What I learned today getting my Scarlet and lenses checked by a lens tech.

[Mike P.]

The back focus setting is probably correct leaving Red and even when you first get your camera. The issue is more likely to be your lens IMHO. Even with the back focus out you should be able to get sharp focus, just the focus marks will not read correct distance on a prime lens. On a zoom focus will be off as you zoom through the range, but you can still set it correctly for whatever distance you are shooting at. Having you back focus set correctly for your lenses does make shooting much simpler.

Yeah, I know, but I'm guessing that these guys are setting focus by eye and not lens marks. In Brandon's case, he's using older glass that apparently needed tuning (along with backfocus adjust) However, Brian's lenses (and another couple of people with Canon mounts) are tack sharp on his DLSRs, leading to the conclusion that it's not the lenses. I mean, sure the DLSRs usually have sharpening applied, but people are adding sharpening to their r3ds in post and it's still looking "out of focus."

Actually, that reminds me: Hey Brian, is your Canon camera's sharpness set to 0/off/lowest? Realistically, that's what you should be comparing your .r3d stills to (as little sharpening as possible).

 

[Brian Iannone]

Actually, that reminds me: Hey Brian, is your Canon camera's sharpness set to 0/off/lowest? Realistically, that's what you should be comparing your .r3d stills too (as little sharpening as possible).

I'll pull out the 7D and try that right now.

 

[Brian Iannone]

I just shot the chart with a 7D.


Canon 7D + Canon 24-70mm f/2.8L

TIFF (34MB): http://www.brianiannone.com/scratch...enses_checked_by_a_lens_tech/7d_20_70mm_1.tif


Scarlet + Canon 24-70mm f/2.8L

TIFF (18MB): http://www.brianiannone.com/scratch...checked_by_a_lens_tech/sharpness_sample_2.tif

 

[Mike P.]

I mean, it could just be contrast because the 7D's is brighter, but the 7D shot looks sharper to me (although 7D is 18mp compared to 14mp of the MX sensor)... Would there be any other reason why the same lens is sharp on the 7D but then not as sharp on the SX other than a.) in-cam sharpening (which is as low as it can be on the 7D) or b.) back focus?

Bri, how do the raws compare? Were the settings the same (shutter, ISO, fstop)? OH, and are the markings off (that'd obviously be a dead give-away that it's backfocus)?

 

[Matt Ryan]

It's gotta be back focus because the 7D shot is sharper. Are your lens markings lining up with the distance your shooting on both when they are as sharp as you can get them?

 

[Les Dittert]

If f/5.6 etc looks the same, then it's probably not the lens. At the smaller apertures the DOF is greater both in front and behind the lens.
You might try racking focus a little on the Red to make 100% sure you are picking the best focus.

I'm getting a funny sense of dejavu here ...

Modern lenses can fairly easily surpass the 80 lp/mm to get sharp images on that sensor. Pixel on/ pixel off type resolution.
I would post the CR2 raw from the canon, it's smaller and has more info in it as well.

I've tried f/5.6, f/11 and f/23, but they all produce the same soft image. I'm going to take a the 24-70mm and put it back on a Canon 7D to see if I'm still getting soft images from that. I don't recall if in the past, my photos were this soft though...

 

[Uli Plank]

It's hard to compare shots with different lighting and contrast for sharpness, our eyes are fooled easily. But I think I see just a little less sharpness with the Scarlet – which is normal!

You have a few less megapixels, plus RED is filtering aliasing more conservatively. That is a good thing to do, since aliasing can be more distracting in motion (panning in particular). Try a Sony FS100 or F3 and you know what I mean…

The next thing to consider while others try to compare their lenses are quality differences in single samples of the same lens. This is also one of the reasons why mass produced glass is cheaper than cine glass. Have a look at the commercials from Cooke or Zeiss, and you'll se a lot of manual work by highly skilled technicians invested! If you go the Canon route, you will have to take into consideration that you may just have a lemon. This makes it very hard to check your back focus, since you can never be sure if your lens is off or the mount. If you adjust back focus for one (preferably a wide one) according to the procedures in the manual, it may still be wrong for another one!

We bought quite a bit of photographic vintage glass for our universities cameras and we had to sort out a few lemons from identical primes.

