Does Letus Extreme lose more light than Brevis

Marco, thanks for raising those points. It's absolutely true that CF1/Le have a characteristic "profile" that shooters need to well aware of, as do CF2Le, and CF3Le. Barry has arranged for a technical review, and we'll be augmenting that with a light loss profile for each imaging element.

Because they do not behave at all given the expected shutter speed/aperture ratios, an XY plot of light loss vs taking lens aperture is the only to predict their performance with a given lens. We've invested in a rear-illuminated box, and chart series from DSC labs. so we'll attempt to quantify the behaviour as thoroughly as practical. There's been quite a few discussions on dynamic range compression with adapters, so expect some interesting analysis of that area in short order.

Cheers :-)
 
I wasn't going to answer 'cause I don't think that there is a worst blind than the one that doesn't want to see.

But by popular demand, here it goes.
marco0782 said:
Wow, you don't have to be a jerk to disagree with someone or have a discussion.



Here are the facts I know, based on shooting 15+ short films and a feature with the Brevis:
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That is nice. I love to see them on my free time. Is there a link to them? or maybe I can rent them at Block Busters.
1) The Brevis does not handle light loss the same as other adapters; each stop you go down on the lens does not reduce light transmission by equivalent stops
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Is the glass half full or half empty.

If you start at f16 and you start opening a stop at the time you do see a linear increase in light. When you reach f4 you stop having more light coming in. That is the only comment I had about the Brevis. "A fast lens is useless if you need more light"

I would expect you to agree with that 'cause you just said the same thing but backward.
2) The Brevis with CF1 renders less bokeh at f/1.4 than the other adapters, similar to what the Redrock/SGpro/Letus render at f/2.8
3) This means that more appears in focus at a given f-stop than with the other adapters
4) And in conclusion, means that pulling focus is easy when you shoot wide open on the Brevis and therefore stopping down to assist focus pulling is not as necessary as with other adapters

When I shoot with the SGpro I find it necessary to stop down to f/2.8 when I need to make things easier on the focus puller. With the Brevis I could have left it at f/1.4. What this means is that the Brevis, which is already half a stop faster than the SGpro, now has an extra advantage relatively speaking because in the same shooting situation I will lose two extra stops of light in order to get more in focus with the SGpro.
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I assume that you tested those adaptors. I didn't so I'll take your word for it.
If you don't understand that then you should test both adapters for yourself. It's really upsetting to find myself attacked when I only came on here to share my experiences to those who might find them helpful. And Barry should just put his assumptions on hold until he actually gets to test the Brevis. The characteristics of the way that the Brevis CF1 handles light are different than anything out there and he's just contributing to misinformation and confusion.
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My friend if you can't handle the heat get out of the kitchen.

I am not going to defend Barry here. He can do that himself. I am just going to answer you comment about assumptions.

Neither you nor Dennis are able to give a scientific answer to the phenomenon. So your quotes are assumptions and I don't see anyone telling you to stop making them.

Don't take it personal.

It has been made obvious to me that there are all levels of expertise and different uses for the adaptors. Not all of you need to use a meter, but wouldn't it be nice to know how to use it? That way most would understand what I have said since the beginning of this thread.

I have been in photography (painting with light) for 30 years and I have teached classes on using and measuring lights to professional photographers. I really don't care if you think I am a jerk. I just hope that everyone reading this can take something useful home.
 
I would dearly like to see a more professional and respectful tone on this forum, and particularely this thread. Please think twice about how you phrase things before hitting the send button.


