Soft Image

[Paul Harding]

Only had my Red 6 weeks and still testing before using it on a job.

I have been using a tokina 11 16, 18 200 nikon, 35 70 nikon. When using the the wide end of the lenses to get say a six person wide shot the images look soft

I have checked the back focus, when using each lens, and adjusted to suit and checked focus with the on board LCD monitor and a 32 inch LED monitor and I am sure I am in focus, is there anything with the camera processing that might cause this?

Thanks Paul

 

[John Marchant]

Probably just the complete lack of sharpening in camera I expect. How are you viewing the image to judge this? Do you have a still you can post?

 

[Johnny Friday]

Only had my Red 6 weeks and still testing before using it on a job.

I have been using a tokina 11 16, 18 200 nikon, 35 70 nikon. When using the the wide end of the lenses to get say a six person wide shot the images look soft

I have checked the back focus, when using each lens, and adjusted to suit and checked focus with the on board LCD monitor and a 32 inch LED monitor and I am sure I am in focus, is there anything with the camera processing that might cause this?

Thanks Paul

how are you viewing the images? are you viewing in Redcine-x? Then, what debayer settings do you have set? 1/4, 1/2, full?? this makes a HUGE difference AND will affect how soft the images look.
More info.....from how you are viewing, what software etc.....

 

[Paul Harding]

Using redcine X and full debayer to QT 1080, Viewing on a 17 inch broadcast monitor which is showing signs of use, also viewing through a Pioneer 50 inch and a new Samsung LED 32 inch both these displays produce good images.
Will post stills tomorrow, I have also done a camera reset and was thinking of black shading, my tests are done in a studio which I can control lighting etc.

Paul

 

[Greg M]

I have checked the back focus, when using each lens, and adjusted to suit and checked focus with the on board LCD monitor and a 32 inch LED monitor and I am sure I am in focus, is there anything with the camera processing that might cause this?

Thanks Paul

How exactly are you checking back focus?

 

[Johnny Friday]

Using redcine X and full debayer to QT 1080, Viewing on a 17 inch broadcast monitor which is showing signs of use, also viewing through a Pioneer 50 inch and a new Samsung LED 32 inch both these displays produce good images.
Will post stills tomorrow, I have also done a camera reset and was thinking of black shading, my tests are done in a studio which I can control lighting etc.

Paul

Well....sounds more like a back-focus issue in that case. I'd say reset everything. Blackshading, setup a chart run out your hdmi to your flatscreen and do a backfocus---make sure you use a proper lens....say 14mm - 18mm or so.....in that range. I'm sure you know how to do it.

 

[Paul Harding]

How exactly are you checking back focus?

Zoom in and focus, zoom out set red back focus on red until both ends of the lens are in focus, as I am not zooming on the test I will set the Tokina to 14mm and focus there and it looks pretty good, the problem seems on playback and after processing, I must be missing something

Paul

 

[Thomas Wright]

Where are you fella? You need a nice nice sharp wide you can trust to do your back focus. If you're in london I can probably help.

 

[Alan Piper]

Thomas is right; you must use either a known lens which you can trust, a collimator, or a proprietary focus checking device (NULL, FDC) to check and set your camera back focus.
Once set, it should not be moved again. Moving it to suit different lenses is not good working practice - different lenses should have a matched back focus.

 

[Johnny Friday]

Thomas is right; you must use either a known lens which you can trust, a collimator, or a proprietary focus checking device (NULL, FDC) to check and set your camera back focus.
Once set, it should not be moved again. Moving it to suit different lenses is not good working practice - different lenses should have a matched back focus.

That said.....if you are in focus (on screen/LCD/EVF) you are in focus....correct? Say you have set back focus and you change to another lens that is off only a slight millimeter or two.....you should be able to pull focus as long as you SEE it in focus....then it should be in focus.

 

[Alan Piper]

Indeed.
Correctly set Back Focus on the camera will ensure that a (correctly marked) lens will register an accurate focus scale.
Focus sharp on the screen and the final image should be sharp.

