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Old February 4th, 2005, 09:09 PM   #1
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When focusing on infinity...?

On my lens, I have two manual rings - one is the rubberized barrel that twists, but doesn't seem to change the focus and the other - which has a push in button to twist pulls the barrel in & out and seems to change the focus. So my question is :
When focusing on infinity, what does the rubberized barrel do? It is the one with the infinity symbol, but I am trying to work out the inner workings here ( and having alot of success), but I want to know what I am turning and why, when I am turning it!

Thanks
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Old February 4th, 2005, 10:05 PM   #2
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Ok, after more testing, I really can't get the hang of this thing. Everytime I try to focus on infinity (or what I think it is on the lens), everything is in focus.
The ring that moves (with the push button), has the 'normal' 1:10, 1:8, 1:6 and 1:5 on it. The rubberized ring has ft and meters on it and the infinity sign. But I don't know what to line up and where!

It is a SIGMA lens
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Old February 4th, 2005, 11:58 PM   #3
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Do you have a picture?

I think I understand what you are saying.

There should be a painted/engraved line somewhere around the focus ring. This is what you want to line the infinity symbol up with. If worst comes to worst turn the ring until you cannot anymore and then look at where the infinity sign ends up.
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Old February 5th, 2005, 09:39 AM   #4
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I will post them shortly after I recharge my battery!

Still a little stumped. Daylight, focused on trees in the background, looks good - as focused as I can get it - the curtains that are about less than 1 foot away are out of focus. So far so good -

Background in focus (infinity, pretty far away, about 3 blocks)
Foreground out of focus (curtains, 1 foot away)

But when I try to focus in on the curtain, which are in the foreground, they will not come into complete focus, they are still blurry.

Ok, so maybe I am too close to the curtain. So, the I pull 35mm rig back a bit farther away - now I am 3-4 feet away from the curtain.

Now, when the curtains are in focus, the background is also in focus! That is not what I want at all!

This is with the INFINITY SYMBOL on the LINE and turning the ring that has a push (depress) button to unlock on it. The rubberized barrel doesn't seem to do anything for focus (maybe only if I pull it out for a macro will it do anything?)
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Old February 5th, 2005, 09:58 AM   #5
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Ok, some more tests. I have tried painstakingly to make sure I am in focus at infinity (and there isn't any real way of knowing because I am eyeing it) and everything was in focus - so this is what I did. I pull the rubberized barrel part out - telescoped it - and noticed the numbers - 35 - 55 - 75 - 105. When pulled out to 105, it looks great - foreground in focus, background, very blurry and vise-versa. So, it is working, but I guess I need to brush up on how a lens works.
I remember Bob Hart saying that 55mm was the best - so I tried that - pulled the rubberized barrel out to 55mm (but did not refocus to infinity, maybe I need to?) and looked through. It wasn't that great. Everything was still in focus. But when I tried it at 105, it was awesome (although everything was alot closer).

Now, I know that 35mm lens still have some DOF, and this is where I focused to infinity, but I am not really getting any DOF at 35mm - so I am still doing something wrong, I suppose ( but I am getting more excited all the time!).

Again this isn't taking into account the f-stops on the camera or anything other marks. I am just trying to focus this thing on infinity right now, where I'm getting some DOF at 35mm!

So, someone with a clear understand of photography, could you please please please give me a quick lesson or send me to a url that has a guide to how lens (and there tick marks, telescoping etc) work? Thanks!
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Old February 5th, 2005, 12:22 PM   #6
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Here is the first test :
http://dvstuff.250free.com/DOF1.WMV

or if it doesn't work, just go to
http://dvstuff.250free.com/

Any comments appreciated!
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Old February 6th, 2005, 05:39 PM   #7
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I am very frustrated with the housing. I don't know how many other went through to the end on this DOF machine, but I will tip my hat to them.

Setting up the two boards with the lens attachment and the CD motor is a piece of cake - even finding out the exact measurement for infinity proved to be tedious, but not taxing as far as mental capacity went. Now, here comes the frustrating part :

I went to radio shack and bought a project box. 8 X 6 X 3. Good enough. Although I wanted a deeper box, this will do.
So back to the project and reading over carefully what the guy from Mediachance did (and he did it in under 2 hours for the enclosure part) I hit a roadblock.

Yes, the enclosure is just a box around the device, but there are alot of other factors to consider.

1) the screws that are used for getting the exact distance for the two boards are now used to hold the entire piece inside the box - therefore, I need to take apart the boards, all the painstaking work I put in to focusing on infinity (although I have measured it for future reference) is going to have to be reset - but worse than that - since the front board is now attached to the Plastic housing, I am going to have to redo the infinity test, but this while it is IN THE BOX! I have small fingers, but goodness, I don't know how the person from MediaChance did it!

2) I only get one chance with this box. Once cut, it is about $10.00 to get another. I don't want to make a mistake.

