A warning about the LA-EA2 adapter with FS100

[cgalgon]

While I'm rarely a contributor, this forum has been extremely helpful for me in the past and so I thought I'd post this message here. I've certainly considered that I missed something obvious that would solve the problem, and I hope someone on this forum will suggest it if that's the case.

I purchased the FS100 in January, out of enthusiasm over its low light capabilities. I'm an event videographer, not a filmmaker, and the idea of a camcorder that can do 21db with an acceptably clean image excited me, even if the camera itself had disadvantages over my EX1s. The camera's kit lens is okay enough but a little slow, starting at f/3.5, but the LA-EA2 adapter was going to make the camera compatible with faster Alpha lenses. So, over the last few months I'd been waiting patiently for firmware 2.0 to arrive for compatibility with the LA-EA2 adapter. It's worked perfectly with my NEX-5n still camera and various lenses, so I thought there'd be nothing to worry about...

As it turns out, the LA-EA2 adapter with the FS100 is little more than a tease, where you're always approaching what you want but never quite getting it. I finally downloaded the awaited firmware 2.0 a couple of days ago. The first lens I attached was a Zeiss 24-70mm f/2.8 lens. The FS100 immediately began focusing and exposing without issue, but then I noticed the iris was set at f/3.5. Wanting to open it all the way up, I tried pressing the FS100's iris button, only to get the message: "Cannot execute functions because of the condition of the lens." One of the less helpful error messages I've encountered. So I fiddled with various settings until finding the solution: deactivate AF. Once AF was switched off, I could adjust the iris as expected, albeit with its own compromises (the camera first goes wide open and then sets to the stop you wanted for the sake of accuracy, ruining the intermittent video). I tested a Sigma 20mm f/1.8 with the same results.

After a day or so of playing with this, and finding no forum topics that touch on the subject, I'm posting with the following conclusions about the FS100 joined with the LA-EA2 adapter:

• You can have AF, but not while controlling the iris (it's stuck at f/3.5).
• You can control the iris, but not while using AF.
• If you try to set the iris and then engage AF, it will reset the iris to f/3.5.
• When in AF, the iris will stay at f/3.5 regardless of environmental conditions.
• The iris cannot adjust automatically even in MF.
• As of now, only e-mount lenses allow you to use AF while controlling aperture, of which there are perhaps 5 at f/2.8 or wider.

So, the LA-EA2 adapter means you can attach fast Alpha lenses to your fs100, but they can't be fast if you use AF. And I'm back to square one.

It should be noted that these problems are unique to the FS100, a camera just updated largely to use this adapter, while my NEX-5n still camera works with no such limitations. Both the NEX-5n and FS100 natively use contrast-detection autofocus, so I can't see why one can work as expected while the other is practically worthless. I would have found this usable if the adapter set alpha lenses wide open, but it doesn't. f/3.5 is chosen regardless of lens.

I realize that not everyone wants AF, but a RNG event videographer needs it at times. And since my interest in the camera came primarily from its low light capabilities, I find it pathetic that I need to choose between light sensitivity and AF on Sony's own $300 adapter. Here's hoping that I'm wrong, and one of you cracked this problem, and are willing to share the solution. Thanks.

UPDATE:
One thing I missed, which makes me feel a whole lot better, is that "push to focus" works (okay, at least). So it's not going to do all I wanted but it's better than I thought.

[Kraut69]

I think you have summarized accurately in one place what has been noted in various threads. This adapter for me has appeal only for its enhanced auto focus abilities, which you can take advantage of only in good light (and using ND filters as required).

[Steve R]

I don't think the "max aperture of 3.5" is unique to the FS100; it's unique to VIDEO use of the LA-EA2. It's always been a known aspect of the LA-EA2.

I've known about it ever since I saw it on the B&H site:

http://www.bhphotovideo.com/c/produc...ns_to_NEX.html

But I also saw it as a footnote on the LA-EA2 page on Sony's site:

http://store.sony.com/webapp/wcs/sto...rtNumber=LAEA2

[cgalgon]

Thank you for the reply. I guess the lesson I should take away is that you can't have everything, not at any price. I'm regularly confounded by decisions Sony makes with otherwise great products, and here we go again. Given how the adapter works as expected on still cameras, I'd hoped there was something I had missed. What a disappointment.

