Thread: Slimbob playing With Iris

Hi Guys

“Slimbob Playing With Iris”

What a great headline to get your attention …..if your sick minded like Midnight Blue
that is …hence his name.

No offense MB you know I love you

Anyway

It has been a hectic few weeks with work on weekdays and weekends so not had much chance to scratch my back never mind get studio stuff done.

However I did manage to get some quick iris tests done last weekend.

PLEASE EXCUSE THE GLARE (TOP RIGHT HAND CORNER) THAT WILL BE SORTED

I feel I am getting very close now to being happy with the look and am looking forward to starting to shoot my stuff!

However I would still like to test the below out of interest and curiosity:

• Try no diffusion in front of key and fill like David recommended.
• I want I try 1/100 shutter speed as Tim mentioned.
• Experiment throwing the background out of focus by putting ND filter in front of lens to allow me to open iris up more.

One thing I have noticed is in this test when the iris is open it is still not throwing the background out of focus. I read that the bigger the gain up value is the more the quality starts to deteriorate!!!

So might end up keeping back ground in focus. not sure.

I have saved up and stocked up on 275 photoflood bulbs (same brand) and back light bulbs so I have years of shooting ahead of me with standardised studio /lighting

One major bummer is the uplight bulbs I used are now obsolete!!!!!!
I have tried same bulbs different brand but different (ie) not as blue and look bad.

I am on this and once I find good bulbs I will stock up too so all is good for a few years.

Who knows by then I might have proper stuff!!!!

Anyway any feedback on what iris setting you prefer is massively appreciated.

Understand it will come down to me in the end to choose but it is always nice to hear other more experienced guys opinions.

Cheers everyone

I thought the halfway between F2.4 & F2.8 looked best or even the F2.8 but my personal taste is a little on the dark side.

The reason the curtain is still in focus when the iris is open is because you have to zoom right in to get a shallow depth of field with this sort of lens your camera has. This would mean you would have to get you camera further back which I know is not easy for you. Also if you do move the camera back and zoom in you may have to adjust the iris again as this will make things slightly darker.

Hope this helps Bob.

Originally Posted by Midnight Blue

I thought the halfway between F2.4 & F2.8 looked best or even the F2.8 but my personal taste is a little on the dark side.

The reason the curtain is still in focus when the iris is open is because you have to zoom right in to get a shallow depth of field with this sort of lens your camera has. This would mean you would have to get you camera further back which I know is not easy for you. Also if you do move the camera back and zoom in you may have to adjust the iris again as this will make things slightly darker.

Hope this helps Bob.

Thanks Dave.....big help!!!!!

I am off today hurray!!!!!

Please could you tell me if your choice is linked to just personal taste or is it also due to a technical error (ie) white shirt burning out (over exposed ) at open & 2 & 2.4 ???

I have watched the video through a few times and am starting to agree with your half way 2.4/2.8 / 2.8 choice
Comedy works well being bright I feel but not too bright to cause a technical problem like over exposure.

My goal with my studio/lighting etc Dave is to create a video that even if people disagree (ie) like it a bit darker or brighter it is technically o.k
compared to me creating something that people in the know would shout over exposed turn down the iris or it out of focus.
I appreciate peoples personal tastes will differ but if I create a well made video then I will feel a lot better and am covering all bases as best as I can .

So was your choice just personal taste or am I over exposed at the other iris settings???

Regarding throwing the background out of focus .

I have been busy watching videos with back ground in focus and out of focus.

And although I appreciate both are correct .... personally I am leaning towards in focus for my stuff .I understands Tim's point about it helping me separate myself from the curtain but I feel with being 4 feet away and using the back-lights and lighting the background curtain separately I am getting a good look without having to throw the background out off focus.

So to keep things easier I have decided to keep everything in focus now.

Getting there Dave

Thanks for your help



P.s - Sorry for saying you are sick minded ...... it takes one to know one !!!!

I don't think any of the settings get the ideal balance between your shirt and your face, but white shirts can be difficult, there is stuff you can do to direct the light to overcome this but I have a feeling your restricted by your equipment.

I also agree that the between F2.4 & F2.8 setting is the best compromise, what are you using to edit? I seem to remember sometime you mentioned Vegas, luckily there are plenty of vegas users that might be able to help with this, does it do secondary colour corrections?

I just pulled a secondary on your face with the section of video at that setting, just to brighten it up a little and get the balance back, here's a couple of screen shots:

By the way. Be careful, you have a lens flare at the top right corner of the screen.

originalby.jpg

primary.jpg

David.

[I feel I am about to demonstrate my huge ignorance of this subject]
I assume that most the time, folk set their focus on the subject. But, if the DOF is greater than the depth of the subject; then could the camera be focused on a point in front of the subject; thus keeping the subject in focus; but making the background more out of focus?
I saw a calculator here, Online Depth of Field Calculator ; but have no idea whether it is useful (as my cheap Flip type cams have fixed lens).

