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

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

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.

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?)

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!

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!

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!

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.

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?

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!

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

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!

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

thanks, Les...
 

am downloading now and will now read up on your system!

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.

Mandy, thanks for reply...
 

While the site is nicely presenting a cool concept, there are little things that have me scratching my head - like I skipped Electronics 101 in high school so as to how to wire the battery to the cd motor is NOT a given for me... guess I'll figure it out. There's also no indication really as to which macro/diopter to use: +2? +4? It depends. I'm assuming based on trying to think the optics through that the "correct" image on the disc gives you something the size of a 35mm film frame/slide - I'm wondering about trying this with a bigger lens camera like the Sony FX1 where the diameter of the lens is bigger than the radius of the CD - but of course, I don't need to have the CD spinning entirely through the camera's field of view since in actuality it's "zoomed in" on the image projected...

Mandy, how's the upside down/backwards thing and do you find if you're cradling the camera/filming while moving that "things get thrown out of whack" too quickly and you're spending your entire life re-calibrating.

One thing I wonder about this versus the other systems being presented here that maybe don't use the spinning CD trick (ie. another spinning ground glass) is that CD's do seem to spin at a very high rate and no doubt the rpm's can affect to what extent you notice "noise" on your footage. This may beg the question of if the CD motor can be tweaked to go faster... if necessary... well, I'll be in a position to try this out in a couple days...

pls. keep us updated...

Ok, wiring the CD player is very simple. You only need two wires, but you have to determine which ones go to the CD motor, because there are a couple that are grounds and a couple that run the motor for the laser. Determine which ones by looking to see where the end off.

There was no mention of what macro he/she used. I have asked at the Mediachance site to speak to Roman, but have not got an answer yet. So without knowing, most people hear talk about 7+ or better (if I remember right).

I haven't really gone for the full housing using the project box yet, so I don't know if things are going to get thrown out of whack just yet, but I don't anticipate it. I am guessing that this will take adjusting here and there to make sure that it is working properly and the focal range is still correct.

When I zoom out with my camera, the image on the GG is really small, so that is why I am using the Telephoto lens to bring it in closer as well as a few other things that seem to be working out quite well. If the lens is big, I think you will get a better picture overall when you zoom in. Remember, you are just cropping when you zoom in closer enough and only get a small portion of the image.

The upside down thing isn't bad because all my shots are static right now - and I am using the magnet to reverse the image on the LCD. The left to right thing is tiresome during testing, but I am getting used to it.

The Spinning CD is not the best route for me, but it is the only one that works right now. One of the challenges is getting the CD to spinning vertically without 'wobble', which is apparent if you look closely at the footage. I don't know why, the CD motor works great and the CD is in good shapes besides the scratches on it. But I guess that learning will come in time.

I would personally like it to go faster, but maybe that is the problem, too fast might make it unstable and prone to more shifts (but thinking about cyntrifical force, probably not). I am using two AA batteries for mine and I can reverse the spinning direction if I need to.

I will let you know if Roman gets back to me. Have you started accumulating the items to build this machine?

I haven't started yet - but I will within the week...
 

I've done some digging here and came up with posts from last year that suggest that ultimately, a spinning CD might not be fast enough, hence the development of "built-from-scratch" systems like the micro 35...

I'll be starting to round it all up within the week - just a lot going on right now...

I hadn't visited this part of the site in a long time - it's amazing to see what people are trying to do...

Some of the various clips posted show a lot of promise...

Mandy, do you have more clips?

I'll keep you posted on how things work out...

thanks!

A question again about infinity. Is it better to have the camera on 35mm or on 105mm when focusing on infinity? I would think the closer the better (105mm) because when I used to focus on tv studio camera, we would zoom in as far as we could go, focus and zoom out - so which is better?

Good thinking, I'm sure your right about focusing best with a tele lens. It'll help me also, because I also didn't set mine on infinity too well.
The DOF artifact is much increased when zoomed in, so adjustments are best noticeable.