[morgan_moore]

Ill be clear I think its a bit dumb - especailly as sony are losing an opportunity to sell me some glass.

No way I would buy into sony glass (beyond the kit lens) without full functionality

To defend Sony however I wonder if the AF system somehow relies on DOF - ie make it too narrow and the AF has little to catch on to - too much and it cant choose ?

S

[Chris Johnston]

I would assume that it's a technical limitation trying to get a mount glass to work effectively on the e mount fs100. What I have trouble understanding is why so many complain about it.
They (Sony) have repeatedly said this is what the adapter will do. Here's how it will work. here's the limitations. etc etc etc.
Then people buy it and complain (after they buy it) that it doesn't do what they want.....
Sony is actively trying to expand their e mount glass lineup, even providing free scematics for third part lens manufacturers but I guess it takes a little time to get that rolling.

but really......It's like I try to sell you my car, you ask what the top speed is. I tell you 85 mph. You buy the car, drive off, and come back 2 hours later complaining it doesn't do 140 mph. Who's fault is it?

[evilthought]

Thank you for the reply. I guess the lesson I should take away is that you can't have everything, not at any price. I'm regularly confounded by decisions Sony makes with otherwise great products, and here we go again. Given how the adapter works as expected on still cameras, I'd hoped there was something I had missed. What a disappointment.

Actually, the PDAF AF (in video mode) works exactly the same way on Sony's still cameras, such as on A55 that has been out for more than two years. The aperture is fixed at F3.5
(or wide open for slower lenses).

Canon, Nikon, and Pentax DSLRs don't have PDAF AF at all in video mode.

In still mode, the DSLR lenses always AF with lenses set to wide open (you can't change that part on any DSLR). The aperture closes down to the selected aperture only when you press the shutter button, then reopens back to wide open. That's why you have DOF preview button on DSLRs. Obviously this mechanism is not going to work with video. These lenses were not designed to AF with video anyway.

However, I don't know why the SLT/LAEA2 don't go wider than F3.5.

[richg101]

I think you should take this as a prompt to use the kit lens more. a really great lens in my opinion. With LA-EA2 you lose your OSS. f3.5 is more than enough. any wider and your videos start to look too shallow - the 'newbie with a dslr look'. The sensitivity and low light ability of the fs100 sensor wont struggle in low light for 95% of the work, and you'll still get shallower dof than most of the cameras used in pro videography thanks to the 3 perf sensor size.

[cgalgon]

I would assume that it's a technical limitation trying to get a mount glass to work effectively on the e mount fs100. What I have trouble understanding is why so many complain about it.
They (Sony) have repeatedly said this is what the adapter will do. Here's how it will work. here's the limitations. etc etc etc.
Then people buy it and complain (after they buy it) that it doesn't do what they want.....
Sony is actively trying to expand their e mount glass lineup, even providing free scematics for third part lens manufacturers but I guess it takes a little time to get that rolling.

but really......It's like I try to sell you my car, you ask what the top speed is. I tell you 85 mph. You buy the car, drive off, and come back 2 hours later complaining it doesn't do 140 mph. Who's fault is it?

I can see how I'm to blame for not doing enough homework, but it's oversimplifying to say I couldn't make the mistake. After all, according to Sony's FS100U product page (and BH's), the FS100 isn't even compatible with the LA-EA2. Nor can it do 25p! I do see (now) that the LA-EA2 mentions f/3.5 in the product page but that could just as easily been outdated info given changing firmware.

[cgalgon]

I think you should take this as a prompt to use the kit lens more. a really great lens in my opinion. With LA-EA2 you lose your OSS. f3.5 is more than enough. any wider and your videos start to look too shallow - the 'newbie with a dslr look'. The sensitivity and low light ability of the fs100 sensor wont struggle in low light for 95% of the work, and you'll still get shallower dof than most of the cameras used in pro videography thanks to the 3 perf sensor size.

You're right, and I like the kit lens fine, especially the OS. However, I do a lot of wedding receptions, and they get effing dark! Now that I've seen that "push to focus" works, however, I feel a bit better about things.