Focussing speed on my E 50mm F1.8 OSS

Started May 15, 2012 | Discussions
viktoriskra
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Focussing speed on my E 50mm F1.8 OSS
May 15, 2012

Hiya,

as the title suggest I am experiencing an abnormal focussing delay on my otherwise fantastic lens. Indoors when shooting 'contrasty' subjects it takes 2 - 3 seconds to focus, outdoors in good light conditions it is circa 1 second. In the same scenario(s) the 18 - 55 kit lens is significantly faster, contrary to all the reviews of these two lenses that I have read. I am using NEX 5N with the 1.01 firmware update.

Has anyone experienced the same problem or have I simply got a bad copy?

Thanks for your help..

Viktor

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Sony Alpha NEX-5N Sony E 18-55mm F3.5-5.6 OSS Sony E 50mm F1.8 OSS
Jerry Canon
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to viktoriskra, May 15, 2012
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I haven't noticed that behavior with mine. It would be nice if you could get hold of another one and compair them side by side. And better yet on different cameras.
Jerry

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Sony E 50mm F1.8 OSS
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viktoriskra
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to Jerry Canon, May 15, 2012

That's precisely what I am planning to do.. The lenses are just so hard to get hold of at the moment, hence this thread.

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Sony Alpha NEX-5N Sony E 18-55mm F3.5-5.6 OSS Sony E 50mm F1.8 OSS
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MBRuss
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to viktoriskra, May 15, 2012

I had this myself at the weekend. Focussed on somebody indoors and the lens cycled all the way through the focus range before coming back almost to where it'd started because the subject was almost perfectly in focus from the last shot anyway. Light wasn't that bad, either - windows behind me.

Lens appears mechanically fine though. This is with NEX-7.

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mimey
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to MBRuss, May 15, 2012

I just compared AF speed of SEL-1855 and SEL-50F18 on NEX-5 and I also found that AF speed is a bit slower with SEL-50F18. Set-up: both lenses at 50mm, f5, SS 1/100s, shooting distance about 3m.

Although I also noticed the slower speed, I do not think that there is anything wrong with the SEL-50F18, because I did a MF comparison and the result was the following:

SEL-1855 @50mm: to change focus from closest shooting distance (25cm) to 3m it takes only a 3/4 turn of the MF ring.

SEL-50F18: to change focus from closest shooting distance (39cm) to 3m it takes a bit more than 1 1/2 turns of the MF ring.

This is more than double the distance of the focus ring to turn compared to the kit lens, which than will obviously take more time.

For the very shallow depth of field of the SEL-50F18 @f1.8 this larger distance for turning the focus ring will give you a lot more precision and ease of manual focussing.

So I guess that our lenses are perfectly fine...

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weavster
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to mimey, May 15, 2012

Yes I agree - of all my e mount lenses it hunts around the most.

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Fredy Ross
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to weavster, May 15, 2012

Gosh I am getting mine tomorrow so hope I have better luck. I will set it to av mode and -1/3 ev as I do for street photography tomorrow night which is what I bought it for as the kit is too slow. Will let you know how I get on. I bought it on Amazon so am concerned it isn't a returned item but nobody else had one.
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Fredy Ross
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to Fredy Ross, May 17, 2012

Got mine and am very disappointed at how long it takes to focus. It is a sunny morning here and got qutie a few outoffocus shots in daylight trying street photography at f2 using av mode and -1/3 ev. My canon G11 never misses like that. Still I want it for night shots so maybe I have to learn how to hold the camera so will try again tonight. I have the 5n. I am used to the kit and I would never get those bad shots with it. Hard to get used to a non-zoom too so that could be my fault.
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cxsparc
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to Fredy Ross, May 17, 2012

Your G11 had at least 3 stops more DOF at the same aperture setting.

So if you set the SEL50 to f2.8, the DOF of the G11 set to f2.8 will be as f8 set at the SEL50. Since the g11 has a minimum aperture of f2.8 at 28mm effectively and f4.5 at full tele, you are bound to get even more DOF in practical use.

The G11 set at 50mm effectively, probably has a minimum aperture wide open of f4. The SEl50 would have to be set to f11 for similar DOF. So while it is easy for the G11 to have most things in focus, even if the AF would have been slighlty inaccurate, it is much more challenging with an APSC sensor camera.

Use touchfocus, and ramp up aperture.

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Fredy Ross
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to cxsparc, May 17, 2012

Perhaps you misunderstood me. I don't want lots of things in focus. I am saying for street photography the lens didn't focus on my subject quickly enough and they were blurred. I have started another thread and shown that the bokeh is wonderful which is why I bought it and will try it tonight for street photography which is why I bought it.
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Fredy Ross
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to Fredy Ross, May 17, 2012

I just thought i would mention that I tried street photography at night and this lens reacted much better than during the day, so maybe it needs more contrasts as although it is night all the shops have bright lights and I ended up with sharper photos than from the kit. Hard to get used to a non-zoom but I am happy till Sony makes a zoom 17-55 IS f2.8 like my canon. Hope Sony is listening.
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wb2trf
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to cxsparc, May 18, 2012

cxsparc, I think you're exactly onto why this lens focuses a bit slower than the Canon and also slower than the Sony kit.

On the other hand, even though I have adjusted a little to the slower focus, I like the image quality so much that I still love this lens. I shoot a lot a t1.8. The results are just beautiful.

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MrT-Man
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to wb2trf, May 18, 2012

A shallow DOF doesn't help focussing, but I think there's more to it than that... I have the Zeiss 24 and the focussing is much faster, even wide open. I realize that a 24mm lens doesn't have as shallow a DOF as a 50mm lens, but still... I'm thinking it must also have something to do with the motor they used in the 50.

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cxsparc
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Re: Focussing speed on my E 50mm F1.8 OSS
In reply to MrT-Man, May 18, 2012

According to a DOF calculator, DOF at 3m distance 24mm f1.8 is about 1.14 m.
For a 50 mm lens at f2.0 at a distance of 6 m, it is 1.15 m.

So if you want to have the same subject size and are able to double the distance for that purpose, the difference is very small.

But - if you have to shoot at the same distance of 3 m (e.g. street photography & stepping onto the highway is no real alternative ), the DOF of a 50 mm f1.8 at 3m is only 25 cm. To get the same DOF as the 24 mm f1.8, you have to set the 50 mm to f8!

So I think the Af has a much harder job in the SEL50 and has to go through the AF capture cycle at a much slower rate to lock onto focus. That being said, I too like my SEL for the color rendition and contrast it gives.

I too would like a 17-55/2.8 or something close. Or a 24mm2.8 at a price below 500 Euros.

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