Zeiss with "triangle-shape" lens stop blades

oscar jimenez · August 26, 2004

HI, I just went to a Rental House to check on a BL 2 package, it had bayo mount, and the primes kit had their lens stop blades when closed down it looked in a triangle shape, the guy showing me the equipment, told me there were some "concerns" about this kind of lenses that they were supposed to be used at a certain stop to avoid flares, ghosts etc. Does anybody knows or can tell the difference beetween octagonal ( round ) and triangular closing position in lenses?

Is there any aberration or strange thing that could possbly happen???

Thank you very much

Oscar

Adam Frisch FSF · August 26, 2004

Oh, yes. The 16mm Zeiss T1.3 from 9,5 up to 25mm all have this iris. I can't remember which

35mm lenses have them, but I have encountered it. Which ones did you look at?

Anyway, they're fine wide open (or very close to it) cause then the barrel of the lens

makes the out-of-focus rings look round. It's when you stop down that the flares and

blurry objects turn into triangles! I really dislike that, but if you're not picky or don't plan

to shoot shallow focus, then it might be less of a problem.

Same problem happens with hard mattes in matteboxes - things out of focus turn into

squares when out of focus (often with some pincushion distortion thrown in so they look

even more mad). It's just one of those mad optical effects - even though you can't see

the hard matte in frame - they turn up on blurry objects. That's why I never ever use hard mattes on the mattebox - I much rather prefer the odd stray flare than have little lightboxes

flying around my frame! Check out the gunfight between Cage and Travolta in Face/Off at

the airport hangar for a good example of this artifact.

oscar jimenez · August 27, 2004

Thank you very much, So i Think I'd rather not be using it, they seem quite problematic. What's this kind of lenses construction name anyway?

Thank you

Kim Sargenius · August 28, 2004

Oh, yes. The 16mm Zeiss T1.3 from 9,5 up to 25mm all have this iris. I can't remember which
35mm lenses have them, but I have encountered it. Which ones did you look at?

The way it goes here in Australia, there are supposedly three versions of the Zeiss Super Speeds, both 16mm and 35mm.

The MkI's have relatively round apertures but do not have standard focus/iris gears, are all different sizes, and different front sizes. Decent sharpness, good contrast, decent with flares.

The MkII's are the ones with the pesky triangular apertures. They are equal size (and even weight - according to a Steadicam op I just worked with), equal front size and standard focus/iris gears. There is also a 50mm (16mm) and an 85mm (35mm). Good sharpness, good contrast, good with flares but somehow they just seem a bit lifeless to me (very subjective).

The MkIII's share the mechanical/size properties of the MkII's but have a round aperture and seem to have a little bit more snap than the MkII's.

Overall, given a choice, I'll go for the MkIII's any day, although the MkII's are the most readily available here. On purely subjective taste I'd even pick the MkI's over the MkII's if I could. On purely technical terms the MkII performs better than the MkI but most times there's more to lens choice than just tehnical perfomance : )

HTH

cheers,

Kim Sargenius

cinematographer

Sydney

Mitch Gross · August 28, 2004

With the various generations of the Zeiss SuperSpeeds, avoid the old T1.4 lenses. They flare a lot and contrary to many lenses perform very poorly when stopped down past T4 or T5.6. The resolution dropoff is readily apparent to the eye. With the newer Mk2 and Mk3 lenses you'll still find that the lenses don't perform as well all the way open as they do stopped down to a T2.8. The contrast and sharpness are lower and the color saturation is weaker as well. Corner resolution and chromatic abberations are also worse when wide open.

If you ever want to learn something about lenses, just ask the rental house to let you test them on their lens projector in a back room. It's amazing what you can see right in front of your eyes.

oscar jimenez · August 30, 2004

A general culture question: what does exactly the term "MK" refers to when talking about a lens? what does it means? is it written down on the lens itself or it goes with serial numbers? I will appreciatte very much if somebody could explain to me, and if it is any book that I could dig myself into.

THank you very much indeed.

Oscar

Phil Rhodes · August 30, 2004

It's a common abbreviation for "Mark".

GWilliamPatrickB · October 18, 2004

HI, I just went to a Rental House to check on a BL 2 package, it had bayo mount, and the primes kit had their lens stop blades when closed down it looked in a triangle shape, the guy showing me the equipment, told me there were some "concerns" about this kind of lenses that they were supposed to be used at a certain stop to avoid flares, ghosts etc. Does anybody knows or can tell the difference beetween octagonal ( round ) and triangular closing position in lenses?
Is there any aberration or strange thing that could possbly happen???

Thank you very much

Oscar

<{POST_SNAPBACK}>

What you are looking at are the real deal MK I's if they had pl mounts then they were converted to pl

GWPB