Scarlet sharpness workflow question

[Matt Ryan]

Thanks everyone for the comments and suggestions so far!

I'm sorry I haven't been able to respond the last few days. I've been out on shoots and tomorrow I'm off for a week long shoot outside the country.

But as soon as I get back I'm supposed to get together and test with another Scarlet user.

Hopefully the PL mount will be here by then, but even if it isn't I'll place the same lens on both scarlets and post the results. I'll also make sure to have a test chart in frame as well.

Your not alone in getting soft images from the Canon mount:
http://www.reduser.net/forum/showthr...by-a-lens-tech

It should be fixed by adjusting flange depth on the adjustment screw on top of the camera. Same procedure as adjusting the pl mount because it's adjusting the position of the sensor, not the mount.

[Craig Wright]

Thanks everyone for your contribution. It is certainly beneficial to read through such discussion.

Miles it would be very helpful to give the results of your adjustments when done - it would certainly give a final perspective to much of the thought shared.


I have been considering the apparent issue of 'back focus' and a few thoughts have come to mind. I may be way off the mark. I would be interested in getting some opinion on the validity of this.

The broadcast camera world is no stranger to back focus. Indeed each time a new lens is attached the back focus is carefully checked. My understanding of its function is to calibrate the position of the 'rear focus element' on the lens to the position of the camera sensor - ensuring correct hardware setup to enable sharp focus. RED (and possibly others?) introduces a paradigm shift. Instead of adjusting the 'position' of the rear lens element, it is the sensor position that is adjusted. Both achieve the same result but from different perspectives. If this is right, the implications are interesting.

Simplistically it would suggest that each time a different lens is placed on the camera a back focus check should be performed. This in its self indicates there is a possibility of a different setting for each lens. Looking a bit deeper this is not necessarily as bad as it seems. RED have the back focus adjustment tool which suggests that all RED lenses are calibrated identically - and once set there is only a need to fine tune periodically. Also being PL glass and of higher quality, it is what you would expect. Further I am assuming most cine glass, also being of high quality will be OK with the RED tool calibration. However, it is the still glass that raises the interesting question. Given the understood, sometimes significant variation in QC, as well as the variety of manufacturers, and given the ability of the RED to expose the weakness of 'average' quality lenses, does it not stand to reason that to ensure the sharpest picture possible from each lens one would need to check the back focus of each lens - potentially resulting in a different setting for each? (It is possible that any differences may be so small so as to be essentially un-noticeable or unnecessary to adjust - however this could only be determined by the user AFTER each lens had been individually checked) I guess what I'm saying is that the back focus check is not so much a necessity for the camera as such but rather for the lens - and will be determined by the number/variety of lenses used . . . .

[Jacek Zakowicz]

Craig the broadcast tech and motion picture tech for BF are completely different worlds. They have very little in common- and for a good reason.
In the MP world typically both lenses and camera are set in prep and left alone for the duration of the job. It applies to all lenses and cameras. That may change but as of now it stands. We make tools to check lenses and cameras but skill is still needed to do it correctly. And that's the biggest hurdle right now IMO- educating users how to perform tasks traditionally left for techs in labs.
Good luck with that!!!!

[Craig Wright]

In the MP world typically both lenses and camera are set in prep and left alone for the duration of the job.

I imagine you're suggesting A lens being matched with A camera and left for the duration of the job. Therefore there are real implications for changing lenses mid shoot, or for that matter between shoots on the basis that 'I had back focus checked recently so all should be well'. To ensure the 'sharpest possible image', back focus should be checked at least every time a lens is changed? And depending on the lens/quality the adjustment may be non existent to significant?

Thanks in advance for your input. This is a new concept for me and one that appears crucial to the ability to capture sharp images.

[Jacek Zakowicz]

I imagine you're suggesting A lens being matched with A camera and left for the duration of the job. Therefore there are real implications for changing lenses mid shoot, or for that matter between shoots on the basis that 'I had back focus checked recently so all should be well'. To ensure the 'sharpest possible image', back focus should be checked at least every time a lens is changed? And depending on the lens/quality the adjustment may be non existent to significant?

Thanks in advance for your input. This is a new concept for me and one that appears crucial to the ability to capture sharp images.

No they are not matched. They all are set to baseline standard so they are truly interchangeable. They typically last the whole job and when they return they are inspected and corrected so they are ready for the next job. This discipline is not maintained in the owner/operator realm for various reasons and hence the issues..

[Craig Wright]

Thanks Jacek. Appreciate your help.

[Jesper Sichlau]

Thanks everyone for the comments and suggestions so far!

I'm sorry I haven't been able to respond the last few days. I've been out on shoots and tomorrow I'm off for a week long shoot outside the country.

But as soon as I get back I'm supposed to get together and test with another Scarlet user.

Hopefully the PL mount will be here by then, but even if it isn't I'll place the same lens on both scarlets and post the results. I'll also make sure to have a test chart in frame as well.

Have you cheched your camera yet? I'm beginning to wonder if my camera has the same issue.