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Old November 23rd, 2005, 08:24 PM   #16
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CCD misalignment part 2

Ok, small update if you would have a ccd misalignment on your Sony.

Quyen's adapter is flexible enough to handle this.

I just took a very small drill, one they use for engravings. Since the macro ring is made of plastic, it's quite easy to shave some plastic off at one side if you have opened it (I also removed the lens). It just takes some patience. On the other side you add some plastic. I just took the glue gun. The macro stays in place, the rest of the construction is moved just a bit, just enough.

See? http://www.lesoup.com/fileadmin/user...e/DSC00028.JPG

Now, my frame should be centered and straighter when i get this whole thing back together. I'm actually starting to have some fun with this DIY'ing.

End of diary...

Now two questions.

Has anyone experimented with ideal distances from condenser to ground glass? My guess would be, the closer the better, right?

Has anyone experimented opposing two condensers to each other with this adapter?
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Old November 26th, 2005, 03:35 PM   #17
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To anyone interested:

I experimented with different distances between the ground glass and the condenser, and my conclusion was that there is less distortion as the condenser gets farther away from the ground glass, however the caveat is that the light begins to scatter, i.e. there is more of a hotspot. This is probably why it's ideal to have the condenser somewhere in-between. My firewire is acting up so I'll try to post some example shots once I get it working again.

The century optics diopter switched out with the Letus' stock macro eliminates all chromatic abbheration issues--that is, issues outside normal levels. My understanding is that all lenses create some kind of blue scattering around the edges of brightly lit surfaces and areas like skies, etc., but we were obviously seeing some extensive abbheration because of the faulty/low-cost macro. Using the Century Optics +7 has really helped my image quality. Keep in mind that if you use it, be prepared to shave a little bit off of the inside of the Letus' plastic lens mount since the diameter of the Century Optics is a tad bit bigger--perhaps half a millimeter or so.

Besides this, however, there is a massive difference in size. The CO macro is a good two/two and a half times thicker than the stock macro in the Letus and at least three times as heavy. It's a nice tight fit, but I'd even more strongly recommend using a rod support system if you go this route. As an added bonus, the Century Optics macro comes with two screw-on covers that fit both ends of the Letus perfectly. Cheers.
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Old November 26th, 2005, 04:01 PM   #18
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An old post by myself concerning condenser distance vs barrel distortion.


Another thing to note, is the further away the condenser is from the ground glass, the more colour seperation.
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Old December 15th, 2005, 07:21 PM   #19
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'Aberration' the movie

Ok. After so much nagging on this forum (by me), I threw together a short movie. And what better title than 'Aberration', my favourite word the last couple of weeks. Uploading it was hell since I'm on dial up for the moment.
It should be here though:

http://www.lesoup.com/fileadmin/user...aberration.mov (QT7 h264 11mb 2 min. 30 sec. 720x440 pixels. I didn't stretch it to 768 because it would reduce resolution)

Please take a look at it. Let me know if I wasted two minutes of your life or not.

Note that:
Because I was filming something geometrical, the barrel distortion was really bothering too much. So I had to deinterlace, correct it and such things, which resulted in a lot of post effort and artefacts and the evident loss of resolution. But it's mmmkay now.

To compare, here is a still from the original shoot. Just flipped. Don't count resolution. I filmed much wider than the correct test distance. But for the movie, I didn't wanted to chop of the chart at the 4:3 markings.


Here are some final thoughts on the Letus. I'm sure you don't need them. The forum is spoiled by test results by now. Recent developments have perhaps made them obsolete. But I've started something and want to finish it, even though I have lost a lot of time by being ill.

-Terrible back focus. A glue gun is not really so exact to work with. Especially difficult for wide angle lenses, if my feeling is correct.
-I had to realign every part as good as possible. I don't even know if it helped. It sure taught me how it works, and that it's easy to repair. So don't be afraid to mess with it (perhaps this is more a positive point)
-Too much chromatic abberation.
-Stretching of the image.
-I would like a lens lock. Some day I will have it too.
-Some fine grain indoors. Can be a problem if your output is dvd. As in my case.
-Glue and tape works better for me than screws in aligning the ground glass plane and condenser.

