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The Prime Lens Super 8 Advantage Pictures


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#1 santo

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Posted 12 November 2005 - 05:46 PM

Here's a couple of pics just for interest sake. I did a few shots comparing the Leicina Special's Optivaron vs a 28mm prime on the same camera to see how much sharpness difference there is. Now this Optivaron has bested cameras like Canons and others in subjective tests like this. Not very scientific, and maybe the Optivaron is underexposed a little so it might be at a disadvantage -- though that is supposedly going to give it a slightly increased edge as it's Tri-X reversal according to common beliefs I've read a lot of times. But no matter what I do in photoshop, it can't match the prime lens. Here they are unretouched.

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#2 S8 Booster

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Posted 12 November 2005 - 06:03 PM

another useless "reference" post by you. not even identical exposure. using an imaginary lightmeter again?
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#3 Robert Hughes

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Posted 12 November 2005 - 06:18 PM

They both look quite good. Did you have both of your lenses collimated to match the camera? My guess is that, given the age of this equipment, more gear is going to be out of specification as time goes by.
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#4 Robert Hughes

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Posted 12 November 2005 - 07:34 PM

S8 Booster - this is the "other" forum. We're all still friends here. Let's keep it that way.
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#5 David Mullen ASC

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Posted 12 November 2005 - 09:44 PM

Seem rather similar, sharpness-wise. Maybe you should try shooting some focus charts at different f-stops for a more accurate assessment.
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#6 Maulubekotofa

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Posted 12 November 2005 - 10:08 PM

I'd like to see the frame lines and sprocket holes - nice scene though. looks like a sicence fiction piece.
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#7 Chris Keth

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Posted 13 November 2005 - 12:25 AM

You should really do better, more controlled tests before you go spouting results to everyone. First of all, you should really have a higher contrast subject to judge sharpness best. Second, your test shots should be properly exposed, or at least exposed the same. Under and overexposure do have an effect on percieved sharpness.
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#8 santo

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Posted 13 November 2005 - 08:11 AM

another useless "reference" post by you. not even identical exposure. using an imaginary lightmeter again?


Actually they were done exactly the same way with a centering of the camera's internal light meter, shot one after another in rapid succession. I don't think I can get much closer for a reasonable informal subjective test than that. I've noticed that the primes tend to be a little brighter looking for some reason. I can't explain it. One would think that they'd appear the same. However looking at other peoples informal tests done pretty much the same way, there is a difference lens to lens when not corrected in post to match. Like here, for example:

http://www.cinematog...les/Compare.jpg

Look at the subtle gray striped background and the details of the hair. Even the brightness varies lens to lens.

But it looks to my eye obvious with my testing of these things on a super 8 level: decent prime lenses are sharper than any made-for-super 8 zoom lens from the 70's. Even the excellent Optivaron. But, as has been suggested by rational posters, charts and various f-stops would be more objective. And maybe some sort of adjustment. Not sure how they would do that with a Leica M bayonet mount. Never heard of it, but maybe they do?

your test shots should be properly exposed, or at least exposed the same. Under and overexposure do have an effect on percieved sharpness.


Yes, they were exposed the same way according to the light meter, one just appears slightly brighter than the other due perhaps to lens differences. Perhaps a poor choice of words with "under exposed" in my initial post -- it just sort of appears to be that way slightly, but it really couldn't or shouldn't be, now that I think about it.
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#9 santo

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Posted 13 November 2005 - 08:29 AM

Actually "cleaner" is a word that comes to mind comparing the two images now this morning.
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#10 santo

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Posted 13 November 2005 - 09:05 AM

I'd like to see the frame lines and sprocket holes -


I don't understand? What would frame lines and sprocket holes tell us?

As I didn't get the telecine with this footage cropped to include sprocket holes and frame lines, the best I can do is this snippet, as the test was the last 20 seconds of a cart as I'm turning off the camera and the image goes shaky as the cart stops during that last second. I don't think it tells us anything other than that, though.

Please explain.

