Macro with Canon 24mm f/2.8 and Nikon 105mm f/2.8

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Rita Ä Berkowitz wrote:

> I had a chance to put a 24mm lens in front of the 105mm and found that I got
> slightly better distance between the lens and the subject. The
> magnification is greater than the 50mm f/1.4 and the date on the penny
> almost fills the frame. This shot was taken at a 45* angle and as you can
> see there is considerable perspective distortion on the date. Is this going
> to be normal with any wide-angle lens reversed? I also feel my depth of
> field is even shallower than the 50mm. In conclusion, I feel this
> combination isn't worth using.
>
> http://www.geocities.com/ritaberk2 [...] y_24mm.jpg


Wow the perspective looks backwards! How could that be?

I'm curious if you tried the 50mm reversed on the end of the 70-200
probably not great I'd guess.


--
Paul Furman
http://www.edgehill.net/1
san francisco native plants

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Rita Ä Berkowitz wrote:

> I had a chance to put a 24mm lens in front of the 105mm and found that I
> got
> slightly better distance between the lens and the subject. The
> magnification is greater than the 50mm f/1.4 and the date on the penny
> almost fills the frame. This shot was taken at a 45* angle and as you can
> see there is considerable perspective distortion on the date. Is this
> going
> to be normal with any wide-angle lens reversed? I also feel my depth of
> field is even shallower than the 50mm.

DOF is ONLY affected by magnification and fstop using the same size format.

> In conclusion, I feel this
> combination isn't worth using.
>
> http://www.geocities.com/ritaberk2 [...] y_24mm.jpg
>


Try it stopped down..

The distortion is porbably the angle and magnification you shot this at..

--

Stacey

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In article <119nd0k8759dmfe@news.supernews.com>, Rita Ä Berkowitz
<ritaberk2O04@aol.com> writes
>Paul Furman wrote:
>
>>> http://www.geocities.com/ritaberk2 [...] y_24mm.jpg
>>
>>
>> Wow the perspective looks backwards! How could that be?
>
>I didn't consider that fact. You're right, the bottom of the date should be
>bigger since it was closer to the lens. LOL! Maybe it's the Nikon
>screaming in pain from not wanting to be mated with a Canon?

I'm fairly sure you must have posted the shot upside down. Turn it over
and it makes perfect sense.
>
David
--
David Littlewood

Archived from groups: rec.photo.digital,rec.photo.digital.slr-systems (More info?)

Regarding DOF; if you stop down your 105mm (which I assume is mounted
directly to the camera) you will likely have severe vignetting. Try
stopping down reverse-coupled 24mm instead while leaving the 105mm wide
open. The reason is that the 105mm lens is far more tolerant of stop
shift than the 24mm. You might get even better results with a
non-macro lens attached to the camera, such as a 105mm/2.5.

Brian

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On 8 Jun 2005 07:16:23 -0700, "BC" <brianc1959@aol.com> wrote:

>
>Regarding DOF; if you stop down your 105mm (which I assume is mounted
>directly to the camera) you will likely have severe vignetting. Try
>stopping down reverse-coupled 24mm instead while leaving the 105mm wide
>open. The reason is that the 105mm lens is far more tolerant of stop
>shift than the 24mm. You might get even better results with a
>non-macro lens attached to the camera, such as a 105mm/2.5.
>
>Brian

I hate to differ, but probably stopping down the reversed lens will
not reduce vignetting (on the contrary, it does increase it in all the
setups I tried, although I don't have the combination of lenses
mentioned above). Normally you stop down only the lens mounted
directly on the camera, and leave the reversed lens wide open. The
general rules-of-thumb are:
1 - use a direct mounted lens of high focal length (if you use a zoom,
you can increase it until you see no vignetting in the final picture).
2 - as you stop down either the direct mounted or the reversed lenses,
vignetting increases, so you may not see vignetting in the viewfinder
or preview screen, but still get it in the final picture. However,
likely you cannot shoot with lenses wide open because DOF is
insufficient. Learn the properties of your setup by experimenting.
3 - the front lens element of the reversed lens should be as wide as
possible to reduce vignetting, so you should use a reversed lens as
fast as possible. 50mm f/1.4 or 1.8 is usually excellent in this
respect, and also cheap. If you use a direct mounted lens with a large
front lens element (e.g., a tele), as a rule of thumb the front lens
element of the reversed lens should be at least as wide. So it is
counterproductive to mount a very fast lens or a very high focal
length on the camera body unless you have another lens with a
correspondingly wide front element to reverse on top of it.
4 - the two lenses should be mounted together at the smallest possible
reciprocal distance. Increasing the distance between the two lenses
will increase vignetting. So it can be a problem to mount a reversed
lens onto a macro lens that has a deeply recessed front lens element.
(If you mount two lenses sufficiently far from each other, you will
end up with a telescope or microscope, but this is another story.)
5 - I always get better results with macro lenses, bellows and
extension tubes than with added reversed lenses. Even a macro lens
with telemultiplier is far better than one with a reversed lens on
top.
6 - a reversed lens mounted on extension tubes or bellows (without a
direct mounted lens on the camera body) usually works great at
magnifications above 1:1.
7 - some camera bodies will produce vignetting when used with very
long bellows, extension tubes or when projection-mounted on
microscopes or telescopes. This vignetting is produced by the camera
lens mount or by internal mechanisms of the camera, and is completely
different from vignetting caused by added reversed lenses. With these
extreme setups, some SLR camera bodies will produce vignetting in the
viewfinder but not in the final pictures, others in both.

My personal conclusions: reversed lenses mounted onto a camera lens
are a great solution for cameras without removable lenses or for
occasional use, but not for frequent work. Equipment that has been
designed specifically for high magnification photography almost
invariably works better. However, there is a lot of fun involved in
experimenting, so by no means let this discourage you.

Archived from groups: rec.photo.digital,rec.photo.digital.slr-systems (More info?)

I've tried numerous combinations with a short lens reverse-mounted to a
longer one. Without exception, stopping down the short lens results is
less vignetting and less aberration than stopping down the long lens.
As I've stated before, the reason is due to different degrees of
tolerance for extreme stop shift in the two lenses. When you actually
try ray-tracing various combinations (in addition to trying them
experimentally) the conclusion is painfully obvious. When I get a
chance I'll post some examples.

Using proper reversed-lens technique will give you a much larger
effective aperture to work with than you could ever dream of with most
dedicated macro lenses. Perhaps your poor image quality is due to
stopping down the wrong lens?

Brian
www.caldwellphotographic.com