Sony FE 24mm 1.4 GM continually focusIng, back focusing, jumping

Started Aug 13, 2020 | Discussions
billorg Senior Member • Posts: 1,286
Sony FE 24mm 1.4 GM continually focusIng, back focusing, jumping

I have a lifetime of experience with cameras and lenses of all kinds, so I am pretty sure when something isn’t behaving correctly.  However, I just wanted to run this past you.  Brand new lens, first time using today on a NEX 5n which is my smallest travel setup. That means an APS-C sensor with a full frame lens.  I use A mount lenses from Sony and vintage Minolta w/adapter as well as manual Zeiss rangefinder lenses if I want to go really small.  Anyway, since this 24mm is an F Mount lens, I don’t have to use the adapter.

The lens is hunting for focus far and wide, nothing like my other AF lenses on this body.  Some of the pictures are backfocused badly which I haven’t seen my cameras do in years, including my full sized full frame dslr’s from Sony, Canon and Nikon.  It is also jittering in and out a short distance (not trying to focus, just jittering when your finger is down on the shutter after it’s in focus).  Lastly, it’s acting as if it’s in continual focusing mode,  but the camera is set to single shot.  The few pics it got right are razor sharp, but I think there’s something wrong with the lens.  Has anyone ever experienced problems like this with a defective lens?  Thanks, Bill

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ZilverHaylide Senior Member • Posts: 1,224
Re: Sony FE 24mm 1.4 GM continually focusIng, back focusing, jumping
1

billorg wrote:

I have a lifetime of experience with cameras and lenses of all kinds, so I am pretty sure when something isn’t behaving correctly. However, I just wanted to run this past you. Brand new lens, first time using today on a NEX 5n which is my smallest travel setup. That means an APS-C sensor with a full frame lens. I use A mount lenses from Sony and vintage Minolta w/adapter as well as manual Zeiss rangefinder lenses if I want to go really small. Anyway, since this 24mm is an F Mount lens, I don’t have to use the adapter.

The lens is hunting for focus far and wide, nothing like my other AF lenses on this body. Some of the pictures are backfocused badly which I haven’t seen my cameras do in years, including my full sized full frame dslr’s from Sony, Canon and Nikon. It is also jittering in and out a short distance (not trying to focus, just jittering when your finger is down on the shutter after it’s in focus). Lastly, it’s acting as if it’s in continual focusing mode, but the camera is set to single shot. The few pics it got right are razor sharp, but I think there’s something wrong with the lens. Has anyone ever experienced problems like this with a defective lens? Thanks, Bill

No experience with either that specific lens or camera, but it almost sounds like the camera and lens are "fighting" each other, in other words, like there is some sort of algorithmic firmware incompatibility between lens and camera.

Considering how much older the Nex 5n is compared to the 24mm f/1.4, firmware incompatibility seems quite possible. Also, isn't the 5n only contrast detect, not phase detect? If so, then acting like CAF mode, cuz that's effectively what it's using?

Have you updated the firmware on the camera? I'd give that a try. But even that might not work, because Sony might have stopped issuing updates for cameras that old. If you live near a retail store or know anyone with a newer body, perhaps you can pair your lens with that in order to know if there's anything wrong with the lens (beyond possible old body incompatibility).

Euell Veteran Member • Posts: 4,884
Re: Sony FE 24mm 1.4 GM continually focusIng, back focusing, jumping

billorg wrote:

I have a lifetime of experience with cameras and lenses of all kinds, so I am pretty sure when something isn’t behaving correctly. However, I just wanted to run this past you. Brand new lens, first time using today on a NEX 5n which is my smallest travel setup. That means an APS-C sensor with a full frame lens. I use A mount lenses from Sony and vintage Minolta w/adapter as well as manual Zeiss rangefinder lenses if I want to go really small. Anyway, since this 24mm is an F Mount lens, I don’t have to use the adapter.

