35mm DOF w. this attachment

[Landon D. Parks]

Can someone tell me if this would be a good "Mini35" adapter? I dont think its the Mini35 name brand, but I'm not sure. It's up @Ebay here:

 

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...3878162607&rd=1

 

It looks fishy to me, but what do I know? It's also only $300.00!

 

Maybee someone has some advice?

Edited March 1, 2005 by Landon D. Parks

[Stuart Brereton]

This adapter was talked about on the Cinematography Mailing list recently. no-one knew if it worked or not, but there was some concern that the interior of the adaptor was painted metallic red, rather than matt black. Any stray light bouncing around in there is going to do nasty things to your image.

 

Also slightly worrying was the assertion that 'losing 1-2 stops of light is by no means significant...' well, maybe not if you're shooting Day Exteriors, but what about Night shoots?

 

I would save your money for the Micro 35.

 

Stuart

[Laurent Andrieux]

Yep. It looks like itis very far from mini35 system, that reduces the dof with a sort of Ground glass the image is taken from or something so.

 

here we only have a plmount adaptator that only allows you to set pl lenses on a video cam. Sure you'll get a better optic quality, but it will still be dv.

 

It only means something if you have or wish to rent pl optics and need some dv footgae with the best optic quality one can have. I actually don't understand why the system should occure a light loss, but if it would have a longer optic calibration than a standard 35 camera,

 

(EDIT : That's the case if you look at the profile view of the system)

 

causing the focus ring to be totally false and - not least - the impossibility to reach the infinite. You actually could do some macro shots and that can be of interest but this is maybe why the samples show are only CU but the girl with the gun which is apparently done from a very close distance unless the deformation is due to another cause...

 

That might also explain this strange sentence : "When using the adaptor with either 16MM or 35MM lenses, the (DOF) depth of field is preserved, and it effectively increases the focal length of the PL mounted lens by 2x" wich doesn't make sense by it self but worries me also about the field of view that seems to be highly reduced if I understand well

Edited March 1, 2005 by laurent.a

[drew_town]

You won't get a 35mm DOF with that adaptor. The mini35 is the only attachment that'll give you the flexibility of 35mm because you're recording a projected 35mm image. That attachment is probably nice in letting you use the lens you'd like but it's going to look pretty much like any other XL1s lens. All the Canon lenses have their disadvantages: standard 16x lens is just junk (bad focus, no control), 14x manual has no servo control and no built in ND's, and the 16x manual doesn't have an iris on the lens. If the 16x manual lens had a iris it'd be the one everyone would probably use. So other options are nice.

[Jason McKelvey]

You won't get a 35mm DOF with that adaptor.

<{POST_SNAPBACK}>

 

Assuming that the adaptor works and you put a 35mm PL mount lens on your XL1, how exactly would it change the DOF characteristics of the 35mm lens? To clarify, this adaptor allows you to use the center 1/2 of the original length of the PL mount lens... so it's not an optical 2x, it's just that the CCD will only see 1/2 the lens information. So, why would the DOF characteristics be different all of the sudden when you put it on a DV camera? My understanding is that you can't change the DOF characteristics of a lens short of redesigning/manufacturing it. By the way, 35mm lenses don't have a shallower DOF field per-say, the focus fall-off is greater, making the background more blurred. I'll submit that the DOF characteristics would remain intacted.

 

Jason

[Glenn Hanns]

....how exactly would it change the DOF characteristics of the 35mm lens?  To clarify, this adaptor allows you to use the center 1/2 of the original length of the PL mount lens... so it's not an optical 2x, it's just that the CCD will only see 1/2 the lens information.  So, why would the DOF characteristics be different all of the sudden when you put it on a DV camera?  My understanding is that you can't change the DOF characteristics of a lens short of redesigning/manufacturing it.  By the way, 35mm lenses don't have a shallower DOF field per-say, the focus fall-off is greater, making the background more blurred.  I'll submit that the DOF characteristics would remain intacted.

 

Jason

<{POST_SNAPBACK}>

 

To the best of my knowledge DOF characteristics are NOT necessarily associated with the type of lens 16mm, 35mm, 65mm (other than specialised lenses like the Frazier lens). The DOF of a lens is affected by focal length, focal distance, iris and recording medium. It?s the recording medium of 35mm that has a shallower DOF to say 16mm at the same focus, focal length and iris. So 35mm lenes DO have a shallower DOF, there is no such thing as focus fall-off because this excludes and assumes that there is no "focus fall up?" which is the second part of your DOF.