I also had a set of second-hand Arri/Zeiss lenses I bought long before my first R1 checked on an optical bank by a specialist to make sure they were OK before even trying a back focus on the camera (which was tricky on the R1). If you have nothing but Canons, you'll need to compare and double-check as much as possible to get things right – tolerances are very tight with the resolution of modern cameras.

What you save on the lenses is partially going into labour…

 

[Brian Iannone]

Okay, here are two untouched raw images that I just shot; same settings, Canon 24-70mm f/2.8L lens.

Scarlet R3D (2MB): http://www.brianiannone.com/scratch...s_tech/red_scarlet_x,_canon_24_70mm_f2.8l.zip
Canon 7D CR2 (29MB): http://www.brianiannone.com/scratch..._a_lens_tech/canon_7d_canon_24_70mm_f2.8l.zip

Scarlet Settings: ISO 800, 1/48th second, f/5.6
Canon 7D Settings: ISO 800, 1/50 second, f/5.6, Sharpness: 0, Contrast: 0, Saturation: 0 (Picture Profile settins)

Also, it appears that the lens markings are off with the actual focus when I use the 24-70 with the Scarlet.

 

[Matt Ryan]

Also, it appears that the lens markings are off with the actual focus when I use the 24-70 with the Scarlet.

Hmmm, that would lead me to believe if the marking were correct when on the 7D that the backfocus on the Scarlet is off.

 

[Brandon J.F.]

if i'm not mistaken you should be able to get a sharp picture even if your back focus is out by using the 'punch in button' to get focus, correct?

No, not necessarily. It depends on the shot. For wide landscape type shots I could never get the shot sharp no matter how I adjusted the focus. Now, after fixing the backfocus, I can.

In Brandon's case, he's using older glass that apparently needed tuning (along with backfocus adjust)...

Yes, that's true, but I want to make sure it's clear to everyone that the backfocus was a problem with the Arri and Vantage lenses as well.

Also, it appears that the lens markings are off with the actual focus when I use the 24-70 with the Scarlet.

After seeing your statement above and the photos you posted I'm pretty much 100% sure your problems are due to the backfocus being off.

 

[Matt Ryan]

After seeing your statement above and the photos you posted I'm pretty much 100% sure your problems are due to the backfocus being off.

I would have to concur, putting the 2 images side by side at 100% with levels and contrast matching the 7D shot is sharper no doubt.

 

[sam karr]

I'm totally ignorant about back focus and some other things. Is back focus off only affecting focus marks? Some people are telling that it should be sharp doing a rack focus even with back focus off. Is it true?
I watched the plant R3D. it's a bit soft but not softer (even less) than dozens of R3D i've downloaded here from different users. Is it not just what red is about? On my 5D, even with sharpness off, it seems my image sharpness is still a bit processed in the camera.
I'm asking because i noticed some slight softness in my scarlet too. With a tamron 17-50 it's sharp at 2 ft, but soft at 7-8 ft. Even when doing a rack focus at 1/200, on a tripod. So I'm wondering if it's an optical illusion, the close shot that seems sharp is maybe as soft as the telephoto one but the object being bigger in the frame it appears sharp. Or a camera issue but then, if rack focusing should show sharpness at a moment even with back focus off, I can exclude that. A lens problem. Or everything is ok and it's just how it works and how it looks.

 

[Ulf Krentz]

While this particular lens may be soft don´t step it down too much as it will add a significant amount of diffraction. I would expect the best results around f5,6. The sensor of the 5D is much bigger in size, so you cannot really compare.

Cheers, Ulf

 

[Matt Ryan]

While this particular lens may be soft don´t step it down too much as it will add a significant amount of diffraction. I would expect the best results around f5,6. The sensor of the 5D is much bigger in size, so you cannot really compare.

Cheers, Ulf

He shot with a 7D which has the same sensor size basically just more mp's. He also shot his test at f5,6.

Okay, here are two untouched raw images that I just shot; same settings, Canon 24-70mm f/2.8L lens.

