Is it possible to get a 'sharp' picture edge to edge?

Hi everyone,

I've just completed a black and white workshop, and have mixed results.
The 8x10s printed by me are ok, but not the 'tack sharp' I'm used to on the
color 4x6s I get from the good lab. Now, before you start chortling, I know
printing the same amount of information on a bigger area will result in some
degradation. I would like to ask you, O' Fonts of Photo Knowledge, is it
possible to get an 8x10 or 11x14 that is sharp edge to edge? I have
reviewed MTF charts on the lenses I have (three primes, 28, 50 and 85 - all
35mm format) and it seems that most if not all lenses have a definite loss
of sharpness as the edge is approached. The near exceptions being the
expensive glass, whose chart looks much like a horizontal line. So am I
correct in saying that 1) all lenses to some degree lose sharpness at the
edges, 2) one cannot get an 8x10 to be as sharp as a 4x6 without spending
some serious cash on the glass and 3) one could combat this phenomenon with
slower film, for increased sharpness, to a point. To summarize: is this
lack of sharpness at the edges an artifact of the format and lenses, which I
should ignore and go out and take pics, or am I doing something wrong? I
did some pics of lens charts to test resolution, and even at the 4x6 one
could see slight light dropoff and a loss of sharpness at the corners, more
prominent on the 28/2.8 than the 50/1.8. Ideas?

Thanks for helping an overworrier,
Scott

 

Nearly yes

serious cash on the glass

Yes. Generally macro lenses are designed to be sharp edge to edge.

sharpness, to a point.

No. Finer grain film will just reduce the overall grain and increase
the possible sharpness, but it can's add what the lens does not capture.

4) Is part of the problem possibly my enlarger lens.

Yes.

 

Other then using a larger piece of film? Ya first of all is the problem
the print or the negative? Bad printing will screw up a good negative. Is
the negative good? If not why? The more you push the limits the more effort
you have to put into things. IMHO 11x14 from a 35mm negative is pushing the
limits hard. But getting a good 8x10 isn't that hard. Not an 8x10 that will
look equal to a 4x6 but a good one. So assuming the negative is good is
something wrong with your printing setup?

Nick

 

I've just completed a black and white workshop, and have mixed results.

It may or may not be possible to get an 8x10 that is as sharp as a 4x6, but
it is possible to get an 8x10 that shows no visible unsharpness when viewed
without a magnifying glass. Let me suggest the following:

1) Slow film. Kodak T-Max 100 is a reasonable choice.

2) Stop the lens down to f/11.

3) Use a tripod.

Then print the resulting negative and see how you like it. If you're still
not satisfied, use a magnifying glass to look at the film grain and see
whether the grain (not the image) is sharp out to the corners. If not, you
need to stop down your enlarger lens more or replace it by a better one.

 

Sharp edge to edge? Unlikely, for a lot of reasons. The main thing is that
a lens plane of sharp focus is not a plane, but a curved surface. Unless
everything you're interested in lies on that surface, it will be to some
degree unsharp. You can help matters by stopping down. This increases
depth of field, making the plane of sharp focus thicker, if you see that I
mean. Some lenses suffer from this "curvature of field" more than others,
but they all do it with the exception of flat field macros. Cheap lenses
are usually worse than higher quality ones.

Since you haven't told us how the exposure was made (On a tripod? No? It
should have been, if you're going to be critical of sharpness! What was the
f-stop? The shutter speed?) further help is not very possible. It may just
be that your small prints *were* unsharp, but since they were small, you
didn't notice.

Also, how were the prints made? Did you use a grain magnifier? If you get
the grain in focus, that's as sharp as things will get.

 

Sure, but all parts of the system from capturing the image, to printing the
image, must be of the highest quality. Technique also plays into this, and the
experience of the operator can help. If you only have limited experience doing
your own prints, then it is indeed tough to get consistent results.

Quite common with many lenses. Take a look at some of the more extensive MTF
charts, and you might find that often f8 or f11 might be closer to what you
want to achieve.

Nearly all, with a few exceptions.

Not entirely true. The enlarger lens now adds another variable. You are going
to twice the enlargement in your comparison, so even with a good camera lens,
and technique, if your enlarger lens is not used at optimum aperture, or even
not that great an enlarger lens, then you will get worse results than the
optimum.

Not really. It might be enough of a difference that you are more satisfied with
the results, but you could chase that direction for a while, especially
considering how many films are on the market.

You may just be super critical. If you are doing architecture, or
photogrammetry, then there is nothing wrong with being super critical, but then
I would say you are expecting too much of 35 mm format. You can look into some
medium format systems that are more suited to extreme edge resolution, if your
work requires that level of accuracy. However, if you go that route, you should
also go with a much better enlarger system.

Sounds to me like you may be doing quite a bit of tripod photography. Since it
seems you are very critical, you might want to try using medium format instead.
Once it is on a tripod, the slight difference in weight and added bulk of
medium format may not be that noticeable.

You may want to check more into enlarger lenses. Schneider and Rodenstock
publish data on the MTF of their enlarger lenses, and you might be able to find
a better lens. Some of these are okay to purchase use, so this is not
necessarily an expense change for your system.

