Red problem !

[Peter Brugman]

Sean,

-I agree with you that a filter shouldn't be necessary at all, a proper one should be built in, maybe in the EX3.
-B&W 486 looks very similar to the Leica UV/IR filters supplied for M8 camera, however they don't make a 77 mm one.
-The B&W 486 is fine apart from very, very slight corner colouring when zoomed out, this is due to the light rays passing the filter at a very oblique angles in the corners. B&W says this happens at wide angles of 60 or more degrees and is inherent in the nature of this filter type.
-When used with Letus Extreme there is no problem.
-Light loss is minimal, in cool daylight only 1-2%, so I doubt light loss is the reason why the filter is not built in.

-Only the Heliopan UV/IR filter gives a greenish cast and is therefore better avoided.

[Piotr Wozniacki]

Originally Posted by Peter Brugman

-When used with Letus Extreme there is no problem.

Peter, how do you mean - you're leaving the 486 between the camera and the Letus adapter?

[Peter Brugman]

Yes Piotr, that is correct.

[Paul Kendal]

Can someone who is at NAB ask SONY what if anything that they are going to do for us about the "RED" (infrared not the 3K Scarlet) problem?

Can the EX1 be retrofitted with a proper strength IR filter?
Or is it up to us to take care of the problem ourselves with a screw-on filter?

[Mike Thomann]

There are IR/UV combo filters available that would serve three purposes; UV filtering, IR filtering, and lens protection. It's much better to pre-filter the light to the sensors so that they can better sense only the needed spectrum. I hope that by insisting on this change that other more important things don't lose their priority.

[Sean Donnelly]

Mike, I think this is a more serious issue than you're giving it credit for. Pre-filtering the light to the sensors is what happens regardless of where in the optical path the filter is placed. I for one don't like to put any glass in front of the lens that I don't have to, since it defeats the purpose of the anti-flare coatings on the front element as well as taking up the filter slot under the stock lens shade. This is an image quality problem that can and should be solved, and sony doesn't have to stop working on the back focus problem to do that.

-Sean

[Piotr Wozniacki]

Guys,

I have just received my B+W 486 filter and put it on my EX1. I have shot some test stuff in daylight; no greenish cast in the corners at full wide, as some have reported. Also, while - without the filter - the picture (using absolutely neutral matrix settings) tends to have some bias toward reds (especially with Hisat matrix), it's completely natural now.

But the real tests I will be doing this evening inside, with some tungsten lighting. I'll try to post some grabs of my girls' black and deep blue garment, which - without the filter - was notoriously recorded as brown or magenta, respectively. With the filter (which has been quite an expensive investment - with duty and VAT paid on top of the B&H price + shipment), I certainly do hope to be getting the right colours...

Peter, my Letus kit being away at the moment - how do you fit LEX on the EX1, with the 486 filter in place of the Letus EX1 thread ring?

[Piotr Wozniacki]

Just a quick update:

Yes, the black clothes look really black, and deep blue are not magenta anymore, with the 486 filter attached in tungsten light (2600-3200K).

However, with all matrix settings being default (for both Hisat and Cinema matrices), red is not properly red anymore; will have to play with the settings and try to correct this.

Also, in tungsten light the corners indeed get greenish tint at fully wide.

All in all, the colours on my V1E looked much better, and without any filtering or the myriad of tweaks needed - this IR problem is something Sony should definitely be made to admit, and treat as a serious flaw on the EX1!

Edit: You can see the clothes looking right with the 486, but the greenish tint also visible (at the furniture, in the corners of the right image). Of course, both pictures are not otherwise identical in their parameters as they were not taken the same day; the WB was not re-adjusted to compensate, etc. - but the tendency is obvious and I picked them on purpose, to show how the filter improves black and deep blue, but introduces other problems instead.

[Leonard Levy]

Could someone post pics of the greenish cast. How bad is it?

This is disturbing to me. i was about to buy a 486 but am worried now.
i talked t a Tiffen rep at NAB about this and he should me new IR filters that were quite expensive (hadn't come up with a price necc yet.) and were made with a very elaborate process.


Lenny

[Piotr Wozniacki]

Lenny,

See my grabs in the previous message.

[Peter Brugman]

Piotr, my 486 filter has threads on both sides, (I believe the slim version has only a thread on one side).
So I screw the filter on the cameralens and then the LEX onto the filter.

[Dave Elston]

Hi Piotr,

Those two grabs are very telling. I have just re-read Adam Wilts' very informative shoot-out (albeit rushed and 'unfair', by his own admission) between an EX1, RED One and F23 - as has already been mentioned he notices the very same IR-heavy color response exhibited by the EX1 (and to a lesser extent the F23)

I hesitate to post grabs linked directly from his article but the effect appears so obviously that I think its noteworthy enough to justify this quote...

"Aside from the progression in shallowness of depth of field, what’s striking is the difference in colorimetry. Both Sonys show Tim’s black shirt as a reddish-purple... "
(from page 5 of his article which can be found here: http://www.provideocoalition.com/ind...s_ex1_f23_red/ )

Hopefully Sony are taking note and will act sooner rather than later. I would also suggest that you pester you're supplier for _atleast_ a reply from Sony on this issue.

Thanks,
Dave.

[Sean Donnelly]

I can now say definitively that the Tiffen Hot Mirror is not strong enough. I picked one up to hold me over until a 486 slim arrives, and it barely has any effect at all.

[Leonard Levy]

Thanks Sean, That's very useful info.

[Piotr Wozniacki]

Originally Posted by Peter Brugman

Piotr, my 486 filter has threads on both sides, (I believe the slim version has only a thread on one side).
So I screw the filter on the cameralens and then the LEX onto the filter.

Thanks Peter; indeed mine is the slim version. Didn't know the double-threaded is available. Two questions though:

- does yours still fit under the EX1 lens hood?
- when using it with Letus on, don't you see any contamination from the reflected IR bouncing between the filter and the achromat?