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Old December 15th, 2005, 04:54 PM   #1
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Reducing vignetting with a fast lens?

Hello!

This is my first post since here, but I've been lurking around since february. I've got a lot of tips and inspiration here and have tried different approaches;
* Cd-spinner
* Beattie (static)
* Bearing

I've found out that the Beattie provided a superb quality without any form of condenser, however, it's scratched and therefore not useable. So the second best alternative (with my budget) is to go for the spinner.

After reading A LOT of posts I've realized that my lenses aren't fast enough, and probably of bad quality. I'm now looking for a F1.4 lens to help me with the vignetting issue. My questions are - will it make a big difference going from F1.9 to F1.4?

Do you have any experience of different brands like Minolta (ROKKOR), Pentax (TAKUMAR), Olympus (ZUIKO), Canon? Carl Zeiss, Nikon and Leica are a bit too expensive for me.... :)
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Old December 15th, 2005, 05:01 PM   #2
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Carl,
Another big factor in my experience is the size of the rear element of the lens. My Nikon Nikkor S has a massive rear lens element compared to the Canon FD's or Ef's. The Nikon is much more forgiving in terms of vignetting as a result. I'll see if i can upload a pciture to show you.

EDIT:

http://wayne.letus35.com/lenses.jpg

Here shows the difference in size of the 2 rear elements, left a Canon FD, right the Nikon Nikkor S
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Old December 15th, 2005, 05:03 PM   #3
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Thanks, that would be nice!
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Old December 15th, 2005, 05:09 PM   #4
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Carl,
Are you using a condenser setup?
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Old December 15th, 2005, 05:32 PM   #5
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Yes, I bought an 8mm zoom kamera. In it I found a lens that I use between the SLR-lens and the ground glass. The 8mm-lens produces a smaller and brighter picture on the gg, without any form of distorsion. However, I still have to zoom "too much" on the glassto avoid vignetting. And as we all know, zooming in too much forces the camera man to move back from the target and therefore some of the DOF-effect is lost. So that's my problem.

I've also tried a very big, what I think is a condenser, from a slide-projector. Unfortuanetely, the barrel distorsion is out of this world. I'll se if I can find any nice shots to post.
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Old December 15th, 2005, 05:39 PM   #6
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Carl,
I too have used a lens between SLR and GG, and it indeed projects a smaller image on the GG. I used this setup in the z1 SG35 test of the Peir at night.

However, lookout for 2 problems, problems that forced me to change my setup. 1: The lens between GG can change the properties of the SLR lens and reduce the DOF effect (widen the DOF).

2: Can create differential focus, so say your filming a res chart, the middle of the frame will be in focus and the edges soft.

Just something to look out for.

EDIT:
Also, the further away the camcorder from GG, generally the less vignetting.
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Old December 15th, 2005, 09:27 PM   #7
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I will probably take a photo of the setup tomorrow, but here's some footage from a Miami Vice parody, "Lomma Vice". "Lomma" is a small town by the sea in southern Sweden where a lot of people go suntbathing in the summer.

Unfortunately the 3CCD Panasonic the adapter was intended for started chewing tape so we had to retake the whole scene again with a consumer 1 CCD Sony. All the caps are deinterlaced, rotated, sometimes cropped (to reduce the vignetting), and color corrected.

Here's the link, all files starting with "lv0_"
http://www.nattvard.com/upload/
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Old December 15th, 2005, 09:30 PM   #8
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Here's a short clip. It looks awful because the spinner stopped spinning once in a while
http://www.nattvard.com/lommavice/?video=all
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Old December 16th, 2005, 04:20 AM   #9
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Carl, if you have a problem with your primary camera, hook up a firewire cable to another DV camera and you can get the good image from the best camera recorded to the deck of the 1ccd camcorder.

Wayne, thanks for that picture of the back of the different lenses. I got lucky and bought what seem to be some good Nikons. I didn't realize all of the issues that can happen with less expensive lenses.
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Old December 16th, 2005, 05:15 AM   #10
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Wayne, do the two lenses have the same F-value?

All the Canon 1.4 that I've looked at seem to have at least as large lbackens as the Nikon on the right.
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Old December 16th, 2005, 05:25 AM   #11
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The canon was a 1.8 and the nikon a 1.4

If the Canon 1.4's have as big a back element, go for it by all means
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Old December 16th, 2005, 05:38 AM   #12
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Quote:
Originally Posted by Wayne Kinney
The canon was a 1.8 and the nikon a 1.4
Yes, Wayne you are attributing the smaller rear element to it being a Canon lens when you should be attributing it to it being a smaller aperture lens, that's all! :)

Rear element size is generally (but not always) predicated upon max size of aperture. The bigger the hole, the bigger the glass has to be.

By the way, this does not refer to F-number, but rather that AND the focal length of the lens. A 20mm F1.8 lens is going to have a very different rear element size than a 135mm F1.8 regardless of what brands. Point being, one must compare apples to apples - focal lengths and f-stops both.
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Old December 16th, 2005, 05:59 AM   #13
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I just won this auction
http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA%3AIT&rd=1

for 10 Euros.

The aperture is defect in the sense that it's always open, but I took a chance. Hopefully nothing else is broken. I guess I can always step down on the camcorder.
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Old December 16th, 2005, 06:04 AM   #14
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Bill,
Thanks for the info.

Carl,
Let us (no Letus pun) know how you get on with that lens.
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Old December 16th, 2005, 06:09 AM   #15
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Yes, I'll keep you updated. Shipping from Germany to Sweden shouldn't be a big deal, since it's within EU and the distance between is quite short. Hopefully I'll get it this year.
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