MISCELLANEOUS Q&A FOR LENSES AND LENS ANGLES

Q:

I have 6.5mm Elgeet and a wide adapter for 5.5mm. Can I use these together?

ANS:

Yes. The difference between the 2 lenses (5.5 and 6.5mm) is minimal. Wide angle lenses on 8mm Bolex camera are typically:  5.5mm, 6.5mm, 7mm, & 8mm. Normal angle is 12.5mm or 13mm and telephoto is approximately 36mm to 38mm also sometimes shown as 1 1/2". Normal lens angle is about 2x narrower that wide angle. Telephoto angle is about 2x narrower than normal. This is of course, a rough approximation. See a better explanation (more complicated - but with diagrams) here:

     http://en.wikipedia.org/wiki/Angle_of_view

CHOOSING A LENS

Distance to the subject and the field of view are to be considered when choosing a lens. Different angle lenses present different views or distortions or compressing of the view. One can first choose the angle - wide, normal, telephoto and then consider the distance. Sometimes the distance is the primary factor to be considered first.  There is some confusion when using zoom lenses where the picture appears to 'grow" as the camera lens is zoom from wide to telephoto.

The are actually several things happening with a zoom lens: 1) The lens angle narrows as the zoom moves from wide to telephoto, and 2) magnification of the image makes the picture appear larger. What is actually happening is that angle is being 'traded" for distance. 

Say you choose a wide angle prime lens for a group shot. You then adjust the camera distance until all the people fit in the viewfinder. You can get close to the subject which is usually best for lighting. Closer also will net a sharper, better picture.

Using a telephoto lens to do the same shot, you WILL have to back up until the group fits. The distance added will cause the light hitting the film (or sensor in a digital camera) to 'fall off. The lower light will usually require a lower relative f/stop than the wide angle F/8 instead of f/11.  There are other considerations. 

What the shot 'looks like' when done is a consideration. The feeling that it gives to the viewer. Lots of stuff. And a lot of it is subjective - your choice (camera operator).  A wide angle, extreme close-up shot of a face will make the face look distorted. A long lens on the same face will need to move back and will 'flatten' facial features (portrait) . In motion pictures, long lenses seem to 'expand time' for moving shot. A car in the distance will appear to take longer to come into the camera's close proximity. Forever it takes to 'get to the camera'. Then all of a sudden, it whips by.

Zoom have their place where you have enough light to be able to trade distance for light. In better cameras, you don't even need to be close to get that picture. Zoom to it. Prime lens' require more camera movement to get to the right position for filming. Sometimes, only the zoom will work. Choices made determine the effect of the lens on the film. 

Q:

I know there is fixed focus Pizar lenses for Bolex which should do the job, but how sharp are they when you use them up close, but within the depth of field?  Do they have that telltale "not critically sharp" look?

ANS:

The fixed focus Pizar are sharp enough at any distance for 8mm film,  but are not designed for extreme close up shooting. The depth of field is infinite on the far end and limited to some fixed distance up close. On a Switar f/1.5. It focuses from about 16" (close) to infinity at f/22 (beyond 60 feet or so). With everything sharp. 

A problem is with the extremely small iris openings such as f/22, any lenses can suffer from diffraction. Diffraction can be seen as unwanted light spots. One type of spot in the lens flare. Diffraction and flare can be controlled with lens shade (hoods) and/or lens coating, or sometimes by just changing the camera angle. At extremely small openings, and depending on the lens used, the fix is to open the iris (small f stop) and uses a neutral density (ND) filter to control the light.

The limiting factor of sharpness with 8mm or any film, is the film grain versus the width of the film. 8mm film stock is cut from 16mm, which is in turn cut from standard 35mm stock. With 3 cameras shooting the same film stock and at the same time, on the same subject, with the same light,  and adjusted for lens differences, the 35mm would have the best perceived resolution and the 8mm the worst resolution. It's the film grain that make the quality suffer as the film image gets smaller.

Look at any 8mm footage. Grainy. Look at the 35mm footage of the same subject. Much nicer. Remember, also that you are generally much closer to projected 8mm footage than 35mm footage. 8mm footage projected in a theater setting would be very bad. Coupled with the projected image, the 8mm will also lose some sharpness from the projection process. Remember, 8mm camera equipment was designed and sold for the "home market". The lost cost of 8mm equipment was achieved by cutting "corners".

Another limiting factor for lens sharpness is there is usually an f-stop area that has the best sharpness for that lens. And it usually NOT at the extreme ends of the lens. The lowest or highest f-stops. F/2.8 typically do best starting a f/4 going to f/8 or so. F22 on the same lens will always have less sharpness. All this varies with the manufacturer and the design, number of lens elements, technology, etc, of the lens. The more money you spend - then better the sharpness. Switars are better than Yvars for Bolex, but both work well with 8mm.

Some of the cost cutting involved with 8mm lenses was the use of lower quality glass, with imperfections in the glass that  tended to be ignored in the really cheap lenses. The imperfections generally didn't show in the final projection and so were tolerable. Projector lenses are even worse. I have a Keystone 8mm projector. You can remove and hold to the Keystone's projector lens to the light and see extremely small air bubbles in the glass! Doesn't affect the projected image at all. Fortunately, camera lenses are better made.

Bolex sold two basic series of lenses: Yvar (cheap), and Switar (more money = better made). The Switars generally had lower f stop ratings (pass more light). Example: f/1.9 Vs f/2.8. At that time, the 1940s to 1965 or so, film was 25 or 40 ASA. You need a fast lens for indoors? F/1.8 or f/1.9 was common. Kern-Paillard and even made a f/.9 lens. An F/1.0 lens would pass 100% of the light thru the lens. The f/.9 lenses are quite rare and typically sell today for about $500 or so on ebay. No loss of light. In fact, the .9 lens GAIN light like a magnifying glass.

Q:
I also know they have these lenses that allow reflex operation on a non-reflex camera. Do these work on the C8 or regular H8 or is the lens to film plane distance different or the lens mount not D-Mount? What is available that would work in place of my 5.5mm C8/H8 lens?

ANS:

Reflex lenses made for D-mount work well. What you get is an accurate view of what you are filming. The reflex mechanism sends the light of the picture via a mirror when the camera's shutter is close. Typical shutter angle is about 180 degrees, so half the time you are filming, you can see the image. The other half of the time, the image is 'hitting' the film. They sell on ebay for $25 and up. Sometimes you see them on a C8 or B8. I seen them on D8Ls, also. Som Berthiot made lenses to convert  non-reflex Bolex models to reflex operation. There were some made by the Japanese, also.

Here's a link to a Som Berthiot at bolexcollector.com:

     http://www.bolexcollector.com/lenses/60berthiot.html

Any reflex lens made for a D-Mount with work on the C8. The Pan Cinor 40R is probably the best lens for the C8. There is a focus diopter for getting sharp pictures for 'bad' eyes (like a binocular), and it uses a "split focus" system. You just turn the focus dial until the 2 split images match up. 

Q:

Was there ever made a 6.5mm viewfinder adapter for Bolexs?

ANS:

Yes, 6.5 Bolex diopters were made. Quite rare now. However, the 5.5 will work for any wide angle lens, since the diopter is just used to "correct' the view as seen by the operator. You just allow slightly less 'room' at the left/right edge of the view to compensate for the difference in the  2 diopter values. The diopters view angle of 5.5 will result in a slightly wider view of finished film when used on a on a 6.5 lens, and even more wide on 7, or 8mm lenses.