35mm Adapter Static Aldu35

[Aaron Shaw]

Just thought of something - this may already have come up:

Would it be possible to use waxed paper of some sort combined with a GG? The paper may show grain I suppose but it may work?

Just a thought!

EDIT:

Sorry, that GG should be just "glass" - No reason for a GG!

[Aaron Shaw]

Just a few questions:

I didn't think these deserved their own thread and since it is related to the issue of 35mm adapters I put it here.

1) How much deeper is the DOF of 16mm lenses (compared to 35mm and a given focal length)?
2) Has anyone here used an anamorphic lens with any version of these adapters?

I'm thinking seriously about using a 16mm anamorphic lens on my adapter but I wanted to clear some things up before I go spend the cash. Also, assuming the lens has a 2x stretch what would that give for an aspect ratio when finally captured to the CCD? Approx 2.7?

[Steve Wardale]

I'm grinding my uv filter with grade 240 silicon carbide, and it sems to be doing a fine job up to now... will be upgrading to 400 and ultimatly 600 when the frosting is dense enough. Is this an accepted way for those of us without A.O.?

[Bob Hart]

Aaron.

As I know it, 50mm focal length lens for 16mm format and a 50mm focal length lens for 35mm format have the same focal length.

What they don't have is the same field of view. You could use 16mm film format lenses but the image projected on the groundglass will be very small which for a 35mm movie frame off the groundglass will give you the cruelbaddest hotspot problem in the whole entire universe.

You can frame inside the image area cast by the lens onto the groundglass ie., the 16mm motion picture frame, but then you will have a resolution problem. Relative to the size of your image, the groundglass texture will be heaps coarser. There will be no depth of field effects to be had which you cannot already get in better resolution from a 2/3" CCD camera. While it is do-able there is no point.

I have used a Proskar Anamorphic cinemascope projection lens and a 16:9 anamorphic lens on a non-erecting Agus version. The Century Optics 16:9 for the PD150 worked acceptably into some 35mm format camera lenses right out to a 135mm F2.8 Auto Tamron Prime which was a bit soft for distance. More recent tests with f1.8 lenses were less encouraging.

If you have a look through www.dvinfo.net/media/hart you will find some composite before-after .jpgs on this subject. The results from the initial tests were encouraging but good sharp images are hard to achieve. The cinemascope lens vignettes below about 35mm and there is a resolution loss from about 40ft to infinity. It was not marketed for camera work. A cinemascope projection lens for 35mm motion picture projection may work better but those things are incredibly heavy. The real thing of course is way outside of the budget of most builders.

The anamorphic lens introduces a third layer of complexity to the task of managing images into the camcorder. Again whilst it is not impossible it may be of limited application except for a special effect where resolution and ease of use are not an issue.

I only tried it because I have the lenses already

[Aaron Shaw]

Ah very interesting. Thanks for the info Bob. Very much appreciated.

So, given the technical difficulties, do you think I would be better off cropping in post? I just hate to give up so much resolution!

[Bob Hart]

You apparently lose vertical resolution whether it be in-cam or in post.

Some have suggested that cropping in post is better than electronic in-camera cropping as you can selectively crop vertically to achieve better composition or correct bad framing.

Depending upon the software you have in your computer, furthur manipulation can apparently degrade your image unless you can do this at the highest resolutions possible.

My personal preference is to use the 16:9 anamorphic adaptor but then I am a glutton for punishment. The main disadvantage is the stretched image in the viewfinder which leads to compositional difficulties.

My reason is that MiniDV/DVCAM yields so-so results on highly complex or finely textured backrounds such as landscapes. The non-coherent image from an AGUS/ALDU tends to smooth off some of the digital artifacts the cams create when trying to resolve them.

In reality, most competent AGUS/ALDU versions with AO5 dressed groundglasses should have no difficulty putting an image of 600 TV lines resolution onto a camcorder chip. This is sharper than the 530 TV lines resolution which is apparently the limit. However, in-camera stretching may drop the performance below that limit.

So my tendency if having to work fast, would be to use the camcorder in electronic 16:9 without AGUS/ALDU for the long shots where sharpness is desirable and for the closer shots, to use the AGUS/ALDU + anamorphic, which should even things out a little.

Apparently, if the image is to be upconverted to HD, MiniDV/DVCAM images can cause problems if they are aquired at the highest sharpness setting of the camcorder. The use of an AGUS/ALDU may well help with this issue.

[Aaron Shaw]

Bob: I'm actually going for more of a scope image than 16:9 so I'll still end up having to crop and loose resolution. If I go from a normal 4:3 image that's cropping almost 50% of my image away :-0

I don't want to use the anamorphic adapter (I have a DVX) because of the limitations it imposes (and the fact that it is $800...). I was hoping that using an anamorphic projector lens would help to even things out a bit but your results don't sound too promising in that regard.

*btw, do you have a direct link to images taken with this setup? I looked on the file server you gave but couldn't find what I was looking for. I found images of the setup but no actual screengrabs/footage.

You make an interesting comment about the resolving power of these 35mm adapters. Do you really think they cause no loss in resolution? That would be great if true.

*Just realized something. By Anamorphic do you mean the projector lens or a 3rd party lens such as century's?

hope this post made some sense.. :)

[Bob Hart]

The 16:9 was Century Optic's. The 2:1 was a 16mm projector add-on for 50mm Bell & Howell projector lens. It is adequate for 3ft out to about 40ft. Beyond that you would have to crop a standard 4:3 frame.

The image should have a title something like aguscine.jpg. I sent them in about midway through this year.

[Aaron Shaw]

Ah thanks Bob. Found the images. You're quite right - anything far away quickly falls out of focus. Too bad really... Maybe I'll use a similar lens for closeups and medium shots and crop for the rest... hmm. Lot's to think about. Thanks!

[Bob Hart]

I forgot to comment on "no loss of resolution". There is a loss of resolution, but in practical terms it is beyond a MiniDV or DVCAM to show anything adverse on a testpattern at least.

On one of the .jpgs in www.dvinfo.net/media/hart there is a split screen cut and paste of the EIA1956 test chart, one half through the non-erecting AGUS35 and the other half direct to the camcorder. There is a greyish cast to the colour, distortion and softness to the edges, due to the less than ideal relay path I used then. I had not manually white-balanced the camera.

Centre resolution shows little effective difference and people are now making better relay paths and groundglasses than mine was then.

[Fred Finn]

Anyone know about using a wide angle lens in place of the standard lens, or perhaps a screw on adapter? The trouble i'm having is that with the zoom i have lost a bit of distance that is needed between the subject and camera (can't remember technical word). So the camera has to be farther away, and then i have a smaller area in the frame (hope that makes sense).

Do you guys know if they make wide angle adapters (only for ease of use so I don't have to rebuild it) screw on or otherwise for the f=50mm lens?

What do we think :)

[Aaron Shaw]

I think you may need an acromatic diopter of some sort (As others have used here) to bring the minimum focusing distance in. I'm not sure how a wide angle would help.

[Fred Finn]

A wide angle on the front of the 35mm. Opening the field of view. I'm focusing with no problem, using zoom to beat the hot spot. Just the decrease in field of view i want to fix. So.....

[Aaron Shaw]

Ah! Sorry about that then :)

What is the focal length of your current lens?

[Fred Finn]

ohh i can't remember... I knew.. The effect i'm looking for is to just fit more of say a room into the field of view, without having to move the camera as far away.