Lenny Levy
 
Hey Doug, do you believe that a translucent GG, as Dennis said the CF1 is, would allow more light to get through than non-translucent GG's and therefor plain and simply allow more light in? I don't now how to calculate ISO to set a light meter myself but this isn't necessarily about how to measure the light but about how much light gets to the sensor regardless of how you measure it. It has not been proven that other adapter GG's are not at all translucent though... :undecided

I have not yet seen two adapters being tested with any other methods, or with a light meter, so I am not personally ready to accept that the Brevis is in fact faster than even the Letus. However, it does seem there are a lot of people --who don't even know each other-- saying it might in fact be faster than all others. And another thing that I am noticing is that there isn't anyone coming forth to clearly stating the opposite. I have not yet seen anyone saying the Letus is being faster than the Brevis... so I think we have covered all areas of the matter as much as they could be before someone does a shoot-out or dissects adapters to find the magic star dust that's adding light hehehe... hahah... which would clearly be cheating Dennis! :)

I think if I get it anyone can so let me re-cap:
_ It seems most people might agree that the Brevis is faster but it has not yet been proven by a shoot-out!
_ It also seems that the Brevis might NEED the flip or a spacer and/or? achromat to avoid soft edges.
_ It also seems the Letus is a superb, solid, high-shutter and extremely fast performer out of the box.
_ It seems the SGpro (and possibly the G35?) take the cup when it comes to the bokeh whores... (great technical term Kholi, hope u don't mind me using it)
_ Lastly it seems that the Brevis provides more creative options that may be somewhat but not completely equatable to being able to switch film stock! And it offers more fine tuning abilities for maximize quality with each individual camera and it's manufacturing tolerances.

Did I miss something? I am sure I missed something... but unless someone can test all or some adapters at the same time then I think there is nothing else to be said that all of you guys haven't already said... well how would I know... heheh... but if there is, please say it clearly so we can all understand it, and without picking sides... I doubt there are any clients here that you may want to convince towards your equipment being better, and we are all helping eachother learn and find other ways to do this stuff. If you are posting here then you are all on the same team. I sure need all the help I can get!
 
Put a movie projector on a wall. Put a sheet up as the screen. Look at the contrast and how washed out it looks. Why? Because the image is passing through to the next surface, wall, etc.

Now put up a real screen and look at how much better the image looks.

It's not a hard concept to understand. The GG only needs to be transparent enough to let light in, so that the HVX can see it. If it's too transparent, the image passes through and you lose color and contrast.

I mean I'm probably COMPLETELY wrong here.
 
No not at all. As usual you point out something relevant and do so clearly! :dankk2:

However I am wondering if taking advantage of multiple points of a ratio between not letting any light or letting lots of light pass through might have more uses than just one ratio... so while the CF1 is NOT going to be the sharpest image, it may have met an imensly useful balance between the two and the CF3 or next Cinefuse might give you the complimentary opposite end.
 
That is nice. I love to see them on my free time. Is there a link to them? or maybe I can rent them at Block Busters.
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Sure when I get back from Slamdance in Utah where my first short film is playing this week I would be more than happy to send you links to stills/clips from films I've shot.


Marco
 
Congrats Marco!

But please let it die out guys...

instead help me with my lens purchase decisions and help me figure out which are the best Nikon primes, something I am sure you both can help me with and something that may play a big factor on which adapter in the event that the CF3 or next GG + flip HD footage isn't as clean as I personally hope and believe it will be.
 
What is your budget? I use the following Nikon AIS lenses which are amazing but can be pricey:

20mm f/2.8
28mm f/2.0
35mm f/1.4
50mm f/1.2
85mm f/1.4


These are all very sharp wide open and no soft corners/vignetting to speak of using the SGpro.
 
my soon to become a reality lens set is - all nikon mount

20mm f/1.8 sigma
35mm f/1.4 AI nikkor - i just bought this today!!!!!!
50mm f/1.4 AI nikkor - i might have to settle for the AIS though
85mm f/1.4 AIS nikkor - i can't find the AI version anywhere???

i'm buying them all second hand. i like the AI nikkors better than the AIS just because of the longer focus draw.
 
Lenses that fast might negate the need for the CF1... probably not though... I am exited to see some numbers...

...but regardless as it was wisely pointed out earlier on this thread, faster lenses are usually better in all other ways also, not just speed... so I am going to try to get 1.8's at least... hopefully 1.4's

My budget, I am HOPING, will be about anywhere from $1,600 to $2,100...

it is because of this that I am thinking the Nikon 28-70 and 80-200 zooms might be the best way for me to get the most creative potential... I am a BIG fan of LOOONG focal lengths... I have lots of use for their perspective qualities... so that's an other plus as 200mm lenses won't be as fast as the speed that makes prime sets so tempting... and also the ease of production is just a huge factor... add the speed of the CF1 at 2.8f and the sub-par focus rings on these zooms may start to sound a bit more of a necessary burden...???

