Flat field lens on DSLR

There's been a fair bit of action amongst 5D/1D owners recently in buying up
old wide angle lenses with very generous field of coverage. And for good
reason too. The don't vignette and distort like the Canon variations do.

Well, I've been photographing painted art (digitising paintings) for some
relatively unknown Aussie artists recently in the lead up to making canvas,
reproduction prints. This exposes camera equipment designed for 3D subjects
to all it's weak points. The lenses available from Canon are just one. The
ideal lens is a flat field lens. I paid a heap for a 50/2 Summicron lens and
took it back for a refund when it didn't live up to it's reputation. Don't
get me wrong, the lens is fine on 3D subjects, just not so good when the
field is flat.

Then I had a local micro engineer machine me up an adaptor for my 5D which
had a screw thread to take an enlarging lens. I missed on the depth of the
first one but by using a bit of math I managed to get the second one pretty
much spot on. I used an adapted focusing rail from my old Mamiya days for
critical focus.

The first few frames I took using a Nikor 50mm enlarging lens were better
than anything I'd used in the "normal" lenses but lacked some colour
definition. Then I used a 75mm Rodenstock I've had since 1971 which I
originally used for enlarging 6x7cm negatives. When I die I want this one in
my coffin!

It is just about as good as it gets now. The alternative was to spend $30k
on a scanning back outfit but with a little ingenuity, some very high
quality parts from the past and patience, I'm very pleased with the results.
http://www.photosbydouglas.com/art-repro-on-canvas.htm if you'd like to see
them.
--
From Douglas...
www.photosbydouglas.com ...about my photography
www.technoaussie.com ...about my Giclee print centre

You could have accomplished about the same thing in Photoshop but it would
not have been as satisfying.

bmoag wrote:
You could have accomplished about the same thing in Photoshop but it
would not have been as satisfying.

Well, I use Photoshop every day and I disagree with you.
Photoshop can do a lot and you can probably find a plugin or action for what
it can't do but it cannot create anything in an image which was never there
in the first place or repair what was mangled by a lens designed for 3D
scenes.

How are you going to compensate for the way the sensor sees blue differently
than the actual blue made by mixing violet? What about the reds too? How are
you going to get this right in Photoshop when you no longer have the
painting for reference? Take a picture of it perhaps? ROTFL.

Douglas

D Mac wrote:

The first few frames I took using a Nikor 50mm enlarging lens were better
than anything I'd used in the "normal" lenses but lacked some colour
definition. Then I used a 75mm Rodenstock I've had since 1971 which I
originally used for enlarging 6x7cm negatives.
I've often been curious what would happen if an enlarging lens (or slide
projector lens) was to be used to take photos, rather than just
projecting them. You can't use a regular camera lens on an enlarger
because of the lack of flat field focus, so in theory at least, enlarger
lenses are better than regular camera lenses. I'd be curious to see some
photos of a regular type subject with this lens configuration.
When I die I want this one in
my coffin!
Buried with you when you die heh? let me know where so I can turn up
with a shovel.

"D Mac" wrote in message
...

| The first few frames I took using a Nikor 50mm enlarging lens were better
| than anything I'd used in the "normal" lenses but lacked some colour
| definition. Then I used a 75mm Rodenstock I've had since 1971 which I
| originally used for enlarging 6x7cm negatives. When I die I want this one
in
| my coffin!
|

I've purchased a Summicron-S enlarging lens on eBay for pretty much the same
purpose and have adapters for both the Nikon bellows (works on film and
digital cameras) and the bellows for my old Bronica S2. Another wonderful
enlarging lens.
Norm

Have you tried a true macro lens, such as Nikon's Micro 50mm and 100mm
lenses? All "true" macro lenses, not macro/close focusing lenses, were
designed as a flat field lenses. Also, some older normal lenses were
made a copy lenses with flat field focus planes. In addition, I
understand Nikon did make some non-macro lenses as flat field lenses
(not checked but told by Nikon enthusiasts). In addition Minolta made a
24mm f2.8 VFC lens with variable focus field, concave, flat and convex.
Good luck.

wsrphoto wrote:
Have you tried a true macro lens, such as Nikon's Micro 50mm and 100mm
lenses? All "true" macro lenses, not macro/close focusing lenses, were
designed as a flat field lenses.

What about the Carl Zeiss Planar lenses? If I remember correctly the
name is referring to the flatness of the field. Tell me if I'm talking
rubbish :-)
Mark

Mark, excellent question, and according to Zeiss it is:

http://www.zeiss.com/c12567a8003b58b...2570fb00445f0c

Wow, learned something today. Thanks.

"D Mac" wrote in message
...

The first few frames I took using a Nikor 50mm enlarging lens were better
than anything I'd used in the "normal" lenses but lacked some colour
definition. Then I used a 75mm Rodenstock I've had since 1971 which I
originally used for enlarging 6x7cm negatives. When I die I want this one
in
my coffin!

Just wondering what the colour rendition is like? I tried this many years
ago, (close-up region only) on slide film, using my 50 f2.8 enlarging lens
and comparing against my normal X-700 camera lenses. The enlarger lens was
so different in colour balance, I decided it simply wasn't worth following
up, but now with custom white balance etc. I'd probably decide differently.
The lenses were all Minolta; a 50 f2.8 Rokkor CE, and various MF Rokkors
including the 50 f1.4MD. In the last few days, I've learnt that my 50 f2.8
CE Rokkor was in fact a rebadged Schneider, which might just explain the
colour shift.

--
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm





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Malcolm Stewart wrote:
"D Mac" wrote in message

Just wondering what the colour rendition is like? I tried this many
years ago, (close-up region only) on slide film, using my 50 f2.8
enlarging lens and comparing against my normal X-700 camera lenses.
The enlarger lens was so different in colour balance, I decided it
simply wasn't worth following up, but now with custom white balance
etc. I'd probably decide differently. The lenses were all Minolta; a
50 f2.8 Rokkor CE, and various MF Rokkors including the 50 f1.4MD.
In the last few days, I've learnt that my 50 f2.8 CE Rokkor was in
fact a rebadged Schneider, which might just explain the colour shift.

--
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm

I'm a long way from being a lens expert but the EL Nikor lens I used had no
colour correction coating. My presumption is (it's a long way from factual
research) is that these lenses respond to colours originating in the 3000 -
4000 kelvin range so colours will be reproduced reasonably correctly if the
lighting when you use one, is in that range. Outside that range, the colours
may shift due to different wavelength response in different lighting.

The whole subject is way past my knowledge area and into optical design. The
Rodenstock I'm using is "colour corrected" whatever that means but it
produces more vibrant colour when used with a flash than the EL Nikor did. I
suspect the Minolta lenses you have could be in the same colour rendition
group as the EL Nikor I used and might surprise you if the light source was
tungsten and not daylight.

I am presently waiting on a new lighting source being made for me which uses
overlapping 6000 Kelvin flouresent lights in a square I will be able to
adjust the size of. I'll have the camera in the middle and the flouros
lighting the paintings. This sort of lighting array is becoming common in
studios... Just add more tubes for more light.