Focus assist light on camera mounted flash.

[HarveyB]

Spoke to Sony support last week and asked why assist light, on camera mounted flash,  is disabled on the A7 cameras.  They said someone will get back to me.

Because of the way the light is mounted on the body, if you are using a large diameter lens, it blocks the assist light.

All other manufactures use the light on the external flash.

This is the only issue I have with the camera.  Maybe not the only one, but the most important.

Any ideas?

[michelb]

Flash based "AF illuminators" can only be used on Sony DSLR/SLT bodies because these bodies use PDAF sensors separately from the imaging sensor. This is actually a pattern of lines projected that lets these AF sensors know which way to go and by how much to move the focusing mechanism to reach proper focus. 

On the mirrorless cameras, there are no separate AF sensors that can use this so they replaced the Illuminator by what is called "AF assist light" but these are only on the camera bodies, and is just that, a beam of red light that tries to help the AF system find something to focus on but in no way tells the AF system either which way to go or by how much.

Confusion often arises because the 2 seem to be the same but really are not. 

 

Something to notice is that the AF Illuminator from the flash ( and all Sony flash units that i know) were designed for the A-Mount cameras that require a pattern to be projected from the camera or flash to help the PDAF system in those cameras to achieve proper focus even on a totally uniform surface ( totally white wall for example).

This was derived from the Minolta AF system and even then some generations of flash units would not allow use of this AF illuminator with previous generations of cameras because the pattern did change on occasion from one generation to the other making them incompatible with previous models

 

 

In theory, this should work with LA-EA2 and  LA-EA4 lens adapters coupled to an A-Mount lens since they use a similar PDAF system from the A-mount cameras but Sony did not implement it in Firmware which is a pity. I mention this because the AF illuminator is a lot less intrusive in both time and intensity than the weird AF Assist Light of the E-Mount cameras.

 

By the way Sony's latest flash ( and only one introduced since the advent of E-Mount cameras) HVL-F32M does not even have the AF illuminator anymore. The red window at the front is now only for WL Control/Reception.

[JCC]

Its also not allowed at many events because your red spots ruin the photos of others.

 

JCC

[HarveyB]

If there is an assist light on the body? why cannot it not also be on external flash.  Does not have to project lines, just light up.  The camera focus does need help.

In all my years doing events, PR etc, I have never seen anyone's else s focus light show up in a images.  someones flash yes. Not saying it does not happen. Would make more sense to be able to turn off than not have it. 

 

If Sony had this on their flash, maybe more people would buy instead of aftermarket. Personally I would pay and extra $300 or $400, if it fixed the focus issue

[michelb]

Did you try the one on the camera ? It can be set to OFF in the camera's menu

 

If the built-in AF Assist light does not help, a flash mounted one will provide no improvement and if a little more powerful or last longer may even be more objectionable . 

[HarveyB]

assist light on flash is disabled by the camera and cannot be turned on. focusing light Never been objectionable to me.

 

I would just like camera to focus better.

 

Guess I am a little upset by sony saying they would get back to me and never did.

[VTC]

See the pics posted here why, as JCC mentioned, these types of assists are banned... particularly the jerkweed at my vintage fashion shoot.

 

http://www.sonyalphaforum.com/topic/6118-no-option-for-focus-assist-illuminator/

[michelb]

Assist light on flash will never work but camera focusing assist light should work if selected as On or Auto in camera menu

[HarveyB]

Why doesn't Sony allow it to work.  Lets stay on topic. Does everyone think the camera focuses just fine? If they think the assist light helps in very low light situations, allow it to work on the flash.

Every other camera maker does.  Have they ever tried it????

The body is very small and the focus light cannot be seen by the lens.

[michelb]

AF on mirrorless cameras is limited to a certain extent by its initial technological developments. No in low light it may not focus just fine since light is the first requirement to get any AF system to work. 

