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Nathan Potter
22-Feb-2009, 20:39
I've read a few general comments here and there about using digital lenses with digital backs but also the use of normal LF lenses are OK to use also. But I've not read anything specific about the design of new digital lenses and precisely what optical design features are so special for use on digital sensors. Are these lenses more highly color corrected? Is there a resolving power advantage for use with small pixel pitch << say 10 um? Anyone know what the deal is here?:) :)

Nate Potter, Austin TX.

Mark Woods
22-Feb-2009, 20:51
The long digital lenses are more or less the same. The "normal" wide lenses can cause vignetting on the digital capture. There are lot of problems that many people are in denial about digital capture -- particularly on motion projects.

Oren Grad
22-Feb-2009, 20:57
Rodenstock's literature says:

The resolving power and the contrast must be at their optimum even at high apertures (f-stop 8 to 11, when used with the relatively small area sensors even from f/5.6) to ensure that diffraction and color noise do not impair sharpness. Furthermore, the correction of curvature of field has to meet the highest demands because of the virtually perfectly planar sensor surface, and the lenses may not generate any color fringes or any visible distortion.

For the regular digital series specifically (Apo-Sironar-Digital, now called Digaron if I remember correctly):

Resolving power is designed for pixel grid widths down to 9 um.

For the HR series specifically:

The Apo-Sironar-Digital HR lenses provide extremely high resolution already from open aperture... perfectly corrected image curvature and a correction for the thickness of the sensor's protective glass. They are the best lenses for smaller sensors with pixel grid widths below 12 um down to 5 um.

Schneider has comparable language in its literature.

Nathan Potter
22-Feb-2009, 21:46
Thanks Oren and Mark. But I have imagined that any LF lens would want to be optimized for flatness of field and the best possible resolution at large apertures even though most LF workers would want to use about f/16 or higher to achieve reasonable depth of field. In a sense it dosen't seem altogether useful to expend a lot of effort on high NA correction since most LF workers don't make use of it. :)

I guess my better question is - Why not use these digital lenses for film photography providing the coverage is adequate for ones needs? They would seem to be somewhat superior in image quality over the best conventional LF lenses.

Nate Potter, Austin TX.

Oren Grad
22-Feb-2009, 21:58
Why not use these digital lenses for film photography providing the coverage is adequate for ones needs?

There's no reason not to. I bought a 90mm Apo-Sironar-Digital specifically for use with 6x9 cm film, and I'm very happy with it.

Anders_HK
23-Feb-2009, 23:07
Rodenstock's literature says:

The resolving power and the contrast must be at their optimum even at high apertures (f-stop 8 to 11, when used with the relatively small area sensors even from f/5.6) to ensure that diffraction and color noise do not impair sharpness. Furthermore, the correction of curvature of field has to meet the highest demands because of the virtually perfectly planar sensor surface, and the lenses may not generate any color fringes or any visible distortion.

For the regular digital series specifically (Apo-Sironar-Digital, now called Digaron if I remember correctly):

Resolving power is designed for pixel grid widths down to 9 um.

For the HR series specifically:

The Apo-Sironar-Digital HR lenses provide extremely high resolution already from open aperture... perfectly corrected image curvature and a correction for the thickness of the sensor's protective glass. They are the best lenses for smaller sensors with pixel grid widths below 12 um down to 5 um.

Schneider has comparable language in its literature.

Hi,

I am new to large format and am current also researching on using it for my Leaf Aptus 65 digital back. My interest is to use my Shen-Hao TFC45-IIB (wide angle 4x5 camera) not only for 4x5 FILM but also for some digital stitching, primarily stitching using 1x2, 1x3, 2x4 and at times 2x6 captures.

Here is what I see;

Digital Large Format Lenses - While some may have image circle up to 6x9 or 120 format, some do not have image circle up to 645 format. Thus they are really not large format lenses per say, but medium format lenses. Their aim is for high resolution on a SMALLER area than 4x5. They tend to be expensive and so does "digital" technical cameras for them that permit sliding, rise and tilt, since because of their small total capture area (including also stitches) there needs to be very fine adjustments compared to 4x5 which is a much larger format.

Traditional Large Format Lenses (high sharpness and optic quality) - Per what I understand, they should be no problem for use with a digital back, provided digital back is not exceeding much beyond 30MP (my Aptus 65 sounds like borderline). Else there can be problem with the high resolution of sensor versus the optics of the lenses, a.k.a. diffraction. Both Aptus 65 and 75 should thus be fine, but P45 may be a problem.

I am now heading down route two of above. Current I am in process of having a custom made sliding adapter made, since I want one with 4x5 or 612 groundglass and which is not as much $$$$ as the ones they sell with purpose of digital lenses. My only lens is current a Nikkor 75mm SW 4.5 and I honest expect it will work fine with my Aptus 65 up to slides within the 4x5 format.

Regards
Anders