Am I expecting too much of my Nettar 515/16?

[bunip]

I'd suggest some care in pulling the plate forward as springs are stainless very thin but hard so they better brake then deform. Would you know how I know this?

 

[choiliefan]

My Nettar 515/16 has three paper shims between the shutter and front standard. Although it seems your pressure plate needs attention, it is also possible your camera was disassembled and shims were misplaced or lost.
It's interesting that your rear lens element was reversed so thinking the camera had to have been taken apart at some point in time.
On mine, which has a very simple 3-speed shutter, the rear lens element is held in place with a cheap wire clip. It's not even a snap ring, its the cheapest thing Z-I could come up with to cut cost.

 

[Alex Varas]

In another thread, https://www.photrio.com/forum/threads/folder-distance-scale-origin-point.160778/page-2#post-2174708 user alexvaras proposes just this morning the same method as I did in post #17 above https://www.photrio.com/forum/threa...much-of-my-nettar-515-16.167101/#post-2174450, maybe slightly better because he has the paper in place, in case it would make a difference.

I would suggest to follow it if you have the tools for it, DSLR, technical film and flashlight. For the other method you need a ground glass of a precise dimension film gate.

On second thoughts, I'm not sure I understand. When the pressure plate is supposed to be pressed against the film gate, the camera is closed. Unless you remove the lens, I don't understand how you can check whether the pressure plate is pressing correctly or not.

Not too carefully! You need to produce some permanent deformation of the leaf springs to achieve something.

When I want to know if it fits I measure the pressure plate with a calliper and take this to the film gate and see how it fits, some cameras the film contact point can be either on the vertical rollers or the horizontal rails where they should be (my guess).
The previous post and this are quite similar, I hope tomorrow I can take some pics of both ways but I guess there are already out there.

 

[Ste_S]

For the other method you need a ground glass of a precise dimension film gate.

Just use some frosted tape, no ?

 

[Alex Varas]

They say so but I have never tried myself, a lot of matte glass from Soviet time around so I have a lot of 6x6 and some custom cut out.

 

[Theo Sulphate]

... I don't understand how you can check whether the pressure plate is pressing correctly or not.
...

I can't directly measure it; I can only infer that the plate does not hold the film as far forward as it needs to be. For example, with a view camera, if I focus the lens on an object at distance d and see the image sharp on the groundglass, then if I move the rear standard back (increasing the groundglass-to-lens distance), objects closer than d will come into focus. This is essentially the same as the film not being pressed far enough forward by the plate.

Not too carefully! You need to produce some permanent deformation of the leaf springs to achieve something.

Unfortunately, I discovered this yesterday...

However, I think I can fix this situation. Details to follow once it is resolved.

 

[bernard_L]

I can't directly measure it; I can only infer that the plate does not hold the film as far forward as it needs to be.

OK. Then it is not independent evidence. Meaning independent from the foreground twigs being sharper than the distant landscape in your first photo. I misunderstood that you somehow had observed that in operating conditions there was a gap between the pressure plate and the film gate.

I am suspicious of my Nettar's pressure plate: it seemed to be pressed flat against the back, with the springs exerting little pressure. I can actually pull it forward a bit.

So, the most obvious hypothesis --bad calibration of the lens focus-- should be the prime (but not only) suspect.But still, better safe than sorry. Try the following: with no film in the camera, watch carefully through the red window the corresponding hole in the pressure plate, or a piece of paper taped on the hole where the backing paper should be, while you close the camera; do you see the pressure plate being pushed back when it come against the film gate?

For those watching this thread who might think I'm splitting hairs or doing too much theory: false hypotheses, especially implicit, can lead to large loss of time and/or failure. How do I know?

 

[Alex Varas]

OK. Then it is not independent evidence. Meaning independent from the foreground twigs being sharper than the distant landscape in your first photo. I misunderstood that you somehow had observed that in operating conditions there was a gap between the pressure plate and the film gate.

So, the most obvious hypothesis --bad calibration of the lens focus-- should be the prime (but not only) suspect.But still, better safe than sorry. Try the following: with no film in the camera, watch carefully through the red window the corresponding hole in the pressure plate, or a piece of paper taped on the hole where the backing paper should be, while you close the camera; do you see the pressure plate being pushed back when it come against the film gate?

For those watching this thread who might think I'm splitting hairs or doing too much theory: false hypotheses, especially implicit, can lead to large loss of time and/or failure. How do I know?

If with this test you want to see how far the pressure plate goes back it's a good idea, I have done it before, it gives you the point if the pressure plate is doing its job or there is somethig to be corrected.

Sadly I came home late today so I will post how-to do it the film with a mark comented above.

 

[Theo Sulphate]

...
Try the following: with no film in the camera, watch carefully through the red window the corresponding hole in the pressure plate, or a piece of paper taped on the hole where the backing paper should be, while you close the camera; do you see the pressure plate being pushed back when it come against the film gate?
..

Ok, I did that and do see the paper flatten; I also notice what I believe is more resistance when closing the back. I can't quantify this adequately because I never performed such tests prior to making adjustments to the plate.

