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Author Topic: Digital lenses on MF backs: is it just marketing?  (Read 7012 times)
favalim
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« on: September 02, 2006, 01:29:51 PM »
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Hi there,
I'm an interior photographer using a view camera (Cambo Ultima 45 and film) and  I would like to prepare a set of lenses in order to be ready for the digital "jump". My question is: are the Digital lenses worth the substitution with the older no-digital? I've read so many different opinions that it makes me think it's more relating to marketing than other. Somone says ther is no difference with the older APO lenses, other says there is but not so big ... bla bla bla.
Is there a clear comparision on the web? what's your experience?

Thanks
Marco
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bob mccarthy
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« Reply #1 on: September 02, 2006, 03:52:36 PM »
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Quote
Hi there,
I'm an interior photographer using a view camera (Cambo Ultima 45 and film) and  I would like to prepare a set of lenses in order to be ready for the digital "jump". My question is: are the Digital lenses worth the substitution with the older no-digital? I've read so many different opinions that it makes me think it's more relating to marketing than other. Somone says ther is no difference with the older APO lenses, other says there is but not so big ... bla bla bla.
Is there a clear comparision on the web? what's your experience?

Thanks
Marco
[a href=\"index.php?act=findpost&pid=75320\"][{POST_SNAPBACK}][/a]


Digital lenses are designed (optimized) for wider apertures compared to the normal view camera. Film (4 x 5) is enlarged 2 to 4 times. So we tend to somewhat ignore defraction to a degree to gain depth of field. My most common aperture is f22/32.  

The digital sensors capture area is "much smaller" (roughly 1&1/2 x 2 inches) so a digital view camera is enlarging the image captured by the lens 5 to 10 times.  This brings the onset of where defraction impacts the image at stops 2 to 3 stops more open than on the film based camera.

The digital sensor can capture enormous levels of micro detail  and the lenses must give sharp results at f8 to f16, normally not a optimum range for standard view camera lenses.

But my Fujinons are pretty damn sharp at the faster apertures so I'm not always sure theory meets reality.

Bob
« Last Edit: September 10, 2006, 10:04:20 AM by bob mccarthy » Logged
marcwilson
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« Reply #2 on: September 02, 2006, 04:20:51 PM »
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so if you are looking for lenses for a view camera to use with 67 roll film..are the digital versions the best options as far as image quality goes..where they give enough movements as the rodenstock digital lenses over 45mm seem to?
would they give much better quality than non digital versions on 67 film?
« Last Edit: September 02, 2006, 04:21:51 PM by marcwilson » Logged

Morgan_Moore
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« Reply #3 on: September 04, 2006, 02:33:35 AM »
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Are the lenses different??

Yes - this is my minimal experience on 22MP


I tried a Rodenstock 45 (non dig) and 47 dig.

The mission was to create two captures into one stiched image (44MP!)

The 45 was wild (really blurred) at the edges - totally unusable - the 47 is far better - the 45 was Ok on one capture with no movement

For lenses 65 and longer, however, my initial observations are that regular LF lenses seem  fine

I think it is to do with digital sensors ability to handle light at obtuse angles rather than the resolution of the lense
« Last Edit: September 04, 2006, 02:35:53 AM by Morgan_Moore » Logged

Sam Morgan Moore Cornwall
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Gary Ferguson
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« Reply #4 on: September 05, 2006, 06:14:28 AM »
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I use a 22MP Phase One back on a Linhof M679 technical camera with Rodenstock Digital lenses from 35mm to 180mm. Because I sometimes also use 6x9 film with relatively large movements I've kept a number of traditional LF lenses for this application.

Comparing even high quality traditional lenses, such as Schneider XL's, with the latest digital lenses it's clear that image quality with digital lenses is superior, especially at wide and medium apertures.

The trade-off seems to be that the smaller the image circle the higher the resolution. You can go even higher in image quality terms. for example with the Rodenstock Digital HR lenses, but then the image circle becomes a little too restrictive for my applications.
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ivan muller
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« Reply #5 on: September 06, 2006, 01:43:52 AM »
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hi Just wondering. If I understand it correctly the new digital lenses are optimised for the more open apertures i.e. 4.5, 5.6 etc. As far as i know and thinking back to the old brochures the film lenses optimum aperture was f22. I am talking about large format lenses. Using large format, the advantage was that you could use the movements and the aperture to get max sharpness. What I dont seem to understand is why the new digital lenses arent optimised at the smaller apertures, say f22? Generally I would think  most users of larger format lenses would want max depth of field with sharpness.
Thanks Ivan
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ericstaud
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« Reply #6 on: September 06, 2006, 02:18:03 AM »
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"What I dont seem to understand is why the new digital lenses arent optimised at the smaller apertures, say f22? Generally I would think most users of larger format lenses would want max depth of field with sharpness.
Thanks Ivan"

Hello Ivan

Diffraction Limited is the key issue here.  Reading this web page is helpful...

http://www.cambridgeincolour.com/tutorials...photography.htm

Past F11 on my 33mp, 6x4.5 sensor with my digitars I am diffratction limited.  I gain corner sharpness and have less lens falloff when stopping down more, but the picture is softer in the center.

