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Old October 18th, 2007, 08:08 AM   #1
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help a letus newbie out with some lens info...

OK. I have been in the industry shooting with stock video lenses for 12 years. I know quite a bit about them. I have used 35mm still cameras and understand the basics of their lenses but do not know much about mounts and all that good stuff.

I am aquiring a LetusXL for my H1 with a fixed Nikon mount on it. Can anyone point me to some decent lenses for this kit and explain the different lens mounts and what I need to learn about them? I obviously will need to purchase a 35mm Nikon and I do not know where to begin! A 50mm is the obvious first choice but which one? And which mount? With the 1.9x magnification factor of the Letus XL would I be better suited with a 28mm instead? Can I use DSLR nikon lenses? A friend has a D40 and I could ty his lens (18-55mm)....but would it even work?

I feel like a bull in a china shop. For as much as I know about all the other aspects of shooting and editing, my brain is empty when it comes to 35mm lens mounts and what will work with a letus.

Thanks in advance. Feel free to point me to any threads that cover this. I have searched but is seems most of you are talking "above my head" on this. You all already know all the basics so it is not being discussed much.

Thanks!
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Old October 18th, 2007, 09:29 AM   #2
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I would be inclined to stay away from digital SLR lenses with one exception, you will find specs for lenses for Nikon mount which refer to "optimised for digital" but are still-image film camera capable.

These have a design feature which is intended to make the angle of incidence of the light upon the sensor being as steep as possible, apparently for the purpose of being friendly to the needs of electronic sensors.

This aspect co-incides with attributes which perform better in groundglass based image relay.

I have used a digital-only lens, the Nikon 12mm - 24mm f4 zoom. It is quite a sharp lens and performs quite well to the standard 24mm wide motion picture frame when accurately mounted relative to the image plane. At f4 however, it only has just over one stop of headroom wider than f5.6, which seems to be the safe limit for consistent groundglass work.

It runs very close to vignetting a 24mm wide frame and does vignette on the 35mm still-image frame at the wide-end of the zoom.

Under controlled and sufficient artificial lighting, it works well. Outdoors in intense high-contrast lighting conditions, that one-stop headroom does provoke groundglass artifacts in some circumstances.

Film still-camera lenses of f1.8 or wider apertures are recommended. The image area is larger than the 24mm approx width of the 35mm motion picture frame.

This means that the reduced image area some groundglass systems yield from lenses remains large enough to cover the frame without or with minimal edge/corner brightness fall-off.

With digital lenses, the smaller image "footprint" leaves much less room for things to potentially go wrong.

Digital lenses of adequate light transmission performance may well be an expensive proposition compared with used still-camera lenses of better light transmission performance.

So to my mind, pre-owned high-quality f1.8 or wider lenses represent both a cost effective and performance effective option.

Last edited by Bob Hart; October 18th, 2007 at 09:35 AM. Reason: error
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Old October 18th, 2007, 10:14 AM   #3
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Bob,

Thanks for the info but I am even more confused. What would be a very good lens to start with that won't cost an arm and a leg? What should I search for that will give decent results?

Marty
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Old October 18th, 2007, 11:49 AM   #4
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Letus Lenses

Here is what I would recommend looking for if you just want a list...

First, all-around lens: Nikon AI 50mm f1.8
Second, wide lens: Nikon AI 28mm f2.8
Third, long lens: Nikon AI 100mm f2.8

Lenses can be highly subjective but that should give you a good basic idea of where to start.
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Old October 18th, 2007, 08:14 PM   #5
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Here's two kit lists for two operators here in the west (of Australia that is).

I concur with Aaron on your first lens, 50mm f1.8 Nikon. It will be the cheapest and enable you to explore the practical aspects and limitations of your adaptor.


1.

Peleng for Nikon 8mm f3.5
Sigma for Nikon 14mm f2.8
Sigma for Nikon 28mm f1.8
Nikon 50mm f1.8
Nikon 85mm f1.4
Nikon 105mm f1.8
Tamron for Nikon 135mm f2.8


2.

Nikon 14mm f2.8
Nikon 35mm f2.5
Nikon 50mm f1.4
Nikon 85mm f1.8
Nikon 105mm f1.8

The second kit is geared for Croszeil ?? follow focus and is used on a P+S Technik Mini35


I have also had a play with a borrowed Nikon 28mm f1.4 and there is a sharpness/contrast difference between this and the Sigma for Nikon 28mm f1.8 wide-open. At sensible tighter aperture settings outdoors, the practical difference might be less apparent.

This might also be expected to apply with the Noct Nikkor 58mm f1.2.

Both of these discontinued top-end Nikon lenses represent a gold standard for groundglass adaptor work but are now priced well out of cost effectiveness for the average enthusiast.

Last edited by Bob Hart; October 18th, 2007 at 08:21 PM. Reason: error
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Old November 13th, 2007, 08:48 AM   #6
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Marty,

A word of advice on using 35mm; (it appears you have never used one before hence all your questions about lenses). Be aware that this adapter will eat up a lot of light. Forget about shooting indoors with no setup. Many people make the mistake of thinking that their footage is automatically going to look better just by adding a 35mm adapter. That is not the case. It actually requires more work and preparation. It is not easy to do "run and gun" style shooting with an adapter unless you have a decent crew or you are very skilled at it! ;-). But I assume that you have a project requiring you to use a 35mm and have a small budget for the added expenses. So here are my suggestions:

Nikkon Lenses (witht he lowest F-stop possible usually between 1.4 to 2.0)

28mm
50mm
85mm
135mm

you will most likely need a follow focus...a decent shoulder mount if you want to do any kind of handheld. Having a first AC to pull focus would be very helpful. A decent monitor (it's very hard to focus with the cheap viewfinder). Lots of lights. And a few Tylenol pills for all the headaches you're gonna get. :-D. Once you learn the workflow and get used to what it takes to work with a 35mm adapter, you will love the beautiful imagery you can get!

Good luck!

Sarah
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Old November 13th, 2007, 09:07 AM   #7
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Thanks Sarah. That information is helpful but a bit late in my case. I was able to use the LetusXL and found it very, very difficult to handle. I was expecting a loss in light, but nowhere near what this sucker ate up. I played with it at length but in the end, found the usefullness wasn't worth all of the stress involved. Especially the low light and then 1.9x magnification of this lens. I only had a 50mm to start out with and it was just too tele for my needs. I actually used a Nikon 18mm-55mm DSLR lens and used a piece of cardboard to hold the iris open. The 18mm became more like a 32mm which gave me a much better idea of the usefulness of this lens....however the fstop on it was 3.2 so the fepth of feel was a little less shallow, which is kinda good as the super shallow DOF is a bit overdone.

Anyway, I will consider using one again when I can afford all the extra gizmos and when a project requires it. The one I am working on will be perfectly acceptable without a shallow DOF, although I was really wanting it!

I notice you are in Stuthers, OH......I am from Niles originally and it's good to see a local Ohioan on these boards.

Thanks.
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Old November 13th, 2007, 09:24 AM   #8
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Hello again Marty,

I go to Niles quite often! (such a small world!). To be honest I am not a big fan of the Letus XL. Like you said the 1.9x is a big let down. Also at high shutter speed it appears you can see the vibrating glass. I have used many 35mm adpators and my favorite are the Brevis and the SGpro Rev3. While the Letus Extreme looks good imagery wise, the setup is kinda odd. It requires you to have 2 sets of rail or you have to raise your camera off the the base. It's not a pretty setup. :-)

Let me know if you need more info in the future.

Thanks

Sarah
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