Homemade 35mm Adapter

[Mike Perkin]

I am in the process of redesigning my adapter. I posted a couple of questions regarding the fresnel len. I didnt get any response so I'll try posting the question again.

1. Is it always neccessary to use the fresnel in the design of the adapter?

2.From the description given by Devin and Spencer regarding their design, am I to understand that the fresnel lens is the same lens used by a typical pocket magnifier. Wouldnt that be the same lens as a magnifying glass?

Thanks for your help
Mike Perkin

[Devin Doyle]

Bob, Spencer and I worked together on both adapters so maybe I can shed some light on the Samigon adapter. First of all, let me post 2 pictures of our adapters:

- the first model for my GL1 http://www.par-t-com.net/mini50_wide.JPG
- the second model for Spence's VX2k http://www.par-t-com.net/mini50/wide_side.jpg

If you watch the test below the one that Spencer just posted on our media page http://www.par-t-com.net/media.html entitled "Completed Mini50 (w/ ground glass)" you'll see that there's distortion in the corners due to the samigon +10 macro. Spencer's new test has no distortion using the same filter. How? The boxes vary in size. Since mine is a bit longer you must move more towards the telephoto end (zoom in) and therefore distortion is introduced. Since Spencer's box is smaller, and the image is projected no further than 1/2" away from the lens, little zooming is necessary. I returned my Samigon and ordered a +10 macro that had glass covering the whole 58mm diameter, not just 40mm or however much the Samigon does. Hopefully this will correct the distortion on my end. +10 adapters generally do introduce distortion, it's just a matter of getting around it. So, if you're interested in the Samigon, build a shallower box. I think overall it's a better image when all the optics are as close as possible, but then you run the risk of not having enough room to adjust everything. I'll keep you posted on which macro I end up using.

[Filip Kovcin]

hi there,

i just bought a pack of 25 CDs produced by (unknown for me, never saw it before) company named MSONIC, from Taiwan.

on the top side of the disk is written:
48x
80min/700Mb
CD-R
Silver-Silver
price (at least in poland for 25pcs approx 4$)

and here is GOOD PART!

there are TWO frosted disk in this pack. One on the top, and one at the bottom. for me they are identical to MAxell ones. (i have one maxell's)
i sent to taylor my pics of it. i beleive the link will follow soon.
i bought it in "Geant" hypermarket (the french supermarket chain common in Poland, where i live).

maybe this will helps someone.

[Taylor Moore]

Here the link to the frosted CD's and pkging.

www.moorefilms.com/frosted.htm

[Taylor Moore]

Spencer, Awesome job. Footage looks great!!!!
Three things:

1. Are you getting pulsing when you rack forcus? Meaning is there a slight image shift....when going between 2 different focal planes.

2. Really want to see some exterior day shots.


3. What is the diameter of your and Devins lens. As the DVX is 72mm and I might have problems getting this rig to be workable.

[Spencer Houck]

Thanks, and to answer:
1. Yeah, there is some "breathing"(i think thats what it's called) when shifting focus, things in different planes grow or shrink, but thats due to it being a still photo lens not meant for racking while recording. Real 35 mm film lenses have complex systems to fix that.

2. We'll try to shoot some exteriors with good light, may take a bit, seeing as it "feels like" -1°F outside.

3. Devin's GL1, and my VX2000 both have 58mm threads.

Spencer Houck

[Ryan Henry]

<<<-- Originally posted by Mike Perkin :
2.From the description given by Devin and Spencer regarding their design, am I to understand that the fresnel lens is the same lens used by a typical pocket magnifier. Wouldnt that be the same lens as a magnifying glass?
>>>

I was about to say no, but stopped myself. From my (limited) understanding of optics, fresnel lenses are designed to spread out light. Upon further thought, that's what a convex lense seems to do, too.

The advantage of a fresnel lens (and why they were first made) is that they weight less and are much thinner than a regular lens.

Anyone experiment with a regular magnifying glass? I'll see if I can dig one up today.

Ryan

[Chris Hurd]

Latest image from Bob Hart:

http://www.dvinfo.net/media/hart/testpnew0+5.JPG

Bob says: Here's another .jpg for the album. I printed another cleaner copy of the
test pattern on photo paper for crisper lines and ran the comparative tst
again. The result is intriguing and confounding at the same time.


It is framed smaller than a test pattern would be therefore the resolution
must in theory at least be lower. But it seems to be up there at around 600
lines horizontal. The Agus image which is the one beneath also seems to have
less stepladdering on diagonal lines than the image direct into the PD150.
It seems the softer image rules. Setting the sharpness on the PD150 might
achieve the same result. The tests are far from scientific as the shots are
in low light and the camera and test pattern not mounted to a common frame."

[Don Mahr]

I'm almost done building mine and am ready to buy a new lens for this. The one I've been using really sucks. Please can anyone one suggest a decent lens to look at for around $200.

Any help would be greatly appreciated.
Thanks

[Taylor Moore]

Well if you buy used you wont' have to spend anywhere near $200.

I would go with a Nikon len, 1.2 0r 1.4 as fast as you can get.

[Curt Kay]

I really want to jump into this... but I think i'm going to wait until someone has some schematics and a solid design. Great job guys! Spencer your footage really looks promising. Could you maybe post some pictures of the Agus50 for the GL1? I have a GL2 and I'm just wondering how to go about making one if I come across some money soon. Thanks! great job!

-Kay

[Devin Doyle]

Curt, we posted pics earlier in the thread. However, Paul Doss was nice enough to copy that post and pics over to his webspace. Visit http://www.thecountrybulletin.com/new_page_14.htm.

[Dmitri Henry]

Hey i was reading a lot on this subject. I have been navigating through all of the 48 pages and i have noticed Daniel's posts where he talked about the gg from an old Zenit camera. I also noticed some one mentioning the soundless brushless vibrating motor. Since i know nothing about motors and not much at all about ground plates i am wondering if anyone knows how to make the "brushless soundless motor" work say with an old GG from the Zenit camera. Guys i own one of those cams they are 70s model of a Zenit B! ( i bet after this post you won't be able to find it on ebay ha). From Daniel's pictures of his model the adaptor is incredibly small and sturdy looking. I am not really that technical, anyone want to contribute some ideas?

[Danny Tan]

here is another test video of mine

www.metafilms.net/upload_files/agus35.avi about 1.3mb

and guess my setup

[Spencer Houck]

<<<-- Originally posted by Bob Hart : Spencer. Is there any chance of getting a frame grab from your Mini50 as a .jpg file up somewhere, maybe even here. Chris has been putting my tests up here so would probably be no problem if you request putting it in with my lot.

Landline speed here is as slow as 752 bytes per second so meaningful Quicktime just is not an option.

I'd like to see if the Samigon is good into the corners as my options are not so good. -->>>

Hey Bob, sorry for taking so long for this.

Screen grabs from mini50 test on VX2000(in a relatively dark room):

www.par-t-com.net/mini50/grab1.jpg
www.par-t-com.net/mini50/grab2.jpg
www.par-t-com.net/mini50/grab3.jpg
www.par-t-com.net/mini50/grab4.jpg

These grabs are after I used Premiere Pro's color corrector, which introduced some grain to the pics, but I think you can get the picture. Notice that there is just a slight bit of vignette, but with a 16:9 crop in combonation with safe margins, it does what we want.

The test can be found here: www.par-t-com.net/media.html

Spencer Houck