With the above in mind, by ..."only see(ing)1/2 the lens information." you are effectively doubling your focal length from 25.. to a 50mm say. This focal lenght change will affect DOF as mentioned above. This also has to be offset by the fact that your going from a 35mm image to a DV CCD which is 6mm, nearly 6 times smaller.

 

Glenn.

Edited March 2, 2005 by glenn@uow.edu.au

[Jason McKelvey]

I don't want to sound argumentative, but I need to post a friendly response...

 

Quote:

"To the best of my knowledge DOF characteristics are NOT necessarily associated with the type of lens 16mm, 35mm, 65mm (other than specialised lenses like the Frazier lens). The DOF of a lens is affected by focal length, focal distance, iris and recording medium. It?s the recording medium of 35mm that has a shallower DOF to say 16mm at the same focus, focal length and iris."

 

DOF characteristics have NOTHING to do with the medium that records the image... that it completely determined by the optics. That's why they created the P&S Technic device, to deliver 35mm LENS performance (DOF and such) to other formats.

 

Quote:

"So 35mm lenes DO have a shallower DOF, there is no such thing as focus fall-off because this excludes and assumes that there is no "focus fall up?" which is the second part of your DOF."

 

Take a prime 50mm and use a P&S Technic adaptor on a XL1.

Take a standard video zoom lens and set up the same framing on another XL1.

Put something in the forground and something in the background of your subject.

Using the iris/shutter on both cameras, set the DOF field to match each other. In other words, make both cameras have a DOF of... let's say 6 inches or whatever. The shots are framed the same, have the same DOF, what looks different besides the ground glass effect from the 35mm lens? The background and forground elements! These are the falloff (fallup?) "characteristics" I'm talking about. I'm working on getting an adaptor in the next few weeks, I'll post frame grabs of my comparisions. If I'm wrong, the pictures won't lie and you'll forgive me of my arrogance.

:)

[drew_town]

The reason you won't get a 35mm DOF is not the lens, it's the CCD and the fact that it's a lot smaller than a 35mm slide. The way the mini35 works is it casts the image onto a slide about the same size as a 35mm slide and your CCD records what's projected on the slide. It's really quite simple: the mini35 records a "35mm" image and the DV camera records what the mini 35 projects. Like I said, the cheap adaptor is nice because it'll let you choose a wide range of lenses to use but don't think you'll magically get a shallow DOF with that thing. Sorry Jason but DOF has a lot to do with the medium. The bigger the platform (CCD's, 35mm, so on) the more range you'll have with DOF. The mini35 fakes a larger format.

[Glenn Hanns]

DOF characteristics have NOTHING to do with the medium that records the image... that it completely determined by the optics. That's why they created the P&S Technic device, to deliver 35mm LENS performance (DOF and such) to other formats.

<{POST_SNAPBACK}>

 

Not right, DOF IS affected by image size that is why a 16mm lens has a greater DOF than a 35mm lens at the same T-stop focus and focal distance. The P+S has a 35mm pickup CCD built into it and this is relayed back to the DV CCD so that the image is captured in the 35mm size optically and then sent to the camera. To be more technical it actually has more to do with the distance from the end of the lens to the recording medium. If the recording device (film/video) is smaller it needs to be closer to the lens to be in focus so youre right to say that its all optics but the size does affect this.

 

Take a prime 50mm and use a P&S Technic adaptor on a XL1.

Take a standard video zoom lens and set up the same framing on another XL1.

Put something in the forground and something in the background of your subject.

Using the iris/shutter on both cameras, set the DOF field to match each other. In other words, make both cameras have a DOF of... let's say 6 inches or whatever. The shots are framed the same, have the same DOF, what looks different besides the ground glass effect from the 35mm lens? The background and forground elements! These are the falloff (fallup?) "characteristics" I'm talking about.

<{POST_SNAPBACK}>

 

What you're seeing there has to do with one of those 4 characteristics, and that is focal lenght.

Do you think a zoom lens on DV framed the same as 50mm on the 35mm pickup of a P+S will also so say 50mm?? I dont think so. This is what is affecting your difference in DOF.

Glenn.

[Jason McKelvey]

Like I said, the cheap adaptor is nice because it'll let you choose a wide range of lenses to use but don't think you'll magically get a shallow DOF with that thing. Sorry Jason but DOF has a lot to do with the medium.

<{POST_SNAPBACK}>

 

I can magically get a shallow DOF by going wide open on any lens, including video. We are talking symantics here... when you say,"DOF has a lot to do with medium" Your talking the format of the lens. You could record that information on cardboard, it wouldn't matter the medium (film, analog, digital).