-Available. Meaning it's here. Now. No pre-orders. No long waiting times.
-Excellent price point.
-Less problems with dust than expected. It's completely demountable. I even cleaned the ground glass (Removing glue with cutter knife, lens fluid and warm water).
-The plastic had in my case the advantage of being able to adjust it a bit for aligning it with my ccd's
-Great light diffusion in highlights. Nice colour feeling.
-Great support from Quyen and he's still continuously improving the product.

And that's it. No more indoor testing. I feel confident enough to go using it in the field. Perhaps even with living people. I will compose my shots trying to hide the barrel distortion and keeping the light controlled.
The adapter isn't perfect. But no adapter can be. It's inherent to it. But I love it anyhow.

Greetings, Kurt
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Old December 16th, 2005, 02:52 AM   #20
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What color temperature (in Kelvin) was the light you used? Is there more chromatic aberration in lower frequencies or higher color frequencies?

I'm not sure, but I think some of the sounds included were forbidden.
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Old December 16th, 2005, 03:15 AM   #21
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Kurt that was impressive - probably the best test i have ever seen for an adapter yet. Nice work. I think you should feel confident on taking your letus and using it in the field, well done to Quyen and Kurt.
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Old December 16th, 2005, 04:19 AM   #22
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Thanks guys.

Color balance was for my redheads. Which should be 3200K, right? Although I ran in to some problems. As you have probably noticed it's recorded in my livingroom. So I got all sort of color casts, for example the red carpet on the floor mixing with the blueisch paper on which the test chart is printed. And my walls are light yellow. All this makes an even white hell, especially if your test chart is 1,5 m wide. The living room lamp obviously had a different temperature (it's one of those 'saving lamps', I don't really know the English word for that). I don't know the color temperature of a black light. But I know I won't be using them anymore. At least, not as long as I'm stuck with 4:1:1 color compression.

About chromatic aberration. It's just a feeling, but only the blue really bothers me.

If some of the sound are forbidden, I think I go to the wrong places, because I think you are talking about the field recordings.
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Old December 16th, 2005, 04:38 AM   #23
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What a superb test! . .and very amusing too! - Grazie
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Old December 16th, 2005, 05:20 AM   #24
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I was joking! I wanted to make a post that would not give away your surprise video. It is definitely the most exciting test chart video I have ever seen. I guessed that the sound you used was from the sound track of the movie "Forbidden Planet" and I used the word "forbidden" to hint that I thought you used that for sound.

I suggest everyone that has or wants to own a 35mm adapter download and watch this video.

For the blacklight, I don't think that's chromatic aberration from the Letus35. The very high frequencies of light are difficult for anything to focus, even the human eye. It is also probably a challenge for your camera's CCDs to properly register that UV color. As for chromati aberration under normal light, I don't think it is very bad. If the colors are off, the white balance seems to have corrected things. Do your colors look very different if you shoot wihout the Letus35?
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Old December 16th, 2005, 07:27 AM   #25
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The letus has absolutely no trouble with blacklight. 4:1:1 DV Compression has. Since the image is strong blue only, compression blocks were about the size of crossword puzzle squares. So I decided to put a blur on the blue channel. Rather blur than blocks. But really, it's merely the camera. The faults of the Letus can be seen in the blacks surrounding the test chart.

About how the Letus changes colors, it doesn't really change the colors but it changes the curves, which become a bit more natural, more as I perceive them in real life, ending up in enjoyment during filming. One downside seems to be a very soft grayisch tone over the image. Sometimes.

About the forbidden planet, sorry, I just didn't got it. I only saw it once long ago. I made the sounds myself, but they are indeed very retro.

Many thanks for the comments. They really make recovering from the worst cold I've ever had a lot more fun.
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