EX1, Letus Extreme Optimization kit, PL mount

[Stathis Athanasiou]

Hello,
I own a Canon XH-A1 and a Letus Extreme, using Nikon lenses for almost two years now and I am very happy with it.

I will be shooting a film, where I want to use a Sony EX-1, so I looked up at the Letus website and saw that there is an EX1/EX3 77mm thread ring, but there is also an EX1/EX3 optimization kit, that fixes some optical issues with the achromat.

I looked up in the forum but I couldn't find any information on what are these issues, so could someone please tell me in a few words what is the problem? Furthermore, my Letus Extreme was bought around Nov.2007, and there is a footnote saying that the opt.kit is not compatible with adapters purchased before Dec.2007 . I guess I cannot use it, right? If it is so, would I have a problem by just using the 77mm thread ring ?

Thanks for your time

[Stathis Athanasiou]

I forgot one thing, I want to use PL-mount 35mm lenses for this film. Is there any reason why I should stick with my Nikon primes? I am asking this, in case this optical problem, which I don't know what it is for the moment, is aggravated when using cine lenses (or not)

thanks again

[David W. Jones]

I won't comment on the achromat issues with your camera,
but I will say that most PL mount Cine glass covers a smaller area than your Nikon still camera glass, so you will have to zoom in further on the GG to fill the screen.
You might see some vignetting or portholing.

[Stathis Athanasiou]

thanks for the reply David,

so, what you say is that the Nikon lenses will function better in "real life" conditions than the PL-mount lenses? Is that correct?

Anyone else want to comment on that? The reason I am thinking about PL-mount lenses is for the superior image quality. If using the adapter cancels out the benefits of using a 35mm cine lens, I would like to know it beforehand, because I will not rent the PL-lens set and stick with my Nikon primes.

[Bob Hart]

The EX1 inbuilt lens and EX3 standard lens have a characteristic which causes soft corners when normal achromats are used. The optimised achromats are designed to compensate.

Best to try to use in-camera ND or external ND filters to keep the camcorder lens iris in the ballpark of f4 - f6.3 which seems to be the sweet spot of the camcorder lens/achromat combination on the specimen I am using.

The better Nikon stills lenses will generally match for sharpness, many motion picture camera lenses but maybe not to a wide-open iris setting where flare and softness may occur.

Stills lenses may not yield a focus pull effect without changing the field-of-view, the so-called "breathing" effect where the image becomes larger or smaller like a zoom movement. The stills lenses may have a less finely controllable focus movement than motion picture lenses.

If your Letus enables you to open up the view of the groundglass wider than the motion picture frame by zooming back to say 38mm to 40mm on the EX1 , then with some stills lenses, you can cheat a little more "apparent" sharpness by scaling the individual groundglass texture "grain" smaller relative to the groundglass image frame area the camcorder sees.

PL-Mount motion picture lenses as mentioned above, tend to throw a smaller image area onto the groundglass (24mm approx) than stills lenses which are designed to cover a 36mm wide frame but cover less width when a groundglass is used. ( the reasons I won't go into ). You may gain better apparent contrast performance with the motion picture lenses but may lose a bit of "apparent" sharpness because the groundglass texture is scaled larger through camcorder having to be zoomed in more.

"Letus adaptors built before 2007?" This may be referring to earlier plastic bodied models other than the Letus Extreme. Your metal bodied Letus Extreme may be quite okay if your existing achromat is of a metal barrelled style which screws into the back of the prism enclosure. You would unscrew and remove your existing achromat and the optimised achromat takes its place.

An email to Letus Direct might get you the info you need. Otherwise post a frame grab of the rear of your Letus Extreme so it can be compared and commented upon.

[Stathis Athanasiou]

Thanks for the info Bob. That was quite clear. So, in "real life" situations, the photographic lenses perform better than 35mm lenses, as this apparent gain in contrast can be corrected in grading, while the apparent sharpness cannot. The thing with the focus pull is tricky, and to be honest it is what I am primarily concerned with, as the focus pullers are used to doing their -very fine indeed- job using the easier to use cine lens, but anyway... Good shot planning can bring the results.

But is this -apparent- gain in sharpness that noticeable ? I love my old Nikon lenses (especially me 50mm 1.2) and I love their "dreamy" picture, but I would feel more calm with a cine lens set, because I haven't used them in such a big project as a feature.

Would someone care to comment on that? Has anyone done a big project (feature or other) entirely with photo lenses?

[Bob Hart]

For a project where added production value has been committed to, like costly lighting, costume and set design and using an established DP or camera operator, I would favour using good cine lenses and giving up a bit of apparent sharpness. If they are a matched set, all the better as you will not have to grade each lens view as much to match in post.

