John what's the size of the fresnel lens 2x3?

<<<-- Originally posted by Peter A. Smith : John what's the size of the fresnel lens 2x3? -->>>

it was 2x3 :) then I cut it up into 2x2

Is the Fresnel lens a subsitiute for a macro lens?

http://scientificsonline.com/search.asp?t=ss&ss=fresnel+lens

Here's are several decent Fresnel lenses you can get and then cut down to what size you need.

Here's another place as well:

http://www.3dlens.com/fresnellens.htm

Do you see the lines from the fresnel lens on your recorded image?

would it be possible to rip a fresnel out of a 35mm slr camera?

Zac

To invert the image you could also inster a dove prism in between the GG and the camcorder lens or fresnel:

http://www.optosigma.com/miva/merchant.mv?Screen=PROD&Store_Code=OS&Product_Code=pg137&Category_Code=Dove+Prisms

John,

Thanks for the answers. I am going to try to get started this weekend. Is the fresnel lens used so that you don't have to zoom in so far? And, how much does it help the problem of not having enough light? Thanks again...

Clay

Originally posted by John Gaspain : HELL YEA! thats what i needed! its adjusted out a little over 1/4". This fixed any vignetting.

Let's see some footage!

If you don't have hosting for your footage, drop me a line at info@ideaspora.net and I'll park a 15mb file on my server for you.

- jim

So is the fresnel a good replacement for a macro adapter? Which would be better?

Thanks

The way I see it, the fresnel is placed between the SLR lens and the GG to focus the light more directly onto the GG.

1..2.3....4..5.6.7.........
[| < |==== | [|[|CCD

1.SLR lens
2.Unfocused light rays from SLR lens
3.Fresnel Lens (about 1/4 inch from the GG)
4.Redirected Light Rays (reduced vigneting)
5.GG
6.Macro Lens attatched to Video Camera's lens to allow it to focus on the 35 mm negative sized image on the GG while zoomed in.
7.Video Camera

Hope this helps some ppl out...excuse my terrible ascii art skills,
Spencer

<<<-- Originally posted by Spencer Houck : The way I see it, the fresnel is placed between the SLR lens and the GG to focus the light more directly onto the GG.

1..2.3....4..5.6.7.........
[| < |==== | [|[|CCD

1.SLR lens
2.Unfocused light rays from SLR lens
3.Fresnel Lens (about 1/4 inch from the GG)
4.Redirected Light Rays (reduced vigneting)
5.GG
6.Macro Lens attatched to Video Camera's lens to allow it to focus on the 35 mm negative sized image on the GG while zoomed in.
7.Video Camera

Hope this helps some ppl out...excuse my terrible ascii art skills,
Spencer -->>>



Have you even tried that ? cause i believe it wont work, the fresnel have to be after the GG and before the Camera.

So does it help light and focus then?
Thanks for the diagram Spencer.

John,
can't wait to see the footage.

Clay

<<<-- Originally posted by Agus Casse :

Have you even tried that ? cause i believe it wont work, the fresnel have to be after the GG and before the Camera. -->>>

I've tried it and its the only way i belive it will work. Also take a look at John Gaspain's design:

http://www.imagestation.com/picture/sraid92/pd377ca006084d6c60555434c2779084c/fa531009.jpg

I don't think the fresnel is accomplishing anything optically if you place it after the GG. By then all is done in terms of vignetting on the GG, nothing you can do to change it from the Camera side besides zooming past it.

Anyone else try out a fresnel?

Spencer

Post some footage i am actually curious cause i didnt use a fresnel, i use a magnifying glass in the Dv lens.

Nice evolved model dude :) how much are you spending so far ?

I am experiencing a high flicker... anyone have any idea why?

here are two pics (after film look post) from video i did today

http://www.orfilms.com/luke1.jpg

http://www.orfilms.com/luke2.jpg

Agus, John, and anyone else who has made one,

How do you know where to cut the holes? Obviously, one hole has to be bigger than the other. Do you just guess as to where they should be?

Is a fresnel lens the same thing as a magnifying glass? I went to Walgreens and got a bausch and lomb "magna-thin" magnifier as it is the closest thing they had that resembled what John used. Is this it?

John, I bought the bigger box (8X6X3) and the GG clears it fine...just a little more bulky. I have all the stuff ready to go, but don't want to mess anything up and have to start over. Also, John, how did you connect the camera to the box?

Ok, can't wait to get started. Thanks in advance for the advice!

Clay

To Peter Sciretta.

High flicker. My guess is you are getting an intensity strobe effect which might be related to variations in density or texture of your groundglass surface and the disk rpm coming close to the frame rate of your camera which means that although the texture of the surface will be moving fast enough past the frame to average out all the small defects, larger patches of say quarter to half a disk size will phase in and out of your frame. The scratches on your groundglass disk - are there some which go straight across the disk or uniformly circular in an even finish?

