Varicam focus issue, help needed!

[Dave Mac]

Just to be clear, we have a DP, I have no experience with a varicam. I’m just trying to help. Also, what could be causing the focus issues? Thanks again,
Dave

[Chris Bell]

HD focus is tough. It is either right on, or not. The main issue with HD is backfocus. Be sure to check everyday as temperature changes can effect backfocus. Other issues could be the projector you are viewing. It is HD? Do you have good footage from the Varicam to compare? Does the footage look sharp on a production monitor?

Other issue could be detail settings. This is subjective, but it is detail turned off? This could render a softer look to the footage.

Chris Bell

[Dale Mccready]

Is the lens good quality? Hopefully. If it is a set of prime lenses such as the zeiss primes then it costs very little extra time on set to adjust the back focus every time the lenses are changed. it’s hard to pick when it is out on set from the monitors and is critical to a good resolution of the image. A little time spent ensuring the back focus is correct saves a lot of heartbreak later. As posted above detail settings in the camera have a good range, so it is possible in an effort to soften the image a little to lose all sharpness if done overtly.

[John Sharaf]

Dale,

I beg to differ with you on both points you make:

Backfocusing the prime lenses has very little to do withg the lens’ actal sharpness, except at infinity which is rarely used; as long as the focus is determined through the lens by the operator. If not backfocused and focused by an assistant reading a measuring tape that’s a different story. The bottom line is that backfocusing prime lenses is a method to assure that the focus markings match the actual measurement, if there’s no camera assistant it’s a mute point.

Secondly, regarding the detail; unlike a conventional SD camera where the picture will definately look out of focus if the detail is turned way down or off, with the Varicam the detail setting is very subtle and normally is turned way down (-19 to -26) in an effort to minimize artificial enhancement (which is what detail really is, and noise)and the picture is still very sharp. In fact Panasonic has added a “High Detail” feature in the new “H” model for the folks who wanted an over-enhanced tv look and couldn’t get it in the range of the “F” models detail scale.

If you have out-of-focus pictures with a zoom lens, then it’s undoubtably a matter of back focus; if the back focus is correct, then it’s a case of operator error. You should be able to tell if the backfocus is to blame if there’s a recording of the operator focusing at the long end of the zoom and then widening out to a soft picture.

JS

[John Sharaf]

One last point, I presume you’re usinh HD lenses; if you’re trying to use SD lenses, even broadcast types, you are definately short changing the image making capability of the Varicam. Resulting softness would definately show up on large projections!

JS

[Dave Mac]

Thanks for the great replies. The day is going better. I’ll get this info to the crew. We are using HD lenses (great ones $$$, good monitor, the projector is not HD. We are going to take another good look tonight. Thanks again, I’ll report back.
Dave

[John Sharaf]

Dave,

If you’re watching on a SD projector, then all bets are off. Somewhere in the chain (presumably in the 1200A VRT you’re using for playback) you’re downconverting in a less than ideal way and the projector cannot do justice to the HD photography created in the Varicam. Do youself and everyone else a favor and get an HD capable projector and a towel to wipe the droul off your face as view the spectacular pictures!

JS

[Dave Mac]

John,
We went to a high-end home theater store (Comtech). One way to see your stuff on an HD projecter. They had a state of the art theater set-up as show piece. They let us camp out for a couple hours, for free. Your right, the images were incredible. Almost too good. The stuff we are shooting today looks amazing on the HD reference monitor. We did some close ups, you could see the guy’s contact lenses, plus some wild nose hairs. Comtech said they could get a good HD projector by Runco for $3,500.00. Does this sound right? We may stick to the reference monitor and use the projector we have to check out how it looks blown up. I’m sure we will head back to Comtech several more times and use the HD projector.
Dave

[Dale Mccready]

Oops, yes thank you for correcting me, my problem previously with back-focus was a zoom lens. But I have tested the Varicam and did feel that on low detail settings the image got smoothed out a bit too much for me and lost some “pop” but this is a personal opinion only.

So the back focus on primes is really just to calibrate the focus measurements? Thats a new tip for me, thanks.