EX1 and Letus Extreme with PL Mount Focus Issues.

[Michael Maier]

Wow. This is bad! I wonder when Hien or Quyen will chime in to address this? Are you guys out there? Some customer service would be nice.

[Michael Totten]

I've decided to return my Letus Extreme adapter.
I'm going to take the "MOVIEtube Jr." lens adapter on a test spin... it cost much more (5K) but I have a feeling it's built like a tank. Will report back.

http://www.abelcine.com/store/produc...ductid=1000224

[Michael Maier]

It looks a lot like the Letus Extreme, which in turn looks a lot like the Pro35. But the Movietube Jr is closer to the Letus than the Pro35. It actually looks like an better built and improved Letus Extreme. I can see just by the pictures that it's better thought out, like the back sleeve that goes over the lens rings ala Mini35. Interesting option. Can't wait to use one.

[Bob Hart]

I am a little confounded by the method proposed for achieving backfocus by moving the pillars.

If this is necessary, my personal preference would be to make small packing shims made to shove into the bottom of the pillar holes to keep the pillars from moving forward deeper into the holes after adjustment. Getting them out again would be difficult. They would need to be paper or cardboard so they could be destructively removed with a pin end.

However. First things first. Caveat - I don't know if the Extreme-front end is similar to the older Letus35 with plastic front-end.

I am assuming it is so here goes for some instructions on getting that pillar rubber back into the hole.

Backyard tools needed.

Two free steady hands. (Have a hair of the dog if you have the shakes). -

Get somebody else to hold front-end or secure it with a vice or geeclamp onto the kitchen table.

Small wornout flatbladed screwdriver or kitchen dinner knife with blunt round end.

Heavy duty tweezers or good ratnose pliers.


Okay. Letus front-end is firmly secured. Now gently offer the rubber up to the hole. The sod won't go in. This is perfectly normal. It would fall out if it was a slack fit and it would not be a good look.

Now use the pliers or tweezers to gently incline the pillar sideways about 10 degrees as you offer one edge of the rubber into the hole in a sideways movement.

Keep a very slight pressure upon the pillar in an inwards direction or have an assistant put a little bit of thumb pressure on it, but not hard because the rubber will ride over, spread and try to turn inside-out, just enough pressure that what you have already offered up stays in place.

Now, whilst keeping that pressure and the inclination in place, gently use your blunt screwdriver blade or blunt knife to ease the edge of the rubber over the edge of the hole, working from one side to the other.

You can rock the pillar a little bit to help this process along.

You will eventually end up with just a little bit of the rubber hanging over. Use the blunt screwdriver or knife to push this in, at the same time put a bit of sideways pressure on the pillar itself to compress the rubber already inside the opposite side of the hole a little.

Once this last piece of the lip goes in, you can press the pillar into the hole. Don't just leave it there as it will likely pop back out inder air pressure.

Work the pillar in a circular direction like the groundlgass panel is meant to move as you keep the pressure on. Eventually, built-up air in the hole will leak past.

You may need to use a blunt dressmaker's pin to slide down around the rubber to let air out but make sure you don't puncture the rubber itself otherwise it may be inclined to come out during operation of the adaptor.

If it is inclined to work loose in operation, bringing the rubber back upwards in the hole slightly and placing a small spot only of yellow contact adhesive around it with a tooth pick and pushing it back in should be enough.

When messing with the contact adhesive, stuff a piece of tissue in the hole leading to the front glass and tape a paper wrapper around the groundglass carrier. You do not want strings of contact adhesive getting on them.

There should be a cottonthread-thin ring of yellow stuff left around the rubber. This should be enough to make things stay put.

An alternative means of insertion of the pillar is to find a piece of small diameter clear plastic tube to use as a compression sleeve.

Wet it with a small amount of water with bathroom soap dissolved in it. Place this around the pillar rubber. You may have to split the plastic tube and trim a little bit out of it for it to fit tight enough.

Tie a thin piece of electrical hookup wire around the tube to squash the rubber, then offer it up to the hole and try to push the rubber out of the tube into the hole.

If you are clever enough, you may be able to make a similar cylindrical compressor sleeve out of a thin strip of spam can or any other thin metal and leave two little elbows folded out on the ends which are only very slightly apart when compressed around the pillar rubber.

Use the ratnose pliers to squeeze these ends in to compress the rubber then offer it up to the hole to slip out of the piece of thin metal as for the plastic tube.

I found it easier to use the blunt knife method once I got the knack of it.

If you get the rubber back in, make sure all the pillars are pushed back into their holes fully and the rear of groundglass carrier to front face of front-end measures the same at all pillars.

Now back to your PL mount.

Again, I am not familiar with the Letus Extreme so I cannot vouch for how far the groundglass rear face is back from the front of the Letus front-end. While you still have it in pieces, use a vernier caliper to measure from the front face of the front-end to the rear face of the groundglass.

You can buy plastic verniers cheap from your handyman store.

If the Extreme is the same as the older Letus, it will be 40mm from the front face to the rear of groundglass panel.

Assemble the front-end with the groundglass carrier, etc back into the tube.

Measure back 40mm or whatever the Letus Extreme groundglass rear face distance for the Extreme happens to be, then scribe a very accurate mark on the outside of the tube body or use a piece of masking tape if you want to keep it looking pretty.

This will be your focal plane.

Now take your PL mount. Screw the clamp ring home, then using the tail of the vernier, measure from the front of the clamp ring to the bottom face the lens with its wings butts up against (the lens flange face). Write this distance on a paper.

