XL1S adapted to 8mm Peleng fisheye?

[Adam Burtle]

have anyone here had access to the PL peleng setup personally, or can verify for me which is the case..

the xl1solutions website is poorly constructed, and i've had difficulty getting an answer from them i am confident with..

[their website says] the 8mm PELENG setup has an effective magnification of 2x, and the stock/original 5.5mm canon lens has an effective magnification of 7.5x?? so the peleng will be much wider of a lens than the original 16x atuo 5.5-80mm canon lens?

this is what i understand to be true, however i am still confused after reading their website, and further confused after stumbling upon this video...

http://noisybrain.com/SDTV/PL-XL/dock_peleng_16XISII.mov

...which makes it seem that the peleng fisheye is actually much tighter than the original canon lens is when it is fully wide.

can anyone answer me definitively.. if i were to fit the PL adapter and peleng 8mm lens, would i be have a WIDER field of view than the original canon lens?

thanks. (sorry for rambling)

[Mizell Wilson]

Adam,

this is a very tricky and touchy subject.

all of it is relative and depends on your experience with the different formats.

the first thing to remember is that focal length, is focal length, is focal length, so at it's most empirical, you would not expect the 8mm Peleng to be wider then the 5.5 position on the Canon i.e. 5.5 is always wider then 8.

Where the conversion factors come into play is the comparative or effective Angle of View, or what the lens is seeing in any given format.

So what are the conversion factors? based on discussions in the P+S forum we have determined the following factors, all approx.:

7.2x = the 1/3" CCD frame compared to the SLR still 35mm frame

4.5x = the 1/3" CCD frame compared to the Academy cine 35mm frame

2.1x = the 1/3" CCD frame compared to the Academy cine 16mm frame

So what do these mean in practice? Let's go back to our 8mm.

On a 35mm motion picture camera the 8mm is considered to be a very wide angle lens, verging on fish eye. As we can see from Don's footage that you quoted, on the XL1s the 8mm looks rather "normal." In general, you are going to get two different compositions with the same lens, based on the taking format.

So where does the conversion factor come into play. Say you wanted to achieve the same composition on the XL1s that you are getting with the 8mm on your Arri 535. Using the conversion factor above, we see that we would need a lens that is a 1.7mm focal length to get the same composition.

Looking at it from the other side, let's say we wanted to get the same coposition on our Arri 535 that we are seeing on the XL1s using our 8mm. Using our conversion factor above, we see that we would need a 36mm on the 535 to get the same composition. 50mm is the normal for 35mm film and we see that 36mm is close to that number, so that 36mm on the 535 would appear to be a realtively normal lens, just as the 8mm looks close to normal on the XL1s, since we're looking at 11mm being the normal for 1/3"

But say you've never extensively shot 35mm still cameras or with 35mm motion picture cameras, then the conversion factors have no real meaning, because you do not have a frame of reference for them.

Here is an interactive example.

- Draw a large circle

- Draw in a stick figure with it's head being dead center

- Now draw the largest rectangle, centered on the center of the circle, as possible within the circle. This will represent our 35mm academy frame. looking at the composition of the shot, you're going to roughly have a shot from the chest up with plenty of head room, depending on how you drew your subject

- Now draw a less retangular object, centered on the circle, that is roughly 4.5 times smaller then the first. This represents the exact same lens, but how the XL1s sees it. What has happened to our composition? The shot has become a close up on the face, or effectively 4.5x more telephoto then it was interpreted by the 35mm camera, but the focal length of the lens has not changed.

So, as far as mechnical adapters go, there is no way to get wider with 35mm lenses then you already achieve with the XL1s stock or wide angle lenses.

I'm afraid that none of this is as succint as i would like it to be, but we'll use it as a start.

mizell

[Jean-Philippe Archibald]

Wow Mizell!

This is the best theorical explanation of the effect of the differents film lens adaptors available for the XL1.

I searched a very long time across this board for some infos, particularly about products from XL1solutions and I never found answer as clear as this one.

Chris Hurd, if you are reading this thread, I think that this could do a pretty good article for the Watchdog web site

[Mizell Wilson]

thanks Jean-Philippe,

but credit also goes to Jeff Donald and Charles Papert for setting me staight on a few things.

mizell

[Chris Harring]

Mizel, got a quick question: what do you mean by 'mechanical' adapters? Is there another kind (e.g. the P + S Technik)?

Lemme know.

Thanks!

[Jean-Philippe Archibald]

I think I could answer this one.

P + S Technik adaptor is more an "optical" adaptor, since it use a ground glass to compensate for the manification and preserve the angle of view of the lens.

Other adaptors like those of xl1solutions and Optek are mechanical. They allow the use of lenses made for other type of mounts.

Hope this help,

[Mizell Wilson]

Jean-Philippe hit it pretty much on the head. :)

mechanical simply allows you to physically hang a given lens off of the camera without any type of optical adjustment to the lens, thus it takes on the properties of the taking format.

The Mini35 does introduce optical manipulation into the light path so that the lenses maintain all the characteristics of shooting as if they were on a 35mm motion picture camera.

I will take this opportunity to point out that the Mini35 is COMPLETELY optical, no electronic image manipulation is occuring.

mizell