The lens is hunting for focus far and wide, nothing like my other AF lenses on this body. Some of the pictures are backfocused badly which I haven’t seen my cameras do in years, including my full sized full frame dslr’s from Sony, Canon and Nikon. It is also jittering in and out a short distance (not trying to focus, just jittering when your finger is down on the shutter after it’s in focus). Lastly, it’s acting as if it’s in continual focusing mode, but the camera is set to single shot. The few pics it got right are razor sharp, but I think there’s something wrong with the lens. Has anyone ever experienced problems like this with a defective lens? Thanks, Bill

It does that until you update the lens firmware to version 02.

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OP billorg Senior Member • Posts: 1,286
Re: Sony FE 24mm 1.4 GM continually focusIng, back focusing, jumping
1

It does that until you update the lens firmware to version 02.

I just checked and it says you can’t update the lens software with a NEX 5.  Maybe it’s just not compatible.  bill

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Euell Veteran Member • Posts: 4,884
Re: Sony FE 24mm 1.4 GM continually focusIng, back focusing, jumping
1

billorg wrote:

It does that until you update the lens firmware to version 02.

I just checked and it says you can’t update the lens software with a NEX 5. Maybe it’s just not compatible. bill

Borrow an A6xxx from a friend and use it to update the lens. Sony says the lens is compatible with your body, but there are some small issues with the aperture ring.

Parenthetically, I would note that this is a pretty large lens for the NEX 5 body.

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LenRivers Senior Member • Posts: 3,218
Re: Sony FE 24mm 1.4 GM continually focusIng, back focusing, jumping

Sort of like putting tractor tires on a motorcycle

OP billorg Senior Member • Posts: 1,286
Re: Sony FE 24mm 1.4 GM continually focusIng, back focusing, jumping

LenRivers wrote:

Sort of like putting tractor tires on a motorcycle

i like it, no larger than other lenses I use on it and much lighter.  I like the NEX sensor a lot and also it’s small size.  I have been thinking about the a7 III but as far as noise at high iso, it’s only a tiny bit better than my NEX 5N.

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OP billorg Senior Member • Posts: 1,286
Re: Sony FE 24mm 1.4 GM continually focusIng, back focusing, jumping

Borrow an A6xxx from a friend and use it to update the lens. Sony says the lens is compatible with your body, but there are some small issues with the aperture ring

Thanks, I'm afraid I don’t know anyone with newer a Sony cameras.  My issues are not with the aperture ring, it’s with the AF.  Bill

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hemp0matic Regular Member • Posts: 228
Re: Sony FE 24mm 1.4 GM continually focusIng, back focusing, jumping

billorg wrote:

Borrow an A6xxx from a friend and use it to update the lens. Sony says the lens is compatible with your body, but there are some small issues with the aperture ring

Thanks, I'm afraid I don’t know anyone with newer a Sony cameras. My issues are not with the aperture ring, it’s with the AF. Bill

Perhaps you could send it to a camera shop and they could install the firmware for you?

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hemp0matic Regular Member • Posts: 228
Re: Sony FE 24mm 1.4 GM continually focusIng, back focusing, jumping

billorg wrote:

LenRivers wrote:

Sort of like putting tractor tires on a motorcycle

i like it, no larger than other lenses I use on it and much lighter. I like the NEX sensor a lot and also it’s small size. I have been thinking about the a7 III but as far as noise at high iso, it’s only a tiny bit better than my NEX 5N.

I had an NEX5N for a few years until it was stolen. I loved it.  I upgraded to the A6000 and that sensor is superior to the 5N with low light.  A friend has an A7ii and that sensor is better at low light in particular, but dynamics as well, especially with black and white is also improved vs the A6K.  I'm just an amateur hobbyist, but I'm upgrading to the A7iii, which at least from everything I've read is significantly improved from the A7ii as soon as I can save the necessary shekels. I think the upgrade to the A7iii would be pretty dramatic from the 5N.  The only downside is the slightly larger size and weight (both marginal IMO) as you use the 5N as a travel set-up.  I think the 24mm GM lens would be a pretty stunning combo with the A7iii.

