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-   -   letus35FE and Olympus lens (https://www.dvinfo.net/forum/alternative-imaging-methods/100214-letus35fe-olympus-lens.html)

Ivan Castell August 1st, 2007 04:13 AM

letus35FE and Olympus lens
 
Hi,

We're planning to shoot with either a DVX100 or a HVX200 and buy the letus35FE. We have the following Olympus lens:

* 14-42 mm ; 1:3.5 - 5.6
* 40-150 mm ; 0:4 - 5.6

I'll really appretiate if someone experienced could answer these questions:

Can this lens be used with the letus35?
It's 5.6f enough or should we get lens with a lower focal length?

Excuse me if this is obvious but I'm really new into this 35mm adapter stuff ;)

Thanks a lot.

Bob Hart August 1st, 2007 10:01 AM

Both lenses lack wide enough aperture for assured groundglass relay work. This is not to say you won't get an image however what you do get may be inconsistent for exposure (will go darker when you zoom in).

Both of these lenses would have to be operated wide-open. You may suffer some resolution loss compared to operating the lenses with smaller available maximum aperture.

You may be restricted to outdoors daylight lighting environments. To light these lenses indoors may require about three times the lighting power you would need for direct-to-camera imaging.

Operating these lenses in their sweet spot may bring you into the range of aperture setting where groundglass artifacts become apparent.

You need to contact Quyen Le to enquire if he makes an Olympus mount. If the flange to focal plane distance on the Olympus lenses is in the ballpark of 42mm - 46mm my guess is that a custom mount could be made and work with the Letus.

Don't take my comments as gospel on this. I do not know the LETUS35FE, have played only with the flip models for XL and HD100.

Ivan Castell August 1st, 2007 11:27 AM

Quote:

Originally Posted by Bob Hart (Post 721734)
You may be restricted to outdoors daylight lighting environments. To light these lenses indoors may require about three times the lighting power you would need for direct-to-camera imaging.

Thanks for your answer.

I can't afford 3 times lighting power (I'm buying this for a shortfilm), so I'll have to go with another lens. I think we could have some old nikon SLR lens with more suitable focal length. I'll know the exact specs in several days.

Quote:

Originally Posted by Bob Hart (Post 721734)
You need to contact Quyen Le to enquire if he makes an Olympus mount. If the flange to focal plane distance on the Olympus lenses is in the ballpark of 42mm - 46mm my guess is that a custom mount could be made and work with the Letus.

I've already contacted Quyen, waiting for his answeer. If this lens are not suitable for th eletus or just for shooting with a 35mm adapter I prefer to get other like Canon or Nikon.

Bob Hart August 1st, 2007 05:28 PM

Whatever lenses you choose, try to get f1.8 aperture. 50mm is fairly easy to come by, this is slightly telephoto on the Letus35 flip for XL.

Sigma do a f1.8 28mm for Nikon which is just a little wide of normal human field-of-view.

Nikon's newer f1.8 85mm has to be about the sweetest out there for sharpness and contrast rendition among the Nikons for groundglass work.

If you can get f1.4 lenses, even better but rarer secondhand.

The f1.4 35mm by Nikon is closest to the normal field-of-view for the Letus35 flip for XL. These are turning up on ebay but still quite expensive.

With f1.8 or wider lenses, your lighting requirement will not be as much though it will remain about two stops higher than for direct-to-camera.

Ivan Castell August 3rd, 2007 02:45 AM

I'll have the lens specs today.

Apparently the letus is light and you can just plug it in the camera, hand hold it and shoot. But does it holds correctly when using the camera on a tripod, for a steady shoot? Does it needs a rod?

Bob Hart August 3rd, 2007 08:39 AM

The Letus35 Flip for XL and HD100 become in effect "the lens" and do not adversely affect the balance of those camcorders. These are both side viewfinder shoulder cams.

The HVX200 as I understand it and I may be wrong, appears to be a consumer style camera with permanent built-in lens and a rear viewfinder.

The Letus35 attaches to the front of this camera style and becomes an added weight for the operator to bear and an awkward burden as the added weight is far forward.

Additionally the camera structure may be damaged if there is no support for the Letus35 and the lens it is itself supporting. On a tripod it is definitely nose heavy and inclined to fall over.

If you cannot afford rods etc., the simple fix is to buy in a 1.5" inch wide half inch thick piece of dressed pine.

Cut off some pieces to make up some packing pieces to fit between it and the camcorder base and to stand on edge to make a vee-block for the Letus35 body.

Make the packing pieces first then customise the vee block for the Letus body as this is easier to get right.

Use a long piece of threaded rod to fasten right through the dressed pine and the pascking pieces to the camera tripod mount and secure this with a wing-nut.

You may find the wingnut may not go onto the threaded rod as quality control is not all that good so a hex nut might be used instead. Do not overtighten.

Buy some strip velcro like the cable handlers use and make up a strap to go over the Letus35 body and keep it firm into the little vee-block to stop the Letus35 from swinging about.

Alternatively you could tap a thread into the open hole on the flip enclosure to fasten the Letus35 firmly to an upright.

This might be a bit difficult unless you have a taper, medium and finally a square thread tap.

Each of the two screws holding the two halves of the flip enclosure together resides in the bottom of two holes and limits the available depth for the taper tap. Do not drill new holes in the flip casework.

Another alternative is to make a saddle and chair arrangement to fit over the front tube.

I added with four screws, one in each corner, a 6" long x 1.5 inch wide piece of 1/4" aluminium flat bar underneath, with several tripod holes of two sizes drilled and tapped into it for selection of balance for different lens weights and to carry a shoulder cuff.

With a small monitor mounted on a side spur on front you also can achieve an awkard but usable sort of shoulder mount arrangement. A bit of blackboard flat paint all over it helps but there is no getting away from its evident junkyard origins - definitely does not have pose value.


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