I looked in B&H and new the 50 and 85 Planar and the 35 Distagon come out to a bit over $2200 without tax and shipping... how much for them used? I mean I ain't no Jason Ramsey that can wrap a blockbuster with one focal length ya know... I am just not that good. MAD props to you for shooting interiors without a wide, I can't wait to see your film.

And what's the difference between the Distagon and the Planar?

Oh! and I have not discounted Nikon primes if they have a nice draw... which should I look at? there is a million
 
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Dennis Wood said:
John, our 2/3" relay project is going quite well. In fact, the HPX500 should be here this week for testing. This is by far the most I've ever even remotely considered spending on a camera, so anyone in Thunder Bay looking to rent one take note :-)
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That's great news. :2vrolijk_08:

So am I correct in inferring that you have a prototype that you'll be testing the HPX-500 with?

Please keep me updated as, of course, there's a project that I'm in need of this system for.
 
John, there is a great deal of testing to do, and with the camera's CAC, interesting options may arise :-) This project will be integrated with several other items in the "skunkworks", so all I can promise is good things for B4 camera owners.
 
Douglas Villalba said:
A 35 mm adaptor is not meant to do TV. It is meant to do film like. That is why it is important for a DP to know how to use meters. How else are you going to know DOP and lighting ratios before the video camera is set up? and, How would he know all theses if (s)he doesn't know the ASA rating of the camera that is being used?
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The only time I use a light meter these days is when I shoot film. For digital, I don't use them at all. For consistent imagery and matching shots, I find my waveform and a good monitor far more crucial. And now with SD cards, we don't even need to refer to our lighting ratios to match reverses, etc. We can just look at the clip instantly.

Now what I really would like to see is a spot meter that has a histogram readout instead of a stop or a footcandle. In otherwords you set the ASA and turn the stop wheel while watching where the histogram moves within a given lattitude. Perhaps you could even set the lattitude to match you cameras or your film stock. Now that would be truly revolutionary and perhaps possible these days.

Back on topic.

I've owned all three adaptors (SG, Brevis and LE). I still like the SG picture the best. I do want to re-test the Brevis as by all accounts seems to be much improved. I'm re-testing my LE as I have suspicions about edge to edge sharpness. But I also think I may not be zooming in enough.

If you don't shoot with a lot of light, the Brevis maybe the way to go. If you like high stops, photographic bokeh and high shutter speeds, the SG is the one.
 
jenningsp said:
yes the context, professionalism, composition and lighting have a great deal to do with how the image looks. but what I'm talking about goes beyond that.

it's an inherent trait that spinners give the image. there is a quality that i can't quite put my finger on. i'll call it "awesomeness" for now...

different adapters, namely their GG's, give a certain "look" too the image. and for some reason spinning adapters look "awesome" 100% of the time and non-spinners look "awesome" only 50% of the time.
t.
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I'm not so sure it's a function of spinning versus vibrating but perhaps the level of diffusion that lends the "awesomeness" you seem so fond of. What I do notice, however, is less random grain from the vibrating GG. The only vibrating GG that doesn't have the grain buzz is the PS, but it cost a bundle. I also don't think they look as good as their first models (which were spinners). I also wonder if light defracts differently from a spinner.
 
Once again I agree with Tim completely. By the way i shot with the Pro35 and the HDCAM F900R today and was surprised at how great the Pro35 looked. If I get a chance tomorrow I may bring my Ex and Letus to see how it compares. Don't know if I'll have time though.
 
i said in an earlier post that i'm not sure it is the diffusion. namely because the LetusEX (which is said to be about the same diffusion as the SGpro) and the brevis CF3 (which is verging on M2 diffusion) also exhibit this same lack of awesomeness....
 
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