Offer your PL mount into the Letus and measure from the front of the clamp ring to the scribe mark on the tube body which is your focal plane. The correct distance should be 52mm plus the distance you have written on your piece of paper. You could do this with the Letus front-end and groundglass carrier out of the Letus body but your chances of damaging something will be pretty good so my personal preference is to have the front-end secured back inside the body for this task.

In the case of my mount, the clamp ring to bottom face (flange) is 5mm, so front of clamp ring to focal plane mark would be 52mm plus 5mm which is 57mm.

This process will put you in the ballpark of correct flange to focal plane, so long as you are able to get the mount tail into the Letus body far enough back.

It is my guess you will need to have it forward of full rearward insertion like the old reversable Nikon-Canon mount. If the tail of the PL Mount is too long to enable you to get it far enough in then something may be wrong I cannot help you with.

To establish correct backfocus from this point on, everything I have mentioned in the sticky thread for Letus XL should be valid.

It will be helpful to make up some round packing shims from cereal pack carboard or icecream pack plastic to go between the tail of the PL mount and the internal face of the Letus to help keep things square and help get it exactly right in the future should you have to remove the mount. The way these work can be seen in the YouTube clip I posted which is linked in the lowermost post of the Letus XL sticky thread.

[Michael Totten]

this is funny. I paid like 1500 bucks to Letus so I can go through this process? I love it! About half way through I couldn't figure out whether or not this post was a joke... this is a joke right? If it's real then I'm impressed with your ability to re-engineer the Letus and if it's not then I'm impressed with your sense of humor. Either way I'm happy to pay more for something that works and works well.
5K for the movietube is fine by me... although, I think I missed the fact that it doesn't have a PL mount? Anyone?

[Michael Maier]

Michael, I believe Bob was genuinely trying to help. He's a very nice guy and one of the most helpful people around here. He always takes the time to write as thoroughly as possible and he is extremely knowledgeable about 35mm adapters.
It isn't his fault that Letus slacked on their job. ;)

[Bob Hart]

I am not joking and admit I initially was a little cross about being thought to be a jokester but that is my problem to deal with.

I am seriously offering this advice at expense of an hour or two of my life which might better be spent on making money, sleeping, breaking bad wind or whatever.

US$5K for the Movietube is going to get you a very robust, precisely engineered, stationary, not moving groundglass system.


Back to the Letus Extreme.

I am not about to go in to bat for the Le brothers. They are grown lads and can look after themselves.

The original Letus was a improvised build by an enthusiast for enthusiasts at an affordable price and who in the large accepted that there was some final trim and adjustment required of them to get it working best.

Current build quality is more robust and precise and this is reflected in the added costs now asked. The product is more sophisticated but is not so sealed up and locked down that enthusiasts cannot get inside and tamper to their heart's content.

The Letus Extreme I cannot yet speak for as a turnkey proposition out of the box as I have not yet got my greasy hands on one.

I found that the early Letus35 with some tweaking could yield pleasing images reliably. A P+S Technik Mini35 it definitely was not but the image was to my view within the last ten percent qualitatively in some of the lens-in-camera versions.

There are people doing serious and good work with the Letus Extreme, happy with what they have and content to live within its means.

If you do not have fine motor co-ordination and mechanical ability, then maybe it is not for you. From time to time, secondhand Mini35-400s come onto eBay in the US$6K to 7K ballpark and 300s at US$2k to 4K.

[Michael Totten]

Bob.

Please accept my apology. It was not my intention to poke fun at you, really I mean that. Rather I was genuinely shocked at how in depth the process was... not to mention the skills it takes to figure something like that out. It was so detailed in fact that initially I couldn't tell if it was a joke. It's a rare kind of post. Now having read it again, it's clear that it is no joke.
Thank you for taking the time to offer this solution for Letus owners.... and thank you for taking the time to figure it out in the first place. If I have offended anyone else on this board than please forgive me.
best,
michael

[Bob Hart]

Michael.

No hard feelings. Sometimes I lose the plot a little in translating from american to strine and sometimes turns of phrase in strine are misintepreted by americans, particular example being our use of the word "mob" which here does not exclusively mean the mafia like it does in the US.

I have taken the liberty of emailing Hien Le with a link to this thread so hopefully he, Quyen or Aaron will respond soon, though with Easter fast approaching, next Tuesday or Wednesday might be a more reasonable bet.

The moving-of-the-pillars thing might have been a much earlier suggested solution relating to the original Letus35 and I am surprised it is still being propagated.

Again I state that it would not be my preferred method because this part of the whole adaptor is where the build precision is pretty good and moving the groundglass itself also has a collateral effect on the camcorder focus via the dioptre.

[Hien Le]

Hi all,

The instruction is for the people we feel are handy enough to do it. Please do not use other's instruction that may void the warranty. We are behind the product and if you call us, we are more than glad to walk you through the process when we think you can do it. Anyway, there is a trick to put the black rubber feet back. You need to use a tooth pick to stuff the rubber feet into the hole first, then push the silver post into the rubber feet, then pull it out to the proper back focus level. The process, if done properly, takes about 10 seconds, if not done right, you wouldn't even get it to go in if you have the rubber foot on the silver post and stuff both in at the same time. Bob is right, you can use the shim method like P+S Technik is using for the their product. Moving the posts in/out is more of a permanent solution (done once), but it must be done right. The new Nikon , PL and Canon EF mounts has the 3 little screws on the back of the mount, so you can use it instead of the shim.

One more note, we do not read forums often. This was brought to our attention by Bob (Thanks Bob) and the best way to contact us is by email or calling our toll free number.

Thanks,

Hien