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#11 David Mullen ASC

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Posted 13 November 2005 - 11:47 AM

It's not surprising that a zoom lens loses a little exposure compared to a prime if both are marked in f-stops -- hence why T-stops were invented.
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#12 Alessandro Machi

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Posted 13 November 2005 - 12:29 PM

It's not surprising that a zoom lens loses a little exposure compared to a prime if both are marked in f-stops -- hence why T-stops were invented.


Because the prime lens has less glass.

Anyone know what the actual difference gained between a prime lens and a zoom lens? 1/4 stop, 1/2 stop?
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#13 santo

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Posted 13 November 2005 - 02:01 PM

Since I'm spending the day creating proxy files for my new project and have nothing better to do, I thought I'd do an experiment to test the difference between first the Optivaron, and then the Cinegon and an ancient Super-Takumar slr lens on the Special, framing exactly the same wall and area and recorded the results the lens shows for correct exposure by the camera's internal metering.

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Of course for the two images at the begining of the thread, I was well aware of this difference and individually metered for the two different lenses just like I did here. There's no link between the camera's meter and the lens being used, just the classic slr style system the Special uses.

So is this the difference between T-stops and F-stops in action in the above three captures? It looks like almost a stop difference nearly.
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#14 Matt Pacini

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Posted 14 November 2005 - 01:15 PM

It's not surprising that a zoom lens loses a little exposure compared to a prime if both are marked in f-stops -- hence why T-stops were invented.



I'm wondering why all lenses are not rated in T-stops, for this very reason, especially high-end still camera lenses. I mean, why wouldn't everyone want to know how much light is actually hitting the film plane?

However, in this case, given the fact he's using the cameras internal light meter, which is reading BEHIND the lens, shouldn't it automatically compensate for the difference?

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#15 santo

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Posted 14 November 2005 - 02:11 PM

I'm wondering why all lenses are not rated in T-stops, for this very reason, especially high-end still camera lenses. I mean, why wouldn't everyone want to know how much light is actually hitting the film plane?

However, in this case, given the fact he's using the cameras internal light meter, which is reading BEHIND the lens, shouldn't it automatically compensate for the difference?

MP


I thought about this dramatic difference and was puzzled by it like you are and figured some of this out for myself, I think. If we assume the Optivaron on the Leicina Special is in T-stops it make sense. As T-stops are how much light is actually hitting the film.

There is no filter between the lens and the film as this is black and white and I didn't engage the internal one, so I ruled that out -- also because the Special is manual in this regard and the user calculates that in himself when manually adjusting the ASA. However, there is a beam-splitting prism to take some light to the viewfinder which accounts for a 20% decrease in the amount of light available to hit the film.

Now, if that's the case, and the Optivaron is designed to be a T-stop reading lens it should take this 20% difference into consideration. However a lens such as the Super-Takumar was never designed to be a T-stop reading lens, let alone one taking into account a 20% light loss to a beam-splitting prism. So it does make sense it should be reading a higher number at an f3.5 or whatever it is there, versus the Optivaron's f4 and a half or so.

However, I am uncertain as the Cinegon. I appears not to be in T-stops like the Optivaron, but rather in F-stops like the Super-Takumar!

At any rate, I came to the certain conclusion that my stills at the top absolutely do not represent any significant difference in exposure after looking at an impromptu "correct, under 1 stop, over 1 stop" experiment with a white door I was shooting as a cutaway. Judging by the startling amount of grain introduced by a single stop over-exposure in super 8 black and white reversal, the darker of the two examples above couldn't be off more than a 1/3 of a stop at the very most, if at all. I've put those examples in a new thread for easier future reference for new people shooting the terrific Plus-X reversal to help improve their results dramatically. "Amazing Super 8 Reversal One-stop Difference" Of course as anybody shooting it properly knows, Plus-X, even in it's new 100 speed form, is pretty close to Kodachrome 40 in grain (or lack of) unless you follow poorly founded "conventional wisdom" and don't expose it as close as possible to correct.
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#16 Chris Keth

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Posted 14 November 2005 - 05:51 PM

I'm wondering why all lenses are not rated in T-stops, for this very reason, especially high-end still camera lenses. I mean, why wouldn't everyone want to know how much light is actually hitting the film plane?

