New Custom Nikon Mount For Letus Is Available

Check the blog out on the New Nikon mount, pictures .I had to re-set the back focus as my shots were soft at infinity with the new mount, so a back focus took care of this.
Note that the new Nikon mount does allow setting back focus.

http://web.mac.com/stevecahill/Steve_Cahills_Blog/Blog/Entries/2008/3/15_Nikon_Mount_for_Letus.html


I will do another blog on "How To" set back focus.


Meanwhile: it is worth while taking a look @ Letus Autopsy on the blog to get familar with the inside of the Letus ground glass and posts for checking ground glass squareness
@ http://web.mac.com/stevecahill/Steve_Cahills_Blog/Blog/Entries/2008/1/6_Letus_Autopsy_1.html
 
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the new mount does not allow for setting back focus? I thought this was the major feature? Damnit, i wish i had known that before purchasing it.
 
I think that it is adjusted for correct back focus for the HVX vs. the EX1. This is what hien said, that they have to make two different mounts because the back focus is different for those cameras. I think I understood him right.
 
I got the new mount and put it in two days ago. No backfocus adjustment - haven't checked to see if it needs adjustment yet.

The mount is rock solid even with my hard to turn 135mm and follow focus.
 
CORRECTION: There is back focus with the new Nikon mount. 3 screws on the back on the NEW Nikon mount, I did not see it at first.
 
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i know how ot adjust backfocus, it was just time consuming having to hook up the camera to the HD TV, setting my focus on infiniti, and trying my best to adjust the backfocus with my hands to the most accurate sharp infinity possible.

Something like on the brevis would have been great. But still, i know the mount will be worth it. I just got lost in the rumors i guess :(
 
This is what it says when you go to letusdirect.com shop>accesories "The ever popular Nikon AI Mount for the Letus35 adapters. Now in a new and improved one-piece version with built in back focus adjustment."
 
I am editing this weekend but I have the new mount just sitting there, waiting for me to use it next week. I am now totally confused about if the new mount has a back focus adjustment and if it doesn't, how else would you set back focus?

Anyway, let me know when all of you get this straightened out. I am so confused, I just want edge to edge sharpness with no unevenness in the entire raster.

Thanks,

Dan
 
The backfocus adjustment won't affect edge to edge sharpness.

I know how to adjust the backfocus properly, it's not hard but you should take care in doing so.

Dan, if you want me to adjust your unit let me know and you can stop by in Santa Monica sometime this week.
 
Kholi said:
The backfocus adjustment won't affect edge to edge sharpness.
Click to expand...

Oh, I thought that on the old mount, if you had the mount not perfectly even, it would result in a portion of the screen being sharp and an opposite portion being soft. Was that not true? When I set my back focus on the old mount, I saw that in the monitor.

Thanks for your kind offer, I will try the new mount and set it up with my focus charts. If its off, perhaps I will take you up on your offer and buy you a beer too ;-)

Thanks,

Dan
 
Orange Juice only.

I suspect that if the glass isn't on properly then definitely. That's something for me to try while I have another Nikon 50mm and my m42 mount Takumar, to see if the Nikon is softer at the edges perhaps due to misalignment.
 
Douglas Villalba said:
Not if it is perfectly square, but there is no easy way of doing that.
Click to expand...

That was the challenge I always had on the old mount, I could hold it so the entire focus chart was sharp but then when I would hold it with one hand and try to lock down the Allen screws, it would slip slightly and I would lose the perfect sharpness. If I had four hands, I could have done it ;-)

I thought perhaps because the new sleeve that fits into the LEX body looks bigger and heavier, perhaps it would make setting the back focus easier and more accurate?

Dan
 
For the back focus, there are 3 screws on the back that allow you to adjust the position that the mount sits on the front tube of the Extreme (screw the 3 screws evenly out so it will adjust the distance between lens and the GG - known as back focus). This is not the best solution to adjust the back focus, that's why I don't even bother to tell people we have it, but it's there :-)
 
puredrifting said:
That was the challenge I always had on the old mount, I could hold it so the entire focus chart was sharp but then when I would hold it with one hand and try to lock down the Allen screws, it would slip slightly and I would lose the perfect sharpness. If I had four hands, I could have done it ;-)

I thought perhaps because the new sleeve that fits into the LEX body looks bigger and heavier, perhaps it would make setting the back focus easier and more accurate?

Dan
Click to expand...

If you're dealing with backfocus, setting proper backfocus would entail measuring from the GG on the Letus to an object that is the focal point of your lens.

Say, an water bottle at three feet away should (even on an SLR) read somewhere very close to three feet. Backfocus is the relationship between Lens and Ground Glass.

Setting the HVX's focus is different.

If the new mount allows the lens to sit flush then edge to edge should be improved partially, you can also use Lenny's Method (phrase coined) to achieve better edge-to-edge which is to focus somewhere in between center GG sharpness and edge GG sharpness.

That's what I've been doing ever since I learned that it does help edges, and it's especially helpful with wider lenses. At least until the HVX upgrade ring is released.
 
Back Focus is possible on the New Nikon Mount

Back Focus is possible on the New Nikon Mount

My mistake! Upon closer inspection there are 3 screws on the new Nikon mount on the rear of the mount.
The 3 screws on the back allow you to adjust the position that the mount sits on the front tube of the Extreme (screw the 3 screws evenly out so it will adjust the distance between lens and the GG - known as back focus).

I have updated the blog to reflect this correction.
 

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hienle said:
For the back focus, there are 3 screws on the back that allow you to adjust the position that the mount sits on the front tube of the Extreme
Click to expand...

Well that's good to know. It's like an easter egg for the Letus.

My primitive technique: I layer gaffer/camera tape of various thickness evenly around four sides of the front opening of the Extreme. Then hold the mount with lens up against the tape. I have an object 3 or 5 feet away (measured from the ground glass). I set the lens to that focus distance. Adjust the amount of tape until it's dialed in. Tighten. Remove the tape (slowly and carefully). This leaves a very thin even gap. Check a few lenses. Primitive? yes. Works? seem to.

I think I like the screws on the back idea better.

Kholi seems to have a way to set back focus - do tell.

Pete
 
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