Here is the front standard. The standard folds out very rigidly; I don't think there are problems here.



Here is the plate, now extended slightly.



Here is the film gate. It seems to me that even if the plate pushes harder than necessary against the gate, the film will always be properly aligned along the flat "rails" -- that is, the film won't be pushed too far forward. You'll notice that raised surfaces above and below the rails help keep movement straight and prevent the paper-backed film from becoming skewed.

 

[Marco Gilardetti]

That's good and will assure that your film will stay flat.

You said you were going to check focus with a groundglass. Did you check it? Because in some of your pictures it looks as if nothing is really in focus, at whichever distance. As the lens has been tampered with many times, you definitely have to check focus at infinity.

 

[bernard_L]

Ok, I did that and do see the paper flatten; I also notice what I believe is more resistance when closing the back.

Good.

It seems to me that even if the plate pushes harder than necessary against the gate, the film will always be properly aligned along the flat "rails"

Beware! I just checked on my Nettar, and I see the same as on my S.Ikonta, as I already mentioned: the rollers are higher than the film rails (I mean of course the inner part, extending over the width of the film). See post #17 https://www.photrio.com/forum/threa...much-of-my-nettar-515-16.167101/#post-2174450. So using a ground glass + loupe I would be unsure where is the plane of the film. I would again recommend the method proposed by alexvaras and myself; see post #24 https://www.photrio.com/forum/threa...much-of-my-nettar-515-16.167101/#post-2174717

 

[Theo Sulphate]

Success! (I think)

So for this experiment I placed "film" where it would go across both sets of rollers and where the pressure plate would press this "film" forward.

I actually bent the springs a bit more to increase the pressure. I also learned how to put the plate back on properly, since it popped off. At first it was a bit of a mystery how to get the springs into all four slots at once. Anyway, it's all correct now.

I placed a crosshatch pattern on the film so that I could illuminate it from behind with a strong light through the red window:



This is my test setup:



Here is a view through the Hasselblad. I checked it with the magnifier in the viewfinder as well. The crosshatch pattern was perfectly sharp. If it looks soft here, it's because I had to focus my phone's camera and it may not be perfect.



So, I think my Nettar is good now.

 

[Alex Varas]

Success! (I think)

So for this experiment I placed "film" where it would go across both sets of rollers and where the pressure plate would press this "film" forward.

I actually bent the springs a bit more to increase the pressure. I also learned how to put the plate back on properly, since it popped off. At first it was a bit of a mystery how to get the springs into all four slots at once. Anyway, it's all correct now.

I placed a crosshatch pattern on the film so that I could illuminate it from behind with a strong light through the red window:

View attachment 222574

This is my test setup:

View attachment 222575

Here is a view through the Hasselblad. I checked it with the magnifier in the viewfinder as well. The crosshatch pattern was perfectly sharp. If it looks soft here, it's because I had to focus my phone's camera and it may not be perfect.

View attachment 222576

So, I think my Nettar is good now.

As far as the crossed lines are facing the lens, yes, it should be fine.
But have you done any other thing to the camera than increasing the pressure done from the film plate?

 

[Theo Sulphate]

...
But have you done any other thing to the camera than increasing the pressure done from the film plate?

No. But I believe that before yesterday, the plate was exerting little or no pressure on the film.

 

[Alex Varas]

No. But I believe that before yesterday, the plate was exerting little or no pressure on the film.

Sounds good then, give it a try and let us know, the worst scenario would be the previous collimation was not on the correct position were the film lays and it can be corrected.

 

[bernard_L]

Success! (I think)

1. Good for you
2. A Hasselblad, no less!
3. Now, the proof is in the pudding, err, I mean in the picture taking. My suggestion: perform a test at dawn/dusk to use max or near-max aperture: more critical test of focus; on a sunny day at f:16 any camera can take sharp pictures. Nettar on a tripod. Subject at 3m. Ideal subject: a fence seen diagonally, with a close spacing of posts. Identify the post that is at 3.0m from camera with something that will be recognizable on the photo. Repeat at 2.0m. Use the rest of the roll for other tests or creative/artistic shots. Which post is sharpest? The marked one? farther? closer? Reason for not testing with landscape at infinity: the correct focus might be in front or in the back. Reason for testing at 2-3m and not at 1m: at 2m and f:4 the DOF is 11cm, larger than the difference between origin at film and origin at lens (I should make a test myself to find out which is which with the folders that I intend to be dependable).

And thank you for being responsive and providing pictures. Some OP's just seem to lose interest and disappear.

 

[Sewin]

Sorry not able to help, but this reminds me of something that happened to my Netter a few years ago (I don't have it now).

For the first six months or so I had it the images were slightly soft and disappointing.
Then suddenly the images changed to being sharp, as if something had been bumped into place.
I'm not suggesting you bang the camera on the table, but I believe a knock put something right on my Nettar.

