Resolution increases with print size?

[doug_broussard2]

This might seem like a dumb question, but I'm honestly a bit stymied.<p>

I've been shooting large format for just under three years now, first with a Crown Graphic and now with a Wisner Traditional Field. A phenomenon that has constantly amazed me is that when printing my large format negatives (TMax 100, typically) I percieve an increase in sharpness as print size increases beyond 8X10, up to 16X20 (the largest I've printed so far).

 

<p>Am I just inventing this perception in my head, or is this a repeatable and measurable effect similar to the 'better for large prints, not so hot for 8X10s' behavior one sees with digital lightjet/lambda prints from medium and large-format scans? Is it possible that my diffusion head has something to do with this effect? Prints I made last fall with a condensor head on a similar (Beseler 45MX) enlarger and the same lens seem slightly sharper. I normally test with 8X10 prints to judge if a negative is worth spending more money (read big paper).

<p>

My other theory is that my focussing is less precise with 8X10 from 4X5 because I can't see the darn grain at f22!

 

<p>

-Doug

[fred1]

Douglas,

lets work backwards for a moment. Are you focusing your negative at

the shooting aperture? Wrong move if you are. Focus wide open and

then stop down. I HIGHLY recommend the Chromega fine grain focuser

(I'm not sure what they call it these days, but it will set you back

about $300 and it will be the best money you can spend if you want

critically sharp prints). I have used them for years. If you are only

taking a 4x5 neg to 8x10 print size or 16x20 print size then you

should see no discernable difference either close up or at a normal

viewing distance. I have taken 35 mm (kodachrome to 8x10 interneg) up

to 14 feet (yup--feet) and it has looked good. This was for Coca-Cola

so it had to be right.

 

<p>

 

I don't understand your Lambda/Lightjet comment at all. There should

absolutely be no problems here given a good file size and the

percentage enlargement is not huge.

[Bill C]

>> �because I can't see the darn grain at f22! <<

 

<p>

 

Doug, are you actually using f/22 on the enlarging lens for your

8x10s? The diffraction limits work on both sides of the lens; f/22

in this setup would probably just about take the edge off your prints

(visually, under critical viewing). If you're really printing at

f/22, try getting that aperture open to about f/11 (or wider) and see

if that doesn't make a difference.

 

<p>

 

If this is NOT the situation, someone (I think Alan Gibson) has

previously described a good focus verification test: essentially,

block your easel up on both sides about 1" and critically focus.

Then, switch one of the blocks to the other side; ie, your easel now

runs from 0" to 2" height. Make a print; you expect the sharpest

point in the middle; if sharpest area is off-center, you have a good

idea how much focus error there was.

[mark_lindsey]

you guys are thinking too hard.

 

<p>

 

 

Doug, yes your prints get sharper because an 8x10 piece of paper

doesn't hold a candle to a 4x5 or 8x10 negative, so as you enlarge

the image, more information from the negative is spread over a larger

surface of paper--allowing more detail to be seen. You can think of

it in a digital sense, lets say the paper has 500 dots per inch

(dpi), the 8x10 paper and the 16x20 paper may still have the same

dpi, but multiplied out, the 16x20 paper has the higher amount of

information contained within it.

 

<p>

 

This is the reason I think the "feel" of an 8x10 contact print effect

is baloney, I don't really think anyone can see the difference

between an 8x10 printed from a 4x5 neg. or an 8x10 contact print. the

paper just doesn't have the resolution necessary to show the

difference between the two. and yes, I have shot plenty of 4x5 and

8x10 and printed it, so I'm not just blowing smoke out of my a**.

 

<p>

 

comments?

[doug_broussard2]

O.K., just got out of the darkroom, where I tried a couple of

things. FYI, my enlarging lens is a 150mm Schneider

Componon-S.<p><ol>

<li>Printed at �16, same neg, same paper (Zone VI Brilliant

grade2, my baseline test print paper). It does seem like

diffraction may have had something to do with the unsharpness I

saw last night. However...