With my 35mm digitar I always shoot at F11.  This lens is equivilent to a 90mm lens on my 4x5.  I would guess that with the 35 digitar set at F11 the depth of field is similar to the 90mm lens set at 22 or 32 on a 4x5 camera.  So I have gained 2-3 stops of light with the same depth of field by going to the smaller format.

The lenses are not optimised for F11 versus F22 for the reasons you are thinking.  By using the calculator on the cambridge site you will see that you can stop down more and still get a sharp image by using: A larger format, lower resolution film or sensor, or printing smaller.

As you make the sensor smaller, higher resolution, or make larger prints, your lenses will become diffraction limited sooner as you stop down (but the shorter lenses on the smaller formats need to be stopped down less).

It is not about lens design or optimization, but about laws of physics, so to speak.

I hope this is in English...  this is a tough topic to write about clearly.

-Eric
« Last Edit: September 06, 2006, 02:29:23 AM by ericstaud » Logged
Nemo
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« Reply #7 on: September 09, 2006, 06:04:34 PM »
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Leica had a technical document about the digital medium and the R lenses ("Are Conventional Lenses Suited for Digital Photography?"/April 2004). They say the only difference is due to the presence of microlenses and filters over the sensor. This affects the image quality of "film-optimized" lenses. Microlenses and filters can be adapted for reducing their negative influence in image quality.

Scheider-Kreuznach has another technical document ("Optics for Digital Photography") and they claim that lenses can be optimized for the digital medium of capture. The idea is to reduce the contrast beyond the Nyquist limit. I don't know if these design adaptations of lenses to digital have costs (size, weight, cost) or if they are incompatible with the requirements for film capture. Olympus' Zuikos (or Schneider's Digitar lenses) are designed "for digital", but there are other systems of lenses designed for digital and film (lenses for the H system of Hasselblad, the former N system of Contax...). Whether compability with film must be preserved, can "digital" optimizations for lenses be made?

Leica thinks all the problems are in the sensors, and a good "film" lens is a good "digital" lens. Schneider thinks that lenses can be optimized for a better performance on digital capture devices.
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Nemo
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« Reply #8 on: September 11, 2006, 05:17:07 AM »
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An interesting article by Erwin Puts:
"The truth about 'digital' lenses"

http://www.imx.nl/photosite/comments/c011.html

(He has the same opinion than Leica).
« Last Edit: September 13, 2006, 04:13:34 AM by Nemo » Logged
Eric Zepeda
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« Reply #9 on: September 11, 2006, 08:30:22 AM »
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Interesting article. I do think there is an argument for "good glass is good glass", especially towards the longer end of the spectrum. It's the shorter end, where the latest designs come into play. The Schneider 35xl Digitar is very sharp, and when coupled with the Cambo WDS is a great setup for interior work. A kit with the 24, 35 and 47xl's would be hard to beat, unless you're able to go the Alpa route. I've a non-Digitar 58xl, and it's pretty sharp with my P25, but the 47xl Digitar is sharper. Admittedly, this is not a great comparison. A much better one would be with a 47xl and a 47xl Digitar.
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ericstaud
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« Reply #10 on: September 11, 2006, 11:36:03 AM »
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Hello Marco,

As well as looking at lenses, are you looking at a new camera?  It is my assumption that you will not be able to focus at infinity with your Cambo using the 24mm and 35mm digitar lenses.  I believe there are very few cameras that can do this.

It is still very difficult to shop for these lenses.  The 24mm digitar has no movements on a 645 digital chip.  The 35 and the 47 digitars have ample movement, and the 60 digitar could do better with its image circle.

Ideally, I am sure that the architecture crowd would love to shoot a vertical image on their A75 or P45 (36mm x 48mm) and shift up enough to put the horizon at the bottom of the image.  This requires a 104mm image circle.  Here are the Schneider Digitar image circles

24mm Digitar:  60mm
35mm Digitar:  90mm
47mm Digitar:  113mm
60mm Digitar:  60mm

Here is what the 47 can do.. It is not tack sharp at the top though..

[attachment=949:attachment]
« Last Edit: September 11, 2006, 11:38:09 AM by ericstaud » Logged
favalim
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« Reply #11 on: September 13, 2006, 05:49:05 AM »
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Hello Marco,
...

Here is what the 47 can do.. It is not tack sharp at the top though..


[a href=\"index.php?act=findpost&pid=76059\"][{POST_SNAPBACK}][/a]


Eric, I just would like to know how much is the differnce between a 58xl non-digitar (you have) and a 60 Digitar.
Unfortunally your pic is not visible.

Thanks
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ericstaud
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« Reply #12 on: September 13, 2006, 12:08:41 PM »
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Hello Favalim,

I would like to know too, but I do not have a 58mm XL.  Unfortunately my ALPA dealer is in New York, otherwise I would be driving there frequently to test lenses.  Fotocare does keep alot of Alpa equipment in stock and Jeff is very helpful.  The 60 is VERY, VERY sharp.  Based on its performance I would believe that the 80 and 90 are also excellent lenses because of their similar designs.  My only complaint about the 60 is the small image circle.  At F11 the image circle has a very sharp cut off, but good performance right up to the edge.  My 47 digitar has a huge image circle, but in contrast to the 60 the image quality degrades as you shift.  As a result, it is easy to do a large shift, have everything look good on your MFDB, and realize when you get home that the top of your image is soft.

-Eric
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