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Old October 18th, 2011, 01:57 PM   #1
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Lens hood modification for filters

Hi folks,

I did a bit of hacking at my NX70 lens hood at the weekend, to make a bit more space for filters.

I put together a quick video here. Nothing too polished, but it shows how a ham-fisted person like me can do this:


Do this modification at your own risk! This may void your warranty!

This mod gives just enough space for the depth of two B+W filters. My Polaroid fader ND filter now fits under the hood, though you probably want to take the hood off for adjustment.

Edit: BTW, this isn't a NX70 shortcoming. I would have had to do something similar on my Sony V1E, with a similar hood. In fact, I can remember having to buy ultra-slim B+W UV filters for it, as regular ones wouldn't fit. The NX70 easily holds a full height B+W filter behind the hood without modification.

Last edited by Mike Beckett; October 19th, 2011 at 11:58 AM. Reason: Added last sentences, after "edit:".
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Old October 19th, 2011, 11:37 AM   #2
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Re: Lens hood modification for filters

Mike - you have another Vimeo film that shows 'no internal NDs visible'. I've never looked at this camera but I'm thinking it's a single " chip? Maybe 1/3", Sony seem reluctant to specify that on their NX70 web page.

Anyway, thing is that if there's no external ND switches (as on the NX5, say) then you can be pretty sure there's internal (undocumented) ND filtration going on. Seems odd that you can't see it as you turn the iris control wheel, but that doesn't mean it's not there - many owners have told me their Panasonic SD900s have no internal ND when it's pretty obvious they do.

How else would Sony stop diffraction spoiling the resolution? Such small-chipped cameras shouldn't really operate at anything much smaller than f/4.5, and outside in sunlight with the shutter speed and gain locked down it would often want to shoot at f/16 if the chip has any sort of half decent low light ability.

tom.
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Old October 19th, 2011, 11:56 AM   #3
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Re: Lens hood modification for filters

This is the thing, Tom. I always assumed that small camcorders would have an internal ND, no matter what. (BTW, the spec says it is a single 1/2.88" CMOS chip, i.e. a smidgen larger than 1/3").

Another user on my Vimeo channel said he had an email from Sony saying that there were NO internal ND filters at all. His reply from Sony was:

Quote:
"the NX70 does NOT have an ND filter of any kind."
Now, it could be open to misinterpretation - do they mean no switchable ND, or no ND at all? But it does seem pretty unequivocal. In auto mode, the NX70 will shut the iris right down (almost closed, at f9.6) very quickly on a bright day (and still be overexposed). This may suggest that there may indeed be no ND. Or maybe not.

Of course, it may be that resolution does get spoiled when the iris is shut down, I haven't tested that. Bit of an "oops" from Sony if that is the case.

I could always take the camera apart to find out. After all, I own a Dremel now!!
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Old October 19th, 2011, 12:38 PM   #4
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Re: Lens hood modification for filters

Chris - other mods - is there any chance this could be split into a new topic?

"NX70 built-in ND Filter" or similar.

It's not really related to the initial topic, and I don't want it to be "buried" for anyone looking for info.
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Old October 19th, 2011, 05:00 PM   #5
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Re: Lens hood modification for filters

Quote:
Originally Posted by Mike Beckett View Post
Now, it could be open to misinterpretation - do they mean no switchable ND, or no ND at all?
I smiled as I read this as (suspicious mind that I have) I too suspect that Sony are being economical with the truth and that what they meant is 'no ND filter switch'. But as you say, the chip is considerably smaller than the EX1's chip, and the EX deems it necessary to have lots of ND on board. And this ND isn't there to let people play with their dof, it's there to keep the image sharp. My NX5 is constantly silent-screaming at me to switch to the next ND. This is not a Sony scream, it's a law of optics scream.

So do the same iris dial test again, but this time look down into the lens using a full telephoto setting. And remember that aperture readouts are only given in numbers you'll recognise - like f/4.8. The fact that this is really f/2.8 with ND applied is kept hidden from us - after all, we're professional photographers, aren't we?

tom.
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Old October 20th, 2011, 11:21 AM   #6
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Re: Lens hood modification for filters

Tom,

I did the same test at telephoto before as well as wide, it's exactly the same. The iris closes to a pinpoint, then totally closed, no sign of an ND inside there. I just couldn't easily video or photograph it.

Either:
(a) There is no ND filter in there
(c) I can't see the ND filter
or
(c) It's an invisibile ND filter

Any of those options is plausible, and I have no way to tell which it is. Sony claim (a).
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Old October 21st, 2011, 06:04 AM   #7
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Re: Lens hood modification for filters

Oh, I'd love to have a look down into the NX70's lens. I suspect your option (c) is the correct one. Say there was a permanent ND grad in there, totally clear at one end of the disc and ND9 at the other. As it turned on its axis behind the iris blades it it would introduce more and more ND invisibly, along with the closing of the iris.

All the cameras I have that use internal and undocumented ND have allowed the iris blades to fully close, so I don't think that fact precludes the use of internal ND. It's interesting to watch the aperture readout on your side-screen - as it appears to correspond with what I'd expect to see happening to the iris blades.

Sony's PDX10 used ND this way. The camera's iris went from wide aperture to f/4.5 and stayed there till all the ND was in place, then continued to close the blades. Panasonic's SD900 shoots wide open, letting ND soak the light to f/5.6, whereupon the blades start to close. But in its still camera mode the blades do as your video shows - they stop down and the internal ND is ignored. Clever.

Shame we've shifted the thread away from your hood mod.

tom.
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Old October 21st, 2011, 11:31 AM   #8
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Re: Lens hood modification for filters

I don't know Tom. If it held the iris at f4.5 until the ND was all in place, there'd be a be a time when the iris stopped closing down when as you turned the dial, this one closes smoothly from f1.8 to f9.6.

Anyway. If you're ever near Belfast, you can come and peer down my barrel any day!
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Old October 22nd, 2011, 09:47 AM   #9
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Re: Lens hood modification for filters

That's why I'm surmising that the ND grad wheel is turning along in sync with the iris blades closing.

Wide open = no ND.
Indicated f/2.8 = aperture blades at f/2 and ND soaking a stop.
Indicated f/5.6 = aperture blades at f/3,4 and ND soaking 1 stops
Indicated f/11 = aperture blades at f4.8 and ND soaking 2 stops. ND is now fully in place so
indicated f/16 = actual f/6.8 and so on.

Only a guess really, wondering how Sony are doing this sleight of hand.

tom


This way looking down into the lens shows what your video shows
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