Totally Home-Made Oscillating Mechanism

[Gev Babit]

I didn't use a condensor cause it wasn't really doing anything, but the image is a little soft and looks low res. Maybe the condensor will make a difference but the one I have has alot of chromatic aberration, I dont want the yellow and blue fringe. I've noticed most of the adapters are soft, what does ps technik use to get it sharp like the camera is without the adapter? James' Micro35 is pretty sharp, sharper than most of the other ones on here.

[Gev Babit]

Does anyone know if it is possible to control auto focus lenses? I have a nikon AF lens that I wan't to make a remote to control focus through the motor but I'm having trouble finding schematics or something that shows how the actual electronics work. I'm thinking of getting a cheap AF camera body and see if I can use the electronics to control the lens. A follow focus unit is
good but this method seems better. Any advice or tech info on this would be a great help. Thanks

Gev

[Les Dit]

Any updates on your device? Did you run into any hotspot problems?

[Gev Babit]

Hi, how is everyone?!!!

I have been working on it and solved the hotspot and optic problems by using a condensor. With the condensor I dont need to use a magnifying glass just the camera.

I have a question about optics though. Im trying to make a follow focus unit by moving the lens front and back instead of using the actual focus ring on the lens. Are there any optical problems by setting the lens to infinity and moving the lens forward and back. I will make sure that the lens doesnt go beyond the focusing distance that it is set by the manufacturer, i.e the closest my nikon can focus is 1.5 feet, I will not exceed that using this method. Instead of using the lens focus ring and custom gears for each type of lens ring, I will be able to move the lens forward/back with the mechanism and be able to make adapters for each kind of lens(i.e canon, nikon) to not exceed its focusing distance. Is there any optical issues?

Thanks,
Gev

[Brett Erskine]

None that I could think of except the fact that the difference between infinity and minimum focus is often measured in a few mm when it comes to back focus. IF you decide to do this mechanism you can imagine the percision that would be needed in order for it to smoothly work properly. Also (as you noted) you would have to set the end marks for each different lens you use.

It's a interesting idea but I would recomend you not do it for simplicity sake. Perhaps you make the back focus adjustable for accurate focus purposes only. Just my two cents. Good luck.

[Gev Babit]

Thanks Brett!

For me, at least, this seems easier cause each lens has different diameters, and the focus ring moves forward a little when you turn it. With this method I find it easier , and I can integrate it with the enclosure.
Here is a test model I built for testing and experimentation..

www.papalico.com/FollowFocus.mov

[Dan Diaconu]

Gev,
I am sure you are aware of macro accessories for still photography that do just that. (it might save you some time of building it) One limitation (I think) would be "marking distances" (if need be) and speed in racking focus (if applies)
Otherwise, great job. You have focus with FF in one! Great! Keep it up.

[Gev Babit]

Thanks Dan!

The macro stuff sounds interesting, where can I find those products from? Im looking for small sizes.


Thanks,
Gev

[Dan Diaconu]

http://216.25.78.123/smallpics/olympus/104100.jpg

google for "macro rails" and once you know what to look for, check retailers on line or local second hand.

[Leigh Wanstead]

Hi Gev,

Excellent work

Can you tell me what is the oscillate theory behind your device? I only know project image to the ground glass. I don't know how motor make your ground glass moving.

TIA
Leigh

[Leo Mandy]

Gev,

What kind of condenser lens did you get and where did you get it? And if you don't mind me asking, how much did it cost?

Thanks

[Radek Svoboda]

Gev,

You said originally that condenser had color fringing. Does fringing get better if you move condenser closer to screen?

The focusing with adapter is problematic because on telephoto you need to move lens a lot and on wide angle only very slightly.

Radek

[Gev Babit]

Sorry for the late replys guys been busy.

Leigh: I put the link to the diagram from the oscillating thread that shows how it works. That should give you the basic idea of how it works, the difference between my adapter and that one is that I use two plates. I suggest you read the oscillating thread as it is explained, and there is alot more information in that thread that has helped me. Look at the pictures and footage of my mechanism in the beginning of this thread, you can learn about it there, I have explained how it works in detail. This is Rai Orz's Diagram from the oscillating thread and the thread itself.

http://de.geocities.com/raiorz/vibro_old/vibro1.jpg
http://www.dvinfo.net/conf/showthrea...threadid=27290



Mandy: I got a condensor from www.surplusshed.com.
In the menu choose "lensfinder" and put in this info. You dont need to put all the info just choose "PCX" lens and put minimun diameter to 48 and it should find it. Verify the results with the stock number.
Stock#: L8115
Type: PCX
Diameter: 48.0
Focal Length: 82
Coated: Y
$4.00


Mandy & Radek: The fringing problem does get better the closer you are to the ground glass. Although when you get too close, for me at least,1mm away, I got a barrel distortion like effect so you have to play with the distance from groud glass until there is no distortion or color fringing. Also experiment with the camera distance from condensor. The condensor works good enough that I didn't use an achromat (Im using the DVX100A).Unfortunatly I couldn't fully get rid of the chromatic aberration because as you move to the sides you see it more. The middle is fine but the sides are not so good. For me its not acceptable but maybe for you it will be. Its not that bad but its still there. I have to say that the condensor gave me the sharpest and brightest image from what I had tried before. The ccondensor works perfect except for the SLIGHT chromatic abberation, so for $4 you can try it and see....it can't hurt to try it and maybe it works for you. Later I got a focusing screen that I bought for 5 bucks that worked pretty good except there was a circle in the middle, so I decided to go with the Maxwell focusing screen and it works the best for me, I am very happy with it.

Here is the distance I used that worked the best for me with the Surplus Shed condensor.

25mm from Ground Glass. The flat side towards the Ground Glass. The condensor is supposed to be as close as possible but this gave me the best balanced image. The Camera was around 15mm away from the condensor. I should not that since the focal length of the condensor is 84mm the camera should be around 3 inches away. I used 15mm instead of 3 inches because I didn't want to use an achromat and make the adapter long. The achromat adds extra glass and distortion. These numbers worked for me, there was no vingeting, hotspot or distortion. The only problem, again, was the slight chromatic aberration. I used the DVX100A so you can get different results with different cameras. I suggest experimenting with the Condensor distance from Ground glass and the Camera distance from condensor to get the best picture and balance between hotspot, distortion, vingeting and chromatic aberration that works for YOU. Im not an optics expert, this is based on experimenting and my limited knowledge of optics.

[Shawn Murphy]

Hey Gev,

Any samples/examples from your latest efforts?

thx.

[Leigh Wanstead]

Hi Gev,

Thank you very much.

Regards
Leigh