However, in this case, given the fact he's using the cameras internal light meter, which is reading BEHIND the lens, shouldn't it automatically compensate for the difference?

MP



It's a mystery. I was shocked and astonished that my girlfriend, who is an advertising photography major at RIT, ahd never heard of a T-Stop. I just assumed that all professional cameras would be amrked in both T- and F-stops. to cover all bases since, I believe, you still do calculations not involving actual light hitting the film plane using the geometrically derived f-stops.
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#17 andres victorero

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Posted 14 November 2005 - 06:32 PM

the difference between f stops and T stops in good lenses are inconsiderable, but they are lenses that the difference can be important. It depends of the quality of the lens.

Hi santo In my next shooting I´ll use plus-X so your test are great for me. can you post a pic of the prime lens of your test.
thanks
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#18 Adam Paul

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Posted 26 November 2005 - 05:53 PM

Santo, could you give more details on the Leicina 28mm prime? Was it specially made for the Leicina special like the Cinegon 10mm? If not, since the Leicina has that prism, shouldn't it be a problem?
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#19 santo

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Posted 28 November 2005 - 02:29 PM

Santo, could you give more details on the Leicina 28mm prime? Was it specially made for the Leicina special like the Cinegon 10mm?

There are only two lenses ever made specifically for the Leicina Special. The Optivaron 6-66 f1.8 zoom, and the Cinegon Macro 10mm f1.8. Actually, the lens tested in the example is an old Super-Takumar 28mm f3.5. I had bought an M42 mount adapter and the lens some time ago and never got around to testing it before. I had some film left on the last cart Tri-X of the short I had wrapped up earlier that day, and decided to quickly put it on a tripod and take a shot out the open window to see what I got. Then I took a couple of seconds with the Optivaron for a comparison. I used a cable release and was careful to set the exposure with the camera's internal meter seperately each time. However, as can be seen, the zoom is a little darker.

If not, since the Leicina has that prism, shouldn't it be a problem?

A few things make this not a problem.

First, because it's designed for the much larger format, only the centre of the lens is used. A beam splitting prism, even one of the highest quality possible like in the Leicina, will throw off the light rays coming in from the outer edges of a lens not designed to take into account the prism as an optical element. However, it has virtually no effect on the rays coming through near the centre of the lens which have a greatly reduced angle and almost are coming straight in to the prism. Sort of like )/ vs. )- . So the prism has very little if any noticeable effect.

What little effect there might be with a 35mm format lens is completely cancelled out by stopping down a lens to about the f4 mark. Because the Super-Takumar is a big old slow lens -- though razor sharp through the centre -- this can't be avoided unless you're shooting way beyond the wide open minimum of f3.5 which is not a good idea. Also, keep this in mind. A 28mm lens in super 8 is going to be a close up lens. There is not going to be any problem getting enough light on a small area for a close-up (like a face) to get it nicely stopped down. At least most of the time with rare exceptions -- and then you'd just use the Optivaron, anyways.

Where the prism does introduce a bit of an issue is that it might throw off the exact plane of focus on the film surface compared to the lens markings. This is why you must use the eyepiece for focusing with such a lens. But as I've found, trying several 35mm still lenses now, the split-image literally "snaps" into place when it's in focus and the results are extremely sharp and in focus on the film when it comes back.

The only potential downside here is that your lens might not actually be capable of true infinity focus. Focus is shifted a little on the film plane. Particularly if you're shooting it wide open and aiming at really far off objects. You could end up with soft shots. I believe the true Leicina expert on here, Sparky, tried to do some astronomical photography and was dissapointed by the results. So simply avoid that, and use the lenses for close ups or at least objects, maybe 50 feet away at most with which you can use the eyepiece and split focus viewer. It's pretty darn sharp that way in my experience.

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#20 Adam Paul

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Posted 28 November 2005 - 06:26 PM

Thanks for the detailed reply Santo. Did you get my last private message?
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