quality of the lens of the fuji GW690 VS (very) good 35mm lenses

[maddav_maddav]

I have just bought a fuji GW 690 III (new) and I am a little

disppointed by the lens. I had read that this lens was very very

sharp, especially at f/11, and the first impression I have is that

it is not as sharp as my 35mm lenses, for example the 38mm of my

rollei afm 35 (compact camera). When I look at the slides (ekta 100

gx) with a 8x or 10x loupe, I have the feeling that I wouldn't see

much more details if I had a more powerful loupe ; on the other hand

I feel that my loupe is not sufficient to see all the "information"

contained in a 35mm negative.

 

I used a hoya filter with the fuji but when I use such a filter with

35mm cameras I generally cannot tell the difference with the "nude"

lens. So I don't think the filter could really diminish the

sharpness of the picture.

 

Also, I noticed that it was a bit soft at infinity when not focussed

there, although the focusing ring was very close to infinity.

According to the depth of field table it shouldn't be. But maybe the

permissible circle of confusion (0.05mm) is too big.

 

What do you think ? Is my fuji normal or is it an underperformer ?

[conrad_hoffman]

Don't know a thing about the 690, but I've never seen a bad Fuji lens. More likely your rangefinder adjustment is off a bit. Also, for any given scene, details are larger on a larger neg, so it won't have the same look as a 35mm neg. Either get some service, or do the old picket fence test- shoot something that falls away at an angle (fence, brick wall, etc.) and see if the image is focused where you set it (do this wide open). Obviously, use a tripod! Probably should check the pressure plate and springs to be sure the film is being held flat too. Filters of any quality brand should have little or no effect.

[jbq]

You should probably be testing at the same focal length to get a better comparison.

 

As Conrad said, you can easily test that your rangefinder is properly calibrated by taking pictures of deep detailed objects within which you can easily identify a specific point.

 

There are papers floating around the web (Ken Rockwell wrote one of them) that explain how to pick the aperture that will get the sharpest image for a given image depth. They have the great advantage of doing that in a way that doesn't invove a subjective "circle of confusion".

[lex_jenkins]

I suspect film flatness is a far greater factor than the lens in ultimate resolution on film with medium format. It's difficult to imagine that the optical engineers would design medium format lenses to a lesser standard than those intended for 35mm cameras.

 

However it's easy to imagine that the variations induced by the multiple layer "sandwich" of pressure plate, paper backing and film could result in compromises to resolution. Add the additional complications of differences in film transport designs and the amount of film surface unsupported over a larger window and it's a wonder any of our medium format photos are ever in perfect focus.

[gary e]

Check to see if you set the pressure plate to the type of film you're using (120 or 220). I've never had sharpness problems with my 670; it's tack sharp as they say. Also, wind slowly to avoid any slack in the spools.

[paul_.]

Maddav: I've used several of these cameras and owned two. The first example I owned (670II, but same lens) was the sharpest, but they are all pretty good (I'm writing this because yes, there is a little variation between individual cameras). Check your rangefinder first by shooting a yard/meter ruler at f/3.5 and make sure the focus is right. You can also tape a piece of ground glass to the film rails, but checking on film is easier. As for film flatness, the Fujis don't have that problem as long as you put a little light friction on the roll as you start it (see your instruction book). Full-frame enlargements printed big (20x24+) will be noticeably better than any 35mm neg, even made with a Leitz or Zeiss.

[maddav_maddav]

Thanks everyone for your contributions.

Well, I'm going to test the focus at infinity and on various targets as you suggested. As for the sharpness I have not said it was bad, only that it seemed less sharp than a top 35mm lens (my contax/zeiss 28-85zoom, or my AFM 35 lens whis is excellent even though inexpensive).

[andrew booth]

When you say less sharp, you mean that the same size of magnified film from the

35mm and 690 is less sharp on the 690?

 

When you print you will of course benefit from the 2 1/2 times greater size of the 690

film... have you tried comparing similar sized prints? I'd guess the focal lengths of the

two cameras should give you a similar angle of view.

[maddav_maddav]

When I say it is less sharp I compare two regions which occupy the same area on the negative, for example a square of 5mm by 5mm. Such a square represents therefore a much bigger percentage of the total area of the 35mm slide. It is clear that a print of the MF slide would be better than a print of the 35mm one.

[nicholas_t.]

The infinity issue sounds about right to me.<br>

Regarding the sharpness issue, if you really want to get the most out of your lenses you need to put the camera on a tripod. Are you doing that?<br>

Also, moving up to a higher speed film might help if you are hand-holding. This way you gain precious shutter speed stops. Camera shake is the biggest loss of quality in sharpness of negs after incorrect focus...