 

[Johnny Friday]

Indeed.
Correctly set Back Focus on the camera will ensure that a (correctly marked) lens will register an accurate focus scale.
Focus sharp on the screen and the final image should be sharp.

Right then....realize many need focus marks to match correctly. I NEVER do since I'm shooting wildlife. But realize that back focus is an issue and needs to be set and close (in my case).

But bottom line, if you see it in focus, then it should transcode in focus.

 

[Russ Campbell]

It's important to remember that most modern day stills zoom lenses don't hold focus throughout the zoom range, so zooming in and setting focus won't result in a sharp image once you zoom back out. I've tried all the newer nikons, sigmas and tokinas with pretty much the same results. Some of the older zoom lenses from nikon and canon, will hold throughout, but with modern day auto focus being so accurate, lens manufacturers aren't designing their lenses to hold focus. hope this helps.

 

[Charles Angus]

Pics or it didn't happen. (Joking)

But seriously, a couple 4k stills would help us diagnose the problem.

Cheers,
c./

 

[PaulClements]

Hi Paul,

Are you using the 1:1 zoom in on the camera? Usually assigned as magnify on one of the buttons on the side if memory serves correctly, number 2 I think.

If you are zooming in on a subject using a zoom lens, getting focus and zooming out again and it comes out soft then yes your back focus is still out.

Even with a backfocus problem it should still be possible to get some good results using the 1:1 especially for objects closer to the camera.

Paul

 

[Jeff Kilgroe]

I have checked the back focus, when using each lens, and adjusted to suit

Uh, oh...

Are you testing and adjusting for individual lenses?

Zoom in and focus, zoom out set red back focus on red until both ends of the lens are in focus, as I am not zooming on the test I will set the Tokina to 14mm and focus there and it looks pretty good, the problem seems on playback and after processing, I must be missing something[/quote

You're just asking for trouble there. As others have pointed out, you want a good wide lens you can trust. As wide as possible. Set focus to infinity and focus on something far away that you can identify sharp focus with -- sides of a building, mortar joints in a brick wall, etc.. Don't use a zoom.

I would recommend finding someone with a NULL lens/target or Optimator or some other device to check your mount. Best practice is to get your mount to be completely accurate, or as close as you can. And then check your lenses. Don't start setting back focus to accommodate lenses, you will never get focus to hold through an entire zoom range if both the back focus/FFD and lens collimation are off. Very few zooms, especially those designed for SLR cameras, will hold their focus through the zoom range. Even cine-style zooms can often have trouble and only some of the best lenses do this and they must be kept in tune.

 

[PaulClements]

Uh, oh...

Are you testing and adjusting for individual lenses?

You're just asking for trouble there. As others have pointed out, you want a good wide lens you can trust. As wide as possible. Set focus to infinity and focus on something far away that you can identify sharp focus with -- sides of a building, mortar joints in a brick wall, etc.. Don't use a zoom.

I would recommend finding someone with a NULL lens/target or Optimator or some other device to check your mount. Best practice is to get your mount to be completely accurate, or as close as you can. And then check your lenses. Don't start setting back focus to accommodate lenses, you will never get focus to hold through an entire zoom range if both the back focus/FFD and lens collimation are off. Very few zooms, especially those designed for SLR cameras, will hold their focus through the zoom range. Even cine-style zooms can often have trouble and only some of the best lenses do this and they must be kept in tune.

Sounds like he's using all still lenses though Jeff so a Null or Optimator would be useless unless they come in a Nikon mount now? It might be that your lenses aren't all collimated perfectly since they're stills lenses, some seem to suffer more than others. As long as the Tokina 11-16 is a good one and not a turkey then using infinity on that might help. Often I go for the long winded approach of testing with a zoom even on PL mount. If you get a zoom to have perfect focus at the long and short and it'll focus to infinity then you have a well collimated camera in my book (Just as long as it's a good lens though). I'd then check other lenses to make sure they are ok too.