Scarlet R3D (2MB): http://www.brianiannone.com/scratch...s_tech/red_scarlet_x,_canon_24_70mm_f2.8l.zip
Canon 7D CR2 (29MB): http://www.brianiannone.com/scratch..._a_lens_tech/canon_7d_canon_24_70mm_f2.8l.zip

Scarlet Settings: ISO 800, 1/48th second, f/5.6
Canon 7D Settings: ISO 800, 1/50 second, f/5.6, Sharpness: 0, Contrast: 0, Saturation: 0 (Picture Profile settins)

Also, it appears that the lens markings are off with the actual focus when I use the 24-70 with the Scarlet.

 

[Matthew Scott]

Unless you're focusing at infinity, then like people have said several times in this post, back-focus is not an issue when trying to obtain a sharp, in focus image - only if you are going by lens markings is it a problem, or focusing at infinity right? Can we please rule out that with Brian's shot, it IS NOT a back focus issue? Because this thread will surely freak out a whole lot of scarlet owners/potential owners, for no reason.

 

[Matt Ryan]

I'm totally ignorant about back focus and some other things. Is back focus off only affecting focus marks? Some people are telling that it should be sharp doing a rack focus even with back focus off. Is it true?
I watched the plant R3D. it's a bit soft but not softer (even less) than dozens of R3D i've downloaded here from different users. Is it not just what red is about? On my 5D, even with sharpness off, it seems my image sharpness is still a bit processed in the camera.
I'm asking because i noticed some slight sharpness in my scarlet too. With a tamron 17-50 it's sharp at 2 ft, but soft at 7-8 ft. Even when doing a rack focus at 1/200, on a tripod. So I'm wondering if it's an optical illusion, the close shot that seems sharp is maybe as soft as the telephoto one but the object being bigger in the frame it appears sharp. Or a camera issue but then, if rack focusing should show sharpness at a moment even with back focus off, I can exclude that. A lens problem. Or everything is ok and it's just how it works and how it looks.

Every lens will be slightly different. Ive had backfocus off where one lens would be off mark wise but sharp at some points. On the other hand I've had lenses when back focus was off that wouldn't get sharp at all. Ive also had a couple situations where backfocus was set correctly, and the lens markings were off. So it just depends...

The Scarlet's image will appear a bit soft but you will still be able to tell what is in focus. I don't sharpen anything I shoot if you want to check it out: matthayslett.com My homepage has some 4k Tiff's with no sharpness (It will autofit your screen so it will appear a bit sharper)( Please keep in mind these are shot at 24fps at 1/48th shutter which will have motion blur with movement). If you add contrast and a bit of sharpening to your Red footage you will see everything "pop" and be sharp. The problem here is the image is slightly out of focus, not just soft. You aren't able to sharpen or add contrast to fix an out of focus image.

It's hard to determine what the issue is without being there in person. Without a second camera running the identical tests with the same settings and a set of several lenses to test focus on. So as of now it's anyone's guess. (We can only go off the images and information given).

 

[Ulf Krentz]

He shot with a 7D which has the same sensor size basically just more mp's. He also shot his test at f5,6.

I was referring to Sams post above, I did read the 7D and 5.6, thanks. Nevertheless it might be helpful to keep diffraction in mind, especially the these "small" sensors (i´m coming from a still photography full frame MF background)

Cheers, Ulf

 

[scott william]

I wouldn't have thought still lenses such as the canon in question or a nikon lens would hold focus throughout the zoom anyway. When i was using nikon glass on the Red One it didn't. Then again i could always get it sharp using the 1:1 focus assist.

 

[Brian Iannone]

I must say, this is a very interesting discussion and I really thank you all very much for your help. Personally, I believe that my issue is a combination of incorrectly set back focus and lack of sharpness in the Canon 24-70mm f/2.8L lens.

In order for me to find out exactly what the issue is, I will be dropping off my Scarlet at RED in Irvine for an evaluation. I will then have an definitive answer to this back focus mystery. While not a perfect lens, I will also be renting a Zeiss 25mm CP.2 to in order to perform a few additional tests with my Scarlet and Ti Canon Mount once RED checks and/or corrects the back focus issue (if there is one).

I'm getting a funny sense of dejavu here ...

Hehehe...


After this entire lack of sharpness incident, I would absolutely love to know how, even with an RPP, an image like this can be produced from an EPIC. ;-)

 

[Uli Plank]

Some photographic zooms are parfocal when the back focus is right, but most are not.