Your 35mm lens centreline axis is also bent off-centre to the left in your second frame so I guess you are at very early prototype stage yet.

According to this link from what i understand: http://www.camerascreens.com/PDF/Installation_Guide_For_View_Cameras.pdf

You put the fresnel lens between the gg and the lens.

Here's a difinition from B&H photo: A fresnel lens is an accessory for a groundglass focusing screen. It helps "even-out" the brightness of the groundglass image and make the image appear brighter. The effect is more noticeable with wide angle lenses. Fresnel lenses are essential when using reflex housings.

I haven't tried this out, but i'm going to assume it should be place between the gg and lens.

Clay just know the size of your SLR lens and Camcorder lens, then get a hole saw or a mill and drill the holes. You need to convert the millimeter sizes to inches e.g. 37mm = 1 1/2 inches
52mm = 2 1/8 inches, 58mm = 2 3/8 inches

Friendly advise from a fellow Texan

Peace Peter

My bad Clay you asked where to put the holes. You have to be careful aligning the lens hole and camera hole. I goofed once and had the lens hole lower than the camera by 1/4 inch. So one side of the film can became useless. Just measure and mark each placement of your holes including your motor and thay should lessen the degree of the vignetting.

More friendly advise from a fellow Texan

Hey Peter,

Thanks for the advice. I got out the ol' trusty tape measure and got the inch readings. I hope to find center of both and somehow line them up and get them centered. I just didn't know if anyone else had any tried and true methods. I am still wondering about where to drill the holes on the box (CD spindle)??? I guess that's what makes this so great...fly by the seat of your pants! Well, we'll see what I come up with if I don't hear from anyone else...

Clay

John, very interested in seeing footge...

I haven't had great luck putting anything together just yet... I guess I'm just not great at putting stuff together...

Just tested my frosted CD with the lens, was surprised it looked very good and it wasn't even in a casing. Will try and get this done over the next week and post some footage.

I put the scratched cd directly infront of my GL2 and it went into macro mode and focussed on the cd, would I still need a fresnel lens or a macro adapter?

I'll test some more when I have a casing.

<<<-- Originally posted by Peter Sciretta : I am experiencing a high flicker... anyone have any idea why?

here are two pics (after film look post) from video i did today

http://www.orfilms.com/luke1.jpg

http://www.orfilms.com/luke2.jpg -->>>

Hey man, that looks really cool, BTW i am upgrading my Agus35 using all the tips that everybody have posted here. I am making a support skeleton using aluminiun rods, also i am making a matte box which can be attached to the whole thing.

I will post some footage soon and also the plans, which seens not necesary ... :-) but still will make them...

for all the newbiews here is some footage.

http://altoque.tv/maserati.wmv

http://altoque.tv/35mmAdapter/kartfilm.mov
http://altoque.tv/35mmAdapter/moto35mmfilmtest2v4.mov
http://altoque.tv/35mmAdapter/spotAdapter35mm2.wmv

http://altoque.tv/35mmAdapter/Agus35maseratitest.wmv

Some pics

http://altoque.tv/35mmAdapter/35mm7_0004.jpg
http://altoque.tv/35mmAdapter/35mm7_0005.jpg
http://altoque.tv/35mmAdapter/35mm8_0001.jpg
http://altoque.tv/35mmAdapter/35mm8_0003.jpg
http://altoque.tv/35mmAdapter/35mm8_0008.jpg

http://altoque.tv/35mmAdapter/moto01.jpg
http://altoque.tv/35mmAdapter/moto02.jpg
http://altoque.tv/35mmAdapter/moto03.jpg
http://altoque.tv/35mmAdapter/moto04.jpg
http://altoque.tv/35mmAdapter/moto05.jpg

Alright, some questions on tightening up the design...

I put mine together tonight, after having received my macro zoom yesterday, and it's functional, but there is a noticable haze around everything.

I used 600 grit sandpaper, and did my best to put down an even surface. I've got my apertures wide open, and setting the 35mm lens to an infinite focal plane, I've set my DV camera's manual focus.

So: how do I remove the haze, or cut it down significantly?

Agus -- in your experience, was haze a problem? If so, do I need to up the speed of my motor? (I'm using a CD motor, but have a Radio Shack 18,000rpm motor at hand...)

Jesus this needs light :)

- jim

Dunno what is haze ....

BTW.. tip for all, i found a little teasure... look for fake cds what are already translucent... they are 100% perfect GG !!!!! I found 2, and i have a 20% image improvement...

what do you mean fake cds?

