aperture and "grain" from the gg

Teddybear, Youve been batting 100% for me so far... I like this. Can you explain this one a little further for me, as I dont understand how shutter causes grain in front of my camera. I understand the correlation of the high f-stop and grain principle you described earlier... but I havent figured this one out yet. Thanks

tedin froybear said:
What will cause the GG pattern to be obvious from the cam side adjustment is a higher shutter speed.


Ted
Click to expand...
 
Last edited:
bwest,

I can only speak with authority about spinners, since the adapters i made and use are spinners. I have used different motor voltages so the results vary.

But the basic thing is, at some point, the cams shutter speed "captures" in time the spining disk. Just like using high speed to freeze athletes in sports photography and for "instant replay" in TV.

Some spinners use 5.9volt motors. I have used a 12v, 5.9v and 3v motors.
They have different effect on cam shutter speed.

Take for instance my current adapter which is for 35mm ( ihave made one for mid format) it is using 5.9volt motor BUT underpowered with a 3 volt battery supply.

It can handle shutter speed up to 60 without showing arcs and grain movement.

I can increase power to 4.5 volts and now it can handle 100 shutter speed.

power it with 6 volts doesnt make my design better because at 250 shutter speed, even if the motor is spinning at full speed, the cam can still "catch" it.

Plus it now has a strobing effect on the image.

Let me just say that grain is there in an adapter with a ground glass. Its just NOT PERCIEVABLE at certain speeds and conditions in fact its virtually invisible, but its there.

There are still several observations ive made in the development of an adapter, for instance you might ask, is it worth the effort using mid-format due to it big gg image? will the bigger GG image produce less grain since you don't have to zoom in so much?

In my 35mm adapter, gg image is 32 x 18 mm.
mid format gg image 42mm x 24mm.

In theory , yes.

In my actual test. NO.

The gains is not that dramatically obvious. So its not worth since the choices of lenses is also limited and expensive.


Ted
 
Last edited:
thanks again TB,
Im now on the lookout for strobbing and arcing that you describe, when experimenting with shutter modes. I do own one of the branded spinning adapters you mentioned earlier and have yet to experience any grain, even with the highest f/stops... none! But this spinner is new to me, as of November07, and I havent enough time behind it yet. Thanks for the heads up, and a great posting.
 
Your welcome bwest,

Do inform us in case you'll be experimenting. At what shutter speed do you begin to see the gg in your setup.

Ted
 
You must log in or register to reply here.
Back
Top