3) I am putting in a DCX lens to cut down on hotspots and glare, it works pretty good, but a pain because of the small work area inside the box.

4) Lastly, I have to make sure that the GG picture lines up with the DV camera lens - and that has to be cut in the back of the project box as well! A task for sure for any person!

If anyone has words of advice (besides giving up), let me know. If anyone has attempted this and come out the other side, encouragement please!
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Old February 6th, 2005, 06:40 PM   #8
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I've stopped to make everything as small as I can, but since you already have the box...
I don't really know the setup of your adapter, but maybe you can make sheaves in stead of holes and use bolts in stead of screws.
If you attach the bolts with epoxy (or some other strong glue) onto the boards (or one of them) , than the box and than put the nut (is this the right word?) on the bold. Now you can adjust the distance by moving the bolts in the sleeve and tighten the nut when it's in the right position.

If I'm talking nonsense, you'd better post a picture of the adapter and the box.
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Old February 6th, 2005, 06:45 PM   #9
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Well Oscar,

Frustration is the mother of invention (or so I say). I had a huge, I mean huge breakthrough!
I am not using a macro filter, and right now, not even the DCX lens and getting awesome results! I found an adapter I was looking for that solved soooo many problems, I just wouldn't know where to start.

As far as the housing goes - I am bolting everything - and instead of jumping into the Plastic PVC project box, I am making a mock up model out of wood for a housing to see if it all goes well.

My problem comes in the adjustment phase. There are four bolts that are used for adjusting this thing, but those same four bolts also are used to hold the three boards to the HOUSING unit - get it? So, I have to run the bolts thru the housing, and THEN try to adjust it aftewards - which wouldn't be that particularly bad except, I am using a 6 X 8 box, and therefore there is no room to stick fingers in to adjust and then use the nuts and washers to hold on tight! I will try and make a 3D mock up in the next little while, but right now I am too excited about the new adapter. I takes all of my worry out of adjust the DV cam and no that I dont need the MACRO filter! I am hoping to be ready to start shooting next week if all goes well!

Thanks for the constant support Oscar! How goes your project?
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Old February 6th, 2005, 10:05 PM   #10
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A new test tonight. This is without a housing, so there is light-loss due to this. Also, without a macro filter (I think I might get one anyways, because my system is a little too complex which will be simplified with a MAcro filter. I have fixed infinity, it is about 44mm away from the GG. I need to stop using the GG I have, it has become scratched, but that is ok because I have another one that is unused. There is still some wobbling and around the edges - hopefully with some padding this can be sorted out. I want to put in a LED light as well.

http://dvstuff.250free.com

or

http://dvstuff.250free.com/dof3.wmv

Comments always welcome!
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Old February 7th, 2005, 09:59 PM   #11
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IMPORTANT QUESTION on this : you can see the light sort of wave in and out when you watch closely - is this because of an unsteady CD or something else?


Ok, another test today. This time in an enclosed housing unit keeping 98% of the light out. I really notice the fogginess because of the pseudo macro filter I am using. Going to have to buckle down and get one for this.

http://dvstuff.250free.com

or direct Download http://dvstuff.250free.com/DOF4.WMV
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Old February 7th, 2005, 11:34 PM   #12
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Hi Mandy - thanks for your efforts...

Mandy, I work at a t.v. station where we use Roman's products (mediachance) and I came across the article for the d.o.f. machine and found myself intrigued....

sorry if there's more info about your work in another thread...?

Does this thing really work? I mean, it sounds good in principle - your tests are interesting...

I too look at the pics of the radio-shack case and wonder how he easily re-calibrated once he had to "lock it down."

But it's a great concept and I'm interested in figuring out if it's worth attempting to use with new Sony HDV cams (I get filmic color with magic bullet, deinterlacing software gives filmic cadence - now this d.o.f. machine will give me depth of field - voila - ultimate film look...)

Please tell us more!
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Old February 8th, 2005, 12:54 AM   #13
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Mark,
If you want to see what HDV looks like with my adapter, see this thread:
http://www.dvinfo.net/conf/showthrea...threadid=38670

I have 1280 x 720 ( 720P ) demo clips that show my progress on the device. No grain. No shake.
See the later part of the thread for current demo clip.
Enjoy!

-Les
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Old February 8th, 2005, 01:39 AM   #14
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thanks, Les...

am downloading now and will now read up on your system!
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Old February 8th, 2005, 07:01 AM   #15
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It works in principle. Still some bugs in it. YEs, the re-calibration thing is something that I struggle with and trying to figure out how to re-set the focal range after you place it within the confines of the project box. There has to be another way. Also, the vibrations of the CD, tend to cause all the nuts to loosen over time (need to fix that as well) and I need a Macro lens to take care of the cloudness that is there, but the tests are looking good so far. I have tried to get a hold of Roman's DOF person to ask all the same questions you asked, because when I was building it, i need to know it myself and went thru alot of growing pains.
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