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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Low ISOs on RED MX

D

Drew Dawson

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Hey Guys,

So I am up to DP my first short on RED next month. I am very familiar with the camera and its capabilities (I have OP'd and AC'd with the camera many many times), but what I am not 100% confident of is its capabilities with low ISO's (ie ISO 100).

I believe that we have no filters for the shoot and the script calls for a shot outdoors. I was thinking about dropping the ISO to gain back some depth of field for the shot, but I have never worked with the camera at anything lower than 320.

How bad is the noise? Is there even any noise with this new sensor?

Any insight would be a great help. Thanks guys!

-Drew
:cheers2:
 
Iso is metadata. Although dropping the Iso will darken the monitor image, it does not make the camera less sensitive. Without ND filters or stopping the iris down, your outdoor highlights will almost certainly be clipped.

Noise will not be an issue outdoors unless you grossly underexpose.
 
I think the MX gets pretty weird looking when you over expose it, which is what you are doing shooting at low iso. I don't like to shoot below 500. It just gets too crunchy and clipy.

Nick
 
Thanks for the comments guys. I forgot about the ISO being metadata. It makes sense that the highlights would clip faster because of that. I will try working around ISO 500 and maybe adding a little shutter. The portion of the film may only be 3 shots, but it is the end of the film so I want to make sure it looks right.

We are shooting with nikon primes. Maybe an easy solution is to use thread on photography nd and circular polas? Although then I would have to also get some IR cut...
 
All you're doing when you adjust the ISO, is using a different code value for mid grey. That means higher ISOs have more highlight protection, lower ISOs more shadow protection. ISO800 is a good mid-point between the two extremes.

Graeme
 
Why don't you rent some NDs? They're usually around $10/day/filter. If it's the end of the movie it should look good, and to look good, you should do it right. Just my $0.02.
 
ND filters should be considered a basic necessity for a camera package, just like lenses and batteries, or a tripod. It's silly to not carry some unless you are absolutely sure you are never going to shoot outside in the daytime. At least with film, you could switch to 50 ASA daylight stock, but even then, I'd want to carry some ND's with me, so definitely when using modern digital cameras that are in the 400 to 800 ASA sensitivity range.
 
I understand the necessity of a good selection of ND, I am just not sure if I will get it since we don't have a matte box. So adding a matte box and filters to the package might be too much for the budget. I was trying to see if there might be a short cut here with cheating the ISO, but I guess I will have to fight for it in the budget.

Thanks for the input guys... It has helped me in the process!
 
Screw on .9, .6, .3 ND filters are your best bet for a cheap solution using Nikon lenses. If you can only have one choose the .6 ND. Don't worry about the IR with MX and a max ND of .9 . From what I understand you don't need to worry about IR pollution until you stack 1.2 ND or more. Please correct me if I'm wrong guys. I don't want to give anyone bad info.

There is also this really awesome screw on variable ND filter that is essentially just two polarizers stack on top of each other. Works awesome on a 5D, but I've never tried it with Red. Its called the Fader ND mk II. Good luck Drew.
 
Yea... A fader ND is a great idea! And I have heard that you need an IR cut for anything over a ND .6

Most guys I have worked with just throw it on 100 percent of the time...
 
Drew Dawson said:
Yea... A fader ND is a great idea! And I have heard that you need an IR cut for anything over a ND .6

Most guys I have worked with just throw it on 100 percent of the time...
Click to expand...

MX is reported to be better than M - usually ok unless going to ND1.2 or denser. But there may still be occasions where IR in a scene is higher than usual and you will need an IR cut filter at lower densities of ND.
 
Sunny

Sunny

The rule of thumb for shooting outdoors is,

With shuter time (inverse) equal to the ISO you get,

T/16 bright sun on sand or snow

T11 bright sun mid-day

T/5.6 open shade

T1.4 to T/2.8 shade

Since you cannot shoot smaller than f/11 for a 4K image, and you need to shoot 180, 172.8, or 144 degrees on the shutter all the time to avoid rolling shutter and other motion artifacts at 24fps, your exposure is about 1/50 sec,

so you effective need about ISO 25 to shoot at f/11 in mid-day sun light.

Since the camera is best around ISO 800 Daylight balance, you can ONLY shoot using ND filters and an IR filter to make up for the ND IR pass (unless you use mirrored NDs).

For high contrast subject in Daylight you would want to go down an extra stop and use temporal noise reduction on the shot, so you would set the camera to ISO 1600 and use ND filters to reduce that to ISO 25 on your light meter.

Its a lot of ND, but you need to have enough head room above mid-tone to deal with the subject contrast ratio above 90% white on the subject. And it depends on how you take your light readings as well, since a subject that is in part back light brings up the issue of how to adjust the ISO vs. the lighting...

In general you want to use higher ISO in bright high contrast light, and lower ISO under flat indoor light with a lower contrast ratio, yes it is backwards from what you would do with film. So you need a pile of ND plus a POLA to control the specular highlights when shooting outdoors under high contrast lighting with any sensor camera that will otherwise hard clip.
 
I would adamantly fight for NDs - not just because you absolutely need them but because they cost nothing to rent and there may be a shot where you want to specifically control the DOF.....fight for them!
 
As to what Dan seays, he is right, and you'll need the same ND's at 320 as you'll need at 1280 with the same T stop/shutter . The ISO setting does not alter at which lightlevel the chip clips.

The reason for shooting higher ISO is to have some more highlightprotection that can be reclaimed in post.

Get those ND's. If you are DP'ing something, you really need them...

Cheers!

G
 
Drew, as someone who shoots Nikons on RED all the time, your easiest, cheapest solution is to get some screw-in filters. It's not the most glamorous approach (a mattebox certainly looks more professional on the camera) but at this point without filters you will be seriously compromising your images. As for controlling flares, you can come up with some DIY solutions for that. Here's what you need in your kit at a minimum.

- ND 3,6,9
- Pola
- IR filter

I would also say if you can manage to get a hold of them, the following might help you even further.

- ND grads
- IRND 1.2, 1.5, 1.8, 2.1

Without filters, there's a good chance your images will start to take on a video feel. You need to be able to control things, especially outside where you may be dealing with some tough extremes.

Good luck and I hope production will sympathize with your situation and do the right thing.
 
No filters for the shoot? They're like $5/day to rent. Tell the producer he needs to sacrifice his morning trip to Starbucks in favor of a filter or two. Seriously, don't know what to say here.

MX does handle IR better. But IR and strong ND are not necessarily related. IR is what it is, different environments have different levels of IR. Certain objects reflect/radiate IR more than others. Lenses differ with how they transmit IR. If you can, shoot a test or two before you go blindly into this.

Generally speaking, in moderate outdoor IR situations, if there is such a thing, you don't need to concern yourself over IR pollution unless you're at ND 1.2 or greater on the MX. But I would still recommend having an IR hot mirror available (most are the equivalent to an ND .3 as well). Then another few NDs to go along with it. If you're stacking more than 6 stops or so worth of ND in front of your lens, be sure you're using truly neutral filters. Many ND's are not that neutral, especially if they are IR+ND combo filters. Don't stack IR+ND filters as you can get increased color casting and/or internal reflections.

IR is a funny thing and there's no magic ND amount at which IR pollution shows up. It's all relative to the amount of IR you may have in your shot. If there's strong IR emitters, such as sun-baked chunks of granite, molten metal, etc.. (extreme examples), you may find that IR pollution could show up with very slight ND or even no ND at all. It also depends on the lens. Smaller primes with fewer elements tend to transmit a lot more ND than larger zooms.
 
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