You may recover some "apparent" sharpness by selectively applying about 15%-25% sharpen in post if you take care to keep your camera video noise levels down by using no gain or -3db and bringing up the lighting.

Remember that groundglass texture, even though moving apparently faster than the camera can resolve, remains additive to video gain noise as a burden to a video compression codec and a loss of sharpness may occur if gain noise is there.

Your DP who has a reputation to maintain, may have misgivings about using any groundglass 35mm adaptor. Unless open minded, he might even adopt a fatalistic "I told you so" attitude, which in turn may introduce a cirumstance of morale that makes it a self-fulfilling prophecy. - "Blame it on the groundglass - I told you they are no good."

Try to promote the ethos that groundglass work is a creative image aesthetic in its own right, which is what they did on "Dear Wendy".

Your DP will not want to be distracted from the creative stuff by having to shepherd the adaptor as well. Having the familiar optical tool set and the follow-focus movement moving in the correct direction will be less discomforting.

To keep the camera operator and DP workloads at sensible levels, you really need to have a wrangler/assistant to make sure the Letus is switched on for every shot and off at end.

The camera op and DP do not need the added work of keeping a constant eye on relay focus, especially if using the camcorder lens for relay, keeping a close eye on the "safe" zone for cine lens and relay lens aperture settings and checking for artifacts with a good on set monitor.

I prefer this monitoring of image quality to be done to the point of obsession "riding the ragged edge" I like to call it. If you are old enough, you may remember the movie title this quote is derived from.

When checking relay focus, the best check is to use a resolution chart with fine lines.

You should also bully the camera operator into using a focus target "every" time a shot is set up and especially for focus pull shots. The LCD screen or viewfinder and eyeball alone are simply not good enough. Pride may get in the way here as the camera operator may take the attitude of "I know what I am doing" or "you do your job and I'll do mine".

One trick is to have a Siemens chart of no more than 20 white wedges around a circle, printed and laminated on a full A4 or "letter" sized sheet of paper and attach that to the mike pole so that the focus check can be done at the same time the "safe" area for the mike is checked. The alternative is to fasten it on back face of the slate.

With cine primes, you may find that the 50mm and longer lenses may throw a wider usable image onto the groundglass than the wider lenses and be tempted to chase the extra sharpness by using a wider groundglass view to camera.

However if you start to zoom back to get the wider view with these lenses to chase "apparent" sharpness, you may confuse the DP who will be finding his instinctive lens choices are not matching his expectations regarding field of view and perspective.

Try to avoid shots where there is a strong element of back light like shooting against the sun or a light bright overcast sky with the sun behind, unless you are going for the silhouette.

Things like strongly lit white branches and treetrunks in front of darker backgrounds in soft background focus may resolve with a ghosting artifact, though I understand that this is less likely to occurr with the Letus Ultimate versus Letus Extreme.

Best also to follow the familiar practice of using mattebox and ND filters to control light onto the groundglass rather than using in-camera ND and in-camera iris controls. It will be a nicer look and will help to preserve contrast.

Make sure though that your camera does not have IR issues. Some cameras will detect and reproduce near infra-red as a red cast over blacks when simple ND filters are used in a mattebox on front. You may need to consider the Schneider tru-cut ????? IR filter to avoid this. Some may choose to keep life simpler and use the in-camera ND only.

If you have time, rent the DVD movie "Dear Wendy" which was shot with a P+S Technik PRO35 adaptor on a custom Sony HD camera head. The DP was Anthony Dod Mantle, more well known for "Slumdog Millionaire". There are helpful "behind-the-scenes" extras on the DVD.

I anticipate you are approaching this with a professional attitude and will schedule useful practice sessions and tests with the equipment for camera operator, DP and lighting guy before the actual shoot to establish the best look.

I hope I have not sent you screaming and jibbering for the nearest source of valium or across town to the nearest Cinealta rental house.

These are my personal preferences and should be weighed against the better advice of others, Chris Barcellos, Philip Bloom and Charles Papert in particular.


There are a few frame grabs from a Letus Extreme here modified for centricity (x-y) adjustment.

http://www.dvinfo.net/forum/let-us-d...extreme-4.html


There is a test chart on Page 1 of the same thread here.

http://www.dvinfo.net/forum/let-us-d...g-extreme.html


I would expect the UItimate, with its inbuilt facility for x-y adjustment to be as good if not better.



I was using as safely wide a view as I could get from the groundglass which for the Sigma-for-Nikon 14mm f2.8 is about 28mm wide-open, about 24mm for f4.

[Leonard Levy]

I was actually the guy early in the life of the Letus Extreme who posted charts on the web disclosing how bad it was on the EX-1. At that time many well know people were raving about how sharp it was on the Ex-1. I was shocked. Sure if you shoot in daylight with the EX-1 at f5.6 or 8.