When I was doing more architecture work, I found that for super critical
sharpness, there were few 35 mm choices. Largely the choice of doing this with
35 mm was more for documentation, the less intrusive nature of the gear, and
the slightly quicker operation. I have used a Nikon 35 mm f2.8 shift lens for
some of this. The advantage of a shift lens for 35 mm is that the image circle
is much larger than it needs to be. When it is only slightly shifted, the
centre to edge resolution on the final image is very even across the 35 mm
frame.

Depending upon what brand of camera you own, you may want to try to find a
shift lens for it. They are slow to use, and not very convenient. It is also
possible to make mistakes when using these, since there are many things to
check while setting up each exposure. However, when doing critical architecture
with 35 mm, it is nearly one of the only good choices, with few substitutes.

The increased coverage trick can sometimes work on 35 mm, if you are able to
adapt lenses from medium format or large format. Pentax, Contax, and some third
party companies make adapters to fit larger lenses onto 35 mm bodies. While
this is not a low cost solution, the results can be very good.


<http://www.agstudiopro.com> Coming Soon!

 

Nope. Get a good 50mm 1.4 or 1.8, stop it down to around f:8 (not just for
depth of field, but also because this turns out to be near optimal for
many lenses for the 35mm format), focus carefully, and eliminate camera
shake (use a tripod and remote release or self-timer, high shutter speed).

Now you should have a decent negative. Next is printing. You need to make
sure you enlarge with a good lens at its optimum aperture, mounted in
an enlarger that holds everything in alignment (negative, lens and easel
all parallel) and focus very carefully.

The rest should be easy .

Normal lenses are often great bargains: cheap and sharp. Canon has
their MTF charts on line; notice that both the 50mm 1.8 II and the 1.4
USM are quite sharp at f:8 almost to the extreme corners. But wide
open is a different story.

<http://luminous-landscape.com/tutorials/understanding-series/understanding-mtf.shtml>
might be helpful.

<snip>

 

Good film for "real" use. Pan F is probably sharper; for the ultimate
(in over-the-counter films) try Kodak Technical Pan - needs a special
developer though. You would probably find these films a bit of a pain to
use every day though.

The best camera lenses should be giving their best at f/8 or even f/5.6.
However, for camera lenses, there should be no noticeable fall-off by
f/11.

Yes. A solid one - and a cable release (or use the self-timer).

If you have a good enlarger lens, then stopping it down more in an
attempt to get more sharpness is doomed to disappointment*. A good
enlarger lens (50/2.8 EL-Nikkor, Componon or Rodagon) will have its best
performance at f/4 or f/4.5; stopping it down further will give
significantly less resolution. Of course, you have to make more effort
to focus accurately (and to check proper enlarger alignment) but
resolution at f/4 is enough to give a sharp 10x8. Resolution at f/11
will never be quite good enough. If your enlarger lens is mediocre, then
I agree replacing it should be an essential step.

*The effect of stopping down is more dramatic for enlarger lenses,
because diffraction effects are much more serious. At 8x magnification
and f/11 nominal, effective aperture as seen from the paper is f/88.
This limits resolution to about 15 lp/mm; combined with degradation from
other sources, this is very unlikely to give a sharp print.

 

See my other post for comments on film and enlarger lenses.

Taking Gordon's suggestion one step further, you should maybe consider
using a 5x4 view camera. A good second hand camera and a selection of
2-3 lenses will cost surprisingly little if you shop around. Film is
very expensive per shot, but (a) you will take a lot less pictures, and
put more effort into each one, and (b) you can, if you need, give each
sheet individual processing.

My 5x4 outfit cost a lot less than my 35mm one, and blows it away for
quality. I use it less now largely because of back problems....

 

Unalterable laws of physics demand that edge performance will ALWAYS
be less than axial (center). It has to do with optics. The very best
lenses (e.g., Leica APO macros and asphericals) have edge performance
that is better than central performance of other manufacturers, but
even these perform better in the center.

Almost, but not quite.

Yes

2)one cannot get an 8x10 to be as sharp as a 4x6 without spending

Yes

3) one could combat this phenomenon with

Are you using a Focotar-2 (Leica) enlarging lens? Glass carrier?

Sounds like you need to set your priorities. If you want top quality,
you're going to have to outlay some big cash.

 

I have had a gang of enlarger lenses, most of them terrible. I now
use a 75 mm Rodenstock or Fuji. I used to use a condenser enlarger and the
bulb kept getting hot spots, which caused me to lose the edges. A dichroic
head and a longer lens cured all. Bob Hickey
WWW.pbase.com/bobhickey/galleries

 

Not true at all. Its entirely possible to design optics which have
better performance off-axis than on-axis. Bear in mind that there are
important classes of optics which are designed to work *only*
off-axis. Dyson and Offner relay systems are two famous examples.

Brian
www.caldwellphotographic.com

 

I would like to thank everyone for their input. A lot of good advice was
given and I certainly do appreciate it. This is what the group was known
for back before the trolls and wars.

Thanks again,
Scott