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Old July 1st, 2008, 10:46 AM   #1
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Letus versus RedRock

Does anyone have experience comparing these two 35mm Nikon Adapters? If so, which one do you prefer? Also, with the RedRock I know one needs to purchase support rods, I assume the same is with the Letus? Also, what size MatteBox or adapter do I need to use the Letus? I've settled on the Z7U for my boss and I'm trying to make sure what I order actually will work for him.

Thank you again for your help.
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Old July 2nd, 2008, 05:15 AM   #2
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Z7/M2 not possible(?)

Hi Jason,
I just posted this message on the RedRock forum;

QUOTE
We have been using our M2 with a Z1 for a couple of years now, with fine results. (SD achromat, hard mounted, nikon glass).

Now we bought 2 Z7's to replace our Z1's. The Z7 is a great camera, especially the (removable) lens is great, and low-light performance is on par with what we were used to in the PD170 days.

The Z7 lens can be set in autofocus or manual mode by sliding the focus ring back and forth. The manual mode is a 'real' mechanical focusing mode, with hard stops.
But:
The minimum manual focus distance is 0.8 meter. For anything closer you have to engage 'macro' mode in a menu. This macro mode however only works in autofocus mode!

When mounting the M2 you want to focus on the groundglass, hence you have to set the camera to macro mode, and set the lens to autofocus.
Zooming in on the groundglass is no problem; there is more leeway than on the Z1. The camera focusses automatically on the groundglass.
So far so good.
When you start moving the camera, panning/tiliting, the camera looses focus on the groundglass and starts hunting to find the new focus setting. This makes using the Z7 with the M2 impossible, except for static shots (which look fantastic btw). The same goes for the S270 shouldermount version.

Anyone else using the Z7 with the M2? Any ideas for a workaround?

happy shootin'
John
UNQUOTE
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Old July 2nd, 2008, 12:06 PM   #3
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Interesting! Thank you for the message. That really stinks. Not that static shots are bad, but still, the option is nice. Do you know if the Letus adapter has the same issue?
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Old July 2nd, 2008, 01:01 PM   #4
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I don't know about the Letus..it seems that it will be difficult to focus close enough for any adapter I guess.

I forgot to mention that the Z7 looses focus on the GG also when performing a rack focus with the 35mm lens.. So use of the adapter would be really limited.
...unless some fellow M2 user has a solution, you might want to follow this thread on the RedRock forum: http://www.redrockmicro.com/forum/viewtopic.php?t=5900

having said all this..the Z7 is an incredably nice piece of equipment, certainly for manual/low light work.. For 35mm adapter work I'd consider the Z1, or one of the HVX's though..
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Old July 2nd, 2008, 01:35 PM   #5
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Thank you for the input, that is really important information to know. I will talk to my boss about it. He wants the camera for pet documentary projects, so it is really all up to him. I think it might push him back into the JVC200U area though he much prefers Sony's. Damn, this has gotten even more complicated.

Thank you once again though, I really appreciate it. As a Sony user, what is your thought about the JVC?
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Old July 2nd, 2008, 02:23 PM   #6
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Sorry Jason, 25 years in the business, always used sony, occasionally panasonic.
Don't have a clue about JVC ;-)
good luck,
John
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Old July 25th, 2008, 09:58 AM   #7
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Quote:
Originally Posted by John Bour View Post
Hi Jason,
I just posted this message on the RedRock forum;

QUOTE
We have been using our M2 with a Z1 for a couple of years now, with fine results. (SD achromat, hard mounted, nikon glass).

Now we bought 2 Z7's to replace our Z1's. The Z7 is a great camera, especially the (removable) lens is great, and low-light performance is on par with what we were used to in the PD170 days.

The Z7 lens can be set in autofocus or manual mode by sliding the focus ring back and forth. The manual mode is a 'real' mechanical focusing mode, with hard stops.
But:
The minimum manual focus distance is 0.8 meter. For anything closer you have to engage 'macro' mode in a menu. This macro mode however only works in autofocus mode!

When mounting the M2 you want to focus on the groundglass, hence you have to set the camera to macro mode, and set the lens to autofocus.
Zooming in on the groundglass is no problem; there is more leeway than on the Z1. The camera focusses automatically on the groundglass.
So far so good.
When you start moving the camera, panning/tiliting, the camera looses focus on the groundglass and starts hunting to find the new focus setting. This makes using the Z7 with the M2 impossible, except for static shots (which look fantastic btw). The same goes for the S270 shouldermount version.

Anyone else using the Z7 with the M2? Any ideas for a workaround?

happy shootin'
John
UNQUOTE
John,
Once you have focused on the ground glass you should then disengage the autofocus mode by moving back to manual focus mode. This should stop the camera trying to refocus when you move the shot. I have done this with my ex1. same deal.
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Old July 25th, 2008, 02:30 PM   #8
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Yup.

