LA-100W Alpha Lens Adapter at DVinfo.net

Bryan Lawler · September 17th, 2009, 09:08 AM

Can anyone confirm this? If I understand this correctly, if I attach the LA-100W Alpha Lens Adapter to the Z7U it records the image correctly without the need to flip it in post. Is this true?

Wacharapong Chiowanich · September 17th, 2009, 10:59 PM

Yes it is. This mount is just plain mechanical mount with no optical lens element inside it. However, the focal lengths indicated on the lenses mounted onto this adapter have to be multiplied by about 7x to give the field of view on the video footage comparable to that of the 35mm still camera format.

Bryan Lawler · September 18th, 2009, 06:45 AM

So, I could get the adapter or one of these (Adaptimax or MTS) for half the prices and get better DOF and control with out having to buy a 35mm system like Cinevate or Letus.

Wacharapong Chiowanich · September 18th, 2009, 08:37 AM

I think you got confused between lens mount adapters such as the Sony and some other cheaper alternatives and depth-of-field adapters such as Letus, Brevis, Redrock, P+S Technik etc. The latter type has much more complex constructions that incorporate optical lens, prisms and additional electrical components to redirect and project the image. The final image projected onto the camera's sensors has the depth of field and focusing characteristics similar to the image produced by true super 35mm sensors.

A depth-of-field adapter normally costs somewhere from US$800 up to US$10,000+. This of course does not include the cost of the 35mm still camera or super 35mm cine lens(es) to be mounted on one of these adapters. Handheld shooting is also very hard if not impossible since an effective system usually doubles or even triples your camera's weight, not to mention the change in the ergonomics dictated by all the add-ons.

Zach Love · September 18th, 2009, 09:21 AM

I think the trouble is that there is a lot of bad terminology out there which has caused a incorrect understanding of lenses & cameras.

I have said it before, but a 50mm lens has the same DOF on a 70mm film camera, a 35mm film camera, a 2/3" video camera and a 1/3" video camera.

But a 50mm lens will have a different FOV on a 70mm, 35mm, 2/3", or 1/3" camera.

Personally I think the "DOF" adapters should be called "FOV" adapters, because they don't change the DOF, they just change the FOV.

A 50mm lens produces a 1.0x "zoom" / FOV on a 35mm camera, while a 50mm lens on a 1/3" (Z7) produces a 7.0x "zoom" / FOV.

When you use a Letus (or any other adapter) what you are doing is getting a FOV of of a 50mm lens as if it was on a 35mm film camera.

When you use a MTF adapter or the LA-100W (which uses Sony Alpha or Minolta lenses) you aren't modifying anything. The SLR lens attaches directly onto the camera. But since the Z7's chips are so small compared to a 35mm negative, the FOV of a SLR lens is multiplied 7x. A 50mm does NOT turn into a 350mm lens w/ this adapter, a 50mm lens on a Z7 has the same FOV as a 350mm lens on a 35mm film camera.

Make sense?

Bryan Lawler · September 19th, 2009, 07:41 PM

Well, here's my thing. My confusion is, if I want to take advantage of the 35mm DOF can I achieve it with the MTS, or the Adaptimax (which does not have a 7.0x) or do have to have the 7.0x that's in the LA-100W or do you have to have a Letus?

Wacharapong Chiowanich · September 20th, 2009, 07:36 PM

What you will need:

-A depth-of-field or super 35 adapter like a Letus (or Redrock, Brevis etc.)
-A 35mm still camera lens such as a Nikon AI or AF F-mount lens with an aperture ring or
-A super 35 cine lens such as a PL-mount Zeiss, Cooke, etc.
-An appropriate lens mount adapter that fits between one of the above lenses and one of the above DoF adapters.

These are the minimal requirements. In practice you will most likely need a lot more like supporting rails, on which a follow focus mechanism needs to sit, a matte box for a specific type of lenses, a tripod or steadycam mounting rig, and so on.

Zach Love · September 21st, 2009, 07:22 AM

Quote:

Originally Posted by Bryan Lawler

Well, here's my thing. My confusion is, if I want to take advantage of the 35mm DOF can I achieve it with the MTS, or the Adaptimax (which does not have a 7.0x) or do have to have the 7.0x that's in the LA-100W or do you have to have a Letus?

First things first, you don't know what you want. This is NOT what you want: "I want to take advantage of the 35mm DOF"

This IS what you want: "I want to take advantage of the 35mm film FOV"

I believe that all of these are just adapters. All they do is let you attach a SLR lens to a Video camera mount. Wanting an adapter to change the DOF is like wanting a RCA to 1/8" adapter to change a mono signal to 5.1 surround sound. Not going to happen.

If you want to see the same framing (FOV) on your Z7 as you do on your SLR, do NOT get one of these adapters. Get a Letus, Redrock, DIY kit, etc.

DOF is determined by two things: the length of a lens (50mm, 135mm, etc.) & the F-stop of a lens (f1.4, f2.8, etc).

DOF is never ever ever EVER controlled by a camera or adapter.

(You can get a wide angle adapter or telephoto adapter which will change your DOF because it also changes the lens's length.)

FOV is also determined by two things: length of the lens & size of the frame (film negative or CMOS/CCD chip).