 

Glenn, true the focal lengths may be different. I don't know how the product in question works. That's why I used the P&S technic product for my example because it relays the whole optics to the CCD. All I'm saying is that you cannot change the DOF characteristics of any lens. It's corresponds to the physical dimensions of the lens, so you would have to change the physical dimensions of the lens to get more or less DOF at any given f-stop and focal length.

 

People are constantly misusing the term DOF. They say that 35mm has a shallower DOF and therefore looks better (film medium arguments aside). Think about this, a 35mm frame with a DOF of 1 foot will look like it has less DOF than a similar frame of video with a DOF with 9 inches. But wait a minute, you say, the video actually has less DOF... but the 35mm frame background looks more out of focus? People need to stop saying "film has better DOF"... it makes no sense. It's all about the optics.

 

Love y'all,

[Patrick Neary]

If I understand the product in question- it looks just like a metal adaptor ring, no optics.

 

A 27mm lens will have the DOF of a 27mm lens.

 

An 85mm lens will have the DOF of an 85mm lens.

[Laurent Andrieux]

No, the dof is not greater in 16 mm than 35 mm at the same focal length, it's just the other way round. If project the image on the same size screen, you have to enlarger the 16 mm much better and this is why.

 

On the other hand, when you want to do the same shot (let's say a medium shot for instance) you have to use a wider lens, that will increase the depth of field, but it's not the same focal length anymore.

 

The smaller the image is, the less dof you get at the same focal length when projected the same size.

 

Therefore, a dv image projected on a wide screen would have less dof than 16mm and even less than 35.

 

The thing is, most video work are seen on tv sets, that give a much bigger dof than a wide screen.

 

This enlarging parameter is included in the circle of confusion.

 

Mini 35 gives you the ability of having a video that looks with less dof and then have the same feeling of dof on a tv set that 35 mm gives on a wide screen.

 

There is no other way to then decrease the dof than using a trick, that does mini35.

 

Back to the pl mount described : they don't say the dof is decreased, they sy it remains the same. Of course it does, since a 8 mm focal length will basically provide the same dof, being a canon or a zeiss on the same dv or whatever camera (I say basically cause, as someone mentionned, the feeling of dof can be a little different since a lens that is very sharp looks like getting worse comparativly when you lose dof, than a poor lens, that slowly loses definition, but has less definition at focus and therefore looks softer all the time).

 

No special trick, same dof.

 

What they mean about the focal length being increased by two is because the pulling of the lens is longer since the lens is further from the pickup device than the film plane should be from the same pl lens.

 

This is also why there is a loss of light.

Edited March 2, 2005 by laurent.a

[Patrick Neary]

"What they mean about the focal length being increased by two is because the pulling of the lens is longer since the lens is further from the pickup device than the film plane should be from the same pl lens.

 

This is also why there is a loss of light."

 

 

If this were true, you wouldn't be able to focus the lens anymore, or it would essentially become a macro-only lens (think extension tubes).

 

Unless this device does have some optical element built it (it sure doesn't look like it), then forget what i just said!

Edited March 2, 2005 by PatrickNeary

[Laurent Andrieux]

As I said before, if you look at the profile photo on their site, it really looks like it. How actually explain there should be a loss of light otherwise ?

 

"If this were true, you wouldn't be able to focus the lens anymore, or it would essentially become a macro-only lens (think extension tubes).

 

It actually would effectivly allow you to do macro shots, not keeping you to focus the lens, but keeping from reaching long distances. Did you notice that all the sample photos showed on the site are CU, but the shot of the girl with the gun, that looks like being shot from a very close distance anyway !

 

For this price I wouldn't be surprised if mounting a PL mount on a dv camera would just make the pulling longer ! look at the stills...

Edited March 2, 2005 by laurent.a

[Patrick Neary]

yes, but pulling a lens even several millimeters further from the film plane will turn it into a macro, and i mean MACRO-only lens. You wouldn't be able to focus further than several inches away.

 

To begin to start losing stops just from extending the lens, you need to be working at 1:1 magnifications or greater, if I'm remembering correctly.

 

could the 1-2 stop loss be from factoring in the Xl-1s prism block?...seems odd!

Edited March 2, 2005 by PatrickNeary

[Patrick Neary]

...a quick look at a magnification table shows that a 1 stop (1 and 1/5 to be exact) loss occurs at 1:2, while you have a 2 stop loss at 1:1.

