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Old July 11th, 2006, 05:19 AM   #1
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70mm lens adaptor, what are the advantages?

Has anyone out there come up with a 70mm lens adaptor for HD cameras? If not, why not? Wouldn't it stand to reason that it would give you a sharper image than that from 35mm adaptors like the Mini35 or the RedRock M2? It would also be affordable if you used medium format lenses like the Mamiya. Anyone have a thought on this? Another thought: If a system like the SI from Silicon Imaging's camera or the REd One allowed for the usage of lens adaptors, wouldn't it be better, in terms of sharpness and image quality, to have a 70mm adaptor rather than a 35mm one?...Just a thought. Anyone?
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Old July 12th, 2006, 10:53 AM   #2
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Hmm... What are the advantages? Not many, really... You're not getting any extra resolution (that's defined by the camcorders sensor), and you're getting an even shallower DoF (not necessarily a good thing!). Grain structure would be reduced (as the relative size of grain would be smaller, assuming an identical or very similar GG), but that's about it - and I don't have a problem with grain on any of the oscillating type of 35mm adaptors as it stands.

Disadvantages are:
Super shallow DoF (your focus puller's not going to like you, and forget splits!)
Slower lenses, so lots more light needed (MF lenses are typically f2.8-f4 wide open)
Larger, heavier physical unit (and the same is true of the lens, of course)
Very limited numbers of Cine lenses available for the format (and those that are will not cover a 16x9 frame)

So all-in-all, not a very good idea, I would think. I met a great guy at Cannes this year who has an M2 and is thinking of modifying it to use MF lenses, so I may yet stand to be corrected - but that's my tuppenceworth at this point!

I think the important point to make is that 70mm (or 65mm, in shooting stocks) for film is advantageous as the resolution of the medium is directly related to the area of exposed film - hence 70mm is better than 35mm but worse than IMAX, for instance.

With video this is not the case, as resolution is determined by number of pixels on a CCD, regardless of the size of the CCD's. With a larger sensor come other benefits, such as better low-light performance and lower noise levels, but resolution remains constant.

Therefore, there is no reason to go to 70mm, IMAX, etc with adaptors, as their chief benefit (higher resolution images) does not transfer, whilst their problems (slow lenses, ridiculously shallow DoF) do, so we would inherit the worst of both worlds. In Barry Lyndon, nobody moves for half of it - that's because they're shooting wide open (by candlelight!) on 65mm and the focus is too problematic to pull if anyone moves!...
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Old July 12th, 2006, 05:47 PM   #3
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Quote:
Originally Posted by Jaadgy Akanni
It would also be affordable if you used medium format lenses like the Mamiya.
Compared to what? a 50mm 1.4 Canon FD goes for around 60-70 on ebay, at max. Try to find a Mamiya even near that price, not to mention the speed difference (1.4 to 2.8).
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Old July 12th, 2006, 10:20 PM   #4
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Dominic and Ben, thank you so much for your response. That was enlightening.
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Old July 13th, 2006, 06:15 AM   #5
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No problem, your Highness!!
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Old August 15th, 2006, 10:30 AM   #6
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There is a guy called Winston Vargas who has a 70mm adapter. It's supposed to be pretty good.
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Old August 23rd, 2006, 08:31 AM   #7
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70mm adapter

Quote:
Originally Posted by Jaadgy Akanni
Has anyone out there come up with a 70mm lens adaptor for HD cameras? If not, why not? Wouldn't it stand to reason that it would give you a sharper image than that from 35mm adaptors like the Mini35 or the RedRock M2? It would also be affordable if you used medium format lenses like the Mamiya. Anyone have a thought on this? Another thought: If a system like the SI from Silicon Imaging's camera or the REd One allowed for the usage of lens adaptors, wouldn't it be better, in terms of sharpness and image quality, to have a 70mm adaptor rather than a 35mm one?...Just a thought. Anyone?

I have the 70mm adapter, precisely I am using Mamiya 645 lenses and a 2 1/4 square groundglass. Check out my website
www.freewebs.com/wvargas
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Old August 23rd, 2006, 08:58 AM   #8
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DOF with 70mm adapter & medium format lenses.

Quote:
Originally Posted by Dominic Jones
Hmm... What are the advantages? Not many, really... You're not getting any extra resolution (that's defined by the camcorders sensor), and you're getting an even shallower DoF (not necessarily a good thing!). Grain structure would be reduced (as the relative size of grain would be smaller, assuming an identical or very similar GG), but that's about it - and I don't have a problem with grain on any of the oscillating type of 35mm adaptors as it stands.