 

[bunip]

maybe your plate’s springs were displaced and after some use got the right place producing the right pressure

 

[Alex Varas]

Better later than never.

https://flic.kr/s/aHsmxQMU6j

 

[Theo Sulphate]

...

I had to test at 4 feet - which is the closest distance actually marked on the lens barrel, even though it will focus closer. Similarly, there is still a considerable angular distance on the lens barrel between 48 feet and infinity.

Once I get this situation resolved, I may put little dots on the barrel for better resolution. At the very least I should confirm what the absolute closest distance is. I believe it is 1.2m (4'11").

Anyway, I made some test photos. The only film I had available was Portra 160, so I'm going to have to wait for C41 processing before I'll know the results. That will be about a week - similar to when I was a little kid and had to wait for photos.

Thanks, everyone, for your help.

Later...

 

[wombat2go]

Good.

Beware! I just checked on my Nettar, and I see the same as on my S.Ikonta, as I already mentioned: the rollers are higher than the film rails (I mean of course the inner part, extending over the width of the film). See post #17 https://www.photrio.com/forum/threa...much-of-my-nettar-515-16.167101/#post-2174450. So using a ground glass + loupe I would be unsure where is the plane of the film. I would again recommend the method proposed by alexvaras and myself; see post #24 https://www.photrio.com/forum/threa...much-of-my-nettar-515-16.167101/#post-2174717

On the old Nettar 6x9 here, the nickel plated rollers are about 0.1mm
below the guide rails. ( shop rule and feeler gauge)
So the film and backing paper are nipped between the guide rails ( pressed steel with stitches impressed)
and the backing plate.

On a Graflex RH10 rollfilm back, the pin rollers look to be level with the guides.

On a Horseman 10Exp, the pin rollers are visibly below the guides.
(I think on this back, the pressure plate is pushed back below the big carriage rollers.

 

[takilmaboxer]

I am also a long time folder user (since 1966) who has disassembled and reassembled many Novars (I love them). I have had the experience that the focus scale on the lens ring is not always accurate. . I use Oleson's method for infinity but sometimes see small discrepancies between the results and real world photos; the ground glass is rigidly flat, but the film may not be.
So! I use a two step procedure: find a subject that is at infinity and has sharp edges and high contrast: distant buildings work great.Set the camera on a tripod and make four exposures (I use f/8), the first with the ring set to infinity; the last at 48 feet; and two in between. Repeat the procedure with an object at ten feet distance, measured with a tape measure for precision; note exactly where you set the focus scale. Develop and examine the negatives with a strong magnifier.
If the infinity setting produces the sharpest image at infinity, and the ten foot setting the sharpest when set to ten feet, all is good.
If one of the not-quite-infinity settings produces the sharpest infinity image, you have found the real infinity setting. If none of them are sharp the real infinity point lies "past" the infinity mark on the lens ring.
I have repeatedly witnessed that even when the infinity setting is correct, the ten foot setting is not. So I obsess on the infinity setting, and mark the ten foot setting on the ring itself. That is my common portrait distance.
And finally, I have a few Novar folders that are in nearly new condition and have never been serviced, and their images are nice and sharp. Good Luck!

 

[Theo Sulphate]

Success in both near and far focusing is what I'm seeing in my test results, a few of which appear below. This is all a result of removing the pressure plate, bending the springs to exert more pressure on the plate, and then re-installing the plate.

These photos were made at 4', the first distance marked on the lens. However, it will focus closer: the claimed closest focus is 1.2m (3'11"). The photos below are center crops from a 4800dpi scan of the negative.

4' 1/10 sec f/4.5:


4' 1/2 sec f/5.6


4' 1 sec f/8


4' 2 sec f/11


The true focal plane on the camera body is not marked, so I had to estimate this.

I made additional tests at 11', 48', and infinity - all were sharp and what one would expect from a 6x6 negative. I've determined that apertures from f/8 to f/22 produce high quality results; f/16 might be the best - at least with my camera. I see flare-like smearing artifacts at f/4.5 and f/5.6, but f/22 is very good - perhaps as good as f/16.

So ends my quest for sharpness with my Nettar; I've learned a fair bit.

Thank you for help and advice all who responded.

 

[Alex Varas]

Congratulations for results and thank you for sharing them.

 

[foveon_m]

It's difficoult to say if your camera is in the mean situation of every Novar 75mm lens or not. I have hundreds of folding cameras and I see that every one is different; if I test 4 samples from the same model, same lens, I'll find different results. I have so many cameras because the more you have the better you can source. Take also into account film flatness that sometimes play a big bias from time to time as you could wind your film in different ways and at different times. I wouldn't waste time and film with a novar; these are cheap and you can get a decent tessar or tessar-like (better two) for 100-150 euros each. there you'll see sharpness and have a lot of fun, but I never saw anything similar to modern lenses sharpness (say planars, xenotars or the japanese similars) even with agfa super isolette, voigtlander bessa II (heliar lens or Skopar) or super ikontas.

sorry for hijacking^^, as an expert for folders, what do you think about Mamiya Six folder, I`m somewhat fascinated by the fokus mechanism.