get confused on where to switch to MF when there is a switch on the lens.  There is a preferred protocol that you are supposed to follow but I can never remember it.  If it gets stuck I just turn the camera off and back on.
In a hurry at the moment but will look up the reference and post later.
john
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Offline REX (aka TG)

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Re: 70-400G not auto focussing
« Reply #5 on: November 29, 2015, 09:32:57 PM »
I had also some times problem  with a99 & 300G only. Problem solved by remove and reinstall the lens
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Offline Chris82

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Re: 70-400G not auto focussing
« Reply #6 on: November 29, 2015, 10:22:41 PM »
On the a99 I usually switch to MF via the menu/ silent control wheel on the front. More often than not it is set to MF and I use the back button af/mf button to AF when I need a bit more speed. That way it does not AF with shutter. Back button focus which is talked about all the time across the Internet. The a7ii has to be done via lens if it has a switch when used with the la-ea3 adapter. I removed and refitted numerous times. So glad it started working again as I could well do without the cost of repair particularly at this time of year.

Offline AScot

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Re: 70-400G not auto focussing
« Reply #7 on: January 29, 2016, 08:26:23 AM »
Back Button Focusing (BBF).

(BBF) is a technique of focusing a camera and maintain that focus. I got the idea from a comment that Chris82 made in his post immediately above. A quick Google shows that lot’s of Canikon users are trying to get their cameras to do it. Apparently, Many photogs use this technique for sports, portrait and landscape shooting. Try it and we can discuss the pros and cons. Many on the internet say they love it and would not go back.

Sony a7, a7R, a7S, a7II, a7RII or a7SII cameras can be reset to Back-Button AF, and focusing is then performed by pressing the AEL button. This probably will also work with all Sony 7 to 9 series cameras, A or E mount. Lower series cameras may not, I don’t have one to check. The steps for the A7 series are shown below, I have not tried the others yet. (A700, A77. A850/900 and A99.)

1. Press Menu> Cog 6 > Custom Key Settings > AEL Button > AF On.
2. Menu > Cog 6 > Custom Key Settings > AF/MF Button > AF/MF Ctrl Toggle.
3. Menu > Cog 3 > AF w/shutter > Off.
4. Come out of Menu. Turn the camera off and on.

Now, pressing the shutter release half way will not AF, you must now press the AEL button on the back to focus by using your thumb. When you see the camera focus, press the AEL button and the camera will automatically show the peaking, confirming perfect focus. The shutter button now only wakes up the camera on half press and fires the shutter on full press.

5. To come out of BBF you need only turn ‘AF w/shutter’ back On, leave the others settings as is.
« Last Edit: January 29, 2016, 08:30:11 AM by AScot »
Sony A7, A850, A77, A700 || Sony>> 70-300G, 28-75 f2.8 SAM, 16-80CZ, 50 f1.4, FE 28-70 OSS, FE 24-70CZ f4 OSS, LA-EA4 || Minolta>> 300 f4 G HS, 200 f2.8 G HS, 100 f2.8 (D) Macro, 50 f1.7, 28 f2.8, 28-135 f4-4.5, 70-210 f4, 500 f8 Reflex, TC x 1.4 HS, TC x 2 HS. || Sigma 21-35 f3.5-4.2. || Tamron SP 24-135.

Offline Chris82

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Re: 70-400G not auto focussing
« Reply #8 on: January 29, 2016, 09:26:37 AM »
 Useful explanation of how to do it on the A7 series cameras Charles. I use back button focus all the time, i feel it suits the way i work and is well suited for my landscape stuff as i normally manually focus anyway but have the option of selecting a focus spot and using back button focus to speed things up.

Offline REX (aka TG)

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Re: 70-400G not auto focussing
« Reply #9 on: January 29, 2016, 12:10:21 PM »
https://www.youtube.com/watch?v=c3XwhOfnnQA

A very good series of tutorial.At first video at 5min and 10 sec you will see that even these experience photographer don't use any more back focus button

Minolta introduce this function since Dynax 9 and until today all models 7/9 offer this option.

Personally I never use it and on a77II I use AEL for eye autofocus and the AF/MF(Holding down) to revert from AF-C to AF-S.
« Last Edit: January 29, 2016, 12:18:55 PM by REX (aka TG) »
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Offline AScot

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Re: 70-400G not auto focussing
« Reply #10 on: January 29, 2016, 10:06:12 PM »
Chris, thank you for your comments. It is helpful to know what techniques others use.

REX, that is a good tutorial, but it is for Canon! But thank you just the same.

I agree BBF is not for everyone and I respect both of your opinions on all things photographic. The fact is that I do not use it very often either. However as this is a learning forum for beginning and experienced Photographers alike, I like to present things like this. It helps to show the true capabilities of our cameras. That is why most of my posts are long winded as I assume my readers are beginners and need a simple and detailed explanation of a subject. Experienced photographers, such as both of you, have the option of skipping the boring parts. :D
Sony A7, A850, A77, A700 || Sony>> 70-300G, 28-75 f2.8 SAM, 16-80CZ, 50 f1.4, FE 28-70 OSS, FE 24-70CZ f4 OSS, LA-EA4 || Minolta>> 300 f4 G HS, 200 f2.8 G HS, 100 f2.8 (D) Macro, 50 f1.7, 28 f2.8, 28-135 f4-4.5, 70-210 f4, 500 f8 Reflex, TC x 1.4 HS, TC x 2 HS. || Sigma 21-35 f3.5-4.2. || Tamron SP 24-135.