Disadvantages are:
Super shallow DoF (your focus puller's not going to like you, and forget splits!)
Slower lenses, so lots more light needed (MF lenses are typically f2.8-f4 wide open)
Larger, heavier physical unit (and the same is true of the lens, of course)
Very limited numbers of Cine lenses available for the format (and those that are will not cover a 16x9 frame)


So all-in-all, not a very good idea, I would think. I met a great guy at Cannes this year who has an M2 and is thinking of modifying it to use MF lenses, so I may yet stand to be corrected - but that's my tuppenceworth at this point!

I think the important point to make is that 70mm (or 65mm, in shooting stocks) for film is advantageous as the resolution of the medium is directly related to the area of exposed film - hence 70mm is better than 35mm but worse than IMAX, for instance.

With video this is not the case, as resolution is determined by number of pixels on a CCD, regardless of the size of the CCD's. With a larger sensor come other benefits, such as better low-light performance and lower noise levels, but resolution remains constant.

Therefore, there is no reason to go to 70mm, IMAX, etc with adaptors, as their chief benefit (higher resolution images) does not transfer, whilst their problems (slow lenses, ridiculously shallow DoF) do, so we would inherit the worst of both worlds. In Barry Lyndon, nobody moves for half of it - that's because they're shooting wide open (by candlelight!) on 65mm and the focus is too problematic to pull if anyone moves!...


You are mistaken about the shallower depth of field with the medium format lenses and as far as the slowness of the lenses, well when will you need better than F/2.8 on a lens for video shoots. The depth of field is in relation to the focal length of the lens and the size of the film plane or in our case the size of the groundglass. There are many lenses on the market for the medium format. The focus will be no different on the medium format then 35mm. Is it more difficult to focus a Hasselblad or Mamiya lens than a Nikon or leica lens on a 35mm camera? The answer is NO. Please check my website and maybe you can see my article on the misconception of Depth of field. The fact is that the larger the film plane or the larger the groundglass ( for the so called film adapters ) the better the image. When working with larger negatives the better the print ... This is a fact.. After 45 years in the business and working with everything from digital to 8x10, I can tell you ...it's a fact. Check out my adapter at www.freewebs.com/wvargas

The use of the Cine lenses is an overkill when you are actually filming the groundglass with the video camera lens how much better is that going to be. To some videographers the look of the equipment is more important than what it does, everyone is trying to please the client by making the camcorder look like a full blown Arriflex. The medium format lenses as well as the 35mm lenses are capable of very high quality. I am referring to high quality lenses such as Nikon, Leica, Mamiya, Hasselblad. These lenses are designed for film and film is higher resolution than video will ever be. Let's be realistic. A camcorder is still a camcorder no matter what you place in front of it, so we do the best we can with them but we don't make them any better. I always ask one question to those that awear by the cine lenses... Can you copy a good quality photograph and make the photo better than the original? Or in our case,. Can you copy a groundglass image and make it look better than the original?
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Old August 23rd, 2006, 10:56 AM   #9
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Are you we ever actually going to see footage from your adapter? Ever?
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Old August 23rd, 2006, 03:01 PM   #10
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Quote:
Originally Posted by Winston Vargas
...The depth of field is in relation to the focal length of the lens and the size of the film plane or in our case the size of the groundglass...
And from the website:
Our latest adapter uses a 2 1/4 x 2 1/4 groundglass with an active image size of 2 1/4 x 1 5/8 which means that you are working with an image that is more than twice the size of a 35mm adapter.

So, for the same focal length lens, the depth of field will be shallower on the 70mm adapter than on the 35mm adapter. Correct?

By the way, I've used the 35mm ground glass adapters, and while I think that P+S tecknik makes the best of the bunch, I agree that you shouldn't worry too much about putting the latest, greatest glass up front. The quality of the adapter and the video camera are the limiting factors.

BTW, for serious film look on a budget, I'm a big fan of Super 16mm :)
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Old September 3rd, 2006, 09:41 PM   #11
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DVD of 70mm adapter footage

Quote:
Originally Posted by Yasser Kassana
Are you we ever actually going to see footage from your adapter? Ever?

I've been on vacation... I have been offering and have sent out many DVD's with 30 minutes of footage. Just give me the address and I will send you one.
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Old January 24th, 2008, 08:35 PM   #12
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Mr. Vargas,
Any update on your Prodofa ?

