I call Hot Rod Cameras Bluff with a $10,000 Bet (for Sharpest PL RF for Komodo)

[Nick Gardner]

It is my understanding that the difference between compensating for back focus discrepancy with the focus ring and having the back focus dead on is seen in focus falloff characteristics.

95% of lenses are literally just moving the whole lens cell back and forth to focus. Look at a view camera. Exact same thing. Unless you have floating elements, or other exotic techniques for minimizing breathing, there is absolutely no difference in focusing the lens by the ring, or by shimming it out from the mount.

Nick

 

[John Brawley]

I will completely amazed and blown away if someone can demonstrably show that there’s a different visual outcome for a typical cinema lens that isn’t quite shimmed right but can still be focussed at a given distance, and one that is shimmed correctly and focussed correctly for the same distance.

A few thousands isn’t going to be noticeable in focus fall off or dof.

JB

 

[kylebainter]

It's 2021, I'm frikkin' tired of marketing hype and lots of words. I spent a lot of the last decade reading too much Reduser and believing a bunch of hype about RED vs Arri because I believed marketing BS and quasi facts and didn't have the money and time to test enough myself. Now I have the resources, I'm not spending another decade doing that. Let's see some proper tests and proof, right?

Bruce Allen
www.bruceallen.tv

^this!

 

[Christopher A. Bell]

^this!

Some days it almost feels like this, doesn't it...?

 

[Phil Holland]

Phil said

I'm 7,000km from home right now filming.

The short and simple version of this thread is:

- Calibration to spec is important, whether you do it or it's out of the box. For any lens. More-so for zooms and anamorphic obviously.
- It's useful to have a mount adapter closer to spec.

I need to reread some of the pages, but that's about it.

If I need to illustrate why this is important I can, but it's fairly common knowledge.

There's been some lofty back and forth, but reread and it's merely about making mounts that are calibrated to specific cameras to spec and there are variables at play that allow for that to be a "good feature". Every camera to date is different when it comes to lens adapters.

The hype and fire came from the pissing competition between two companies, that's between them.

For me, the only thing I can say and care to make a point of is back focus is critical if you want to achieve the best performance out of your lenses. Only point I'm making. No hype.

 

[Robert Hofmeyr]

For me, the only thing I can say and care to make a point of is back focus is critical if you want to achieve the best performance out of your lenses. Only point I'm making. No hype.

I'm happy this thread was revived, because I learned a lot from it, but I do wish we could agree on something at the end. The debate at this stage seems to come down to whether back focus affects sharpness on spherical lenses. Phil, I think you believe it does, as do others on this thread whose opinions I also value.

A while back in response to Jacek saying back focus had no effect, you said:

Looks like I need to post some examples. "as far as film makers are concerned", most interesting statement that made me actually angry today.

Be back in a few days when I'm done shooting I guess.

Do you (or anyone else in the "imperfect back focus compromises image quality" camp) have any examples they could share?

 

[Phil Holland]

Do you (or anyone else in the "imperfect back focus compromises image quality" camp) have any examples they could share?

18mm Master Prime should be able to show you exactly what's going on.

I think a 180mm Leica-R for that matter as well.

I'll be in New Mexico for 60 days after this shoot onto the next. Haven't had much free time this year. Been out of town for most of it.

 

[Robert Hofmeyr]

18mm Master Prime should be able to show you exactly what's going on.

I think a 180mm Leica-R for that matter as well.

I'll be in New Mexico for 60 days after this shoot onto the next. Haven't had much free time this year. Been out of town for most of it.

Okay, fair enough. I don't have either of those lenses. Anyone else up to doing this? I think it would be relatively simple if you have the tools.