Correcting the multiplication factor on DSLR's/optics question

I have been contemplating getting a DSLR for a while, but the
multiplication factor on the lenses has made me want to wait until
full-frame CCD's become less expensive. I contemplated adapting my old
digital camera to take Nikon lenses after I found this:

http://www.davearney.org/cam/

So I tried something similar with my old digital camera:

http://barron.cfdeveloper.co.uk/makepage.cfm?Page=HP120

Then, I found this article where someone has converted a Casio digital
camera to take Leica m39 tread mount lenses:

http://www.digit-life.com/articles2/m39var1/

However the multiplication factor was an even bigger issue because the
CCD was even smaller than on a DSLR. Now, I'm really curious as to
whether or not someone could make something usable with an F-mount. I
sold my old (crappy) HP and got a cheap (sold as a "parts" camera) 2
megapixal Nikon to sacrifice. What I was wondering is if it's possible
to add some optics in front of the CCD that would shrink the incoming
image so that the multiplication factor wouldn't be so big? At first, I
was thinking of just adding a wide-angle converter to the front of the
lens, but then you're still just taking a crop of the full image
available--i.e., you lose the resolution of the lens. Is it possible to
use a wide-angle converter between the lens and camera body (like you
do with a teleconverter) to grab more of the incoming image? I'm
guessing a consumer point and shoot CCD won't really notice a
difference in the loss of lens resolution from taking a crop of the
full image available, but it would also be much more convenient if the
wide-angle converter is permanently fixed to the body and you don't
have to add a wide-angle converter to a lens every time you switch
lenses. I'm sure someone out there is screaming "blasphemy" or "moron"
but I really don't know enough about the optics except what I've seen
on those websites and tried myself. I couldn't find any information on
the Internet on the placement of wide-angle lenses on the back-end.

On a side note, I was interested in taking out the electronics of the
digital and placing them inside an old Nikon body, so that the rig
looks like a real DSLR. But, I don't have a spare body. If anyone knows
where I can get a cheap non-functional body, or has one they wouldn't
mind donating to a "good cause", I would appreciate that too. Call me
old-fashioned, but I just can't justify sacrificing a working Nikon
just to see if my Frankenstein camera can work.

Just get a DSLR. They have much larger sensors than 'regular' digital
cameras and that provides better quality images, especially low light
high ISO performance. The only difference is you may need a new wide
angle lens to compensate for the size difference. Full sized sensor
DSLRs are very expensive and that probably won't change soon.

wrote:

I have been contemplating getting a DSLR for a while, but the
multiplication factor on the lenses has made me want to wait until
full-frame CCD's become less expensive. I contemplated adapting my old
digital camera to take Nikon lenses after I found this:

http://www.davearney.org/cam/

So I tried something similar with my old digital camera:

http://barron.cfdeveloper.co.uk/makepage.cfm?Page=HP120

Then, I found this article where someone has converted a Casio digital
camera to take Leica m39 tread mount lenses:

http://www.digit-life.com/articles2/m39var1/

However the multiplication factor was an even bigger issue because the
CCD was even smaller than on a DSLR. Now, I'm really curious as to
whether or not someone could make something usable with an F-mount. I
sold my old (crappy) HP and got a cheap (sold as a "parts" camera) 2
megapixal Nikon to sacrifice. What I was wondering is if it's possible
to add some optics in front of the CCD that would shrink the incoming
image so that the multiplication factor wouldn't be so big? At first, I
was thinking of just adding a wide-angle converter to the front of the
lens, but then you're still just taking a crop of the full image
available--i.e., you lose the resolution of the lens. Is it possible to
use a wide-angle converter between the lens and camera body (like you
do with a teleconverter) to grab more of the incoming image? I'm
guessing a consumer point and shoot CCD won't really notice a
difference in the loss of lens resolution from taking a crop of the
full image available, but it would also be much more convenient if the
wide-angle converter is permanently fixed to the body and you don't
have to add a wide-angle converter to a lens every time you switch
lenses. I'm sure someone out there is screaming "blasphemy" or "moron"
but I really don't know enough about the optics except what I've seen
on those websites and tried myself. I couldn't find any information on
the Internet on the placement of wide-angle lenses on the back-end.

On a side note, I was interested in taking out the electronics of the
digital and placing them inside an old Nikon body, so that the rig
looks like a real DSLR. But, I don't have a spare body. If anyone knows
where I can get a cheap non-functional body, or has one they wouldn't
mind donating to a "good cause", I would appreciate that too. Call me
old-fashioned, but I just can't justify sacrificing a working Nikon
just to see if my Frankenstein camera can work.