A 50mm lens on a Z7 & 35mm film camera will produce the same DOF, but very different FOV.

I highly recommend that if you want to be a professional photographer (video or still) you NEED to understand the difference between DOF & FOV. Any good book on advanced photography should go through it and can be found at your local library. Or you can check out these links:

Field of view - Wikipedia, the free encyclopedia
Depth of field - Wikipedia, the free encyclopedia

DOF vs FOV for a photographer is like motor oil vs gasoline for a car mechanic. Two very basic things, that if mixed up will only cause problems.

September 17th, 2009, 09:08 AM	#1
Bryan Lawler Regular Crew Join Date: Jan 2005 Location: Joplin, MO Posts: 28	LA-100W Alpha Lens Adapter Can anyone confirm this? If I understand this correctly, if I attach the LA-100W Alpha Lens Adapter to the Z7U it records the image correctly without the need to flip it in post. Is this true? __________________ Bryan S. Lawler http://www.chasingdaylightproductions.com

September 18th, 2009, 06:45 AM	#3
Bryan Lawler Regular Crew Join Date: Jan 2005 Location: Joplin, MO Posts: 28	So, I could get the adapter or one of these (Adaptimax or MTS) for half the prices and get better DOF and control with out having to buy a 35mm system like Cinevate or Letus. __________________ Bryan S. Lawler http://www.chasingdaylightproductions.com

September 18th, 2009, 09:21 AM	#5
Zach Love Major Player Join Date: Jul 2006 Location: Chicago, IL Posts: 944	I think the trouble is that there is a lot of bad terminology out there which has caused a incorrect understanding of lenses & cameras. I have said it before, but a 50mm lens has the same DOF on a 70mm film camera, a 35mm film camera, a 2/3" video camera and a 1/3" video camera. But a 50mm lens will have a different FOV on a 70mm, 35mm, 2/3", or 1/3" camera. Personally I think the "DOF" adapters should be called "FOV" adapters, because they don't change the DOF, they just change the FOV. A 50mm lens produces a 1.0x "zoom" / FOV on a 35mm camera, while a 50mm lens on a 1/3" (Z7) produces a 7.0x "zoom" / FOV. When you use a Letus (or any other adapter) what you are doing is getting a FOV of of a 50mm lens as if it was on a 35mm film camera. When you use a MTF adapter or the LA-100W (which uses Sony Alpha or Minolta lenses) you aren't modifying anything. The SLR lens attaches directly onto the camera. But since the Z7's chips are so small compared to a 35mm negative, the FOV of a SLR lens is multiplied 7x. A 50mm does NOT turn into a 350mm lens w/ this adapter, a 50mm lens on a Z7 has the same FOV as a 350mm lens on a 35mm film camera. Make sense? __________________ Nothing says you're a serious video maker like S-VHS

September 19th, 2009, 07:41 PM	#6
Bryan Lawler Regular Crew Join Date: Jan 2005 Location: Joplin, MO Posts: 28	Well, here's my thing. My confusion is, if I want to take advantage of the 35mm DOF can I achieve it with the MTS, or the Adaptimax (which does not have a 7.0x) or do have to have the 7.0x that's in the LA-100W or do you have to have a Letus? __________________ Bryan S. Lawler http://www.chasingdaylightproductions.com

September 17th, 2009, 10:59 PM	#2
Wacharapong Chiowanich Major Player Join Date: May 2008 Location: Bangkok, Thailand Posts: 400	Yes it is. This mount is just plain mechanical mount with no optical lens element inside it. However, the focal lengths indicated on the lenses mounted onto this adapter have to be multiplied by about 7x to give the field of view on the video footage comparable to that of the 35mm still camera format.

September 18th, 2009, 08:37 AM	#4
Wacharapong Chiowanich Major Player Join Date: May 2008 Location: Bangkok, Thailand Posts: 400	I think you got confused between lens mount adapters such as the Sony and some other cheaper alternatives and depth-of-field adapters such as Letus, Brevis, Redrock, P+S Technik etc. The latter type has much more complex constructions that incorporate optical lens, prisms and additional electrical components to redirect and project the image. The final image projected onto the camera's sensors has the depth of field and focusing characteristics similar to the image produced by true super 35mm sensors. A depth-of-field adapter normally costs somewhere from US$800 up to US$10,000+. This of course does not include the cost of the 35mm still camera or super 35mm cine lens(es) to be mounted on one of these adapters. Handheld shooting is also very hard if not impossible since an effective system usually doubles or even triples your camera's weight, not to mention the change in the ergonomics dictated by all the add-ons.

September 20th, 2009, 07:36 PM	#7
Wacharapong Chiowanich Major Player Join Date: May 2008 Location: Bangkok, Thailand Posts: 400	What you will need: -A depth-of-field or super 35 adapter like a Letus (or Redrock, Brevis etc.) -A 35mm still camera lens such as a Nikon AI or AF F-mount lens with an aperture ring or -A super 35 cine lens such as a PL-mount Zeiss, Cooke, etc. -An appropriate lens mount adapter that fits between one of the above lenses and one of the above DoF adapters. These are the minimal requirements. In practice you will most likely need a lot more like supporting rails, on which a follow focus mechanism needs to sit, a matte box for a specific type of lenses, a tripod or steadycam mounting rig, and so on.