DO NOT USE THE OLD ACHROMAT ON AN EX-1 if you care at all about visual quality. With the Ex-1 wide open your corners will be extremely soft. It is unacceptable in my view. However Letus responded very quickly with an upgraded achromat and a ring designed specifically for the 77mm EX-1. The ring is small potatoes. The achromat is essential and it did quite a good job. Good enough so that you can get away with shooting with the EX-1 wide open and still not notice that the corners are still a touch soft in most situations. f2.8 is better but I don't think you need to go to 4 or 6.3 as Bob suggests. its simply not practical in any indoor shooting and I challenge most people to ever see a difference.

That said an Ultimate has better sharpness and especially corner resolution and I recently tested an SGBlade that also was noticeably sharper in the corners. Will you see those differences - maybe. But you will definitely see how miserable the original achromat is on the EX-1.

PL mount lenses vs. Nikons? Depends what you're shooting. If you need to rack focus accurately and often PL is better. Super Speed lenses are designed to be best wide open and Nikons aren't. Depends on the lens though. If a zoom lens at 2.8 works for you, Nikon's modern series of zooms are extremely sharp, flexible and tiny compared to a PL mount zoom.

I can't afford PL's so I generally shoot with Nikon's, but I shoot lots of corporate heads. PL's would be a waste of time.

Lenny Levy

[Bob Hart]

Stathis.


Furthur to the above, here is a link to a clip shot with a Sony Z1 with two cine lenses, an Angenieux 25mm-250mm zoom and Kinoptik 9.8mm ultrawide.

OLD ROLEYSTONE RETAIL DRAGSTRIP By Bob Hart On ExposureRoom

I zoomed back a bit far with the Angenieux and although the lens throws a wider image to groundglass than the Kinoptik, you will observe softening in the corners where the lens was not designed to throw its image. I also picked up an edge.

Both of these lenses are soft compared to modern primes but the Angenieux as soft and old as it is, still has sweet contrast. However if I wanted the agility and ease of using a zoom, I would as Leonard suggests, go with the Nikon f2.8 zoom and use the wider groundglass view it may permit to pick up a bit more "apparent" sharpness.


As for selection of the camera iris to the zone f4 -f6.3, this is of course when lighting conditions permit. It is the sweet zone of my own EX1/Letus Extreme combination. Among other things, this setting range maintains a deeper depth-of-field of the camcorder lens itself than f2.8 though the groundglass plane, a hedge against the relay focus being slightly off.

If light is low, I would of course open the camcorder iris to wide before using added gain.


Leonard.

If you do a little test with the EX1 special achromat - point your Letus at the blue sky or a bright plain object, close the Nikon or whatever lens is on front to f11 - f16 to make the groundglass visible at camcorder iris wide-open, pull camcorder relay focus very slowly through the groundglass and you may see what I am getting at, a very subtle ring of sharpest focus which starts at centre and moves outwards or vice-versa.

At movie frame size it seems even more subtle.

It is by no means a deal killer at all and in a practical environment, as you suggest, is unlikely to degrade the image noticeably if relay focus is correct. If the lighting resources are there, a camcorder iris setting in the f4- f6.3 zone is what I would prefer, just for the hedge against relay focus drift if nothing else. Any slight artifact that might be there is also going to go away the moment you switch the groundglass motor so I am probably just being a bit obsessive. I do favour obsessive.

[Leonard Levy]

Bob,
You have proven many times over on these forums that your are exacting, a perfectionist and extremely knowledgeable and I deeply valuable your input. You are absolutely right about the Letus corners. I was simply adding a touch of real world practicality which you understand as well.
There used to be a lot of "experts" asserting that you shouldn't use a 35mm adapter with the video camera at less than 5.6 or 8 because you lost sharpness. This was ridiculous - that would be unusable gear in my mind.

Actually when that Letus achromat came out I was astounded at how good it was compared to anything I had seen before on the HVX. Generally I almost never can afford to shoot beyond 1.9 or 2.8 and at that point it becomes a trade off - is it better to stop down the Ex-1 or say my Nikon? Many times I've seen the 35mm lens improve more than than the Ex-1 by dropping a stop.

All tests were down with the Ex-1 at f1.9. I actually did do tests at 2.8 and 4, and of course they all improve for the reasons you mentioned - more depth of focus on the screen itself in the video camera.

[Stathis Athanasiou]

Leonard I was searching your older posts and found the one where you point out the edge focus problem.