Tomorrow, since I am off, I am going to be focusing (no pun intended) on getting the infinity thing right. I want to be able to put together my DOF machine and not worry about it again. Then I can start thinking about putting it a project box and getting a macro filter.

I also updated my site :

http://dvstuff.250free.com

The video was really dark because night was falling, so I boosted the levels which is why it doesn't really look normal.

Oscar,

I did some more test today and YES it is alot better when I use the 105mm for my focus on infinity and then pull back to 35mm. Focusing is a pain as it is, the calibration is really tough, but it seems to work better at 105mm because things are alot clearly when trying to calibrate.

Website updated with new video test.

http://dvstuff.250free.com

One more thing :
Just a reminder to those that are working on this : good batteries are a MUST! I have been using a set of batteries for about 2-3 weeks and they are running fine, still some juice in them. After using my new GG, it didn't look so good and the CD spin seemed a little sluggish - BUT without the CD, it spun very fast. I thought it might have been the new GG CD. So on a hunch, I decided to change the batteries - and WOW! What a difference! All the lines and little breaks in the GG went away and the CD spun like a top. Going to keep a fresh set on hand and possible get some high energy rechargeable for this.

New footage coming with the new focus on inifinity.

BTW anyone got a recommendation for rechargeable that keep their juice and last?

Is it a little color shifting in the left of your footage?

About focusing:
It is still hard to focus really good, when you'll be actually filming. You don't have a focusing circle like photo camera's have. Somewhere on the board I mentioned a separate viewfinder, and measuring the distance with a tape measure.
But I'm thinking, maybe those laser measures are precise enough, and could be mounted on the adapter. You'll be able to point a laser on the subject, copy the distance on the lens and that's it.

I doubt if anyone is capable to pull focus on something moving out of the sharp area.

I don;t know if there is colour shifting, maybe. I ordered a 7+ to 10+ macro filter today. I can't wait any more. I also went outside and got some footage, going to view it and see what it is like.
As for the laser measurement, tape will do the same trick like on a real production, but if you are lacking crew, I think that would be a good idea and that way you can set the barrel to the correct distance. Once you are outside of that sharpness area, you are right, there is no coming back - got to move the camera. How are thing with your system?

Mandy, thanks for asking, my adapter is almost finished. Some big things which will take some time are an anamorphic lens (I'll try to make it with a little curved acrylglass box filled with water) and a viewfinder.

Also, the colors on my tests are very nice, warm and saturated on the reds. I don't know if it's the GG I am using now, but when I test a GG with window foil, I'll know.

Oscar, that is great that you are getting some vivid colours! I want some! I am wondering how you are getting such great and vibrant reds etc.

Are you using a macro lens? As I have said, I just ordered one, I hope that does the trick - but besides that, what are you using as GG to get such good colours going (if it is the GG)? Any other updates to your website? New pics of the machine?

Looking forward to it!

Also that anamorphic lens with the water thing sounds astounding! I would love to have a look see at it when you are ready - that is pretty ingenius - does it really work?

I really don't know yet (on everything you asked), but as soon as I know about the colours, I'll post on your GG tread.

Last test before I get my Macro. These is no sense testing anymore, I know what needs to be done to change this and without getting the focus right or the sharpness of details, I can't get beyond the prototype stage.

http://dvstuff.250free.com

This is using my homemade GG, I like it alot better than the frosted CD that came with the DVD packs. I am going to start looking into the spray glue with different types of surfaces for this.

Oscar,

That cool. Let me know how things turn out.

I am reading this little tidbit about lens :

Taken from the URL

http://www.digicaminfo.btinternet.co.uk/dslrlenses.htm

"Most SLR's are given as having a focal length multiplier of a certain size in order that it can be worked out what the focal length/field of view are, in 35mm terms, and this is relative to the size of sensor used. Thus Canon's 1D has a 1.3x, all Nikon, Pentax and Fuji's a 1.5x, Canon's other SLR's a 1.6, whilst Sigma's have a 1.7. The 4/3rds sensor is half the area of a 35mm frame so a 2x factor gives an equivalent focal length. So the 14-54mm standard lens fitted to the E1 equates to 28-108mm in 35mm terms. The smaller the sensor, the larger the multiplier factor will be. "


Now, because I am building the DOF machine, I have to make the Focal length adjustment myself on the fly, it is sort of hard, so I was hoping this would help. It says that Sigma's 35-105 Zoom (which I have) have a 1.7 - but 1.7 what? Inches? Cm? This will enable me to accurately set the infinity focal length.