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OP billorg Senior Member • Posts: 1,286
SOLVED

So, I found a good camera/lens compatibility page on Sony’s site (https://support.d-imaging.sony.co.jp/www/cscs/lens_body/index.php?mdl=NEX-5N&area=gb&lang=en) and as I feared, this lens is not compatible with the NEX series. The firmware flash of the lens does not address the main problem - the AF. Here is the list of the things that don’t work when you pair a NEX with the 24G lens (focus hold is the dealbreaker):

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ZilverHaylide Senior Member • Posts: 1,224
Thanks for the follow-up. A few more thoughts:

billorg wrote:

So, I found a good camera/lens compatibility page on Sony’s site (https://support.d-imaging.sony.co.jp/www/cscs/lens_body/index.php?mdl=NEX-5N&area=gb&lang=en) and as I feared, this lens is not compatible with the NEX series. The firmware flash of the lens does not address the main problem - the AF. Here is the list of the things that don’t work when you pair a NEX with the 24G lens (focus hold is the dealbreaker):

Thanks for the follow-up. Many OPs never follow-up on the resolution of their original posted problem.

Widespread advice/"common knowledge" is "spend your money on good glass, not bodies; good glass lasts forever. Etc, etc..."

That ignores multiple factors, such as the incompatibilities you experienced and found documented. Sometimes, because of technological paradigm shifts (i.e. phase detect vs. contrast detect AF) and/or manufacturer loss of support for "forever" compatibility, one has no choice but to put some money into updating camera bodies (a rude awakening if that money isn't available in your savings or budget).

I personally think that another two issues should factor into such decisions, but are unstated and often ignored.

1) familiarization with the equipment, its use, and muscle memory. That argues for keeping camera bodies as long as possible. But long-term satisfaction with that camera means that its capabilities meet your needs. That in turn is an argument for not "under-buying" in the selection of a camera body (finances permitting).

2) sometimes, one hears stated that "such and such lens isn't 'good enough' for some new high-resolution camera body". That's actually false, even an outright crappy lens will never be worse with a high-resolution sensor than it was with a lower-res one, and often it will be modestly improved (and potentially further improved, because a greater number of pixels allows for more elaborate post processing). Such a pairing might not be economically optimal, and wouldn't make sense to go out and purchase as a new combination. But if you already have a bunch of old lenses, they might all be modestly improved by a new, higher-resolution (higher pixel density) body (improved at the level of the entire photo, not pixel-peeping small pixels against large ones). They certainly won't be worse than on your existing body. (The principles behind this were explained quite well in a couple of white papers Zeiss put out a number of years back exploring MTF; sorry I don't have titles or links handy).

Euell Veteran Member • Posts: 4,884
Re: SOLVED
1

billorg wrote:

So, I found a good camera/lens compatibility page on Sony’s site (https://support.d-imaging.sony.co.jp/www/cscs/lens_body/index.php?mdl=NEX-5N&area=gb&lang=en) and as I feared, this lens is not compatible with the NEX series. The firmware flash of the lens does not address the main problem - the AF. Here is the list of the things that don’t work when you pair a NEX with the 24G lens (focus hold is the dealbreaker):

Yes, that is the correct page, but I see nothing there that says the AF doesn't work with the NEX 5n, although there are various other incompatibilities.

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snapa
snapa Veteran Member • Posts: 5,087
Bill

billorg wrote:

It does that until you update the lens firmware to version 02.

I just checked and it says you can’t update the lens software with a NEX 5. Maybe it’s just not compatible. bill

Why the heck don't you simply upgrade your very and antiquated old NEX 5 to the a6400 and enjoy all of your lenses ever more?! Your pictures would look better, and your keeper rate would probably double. Let your NEX 5 go, it has served you well.

PS, read my signature. I upgraded from my NEX 5T straight to the a6300, and it was a great upgrade in every way! You should do the same with your NEX 5, just let it go. 

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