I have 2 lenses of Mamiya 645 80mm and 45mm both f2.8 also several nikon lenses such as 50mm/1.4 80-200mm/f2.8

Is it possible I use prodofa and make DIY mamiya mount for nikon lenses ?
Or any available lens adaptor : nikon lens to mamiya adapter ?

The camera I use mostly Sony V1P (lens thread 62mm) , and sony Z1, since these are most available for rent here in my country. We also like to use the prodofa with Canon HV20 (thread size 37mm??). What additional adapter we need to use these V1, Z1 and HV20 ?

TIA, Agatha
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Old January 30th, 2008, 10:01 AM   #13
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70mm film adapter available at Adorama in New York

My 70mm adapter now known as the (PRODOFA) Pro Optic 645 medium format adapter is now available at Adorama camera in New York City. Adorama.com Check it out. It's priced at $749.95
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Old January 30th, 2008, 10:53 PM   #14
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I have built a medium format adapter with excellent results. There are several advantages:

I found that using ANY achromatic diopter (which is necessary with most cameras when using 35mm adapters) invariably degrades the image, even if you use a high quality one such as the Cinevate HD achromat. Using an achromat is not necessary with a medium format adapter since most cameras (I have an FX1E) can easily focus on a 60mm wide frame.

Also, the grain of the ground glass, and the "impurities" of the Fresnel lens, will always cause a slight softening of the image, even when the adapter is vibrating or spinning. This effect is much reduced when the area of the ground glass is 4x as large.

The adapter is also not much bulkier than 35mm ones, and not heavier since you don't need an achromat (as an example, take a look at Winston's adapter, which is not much larger than the Brevis35).

And there are excellent and very cheap lenses to be found! I opted for a Pentacon Six / Kiev 60 lens mount. Take a look here for information:
http://www.pentaconsix.com/LensTest.htm

Note that these lenses are not necessarily slower that the 35mm equivalent lenses. In order to compare them, you have to take into account the ABSOLUTE aperture of the lens, that is, the number you get by dividing the focal lens by the maximum f-stop. So a 80mm f/2.8 medium format lens is roughly equivalent to a 50mm f/1.8 35mm-format lens, a 180mm f/2.8 MF lens corresponds to a 120mm f/1.8 35mm-format lens and so forth. Thus, in practice, the standard lenses commercially available in both formats will behave similarly in terms of speed and will also give give you roughly the same depth of field.

Theoretically, the larger format has the -potential- to yield an even shallower depth of field, but in -practice- there is little difference. For example: if you were to find an medium format 80mm f/1.4 lens (which you won't) THEN you would get a shallower depth of field since such a lens would be equivalent to a 35mm-format 50mm f/0.9.

Greetings!
Atilio.

Last edited by Atilio Menendez; January 31st, 2008 at 09:50 AM. Reason: added some explanations
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Old January 31st, 2008, 01:36 AM   #15
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You might also want to look here:
http://www.rickdenney.com/bokeh_test.htm

and here:
http://www.kievaholic.com/mediumformat.html

Apart from using several Kiev and Zeiss lenses with my "70mm" medium format adapter, I use them on a "normal" film camera, a Pentax 645, with fantastic results. In terms of sharpness, I can confidently say that these lenses are overkill for any video application, just like almost any 35mm lens. For me, the most important factor is the bokeh of the lens, and that is not specific to any format.

By the way, almost all medium format lenses can be used with 35mm cameras or 35mm video adapters by using adapter rings. (Then they are in fact slower and the numbers mean what you would expect - a 80mm f/2.8 MF lens, when used with an 35mm camera, will behave just like any old 80mm f/2.8 35mm-format lens).

Nevertheless, 35mm lenses cannot be used on MF cameras since the focal flange of medium format lenses is longer.

Still, if you have, say, an adapter such as Winston's with a Mamiya 645 mount, there are cheap adapter rings which allow you to use lenses with other mounts, such as the much cheaper Pentacon Six/Kiev 60 lenses.

So, to sum it up, if you use a 35mm adapter, you can use it with almost any lens, be it for 35mm or MF. If you use a MF adapter, you are stuck with MF lenses, but there is a larger variety of MF lenses than you might think, there are many quite cheap and excellent lenses to be found, and MF adapters have the potential to produce better images, since no diopter is required and the area where the image is projected is four times larger.

Last edited by Atilio Menendez; January 31st, 2008 at 10:05 AM.
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