There are three basic types of 35mm adapters, they are mostly differentiated by the movement (or lack of) of the imaging screen
- Static
- Vibrating
- Spinning
All adapters have a piece of frosted glass, like a focusing screen from an old SLR. The 35mm lens projects its image on THAT glass, not the cameras sensor. The camera is focused on the frosted glass and not the world outside.
in a "static" adapter, this glass just sits there. Since its static, you can see the grain pattern, grain is OK, like film, but since it doesn't move it CAN look a bit off. You don't often see the grain, so its not as big of deal as some folks make out to be.
"Vibrating" adapters have a little buzzer hat vibrates the frosted glass at a high frequency. This makes the grain, when you see it, appear more random and somewhat blurred.
A "spinning" adapter has a circular piece of frosted glass spinning at a fast rate of speed. The effect is similar to the vibrating adapters but has much better performance and you almost never see the bad grain.
As you can see the three rise in complexity, not moving, moving a little, and moving a lot.. The price increases with the complexity.
On all 35mm adapters the image projected by the 35mm SLR lens onto the frosted glass is inverted. Some 35mm adapters have an additional set of optical elements that will re-invert the image. This is commonly called a "flip" module.
To flip or not to flip is the question..
With out a flip stage, the image your camera records will be upside down. As this is an all digital age, flipping it back right side up is easy to do once the image is on your computer. Filming to an upside down is tricky, but doable.
With a flip module you don't have that problem, but you do have SOME light loss and you will spend more money.
On my rig you can see the hfs100 and the Letus Extreme with a canon FD 200mm prime lens. You can clearly see the FLIP module (integrated into the Letus) You can also see that the entire system is mounted on a set of support rails. For the Letus this is a MUST. That sucker is HEAVY and will strip your cameras filter threads right out if not supported.
You can also see the 7" monitor that I have for focusing. With manual focusing in HD a bigger screen really helps, many consider it a requirement. FYI: When you go with a 35mm adapter setup, you no longer have AUTO FOCUS ability. NOTE: If your adapter doesn't have a FLIP module, then you can always just turn the external monitor over. (common practice)
So you have two main decisions:
Which technology (static, vibrating or spinning) and to flip or not to flip.
Top of the line would be a spinning glass system with integrated flip. Bottom of the line would be static no flip.
You can spend as much money as you want. There are lots of accessories and "good to haves," but you can add those over time so I don't consider them an UPFRONT expense.
OK, thats enough for now, as I just went through this research, selection and purchase process for my setup, I can offer you lots of very specific advice.
Just ask.