--
Paul Furman
http://www.edgehill.net/1
Bay Natives
http://www.baynatives.com

Just further on the bit about mounting it inside an SLR: I was planning
on replacing the focussing screen with the LCD screen, so you get the
feeling that you're using a regular SLR. In practice the parts may not
all fit in the body the way I vision, but it would be an interesting
project nonetheless.

wrote:
I have been contemplating getting a DSLR for a while, but the
multiplication factor on the lenses has made me want to wait until
full-frame CCD's become less expensive. . . . . . .

Probably better to wait another year or two. In the world of video, both
OpTex and Century Precision made adapters to fit on the Canon XL1 and
XL2. Those adapters allowed fitting a 35 mm still camera lens, and
retaining the focal length and field of view. Both involved some complex
optics in a long tube, and both were (are) very expensive.

You could probably put together an arrangement of optics to eliminate
the cropped field of view. I don't think it would be simple. I also
think it could cost quite a good sum of money.

If you want full frame 24 mm by 36 mm with a Nikon lens, you currently
have a few choices:
- Nikon lens adapter for a Canon full frame D-SLR;
- Kodak DCS 14 (two different models, sometimes under $2500 used);
- Horseman DigiFlex with medium format digital back (expensive);
- Sinar M camera system with Nikon module and medium format digital back
(huge and expensive)

My suggestion is to wait for Nikon to introduce a full frame D-SLR, and
then for the used price to go down, or for a lower cost second full
frame body to be introduced. Kodak might also release another full frame
D-SLR for Nikon mount lenses, but probably not much less than a top of
the line Nikon D-SLR would cost.

Ciao!

Gordon Moat
A G Studio
http://www.allgstudio.com

"Paul Furman" wrote:
Just get a DSLR. They have much larger sensors than 'regular' digital
cameras and that provides better quality images, especially low light high
ISO performance. The only difference is you may need a new wide angle lens
to compensate for the size difference.

True. But...

Full sized sensor DSLRs are very expensive and that probably won't change
soon.

The extra US$1800 or so the 5D costs seems pretty cheap compared to the
headache of having to multiply or divide by 1.6 every time you think about
taking a photograph...

David J. Littleboy
Tokyo, Japan

In article ,
"David J. Littleboy" wrote:

Full sized sensor DSLRs are very expensive and that probably won't change
soon.

The extra US$1800 or so the 5D costs seems pretty cheap compared to the
headache of having to multiply or divide by 1.6 every time you think about
taking a photograph...

I think most of us fall into one of two categories:

1) those who put the camera on a tripod, use a tape measure to find the
exact distance to the subject and the size of the subject, calculate
which lens they'll need, put a light meter up against the subject,
calculate the exposure by hand, set the aperture and shutter speed.

2) those who look through the viewfinder and twist the zoom until it
looks right.


Those is the first group can and do cope with all sorts of film/sensor
sizes and lens focal lengths and wouldn't even remark on the calcualtion
to fgure the fiield of view from those becuase they've alwasy been doing
it *anyway*.

Those in the second group don't know or care what numbers are printed on
the lens. They'll have a wide angle lens and bring-distant-stuff-close
lens and who cares what the numbers say?


The crop factor is something they think about when deciding what to buy
but not, that I can see, something that you think about when taking a
photo.

--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------

On Wed, 8 Feb 2006 07:08:27 +0900, David J. Littleboy wrote:

Just get a DSLR. They have much larger sensors than 'regular' digital
cameras and that provides better quality images, especially low light high
ISO performance. The only difference is you may need a new wide angle
lens to compensate for the size difference.

True. But...

Full sized sensor DSLRs are very expensive and that probably won't change
soon.

The extra US$1800 or so the 5D costs seems pretty cheap compared to the
headache of having to multiply or divide by 1.6 every time you think about
taking a photograph...

True, but people could choose a different brand DSLR and not only
save far more than US$1800, but spare themselves the complex math.
headaches by getting a camera having a 2.0 crop factor. This sensor
isn't quite as large as those in other DSLRs, but compared to the
digital P&S cameras having tiny sensors with truly 'insanely small
pixels', the 2.0 factor sensors are virtually olympian sized.