Quote:
Originally Posted by Alexander Kubalsky View Post
John,
Once you have focused on the ground glass you should then disengage the autofocus mode by moving back to manual focus mode. This should stop the camera trying to refocus when you move the shot. I have done this with my ex1. same deal.
That's what I would do. Can't see why it wouldn't work.

Jus.
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Old July 25th, 2008, 03:33 PM   #9
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When the Le brothers have sorted their 1/3" direct relay for JVC GY-HD---, this relay should fit your Z7.

The lens mount profile is identical and I have offered up a P+S Technik Mini35 JVC relay to one and it fitted. There is a small panel of conductors in the mount which the JVC does not have. These are slightly recessed so should not touch the plain mount of the Letus relay.

Last edited by Bob Hart; July 25th, 2008 at 03:34 PM. Reason: error
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Old July 25th, 2008, 08:55 PM   #10
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I haven't actually used the adapter but I own a Z7 and another solution I might suggest is to leave the ring forward so macro is on but use the menu based manual focus which works just like the focus on a Z1. This style allows you to lock focus at manual settings.
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Old August 8th, 2008, 02:27 AM   #11
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Z7 + adapter

So, does the workaround work re the focus issue?

I've got a Z7 and am looking at using an adapter but don't like the idea of leaving autofocus on.

One of the reasons I bought the Z7 and not the EX1 (pre EX3) was for the interchangeable lens and the possibility of not using the stock lens but instead mounting 35mm lens on an adapter mounted directly on the camera body.

However, still no sign of a relay from Letus.

Also, because the aperture is set on the stock lens barrel, once this is removed I wonder what kind of control you can have over exposure - assuming you want to keep the 35mm lens wide open to make up for adapter's loss of light, for the shallow depth of field and to avoid ground glass patterns. So now I'm back to thinking that an adapter at the end of the stock lens is not a bad thing.

Any thoughts or experiences?

Mickey
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Old August 10th, 2008, 06:20 AM   #12
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I have had a bit of a play experimenting with the genuine P+S Technik JVC GY-HD--- direct relay on back of a Letus Extreme to see if it is viable to shove the Extreme on front of a SI2K.

The 2/3" CMOS image area of the SI2K may be a little large for the 1/3" relay lens despite the larger screen area of the Letus groundglass. Until I have an underscanning monitor to study I won't know if this is workable. The P+S relay also has a small exit pupil which may not suit the 2/3" image area. Chances are there may be corner or edge softness and brightness falloff into the corners.

The JVC KY-F50 camera I am using is SD only so edge softness truths are not easily seen.

It seems however, that the Mini35 JVC relay which apparently also fits up to the Z7 may work on the back of the Letus in place of the Letus own achromatic dioptre. It seems it would have to be very closely coupled, more so than to the genuine Mini35.

P+S Technik set their relay up to be sharp on their groundglass at close to its equivalent of distant focus.

There might be a little wriggle room to go closer with the relay lens and use its focus adjustment to gain a little more of the available groundglass area the Letus screen offers. I have yet to try this with the genuine JVC camera however.

The real world decrees that there will be little extra more image area to be had from the Letus versus the Mini35 itself with the Mini35 relay to a 1/3" camera because this relay has been optimised for the genuine motion picture frame of about 24mm.

This reprises the same "multiplication factor" issue which was one of the complaints about the original Minolta based Letus direct relay for JVC GY-HD--- and Canon XL camera families. Whilst the frame size of that relay was close to faithful to the genuine movie frame as is the Mini35 itself, this area represents a small area of the Letus groundglass.

Please do not go out buying P+S relay lenses from on-line auctions on the strength of my comments as you may be disappointed if I am wrong, which is a distinct possibility.

Last edited by Bob Hart; August 10th, 2008 at 07:03 AM. Reason: error
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Old August 10th, 2008, 10:25 AM   #13
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Postscript to my previous post.

Using the P+S 1/3" relay for the larger Letus screen to a 2/3" imager is a dead end. The 2/3" imager shows a significant portion of the groundglass carrier frame edge.

A Nikon 35mm f1.4 will yield coverage of the Letus groundglass screen to a 2/3" imager with the Letus achromat in place in the rear of the "Extreme". It appears though that there is too much resolution lost through the Nikon for this to be a workable option to relay the Letus Extreme to the SI2K.

I was not able to achieve even MiniDV resolution via this route as the attached image illustrates. A properly engineered solution will be the only way to go, no doubt what the Le brothers have discovered and acted upon.

The smaller image area laid within the 2/3" imager by the Mini35 relay appeared to be sharp to the SD camera I was aquiring the image with. Next opportunity which won't be soon I will put this on the front of a JVC GY-HD111 to see what happens. If it is good for the HD100 it should also be for the Z7.
Attached Thumbnails
Letus versus RedRock-letus-ky-f50-test-contrast-adj-frame.jpg  

Last edited by Bob Hart; August 10th, 2008 at 10:48 AM. Reason: error
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