LETUS Advertising "Absolutely no vignetting"...

A

arno

Well-known member
In the advertising of Let Us they say the're "Absolutely no vignetting". I use the best lenses, Zeisss Contax with Eos mount (the best still lenses besides the Leica's) ... on my Let us Extreme.
But the're a lot of vignetting with my Zeisss 28mm/2.8.
(or i do have to zoom in a lot -30 on my hvx)
So I can absolutely say the're is vignetting with one lense.

But I am not complaining about the Extreme. It's a great tool!

Arno
 
You have to zoom in to where you're filling the HVX's frame with the ground glass. That number will be different for different cameras, but on an HVX it should be around 27mm.
 
Barry, I did understand. But I have to zoom in over 30. About 31/32.
I bought the lens specialy for wide shots. But now it's ca. 35mm... And when I want a 28mm wide view I have to buy a 25mm or better, a 21mm Contax Zeiss (21mm=+€2000).
 
Are you talking about Z30? or 30mm? Because Z30, sure, that's probably fine, but 30mm? That seems too far.

Take the lens off entirely, and just zoom in to the point where the edges of the ground glass frame disappear and you see nothing but ground glass. At that point you should be able to use any lens with no vignetting, unless of course the lens itself vignettes (such as my Peleng 8mm, that will vignette horrifically on a 35mm frame because it's a fisheye).
 
Some lenses vignette no matter what DOF adaptor or SLR camera you use, specially wide open wide angle lenses. It`s not visible or let`s say distracting on locked shots but with moving camera it will become visible and distracting at times. I almost don`t know any wide lens that don`t vignette at all wide open unless they are designed for modern cropped frame size cameras. I used to love vignette on my still pictures for years but lurking in the forums almost changed my mind.
I`ve heard that Zeiss lens are one of the worst in terms brething, can that be true?

T
 
My Nikon 20-35mm F2.8 doesn't vignette, have any light falloff and only has a bit of CA on my brevis with CF1Le..... It has less distortion than the 20 and 24mm primes and it seems that the primes vignette on most adapters...and it only cost less than one good condition 24mm F2 haha.

Beautiful :)
 
Barry_Green said:
You have to zoom in to where you're filling the HVX's frame with the ground glass. That number will be different for different cameras, but on an HVX it should be around 27mm.
Click to expand...

Sorry for being so dense tonight but what Z number would that be?
 
I haven't used "Z" numbers since I got the HVX. It's been turned to ft/mm from day one. Why would you still be using Z numbers?
 
Barry, just curious for my own comparisons... is that number for the 35mm frame size, or just to fill the hvx frame?

Late,r
Jason
 
Very good reason to use "Number" Barry. On most adapters ( not teh Letus Extreme) the focus distance falls inside the "Macro" range so its useless for keeping track of where you set your adapter focus. With "number" you can read outs on the full range.
 
35mm cine frame size. Filling the HVX frame happens at somewhere around 17mm IIRC and gives you a vistavision/35mm still-frame size.
 
Last edited:
Lenilenapi said:
Very good reason to use "Number" Barry. On most adapters ( not teh Letus Extreme) the focus distance falls inside the "Macro" range so its useless for keeping track of where you set your adapter focus. With "number" you can read outs on the full range.
Click to expand...
For focus maybe, but not for zoom... I set focus inside the adapter with autofocus anyway; once it locks on the ground glass you put it on manual and tape it down, no?
 
I do the auto thing when it works, but for some adapter screens it doesn't work well for me (Brevis, Redrock) so I do it by eye. Also sometimes i've found that the center and corners are not precisely the same, so I try to optimize in between. Regardless of how you do it, having the readout on "Number" allows a quick double check that nothing has moved radically.

I usually bring a large poster size focus chart and double check corners and center with that after the lens is on. Don't know if its neccessary, but it makes me feel secure and number is a good reference. Maybe with the newer adapters with the flip optics they will feel flatter.
Maybe i'll come to trust the auto eventually, but i don't yet.

In the thread above you meant 35mm cine size didn't you?

- lenny Levy
 
Regardless of how you do it, having the readout on "Number" allows a quick double check that nothing has moved radically.
Click to expand...
I see what you're saying, but... I dunno, the numbers are just too vague. Too much variation between numbers; there's only 100 numbers from minimum to maximum. The distance readout has at least 2x to 3x as many "increments" making it a lot more accurate. You can move the ring pretty darn far before the increment changes (well, at least at the further end of the scale) so I don't trust the numbers that much; I'd rather rely on the mm readings since there's a lot more of those increments and you can't move the ring as far.

But if, as you say, some of the adapters require close-focusing down into the macro range (which makes the distances "disappear") then yes you'd have no choice but to use the numbers.

In the thread above you meant 35mm cine size didn't you?
Click to expand...
Yes, 35mm cine, and I'll go and change that. I guess I'm old-school but I still don't understand why we even care what the 35mm still equivalency is... :)
 
Lenny makes a good point. The numbers should only be used to get you in the right area and back focus should always be done by eye using the best focus aids you have at your disposal. The depth of field that applies between the camera and imaging element when using an achromat is incredibly shallow. A few of our users have reported that even camera temperature affected their back focus...something I've never checked myself.

To demonstrate this, remove the achromat and affix it to your camera as if you were using it as a macro lens (a very strong one, btw) and try focusing sharply on a planar surface, like a stamp, 5cm from the camera. It's impossible without a macro stand to get sharp edge to edge focus..and it's why we align our imaging elements to +- .001" in the Z axis.

Lambchop, your experience with CF1Le is exactly why we did all of the R&D (ongoing) ... to get nice full frames from slower wide angle primes :-)
 
You must log in or register to reply here.
Back
Top