If you look further down the chart, I can see that the Sigma falls under the 1.7 (I guess), but since mine is a 35-105mm zoom, I cannot figure out where to go from here.

When I set the infinity, I am using the 105mm and zoomed in as far as I can go, so that when I zoom back, it will be in focus.

Any help on this?

The 1.7 is a multiplication factor. However, it is not an issue with these adapters. It's only when 35mm lenses are used on digital SLRs which have smaller imaging areas.

Ok, so no help there I guess. Darn it! I want to set this exact!

Ok, so now I am really confused on this FOCUS TO INFINITY mechanics :

http://dvstuff.250free.com

Here is what I did. I took my DV cam out of the equation, using only a magnifying glass and the GG, I zoomed out to 105mm at inifinity on my SLR - then I adjusted my GG to focus in properly. Came in clear - see first picture.
Now in my experience, if you focus on infinity, you zoom in and focus - when you zoom out, even else is in focus as well. Not so with this : seem picture 2.
In picture 2, I zoomed back out to 35mm, leaving the rubberized part on infinity. Blurry and unuseable!
I am guessing the SLR work different than TV cameras?

Also - I had to institute the DV camera to take these shots - but even without it, using only the magnifying glass agains the GG - the 35mm at infinity is not sharp at all.

Does anyone know what is going on?

Ok, after thinking about it last night - I am mixing about zoom/focus to infinity with Focal Range. Ok, got it. Now I can move on.

When calculate for focus length-

1) do you measure from the front lens to the object

2) or do you measure from the back of the lens to the object

3) Or do you measure from the GG to the object

Thanks

technically, the focal plane...
 

Mandy, if I remember correctly, your focal plane should be where focused ie. GG so should measure from GG when it's in the right place... On movie sets when they measure focal distance, they don't measure from end of lens - there's a line on the camera body indicating where the focal plane is "inside" the camera and focus measurements are taken from that marker...

Quick question since I'm new to all this - does field of view when you build this and film with vidcam via macro pretty much match what you see if you just have your lens attached to SLR camera body and look through eyepiece? Ie. does lens on SLR body work effectively as "director's viewfinder" or does the ballgame change drastically once lens is on adaptor? I think it should be the same, right?

Mark,
it should be the same, but only if you have the light well spread on the GG. Otherwise you'll have to zoom in on the GG to get rid of the dark edges.
I'm thinking of taking apart a photo camera and cut off all but the lens mount and the eyepiece to use it as a directors viewfinder ánd a separate attachable viewfinder on the adapter.
But maybe I'll build it with spare parts.

Mandy, here's a thought?
 

Just visited your site and saw your chart/couch tests for infinity - remember that Mediachance recommends focusing on something "far away." I'm wondering if you're too close to your focus reference object (ie. chart) for it to work right? Infinity is supposed to be far away...

I dunno. I'll be doing this tomorrow, so I guess I'll report then!

Good luck!

I stupidly, yes stupidly assumed that infinity would be ok at 3 meters. My bad, my mistake. Taking Jonathon advice, I measured out 1.6 meters at 105mm - which is the nearest point on my SLR and focused to that on the chart (which works great). It now looks better and seems to focus alright. I won't be able to really tell until the MACRO filter that I ordered comes in - called today and still not there!

Right now I am trying something new. I have tried the Tracing Paper route - and mine is too thick. Nice picture from the GG, but too dark. I need a light grade or gauge. Still looking - but what I did was this :

I sprayed the CD with Spray glue and then looked at it - my goodness, doesn't it look like a frosted CD with just the glue on it? Going to run some test when it dries to see if this is another viable option.

Mark, good on you! Keep me posted on your progress.