 

It does not work in flash because it is not a light but a pattern being sent toward the subject. Each camera brand has its own pattern and even each generation of flash of  a single brand has evolved and often  makes it incompatible with the previous generation since the invention of this in 1985.

 

For example, the 1985 Minolta Maxxum 5000/7000/9000 AF cameras had a single AF sensor and for this, the flash units from that generation ( 1800AF, 2800AF and 4000AF) were designed to emit a certain pattern. When they brought about the following generation of AF cameras in 1988 with 3 AF sensors, the pattern from the previous generation of flash units could not be recognized by the newer cameras so the AF illuminator was already being disabled when used with that previous generation of flash units.

 

If you look at the examples from the link VTC posted, notice the long lines at the bottom of the lady's belly as opposed to the vey short lines on the man's shirt. This difference in pattern CAN NOT be recognized and used to assist in AF by non compatible cameras.

 

Every traditional DSLR out there from Nikon/Canon or later SLT cameras from Sony use the traditional PDAF sensors built into somewhere in the viewfinder or mirror box and these can use the illuminator from compatible flash units. Mirrorless cameras can not and you are for now limited to the built-in AF Assist light. Even the newer Sony A99II does not have the Assist Light on-body but can take advantage of on-flash AF Illuminator because it has the PDAF sensors in the mirror box. But then it has the more traditional AF system from earlier SLR generations

 

E-Mount Cameras were designed with on-sensor AF sensors ( contrast detection at first that would have no use for a pattern) and much later what is called on-sensor PDAF,  but this is a different technology and size and can not use the patterns emitted by traditional flash unit  AF illuminators

And so on and now cameras have up to 79 traditional AF sensors that are built-into the viewfinder. ( God knows how many). 

 

You are trying to use a Windows 95 piece of software or accessory with a Windows 10 tablet

[HarveyB]

Hi,

How do you know the camera cannot use the pattern to help focus?  Has Sony ever tried?  The pattern, may not help, but it is a light.

Just saying it is because it is is not an answer.

The A7s, all of them focus using the senor that takes the image.  Extra light must help because there is a focus assist light.  If it could see the pattern from the flash, would it help?

The pattern is a light.  Is the pattern built in to the plastic lens on the flash.

[HarveyB]

What does Sony say about this?

[jtberg01]

Flash based "AF illuminators" can only be used on Sony DSLR/SLT bodies because these bodies use PDAF sensors separately from the imaging sensor. This is actually a pattern of lines projected that lets these AF sensors know which way to go and by how much to move the focusing mechanism to reach proper focus. 

 

On the mirrorless cameras, there are no separate AF sensors that can use this so they replaced the Illuminator by what is called "AF assist light" but these are only on the camera bodies, and is just that, a beam of red light that tries to help the AF system find something to focus on but in no way tells the AF system either which way to go or by how much.

 

Confusion often arises because the 2 seem to be the same but really are not. 

 

Something to notice is that the AF Illuminator from the flash ( and all Sony flash units that i know) were designed for the A-Mount cameras that require a pattern to be projected from the camera or flash to help the PDAF system in those cameras to achieve proper focus even on a totally uniform surface ( totally white wall for example).

This was derived from the Minolta AF system and even then some generations of flash units would not allow use of this AF illuminator with previous generations of cameras because the pattern did change on occasion from one generation to the other making them incompatible with previous models

 

 

In theory, this should work with LA-EA2 and  LA-EA4 lens adapters coupled to an A-Mount lens since they use a similar PDAF system from the A-mount cameras but Sony did not implement it in Firmware which is a pity. I mention this because the AF illuminator is a lot less intrusive in both time and intensity than the weird AF Assist Light of the E-Mount cameras.

 

By the way Sony's latest flash ( and only one introduced since the advent of E-Mount cameras) HVL-F32M does not even have the AF illuminator anymore. The red window at the front is now only for WL Control/Reception.

This is pretty much a deal breaker for me as an event photographer. Luckily I kept my Canon!