On 7 Feb 2006 12:12:22 -0800, "
wrote:

I have been contemplating getting a DSLR for a while, but the
multiplication factor on the lenses has made me want to wait until
full-frame CCD's become less expensive. I contemplated adapting my old
digital camera to take Nikon lenses after I found this:

http://www.davearney.org/cam/

So I tried something similar with my old digital camera:

http://barron.cfdeveloper.co.uk/makepage.cfm?Page=HP120

Then, I found this article where someone has converted a Casio digital
camera to take Leica m39 tread mount lenses:

http://www.digit-life.com/articles2/m39var1/

However the multiplication factor was an even bigger issue because the
CCD was even smaller than on a DSLR. Now, I'm really curious as to
whether or not someone could make something usable with an F-mount. I
sold my old (crappy) HP and got a cheap (sold as a "parts" camera) 2
megapixal Nikon to sacrifice. What I was wondering is if it's possible
to add some optics in front of the CCD that would shrink the incoming
image so that the multiplication factor wouldn't be so big? At first, I
was thinking of just adding a wide-angle converter to the front of the
lens, but then you're still just taking a crop of the full image
available--i.e., you lose the resolution of the lens. Is it possible to
use a wide-angle converter between the lens and camera body (like you
do with a teleconverter) to grab more of the incoming image? I'm
guessing a consumer point and shoot CCD won't really notice a
difference in the loss of lens resolution from taking a crop of the
full image available, but it would also be much more convenient if the
wide-angle converter is permanently fixed to the body and you don't
have to add a wide-angle converter to a lens every time you switch
lenses. I'm sure someone out there is screaming "blasphemy" or "moron"
but I really don't know enough about the optics except what I've seen
on those websites and tried myself. I couldn't find any information on
the Internet on the placement of wide-angle lenses on the back-end.

On a side note, I was interested in taking out the electronics of the
digital and placing them inside an old Nikon body, so that the rig
looks like a real DSLR. But, I don't have a spare body. If anyone knows
where I can get a cheap non-functional body, or has one they wouldn't
mind donating to a "good cause", I would appreciate that too. Call me
old-fashioned, but I just can't justify sacrificing a working Nikon
just to see if my Frankenstein camera can work.

If you want to build your own camera... try to get some lenses from old 16mm
movie film cameras... some were adapted to video security use in the 70s, EG the
Shibaden camera... they throw a smaller image... I used to have some but sold
them a while back...

" writes:

However the multiplication factor was an even bigger issue because the
CCD was even smaller than on a DSLR. Now, I'm really curious as to
whether or not someone could make something usable with an F-mount. I
sold my old (crappy) HP and got a cheap (sold as a "parts" camera) 2
megapixal Nikon to sacrifice. What I was wondering is if it's possible
to add some optics in front of the CCD that would shrink the incoming
image so that the multiplication factor wouldn't be so big?

Essentially, you need a specialized piece of optics to shrink the scale
of the image, sort of like a telescope operated in reverse. But, it
needs to operate in the converging-rays environment between lens and
sensor, not the parallel-rays environment of an ordinary telescope (so
literally using a telescope in reverse isn't likely to work).

In addition, you want the final image to have much higher resolution
(in terms of lp/mm) than what the original lens could achieve. More
precisely, you want the final image to have the *same* resolution when
measured in terms of line pairs per picture height, but if the sensor is
1/5 as high as the lens was originally designed for (which is about
correct for the better P&S digicams), the image is 1/5 as large, and you
need 5 times more line pairs per mm to get the same number of line pairs
per picture height. So if the original lens resolves 50 lp/mm nicely,
your conversion optics need to resolve 250 lp/mm on the output side -
quite a challenge. Oh, and you want perfect colour correction (no added
colour fringes) and flat field.

On top of that, the conversion optics needs to accept all the light that
comes through the main lens up to some f/number, preferably wide open.
If you're going to use multiple "main" lenses, the conversion optics
have to do this for all of the possible exit pupil locations for all of
those lenses.

In short, making this work well is a very difficult optical problem,
more difficult than just designing a new lens for the smaller sensor
from scratch. Someone (Nikon?) did do this once, but abandoned it.

Dave

"Bruce Hoult" wrote in message
...
In article ,
"David J. Littleboy" wrote:

Full sized sensor DSLRs are very expensive and that probably won't
change
soon.

The extra US$1800 or so the 5D costs seems pretty cheap compared to the
headache of having to multiply or divide by 1.6 every time you think
about
taking a photograph...

I think most of us fall into one of two categories:

1) those who put the camera on a tripod, use a tape measure to find the
exact distance to the subject and the size of the subject, calculate
which lens they'll need, put a light meter up against the subject,
calculate the exposure by hand, set the aperture and shutter speed.

2) those who look through the viewfinder and twist the zoom until it
looks right.


Those is the first group can and do cope with all sorts of film/sensor
sizes and lens focal lengths and wouldn't even remark on the calcualtion
to fgure the fiield of view from those becuase they've alwasy been doing
it *anyway*.

Those in the second group don't know or care what numbers are printed on
the lens. They'll have a wide angle lens and bring-distant-stuff-close
lens and who cares what the numbers say?


The crop factor is something they think about when deciding what to buy
but not, that I can see, something that you think about when taking a
photo.

I think there are a lot of people in between those two groups....Or, they
are gradually going from the second group toward the first........