Pan Cinor Lens filtering effect?

[mr_x]

Hi,

Been using a Pan Cinor zoom lens (17mm-85mm) on a Bolex H16 and metering it with a handheld light meter, a Lunasix https://c2.staticflickr.com/4/3229/2799 ... b01b11.jpg

Film I've been using is (fast running out) 7285 Ektachrome (asa100) http://www.yalefilmandvideo.com/img/7285%20VI.JPG. The results are dark though, like one or two aperture stops smaller than required.

Is it that this comparatively massive zoom lens is doing its own filter job, & the numerous optics are cutting out several stops of light? Any ideas please?

Thanks

[mr_x]

Gonna do a test - burn some footage - should have done this ages ago but moving home has interrupted all sorts of projects. Found some old cine literature on Google Books which suggest that the more optics in a lens, the more light is gobbled up. By my results so far I guesstimate the Pan-Cinor is losing me between 1 to 1&1/2 f-stops of light, so I can probably ditch a ND filter, which will be good news.

[doug]

Presumably this is the lens with dogleg finder ? Mine doesn't absorb more than about 0.8 of a stop. In fact if you look at the f2 mark it gives the T-stop as 2.66 (in red) ? Maybe there is something amiss with the iris blades, or is the aperture ring not lining up properly ?

[mr_x]

Presumably this is the lens with dogleg finder ? Mine doesn't absorb more than about 0.8 of a stop. In fact if you look at the f2 mark it gives the T-stop as 2.66 (in red) ? Maybe there is something amiss with the iris blades, or is the aperture ring not lining up properly ?

Thanks, you're right. I didn't know what T stops were until I hit this problem. But 0.8 of a stop is enough to throw an exposure, if its critical, right on the edge. The aperture ring lines up okay. I still need to do a test though. I use a multi-ND filter on the lens which has its minimal factor at ND2. This probably means I can ditch the Bolex filter slot ND2, that extra filter - which didn't take into consideration the 0.8 of a stop of light absorbed by the lens - probably threw the whole shoot.

Use the multi-ND because my H16 has no variable shutter, so the ND filter stands in for lap dissolves.

Ric

[doug]

Yes I find the 100D doesn't like much underexposuring. The PanCinor is a nice lens, maybe rather slow to focus but the viewfinder is so lovely and bright. The only thing I made a mistake on once was I didn't have the lens screwed on really tight, and of course the result was out of focus although the finder image showed sharp. Incidentally, it also seems to cover Ultra-16, and I'm aiming to convert the finder for this. Not sure if it'll cover super-16.

[mr_x]

Results have been alright, if imperfect - it's taken ages because I moved home, but the last shoot trialled both the H16 and the Pan CInor. It's fine tuning now. Things keep going pear-shaped, I practiced with the cable release but out in the open I couldn't sort it, it kept falling off, so I managed without. The new test will give me an excuse to have another go with the cable. The one thing I can't do is pop a lens hood on because the variable ND filter takes up that filter thread, can't have everything I suppose. The lens is also heavy enough without anything else on board.

When I used the original 3 fixed lenses I used to film blind, on a sunny day with the lenses stopped down to f.16 all you saw through the viewfinder was slate grey can't use the parallel lens because I often need to superimpose imagery when I multi-expose, and fine as the parallel lens system is, it cannot accurately register shots like that. By comparison the Pan Cinor is a dream - I can see what I'm filming - just have to make sure the camera body is lined up with a spirit level before I shoot, still don't trust the screw-fit lens assembly 100%

[mr_x]

Now waiting (& waiting) for a sunny day to do that lens test

Meanwhile https://youtu.be/crBUTuCh57U