I've never been a fan of the wide lens thing myself because when you check back footage of a tree branch 500 metres away it'll always appear slightly out on Red because of the lack of sharpening and OLPF so you can often start second guessing the collimation. You also find that some lenses focus beneath the inifinity mark and some are bang on the infinity mark. The point is that this way the camera is only collimated to one mark. Having a zoom collimated through it's entire length has generally given me the best results with the Red.

I haven't used the Null lens though so perhaps I'm being unfair. I've used the optimator however and wasn't entirely pleased with the results. At the end of the day whatever you get most use too and trust is the best way. There's no subsitute for sticking as many lenses as possible on to test!

Paul

 

[Denis Buhot]

still lenses then ?

still lenses then ?

It's important to remember that most modern day stills zoom lenses don't hold focus throughout the zoom range, so zooming in and setting focus won't result in a sharp image once you zoom back out. I've tried all the newer nikons, sigmas and tokinas with pretty much the same results.

Nothing to add... it seems like being the real issue here...

 

[Jeff Kilgroe]

Sounds like he's using all still lenses though Jeff so a Null or Optimator would be useless unless they come in a Nikon mount now?

The Optimator has interchangeable mounts. I'm also making the assumption that he has access to the full PL mount of his RED One. The RED and Optitek Nikon mounts are pretty consistent and accurate when installed onto a properly set RED One. Set the mount, then remove the PL portion and install the Nikon parts... Or use an Optimator with a Nikon mount on it.

The problem with testing multiple lenses, is you're all over the place and just because you may trust one lens over another, that doesn't guaranty it or any other are correct.

I've never been a fan of the wide lens thing myself because when you check back footage of a tree branch 500 metres away it'll always appear slightly out on Red because of the lack of sharpening and OLPF so you can often start second guessing the collimation.

I agree about the wide angle lens thing and also about the softness. There is a lot here that depends on experience with the camera or similar systems. Even when soft due to the nature of the sensor / OLPF, it's still not a problem to tell when something is in focus or not when you really know what to look for. It's hard to quantify or really explain it.

You also find that some lenses focus beneath the inifinity mark and some are bang on the infinity mark.

Yes... And with still lenses, the marks are pre-manufactured and uncalibrated. To properly use a lens for setting your back focus, you must know where infinity truly lies in relation to the marks. And finding what appears to be infinity focus, or any other specific distance focus point, on a lens with uncalibrated marks and a mount that is not properly set, is just kinda silly. But then again, I see people doing it all the time with the RED. Personally, I would never trust any SLR lens for setting my back focus. I won't trust most PL mounted cine lenses either. The NULL lens works great, it's a very short focal length with a narrow FOV and permanent infinity focus. It gets a lot of mixed reviews, but I think that comes back to two things; people are unsure of what to point it at and what to look for to verify focus. When setting the back focus on RED with a proper tool like the NULL, if you're doing it right, the image will seem to pop into focus when it's right.

The point is that this way the camera is only collimated to one mark. Having a zoom collimated through it's entire length has generally given me the best results with the Red.

Having a zoom collimated through its entire length has nothing to do with the back focus on a camera. I still maintain that if you're setting the mount on your camera to best accommodate a lens, especially a range of focal lengths on a zoom, you're just asking for trouble. It may give you the best perceivable results with your lens collection, but that doesn't make it right or the best possible. It's best to get the mount exactly right and then if your lenses don't work, get them serviced and properly collimated.

 

[Paul Harding]

Quite a lot of info there guys, thanks.

First let me try to be clear what I am doing.

I am not zooming, I am using a brand new Toikina 11-16 and a new Nikon 18-200 set to 18, I have measured the distance from a simple chart to the camera's film plane, set that distance on the lens and set back focus on the Red until sharp. Both these lenses have the same back focus setting on the Red. I am using the button to zoom for focus.

If you had a choice to shoot a scene that you need to frame people with a frame width of say 16 ft, would you prefer use a wide angle, or space providing use a longer focal length and move back.

Thanks Paul