Bob, now that is an analytical post! The DP is a good friend of mine and we work together for almost 10 years, so we go through the process of selecting our camera and lens equipment together. The thing is, he owns an EX-1 and I own a Letus and both of us own A LOT of very good Nikon lenses. So, now that we are doing the feature, we thought of combining our equipment in order to re-invest some of the money of the budget in other parts of the production, because although we have a decent budget, as everybody in our business knows, money is never enough...

Our other option goes a totally different route. We are also thinking of cooperatively buying the SI-2K and be the first people to own the camera in our country. In fact we are going to Germany for the demo presentation at the end of the month. As I see, you own the SI. In very few words, is it THAT much better than a Sony 750 or 900 with cine lenses? If we are going to buy the camera, it is not only going to be for the film we are now doing, but also as an investment, renting it. So is it that much better when it comes to image quality? And I am not talking about the technical stuff like 2K resolution and the such. I am talking about perceived image quality, about skin tones, about grayscale levels.

[Bob Hart]

There is some contention and argument about the virtues of a single sensor 2/3" cam like the SI2K versus a 3 x 2/3" sensor cam like the Sony cameras you mentioned.

Cine lenses should not be put on a 3 x 2/3" sensor camera unless there is an optical adaptor between the lens and sensor because the prism split introduces a few small problems with the image from a lens designed for film which is in effect a single chemical sensor.

Single sensor cams like the RED and SI2K are fine with film lenses. So also I believe are the ARRI, A-cam (digital) and Kinor.

What my DP and mentor likes about the SI2K compared to the other 2/3" video cams he has used is for the first time in his career, he has been able to regard the camera as a film camera and the latitude in being able to grade the image and alter it.

The recording system is file based. There is no need to convert the files unless you want to edit in another system like ProRes or Avid's DnxHD. There is no capture stage as from tape.

At first glance, the SI2K image looks softer than the Sony EX1/EX3 cameras. The image from the SI2K has not been sharpened before going to file. The image in the EX cams has.

With the SI2K images, you apply digital sharpening in post as required. The image from the SI2K is described as a "raw" image. It is not a true "raw' image in the sense of a DPX from a film scan because it is digitally compressed but for practical purposes it can perform as conveniently well and faster.

The codec used in the SI2K is cineform which is claimed to be superior to HDCAM. I can't provide evidence for this claim myself. You would have to research it.

The SI2K uses a 2/3" sensor. There is an argument put up about why "go back" to Super16 film which is in effect what the SI2K reproduces more or less in its look. Everyone it seems wants a 35mm film look.

The quick answer is that the SI2K morning images can be in the edit bay being cut and assembled while the same day afteroon shoot is still happening if several drives are being swapped out. Presently with the RED, there is a two-stage process which has to happen.

Some operators choose to shoot RED footage with a cropped sensor to a 2K Super16mm image size.

I understand from hearsay that Sony's HDCAM post-production flow is also as user-friendly and immediate as the SI2K. The entire system is more costly to buy.

Whatever you decide, you need to be mindful that you may have to upgrade your edit suite to manage the images in real time. You need to purchase good lenses, primes preferably as well as a good zoom.

Maybe a heavier tripod if you are going with the full SI2K system including the recorder unit. I would recommend you do if you want something which is turnkey out of the box and does not have to have software installed, tweaked and set up on a laptop computer.

There is a lot of learning to do like you would find if you migrate to a higher end Sony camera and HDCAM post-production workflow.

The SI2K is in effect a computer which does double duty as a controller of the camera head and records the images to a file.

Once you are trained up and are running the system properly, you should find it operating reliably. You will also find that it is a power hog compared to the EX camera family and you will need to invest in new battery systems.

The camera head in its recorder unit is not light and compares to a studio version of the CP16R film camera in weight and convenience of use. You can run the head remotely from the recorder unit or use a suitably powerful qualified laptop computer in place of the recorder unit.

It is not as agile portable as the EX cameras. By the time you assemble an EX3 to a groundglass 35mm adaptor you have in effect what should be regarded as a studio camera except the combination is still self-contained and cordless if you have no mike connected.

What you may discover if you buy in the SI2K system is a resistance by clients and production entities to step into something new.

The post-production workflow is their responsibility but not one they may be willing to invest in even if it is a small cost for the cineform plug-ins compared to the total cost of their operation. You may find yourself having to offer the entire workflow from camera to end-product for clients to use.

Some younger operators, recently graduated from University over here shot a short horror film on the SI2K. They are absolutely pleased with what they have achieved even if I am not so keen on blood and violence myself.

They have a website Trespass – Movie by Damien Giglietta and a facebook entry for Trespass. They hope to release it before the end of this month.

There are a few frame grabs here at the bottom of the page :-

http://www.dvinfo.net/forum/silicon-...stralia-4.html

Send me an email via dvinfo and I will get you an address to two passworded clips which are only for limited access.