<li>I then raised the enlarger head so that the illuminated area

was about 16X20 inches in size. I left the 8X10 easel in the

same place and printed the negative on an 8X10 swatch, roughly

centered. I tested this at �22. </ol><p>

Lo, and behold: the results seemed much sharper than even the

8X10 at �16. I did it again to make sure.<p>

Personally, I'm inclined to think that this effect directly correlates

to enlargement size. I believe the eye has difficulty perceiving the

inherent sharpness of the negative at smaller enlargement

factors. When the enlargement factor is increased to 16X, the

inherent sharpness is much more apparent; there is more paper

area for the eye to discern subtle diferences that are lost in a

small print.<p> For what it's worth, the Alan Ross contact print of

Ansel's Clearing Winter Storm on my wall is frighteningly sharp,

but details like the trees on top of El Capitan would reveal more

detail printed at larger sizes, simply because extremely fine

detail in the negative, imperceptable at it's native (8X10) size,

becomes apparent as it is printed on a larger area.<p>I still can't

see the grain at 16X20. Damn Tmax. ;-)<p>I may have just

re-invented the wheel, but thanks to everyone for the various

comments and insight.<i>An explanation of my lightjet

comment:</i> over at photo.net, some of the more enlightened

regulars have been discussing the relative merits of small digital

prints. To whit: Many argue that an 8X10 printed from a 6X7 neg

optically would be sharper than a scan and lightjet print of the

same negative. Experience seems to bear this out; because of

it's relatively low resolution (30x.x dpi in my prints) but extremely

high acutance and accuracy the lightjet really starts to shine

where optical enlargements begin to dissapoint.

[wilhelm]

How old are you? Do you wear glasses? Perhaps your eyes can't focus

close enough to get a sharp 8x10 but you can focus okey at the

greater distance to the 16x20?

[doug_broussard2]

I'm 28, and don't have corrected vision. I make sharp

photographs without focussing aids like loupes regularly. I

haven't had my vision tested in the past ten years, but I have

been known to freak people out by reading eye charts at long

distances.<p>In college and when I first came to California, I

partied and drank a lot; that affected my vision, so I cut back quite

a bit. I have one-two drinks a week at most now, and I've noticed

that my visual acuity and visual purple has improved markedly; I

can't recall it being deficient at any time.

[mark_lindsey]

Doug,

 

<p>

 

I have an alps md-5000 that makes amazing prints in both bw and color

and they are extremly sharp, it really shows up in small prints up to

8x10 and down to 4x5 or even smaller. You should check it out, they

aren't very expensive.

 

<p>

 

As for the detail sharpness of the 8x10 vs. the 16x20, this is an

effect that I have noticed and theorized on for several years. It

seems to make sense to me.

[chris_patti1]

Doug,

 

<p>

 

I have no idea about the resolution issue, but 1-2 drinks per week is

not enough. Latest research suggests you should have one a day. Red

wine is probably best; I like pinot noir.

[doug_broussard2]

Hmmmm...back to the vision thing.

<p>

I'd never thought of this before...perhaps it was a bit myopic of

me (ha ha).<p>

I can 'close focus' my eyes to about two-and-a-half inches in

stereo. Luckily for the purposes of this test, I cut myself pretty

badly last night and have a gauze bandage on my finger with

loose white individual threads perfect for an informal test.<p>I

can pick out an individual thread standing off from the gauze at

three inches with stereo vision. With monocular right eye, I can

focus at three inches, and monocular left, two and three quarters

inches. I'm thinking the differential at least points to the need for

an optometrist's opinion.<p>

My tests still suggest that some degree of enlargement beyond

4x might be more peasing to the critical viewer, but I'll get

checked up anyway.<p>To contributors: thanks to everyone for

the advice and ideas. Next time you're in Santa Cruz, e-mail me a

couple of days ahead of time, and I'll gift you with a tomatoes,

basil and and fresh zucchini from my garden!

[paul_schuster1]

OK, here is my simple take on what's happening. the LF negative just

has so much more information than what can be shown on an 8x10

print. some images do well at this size, others really stand out

when enlarged to show more.

 

<p>

 

imagine I went down to the corner and made a nice 4x5 of the church

down the street (and I actually get all the tech stuff right). let's

say I frame an area that is... 40 feet high and some 30+ feet wide.

 

<p>

 

now when I print an 8x10 there is a lot of information that just

doesn't make the detail. my result may not be that interesting. but

when I go up to 16x20 I can start to read the grafiti left by local

gangs or the cigarette butts left by the nuns (another form of a

neighborhood gang). maybe neither pictures are really worth a damn,

but the larger may indicate different elements and show off the

detail. it might be as simple as the subject is so much larger than

your resulting print size, you are in fact reducing.

 

<p>

 

just a thought,

 

<p>

 

paul schuster

www.schusterphoto.com (having probably 7-20 drinks a week, and my

vision just gets better!)

[charles_li1]

It seems that enlarger lenses have optimal enlarge ratio. Take a look

at the Schneider's side:

 

<p>

 

http://www.schneideroptics.com/enlarge/Datasheets/componon-s/cpns5,6-150/cpns5,6-150p1.htm.

 

<p>

 

If I get it right from the chart, geometic distortion of your lens

become prominent when enlarge ratio drops below 2.5 (i.e. u/u' > 40%).