Sony SAL1650 DT 16-50mm f/2.8 review on FS100

Thanks Shawn for the review. Are you using the Sony LA-EA1 adapter for this A-Mount to E-mount lens? If so, when changing iris with it, does it go up and down in full stops without "opening up" to full aperture? (that's why I didn't opt for this)

Currently I'm using a Sigma 17-50mm f/2.8 Nikon mount lens with a cheap adapter that works ok , with built-in iris control in the adapter. The problem with this lens is that it isn't parfocal, so focus changes as the focal length changes, which sucks badly (I also use a tamron 28-75mm f/2.8 nikon mount, which is more parfocal).
 
My pleasure. I am using the Sony LA-EA1 adapter but have a LA-EA2 on order, although I think I'll probably have to wait a bit more for firmware for the FS100 to be released. My Sony rep told me in late August that in his tests of the LA-EA2 adapter on the NEX5N with pre-release firmware that smooth iris stepping was possible. The LA-EA1 currently opens up the whole way or closes down between stops so you can't use it while recording live.

I have tried a bunch of FotoDiox adapters and the one with the aperture ring didn't have the tightest fit with my lenses so some of them had more play than others, which I didn't like. I don't think it affected the image but I switched back to the LA-EA1 adapter as I like a tighter fit. My Minolta 70-210 f/4 "beercan" fits pretty snug but many of the others don't, specifically my Konica Minolta 28-70 f/2.8.

I hear you on the parfocal challenges. I've tested about 20 lenses now in order to find parfocal lenses for the FS100 and althought I didn't place as much importance on being parfocal on the wide lens (because the wide is more likely to be handheld and full wide and I'd change the focal length by moving my feet) but was pleasantly surprised when it was perfectly parfocal.

The beercan is parfocal as well.
 
Shawn-

Does anyone know if the kit lens, 18-200mm is parfocal?

Thanks in advance.

Be well

Rob
Smalltalk Productions
 
The e-mount 18-200mm kit lens is actually parfocal although because it isn't a fixed aperture lens, the iris ramps up or down.

In orther words, the lens itself is f/3.5-6.3 so unless you film at f/6.3 the entire time, the iris changes as you zoom-in.
 
I'm hoping, sooner than later, that 3rd party manufacturers, or even sony, releases some fast zooms (16-50mm, 70-200mm or 50-150mm) f/2.8 lenses in e-mount, rather than having to use a $300-$400 adapter
 
Nice review. I was considering the Sony A77 and was glad to see this lens bundled with it. Its the best "Kit Zoom" I've ever heard of yet lol
 
ShawnLam said:
The e-mount 18-200mm kit lens is actually parfocal although because it isn't a fixed aperture lens, the iris ramps up or down.

In orther words, the lens itself is f/3.5-6.3 so unless you film at f/6.3 the entire time, the iris changes as you zoom-in.
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Parfocal means that focus holds while you zoom. It has nothing to do with the iris. I have the e-mount 18-200 kit zoom lens. It DOES NOT hold focus while you zoom and the iris changes while you zoom until you get to f5.6.
 
rejdmast said:
Parfocal means that focus holds while you zoom. It has nothing to do with the iris. I have the e-mount 18-200 kit zoom lens. It DOES NOT hold focus while you zoom and the iris changes while you zoom until you get to f5.6.
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Actually, to F6.3:(
 
rejdmast said:
Parfocal means that focus holds while you zoom. It has nothing to do with the iris. I have the e-mount 18-200 kit zoom lens. It DOES NOT hold focus while you zoom and the iris changes while you zoom until you get to f5.6.
Click to expand...

Correct - Being parfocal has nothing to do with the iris. The lens does ramps (iris changes) when you zoom in if you are anything faster than f/6.3.

Try your parfocal test again. For a lens to be parfocal it has to hold focus when you zoom OUT. Technically it has to hold focus when you zoom back in as well but in order to test it, you have to first start at full telephoto, then manually focus, and then zoom out. If the lens holds focus throughout the entire range (and not just full telephoto and full wide), then the lens is parfocal.

Starting at full wide will rarely produce an in-focus result when you zoom in. The reason is that the depth of field is greater when you are wide and shallower when you are at full telephoto.
 
ShawnLam said:
The reason is that the depth of field is greater when you are wide and shallower when you are at full telephoto.
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Being a pedant the DOF is the same irrelevant of lens lenght, wide lenses we tend to perceive more DOF

You dont get more DOF, just the image is less magnified

DOF is a function of Fstop and Distance

Day to day of course a parfocal zoom is typically used by as described !

S
 
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