The classic focus point when there is a person in the scene is to have the eyes as the focus point. I know in photography they say about focusing 1/3rd way into a scene but I don't think that sort of thing is applicable in this case. The reason for my choice Bob, was seeing the balance between the shirt burning out and the darkness of the face ie after F2.8 the face is too dark. Before F2.4 the shirt has lost detail. So as David has said "compromise" which is often the case, especially when your working with equipment that is not ideal.


Having said that I think you have found a great look and providing the audio is good you will have technically a very nice video. Now all you have to do is be funny.

It's rare that all who comment agree, but I'm with the rest of you in terms of the exposure setting which works best (between F2.4 & F2. - assuming none of the other variables change (lighting, ND filter, shutter speed etc).

If you can't manage it, don't get too hung up about throwing the background out of focus. As you rightly say, you're already using other techniques to separate yourself - backlightng & a very neutral background. If you can't do anything with the focus though I'd be incluned to soften some of the lines in the curtain by repositioning the lights so they are not quite so side-on. It's good to be able to see the texture, but i'd say it's a little too contrasty at the moment.

I agree the face is a little dull in comparison to the white shirt. Whilst you could do this is post (as your face isn't moving much this would be quite easy) I wonder whether it would be feasible to put an additional light on your face (using barn doors or whatever to prevent that light spilling on to the shirt). It just gets more & more complex.

Not sure if you've got Secondary Colour Corrector in your version of Vegas, but there are several other tools you could play with (I'd work with levels & colour curves)

If I was you I'd stay away from colour/contrast correction if you can. A anything you do to alter the image in post will ultimately result in picture degradation. Plus it just gives you more of a learning curve to get over before you actually start filming. This sort of thing can be done later when you are more familiar with the software you're using. After all you've spent a load of time setting up your studio so you get things right in camera which is how it should be. Using a semi opaque flag could take the brightness off the shirt if you have the ability to position it correctly. BUT I feel we are getting to tide up with the technicalities of the image when the whole package should be considered.

Now that you have got this close to having things set up right, seeing you in action with audio is the only way to be able to really assess what needs to be done to tweak things on the technical side. Your movement may make all the difference to your set up.

Originally Posted by Midnight Blue

If I was you I'd stay away from colour/contrast correction if you can. A anything you do to alter the image in post will ultimately result in picture degradation.

Whilst I agree entirely that fixing it in the shot (I like the idea of semi opaque flags) preferable to fixing in post, as you've raised it - is the above necessarily true?

In this case we would only be adjusting mid tones, so turning, say RGB (35,130,187) into (45, 140, 197) isn't going to lose anything - unlike trying to increase all colours by 10 in say (35, 140, 250) where w'd lose some of the detail in the blue channel. I suppose this is where a secondary colour corrector comes into its own, in that you can lmit the chroma and lumionsity on which this would have effect.

Am I thinking along the right lines?

I think your best to get on with filming too, but keep in mind you need to do very little to get that secondary in or to adjust the light on your shirt. But there is no harm in returning to it later.

I'll address a couple of points incase you want to get back to it.

anything you do to alter the image in post will ultimately result in picture degradation.

Sorry about this midnight, that's a non comment it's just part of the grading process. In the ideal world everything would be set in camera and all the shots would come out as needed, but pretty much everything you watch on TV or cinema has had colour adjustments made to it, deliberately, and for good reason. The higher end cameras use codecs that have far more room for adjustment before any problems occur and the lower end not so much. With any camera the less light that is on a subject the greater the issue. Your clip has plenty of light and required very little in the way of adjustment, you have zero potential degradation issues.

I intentionally downloaded your clip to test this before posting to make sure I wasn't going to waist your time to find you just ruined your clips, if there were issues I'd have tested dropping the exposure on your shirt in the clips with a lower f-stop instead. It would have been a compromise as it wouldn't have no details in the creases but it never mattered anyway.

I raised the highlights a fraction, lowered the shadows even less then raised the mid tones even less again to spread the stretched section of the range back. I can highly recommend studying colour work in post, lighting and post colour work go hand in hand and the more you know of one the more you know of the other.

If you did want to look into that, or return to it, and don't have secondaries in your NLE you could probably still do it with 2 tracks of video and a feathered mask, it's all it was really.

Or if you want to try and get this in camera you could go the ND Filter route. You can put it in front of your light but only over the lower half, or in front of your lens in the same way. But the issues with getting the positioning right with what you have is why I asked if you could do it in post to allow you to get on to shooting your stuff and past your experiments.

David.

Here's a wee edit, I forgot to add this Bob. Where you read semi-transparent flag in these posts, change that to ND Filter and go from there.

David.