<<<-- Originally posted by Danny Tan : what do you mean fake cds? -->>>

They are the CDS that protect the CDR in the 50 spindle packs, they are useless, and they are crystal clear. but some have a traslucent texture in one side that works a like a perfect GG

Agus,
Are you saying do not sand the translucent CD we get in the case? Fake CDs, this is all I can think of. "ook for fake cds what are already translucent." Then, what is the purpose of spinning them? I have all the stuff sitting in front of me to make the AGUS35, but want the best results...that's why I haven't made it yet! Spill the beans Agus! We need detailed news! You are the man....

Clay

No no no ... most spindles comes up with fakes cds that are absolutely clear, but some of them in one side have a sanded texture just like a real Ground Glass, those are not needed to be sanded... cause they have a sanded texture already made..

i have been trying to build a baseplate with rods similar to http://www.jbkcine.com/i-1.JPG

i made it, but still isnt too rigid. need to work more...

ANOTHER TIP..

when painting the Agus35, be sure to paint the inside side, cause if you dont, any scratch could ruin your paint and you dont want any outside light to ruin the image in the GG

can you post pics of your ground glass? i am using the "fake CD" that came in my spindle and used 400 grit sandpaper to sand one side but i want to see how yours looks like

Agus,

What brand of CDs are you buying that have this "already grounded glass?" The two I have are clear, so I must frost them myself (man I hope I don't screw both up!). As for the support, I am hoping to get some long rectangular aluminum brackets that create a mount to both my camera and box (I plan to use lots of washers). We'll see what old Lowe's (a hardware store here in Texas) comes up with! The more the better...keep posting everyone!!!!

Clay

and also, can you post pics of how your metal mounts with go on your camera?

By "haze" I mean that the image has some crisp details that are obscured as if they're shot through a fog. I'm re-attempting my initial design today, using the Radio Shack motor instead. If increasing the disc's rotation doesn't help, I'll assume it's the ground glass that's causing my problem.

Agus -- what kind of motor are you using to spin your GG?

I can tell you the best motor by far is one from a cd disc man

Well, that remains to be seen. I've already used one, and it's certainly quiet and stable, but it may not rotate at a high enough rate.

More to the point -- I've seen a lot of Agus's footage, but little of everyone else's. So I'm inclined to use Agus's design as the best point of reference.

400 !!! damn , i complained cause i used 600, use 1000 !!.. about the pics let me see what i can do.

i went to home depot and the highest they had was 400!! let me know where you can find 1000 grit online

I really want to build an Agus35 but before I do I want to get my info right, so please bear with me on this one.

Does the .7x wide angle converter (Century Optics) or the Achromatic Diopters (Century Optics) create depth of field to be used with the Agus35?

I'm not to keen about the physics of light and the lenses you guys are using. What lenses do you guys recommend to a novice like myself who doesn't know much about SLR lenses?

I want to do some close up work, like with the achromatic diopter mentioned above. What lenses would you guys recommend?

Is a eBay a good source to find these things? What about Ritz, or B&H Photo Video, etc.?

The interchangeability of lenses have been adressed before and I wanted to know all lenses were compatible with the F to C mount adapter mentioned in a post earlier. Thanks for your guys' help!! :]

i found some 1500 grit online. should i get that?

You can find "Sanding Films" where they sell plastic models. They are made by Testors and the finest is REALLY fine. I used the next finest to start with then used the finest to finish. I started my adapter last nite and I will post some pics as it progresses.

Tom

do you have a link to the product?

Randy,

I had the same confusion with the wide angle adapters, but they are saying you need to get one that is wide angle and macro so that you can use the macro part, not the wide angle part. Go to ebay and type "wide angle macro ??mm", with the ?? being your thread size needed. That's where I got mine, and it was only $32. As for the SLR lens, get the best one you can. I would try to find a 50mm f1.8. The 50mm is the closest to what the eye sees. Remember, you want the best lens possible! Good Luck...

Clay

if you had a 50mm slr lense then you would want a wide angle macro 50mm?

nvm, i found a wide and macro lense where the front lense detaches and then it becomes a macro lense! perfect for this right? and also, i bought some fresnel lense. would that help the vigenetting and stuff if i put it between of the macro lense(connected to camera lense) ang the ground glass?

Danny,

The macro is for the video camera. You don't need the wide angle part. Here:

Camera - macro - spinning cd - fresnel - SLR lens

That's the order. If you are confused about mm, look at your video camera lens and there will be a number (37 for mine) with a circle and a line through it next to the number. This is the thread size for filters, extensions, wide angle and macro lenses to be added to the video camera. Hope that helps...

Clay

ok i get it now. so the wide angle macro lense with the detachable wide angle lense will work then right?

Any cheap macro filters for the gl2?

yea probably. agus used a magnifying glass in his original one i think

The gl2 shouldn't need a macro lens at all. It can focus on things all the way up to the lens itself.

ok so can some1 confirm that the GL1/GL2 doesn't need the macro lense? i dont wanna waste $40