[john_stockdale2]

Just one thing to add. You mentioned circle of confusion. These are notorious things! If you're worried about focussing accuracy and lens quality, follow the above advice about focussing tests. After all that is cleared up, read about the depth of field issue: you will find that the lens markings for depth of field are pretty woeful. It's a tradition.

 

I try to use DoF markings for an aperture two stops larger than the taking aperture, especially for the far end of the focussing range if it's infinity. Even that will not give you the optimum sharpness if you're doing lens comparisons.

 

Also, remember that the larger the film size, the harder all this becomes. Which is why medium format is better than large format. (ok, not always)

[andrew_schank]

I did a test a while back comparing the Fuji 90mm lens from the 6X9 camera to the 60mm lens on the Fuji AF 645 camera. I took several of the same images with both cameras (framed as close as possible). I was surprised to find there wasn't any more detail captured with the 69 camera than the 645, and if anything, the 645 shots had more "snap" to them. I concluded the 6X9 format had less depth of field and that was contributing,(making rangefinder accuracy more important) as well as film flatness, and the fact that the outright resolution of the lens was good but not spectacular.Its much harder to make a lens exceptional when covering that huge neg. That Fuji 645 60mm f4.0 lens was as sharp as my best 35mm lenses, even when comparing a 35mm sized spot of the larger 645 neg.

[john clark]

I've tried just this with my Mamiya 7 lenses versus the Contax G lenses. I'd say, that on a mm-for-mm basis, the Zeiss G lenses are just that little bit sharper than the Mamiya ones. Nothing significant, yet subtly different. However, factor in the size of the negative and the Mamiya has the potential to destroy the Contax at any given print size beyond 6x4s, in terms of tonality, grain and perceived 'sharpness'.

 

I'd be surprised if you found that your compact outperformed your Fuji though - perhaps there is another issue to consider?

 

John

[maddav_maddav]

The slides were not shot with a tripod. I didn't think that it could matter when photographying far objects at a speed of 1/250.

I'm going to shoot some more pictures.

As for the rollei afm 35, it's a compact but it has nevertheless a very good lens. According to the MTF chart (you can see it on rolleiclub.com), it is as good as my contax/zeiss 50mm at medium apertures.

[gary_frost1]

Even at 1/250 sec you still need a solid tripod to be sure of no

camera movement compromising your test. I went from the best Nikkor

primes to the GW690III without any disappointment in image quality.

It may take a bit getting used to f11-22 instead of f 5.6-11 to

get the DOF you want. I would repeat your tests with more care and

a tripod. Also, if you have a 90-105mm lens for your 35mm it may

make the comparison (on a light table at the same magnification)

easier.

[matthew]

The circle-of-confusion allowance is greater for medium format or large format film sizes, as they do not have to be enlarged as much to reach a given print size. So if your want you 6x9 chromes to have as much snap and definition as 35mm chromes, be more conservative with the DOF gauge. I typically go one or two stops in from what is marked. Other tips: shoot right on infinity for distant objects, and keep the film tight when winding on (film flatness as discussed above).

 

I have had success handholding the GSW 690 - good results even down to 1/30 sec, which I can't do with a 35mm SLR, but a tripod is necessary for tests. When testing the rangefinder, focus close in as well; try at 1 meter on the picket fence (or newspaper-on-the-floor) test.

[maddav_maddav]

Some of you told me their fujinon 90mm lens was just as good as their best 35mm primes e.g. contax G or nikkor lenses. Under which magnifying did you compare your lenses ?

 

By the way, how can one check that the lack of sharpness is caused by the insufficient flatness of the film and not by the lens ? Maybe it is possible to look at a ground glass with a loupe to check the lens. However I read that the resolution of the lens is always much higher than the resolution of the system { film + lens }. Therefore even if the resolution of the lens was inferior to the "normal" resolution, resulting in an insufficient resolution of the system, the resolution of the lens alone could still be high enough for the problem not to be detected by this simple examination. Is my reasonning correct ?

[gary_frost1]

Use Velvia and a 10X loupe on a light table for the test.

 

Film flatness will show up as uneven areas on the frame: some in

focus, some out. I wouldn't worry about this with the Fuji, I've

never seen a problem with mine. The film path is straight and the

film gate is a solid design. (just make sure the 120/220 pressure

plate is in the right position)

 

It really doesn't matter how good the lens is without considering

what ends up on the film: meaningless to a photographer, so no need

to speculate.

 

You can check the film plane focus accuracy with a ground glass.

Just make sure it is only resting on the inner rails.

It is unlikely the distance scale on the lens would develop an

error(...unless it was disassembled.)

 

If you just got this, I would suggest you go ahead and do the

careful testing. If you are not happy with it, then return it.