Bronica PS 40mm performance and quality?

Hi,

<P>

I recently purchased 40mm PS lens to my Bronica-SQ. Because that lens

was used, I went soon out and tried it.<br>

<P>

At first It results looked nice, then I got <a

href="http://www.cs.helsinki.fi/u/jvuokko/tmp/link/bw2004-36-17%20mustakoski%20viilatehtaan%20suuntaan.jpg">this

picture</a> (160KB, 700x700pix). The flare seen in the picture is not

my main worry, but the way how trees at upper left and right corner

are too blurry. It might be caused by wind, so I made more tests.<br>

<P>

I took test photo where around corner was target which was definetly

not affected by the wind:<br>

<img

src="http://www.cs.helsinki.fi/u/jvuokko/tmp/link/ps40-test1-small.jpg">

<br>

<p>The test image were shot using f/16 and lens focused to infinity. I

chosed f/16 because that is aperture which is used lot in landscape

photos.<br>

<P>

Here is the link for <a

href="http://www.cs.helsinki.fi/u/jvuokko/tmp/link/ps40-test1-fullsize.jpg">larger

version</a> (600KB, 1700x1700pix), scanned at 800dpi. In this image

the poor quality at upper right corner is visible.<br>

<P>

And then finally, <a

href="http://www.cs.helsinki.fi/u/jvuokko/tmp/link/ps40-test1-detail.jpg">3200dpi

crop</a> of upper right corner (300KB, 360x900pix).

<br>

<P>As far as I know, Bronica Zenzanon PS 40mm has very good

reputation, so my question for other PS40 (or S40) lens owners is that

should corner quality be better than that or is that normal?

<p>I wanted to be sure that there is no aligment errors in the lens,

so I took test photos also by setting my camera upside-down on my

tripod. The result was quite similar: Resolution of lower left corner

was identical to resolution of upper right corner.<br>

<p>My lens has short warranty time so if this is something that really

indicates flaw in the lens, then I'm going to return it.

hi Jukka,

just some thoughts that come to mind,

shooting at f16 ( generally speaking ) is not going to be as sharp as shooting around f8 - f11 and

corner sharpness (or the lack thereof ) can also be improved by using a glass neg carrier ( glass on one side , neg carrier on the other ) . i've got a nikkor 40mm for my bronica s2a and the images are corner to corner sharp. the biggest improvement came from shooting at f11 and using a single glass carrier. hope this helps. gonzalo.

Jukka

The problem may be a Depth of Field issue. By focusing at infinity, you have reduced your effective DOF, especially on your near end. When I shot landscapes (and I have the 40S version), I use the hyperfocus mode. I set the infinity position opposite the f-stop I'm using (usually set it a one f-stop less for good measure if I can). That is set your infinity mark opposite the f/16 mark on the left side of the lens barrel (hopefully the S and PS models are set up the same). Reading the distance opposite the f/16 mark on the right side of the barrel should show a distance around 8 feet. Your hyperfocal range is set for 8' - infinity. Everything within that range should be in relative focus. The hyperfocal range extends 1/3 in-front and 2/3 behind the actual point of focus and shrinks with larger aperatures and expands with smaller aperatures.

I can shoot landscapes all day and never look thru the viewfinder to focus.

I think this lens is a Distagon type design like the hasselblad

40mm - which i tried out in similar circumstances - the results

where similar... however, where it did score was the central

image sharpness which was outstanding (and theres not a lot of

detail here in your picture!). Also, i suspect that infinity at the

corners is the worst case scenario for this type of lens design -

try it at a middle distance instead.

Brian, I have also test picture of same setup where I used f/16 and I focused to hyperfocal using f/8 marks. Still corners were blurry :(

Simon, My lens also performs great at central area. And also almost at corners. The big falloff is visible only at corners (and usually there are nothing but sky). So maybe this is typical flaw in this type of optics and I don't have worry too much?

And ofcourse, when cropping to 6.45x6 format, corners does not matter.

One last try. Do the obvious. Two shots. 1) Sharp focus using central split image of focus screen of near object. 2) Sharp focus using central split image at objects far at infinity. In each shot, before you expose, recompose to place the respective objects you used to obtain clear focus to the far edges of picture frame. Camera must be on sturdy tripod. Use mirror lock up, cable release. If this still produces unacceptable images in corners, use the negatives as proof to get your money back.

I bought a used 40 PS off EBay. It's really quite a performer - in the center and corners.

PS, imperative that you also change your film back to a different one for this final test.

Problem could be an alignment problem in a film back, and not problem in the lens.

On last point: My gut instincts tells me it's either a film back, film flatness, or film scanner issue.

You must use a different back for test, also you must examine negatives with a decent 8x loupe on a light box. Using a scanner to eval negs just doesn't cut it.

(I don't want you to push the 'panic button' and return an otherwise awesome lens for nothing)

Scanner issue it cannot be: In my scanner, film flatness is best around corners ;)

And that fuzzines at corners is easy to see using only 4x loupe :(

It could be film flatness issue, however I haven't ever noticed any problems with my other lenses.

I'll take test images to slow slide film and if there still is too much softness at corners - then it's time to talk about warranty with dealer...

Forgot to say.... I'll include close ranges to next test. Take test with other back and include similar shot with another lens (80mm).

That should at last clear things.

I think it's time for little update if someone is strugling with same lens.<p>

I sent lens to the service for check, the didn't found any flaws.

<br>

But I was still suspicious. I returned lens to the seller. Then I begun searching for replacement lens.. That took long, Bronica stopped all production - so no new lenses any more.<br>

Next I did lot of searching in my home country, but got nothing. These lenses are rare stuff.

<p>

At last, I found one really good from eBay and bought it. The mechanical quality was much better than in lens I had before. This was newer piece I think. Great!

<p>

Then followed the field tests... And the result? Performance of the lens was quite similar to my previous one!

<br>So it's definetly lens feature... As for aligment, I have tested that and no difference.

<p>Now I just have to accept that wide lens like this has poor corner performance...

<p>

<br>

<a href="http://www.photo.net/photodb/member-photos?user_id=1090556&include=all">-- Jukka Vuokko</a>