[Laurent Andrieux]

Ok, but how to explain that loss? did you see the profile photo ?

[Patrick Neary]

It's a mystery to me!

 

The photo of the product on their website clearly shows just a simple metal adaptor ring, no optics.

 

Again, maybe the prism block robs some light?

 

I'd love to hear their rationale for the light loss. :blink:

[Rik Andino]

To answer the original post...this is a decent adapter that does work

And you can mount your PL-mount lens on it...

 

But it is not the P+S Technik Mini35 adapter.

 

Unlike the P+S Technik Mini35 adapter however

This adapter doesn't give you 35mm ANGLE-OF-VIEW

Meaning a 50mm PL-mount lens on the XL1 will have more of a telephoto effect

And so on...So you'll need to use wider lens to get the same Angle-of-view

 

I dunno what's the fascination with using PL-mount lens on DV cameras

Besides having more control on the depth-of-field I don't see any advantage

It's sorta like putting a Ferrari motor on a bike

 

If you really want to use 35mm lenses on an XL1

I recommend getting the Canon EF Lenses adapter

Canon Lenses are cheaper than PL-mount lens and easier to find.

 

 

Anyways good luck

[Laurent Andrieux]

The photo of the product on their website clearly shows just a simple metal adaptor ring, no optics.

 

Again, maybe the prism block robs some light?

 

The profile photo shows that the optic is much more further from the pick up device than a pl lens is from the film plane

 

What prism ? The cameras's one ? it is there anyway, Pl mount or not... Shouldn't do any difference...

[Jason McKelvey]

I think it's that the ccd only sees half the information. I'll try to post a crude pic. The black would be the 35mm frame, the white is what the ccd sees... meaning a tighter looking telephoto frame.

[Jason McKelvey]

in answer to the question about why anyone would like to use PL lenses on DV cameras... I'll ask this question, have you ever tried to pull focus on a DVX100?!!? Have you seen the breathing problems with standard canon lenses? wireless FF on a steadicam using a PD150? Both of these problems are a pain when trying to composite creative shots but are limited by the lens. A lot of people say, just shoot film. Well, while some are saving and scraping to save up enough to buy 2 rolls of film (and processing), we are shooting things that look great on TV (our target) today. If it's for the big screen, that's a different story. Did anyone see 28 Days? They used an adaptor similar to the one we are talking about with an XL1... I think even from the same company. An SDX900 would have looked so much better, but the 35mm lenses did make an optical, visible difference.

 

Jason

[Patrick Neary]

The profile photo shows that the optic is much more further from the pick up device than a pl lens is from the film plane

 

What prism ? The cameras's one ? it is there anyway, Pl mount or not... Shouldn't do any difference...

<{POST_SNAPBACK}>

 

The flange focal distance for a PL mount camera (this is from specs for the Arri 35BL series) is 51.97 -51.98mm. One reason for this depth is to clear the mirror shutter of the camera. I don't know the flange focal depth of a Canon XL-1, but it's clearly much less than 51.97mm, so to acheive proper focus with a PL mount lens on that camera, you need to move it away from the camera body 51.97mm minus Canon's specified flange focal depth. If you peer deep into the lens mount of any Arri, you'll see it's quite cavernous compared to what you see looking into the XL-1's mount.

 

As for the prism block, I know at least in professional cameras, like a digibeta, the prism block is rated at a stop, usually around 1.4. I'm no expert on CCD prism blocks, but I assume this means that the prism block arrangement is robbing a certain amount of light coming through the lens. My guess is that if the lens hasn't factored this into the design, then your lens stops (even T stops) will not correspond to the actual amount of light hitting the imaging chips.

 

Somebody here must know more about the details of prism block characteristics than me, hopefully they can confirm my guesses or crush them like a little bug!

[David Mullen ASC]

If the CCD block & filtering design is robbing light, it just means that the base sensitivity is lower -- you don't remark lenses to compensate just like you don't change the markings on a lens to compensate for different speed film stocks in a film camera. A lens has f-stop markings based on its physical dimensions and T-stop markings based on the light transmitted out the back of the lens -- what happens after that is not the lens designer's concern, exposure-wise (focus-wise, yes...)

 

However, there are exposure compensations necessary sometimes with extension tubes, macro focusing, etc.

[Patrick Neary]

Crushed like a bug!!! :) (I couldn't find "embarrassed face")

 

So the claimed 1-2 stop light loss for this thing is still anyone's guess...At some point one of us is going to have to just write the company and ask what's up with that?

Edited March 3, 2005 by PatrickNeary