Tessar 105/4.5 Nettar IQ

[PaulC]

I've been giving the Nettar 516/2 another outing. I'm finding the tessar lens a bit difficult. I'm not sure if I've got camera-shake, a soft lens, film sag, an exposure problem, a grainy film or a scanning problem. Whatever it is, the results seem to be less sharp than I would expect from a 6MP digital, which is not good for a 6x9 film.

Shot using Fuji Pro 400H, at around f22 with a shutterspeed of 1/250 (supposedly - the top shutter speed is usually slower than stated, they say).



that doesn't look bad, but look at a 72dpi crop from a 6MP version of the scan:



That's about as sharp as anything in the image. Is anyone able to diagnose the problem?

[luisalegria]

You've got your problem sources covered I think. I haven't really had much better results from any 120 film camera so far, and that includes a Rolleiflex. In order, I think the likely problems are -

1. Scanning problem. Very likely, if you did this on a flatbed scanner. You lose an amazing degree of IQ on a flatbed scanner. The film is not flat on the usual film carrier, the scanner DOF is only nominally covering the variations in film depth is my take on the situation. I've had somewhat better results laying the film on the scanner glass held flat with a clear plastic piece, with the dull side of the film down to avoid moire (only works on B&W though).

2. Possibly not properly focused. DOF calculations for film do not hold up for pixel-peeping, you have to be way more precise.

3. Film flatness problem. These old sheet-metal folders aren't necessarily straight, there is also a huge unsupported area.

4. Film. I get better results with 100 B&W. 400 Color positive film may not be the best option for these old lenses.

[scsambrook]

Luis' points are all relevant and any or all of them could apply. Just one thing to add -

I'm not qualified to comment on scanning issues but something from the distant past may possibly be relevant ...

When the good old UK "Amateur Photographer" tested folding roll fim cameras back in the early 1950s they often did a high-technology checking exercise using a piece of ground glass positioned in the film gate and a high-power magniying glass. Well, not so high-tec maybe. But they frequently found what they called "collimation errors" which degraded lens performance, especially at long distances. In other words the cameras had front-focus or back-focus problems. It's not easy to tell from the picture you show, but it seems to me that the near foreground is the sharpest part of the image - if so, then maybe that's the kind of problem you're fighting. Just a suggestion, not an assertion!

And as a subsidiary point, as I said, I know nothing about scanning negs but I wonder if your scanner is able to resolve the grain on a negative? When I did b&w work in the 1960s, the classic test of an enlarging lens was to use a grainy neg in a glass sandwich carrier and make a 15x12 inch print from it. More lo-tec, but it did sort the good from the bad. If the grain wasn't sharp, then the picture couldnt be. That might be something of an irrelevance in this case, I suppose.

[PaulC]

I think collimation may be a significant problem - I'll give that test a go. I've never got anything out of this particular camera that has been up to scratch, whereas my Beirax, Nettar 6x4.5 and Franka Solida can all produce first-class results. Even the early Bessa manages to get sharp results in the easiest of conditions.

Here is a 100% 72dpi crop from the Solida 6x6, at 6MP, which I suppose is a far more stringent test than 6MP from a 6x9.


It is much sharper than the other one (though the film is Reala 100). Both this and the previous shot were set for hyperfocal distance but the far horizon is oof with the Nettar, when at f22 almost everything should have been sharp.

[PaulC]

Oh dear ...

I've just checked the focus and it seems to be OK... then I noticed there are three small black screws on the outside of the barrel, one at about 1.9m, one at 4m and one at infinity. There is a red dot at about 12m marking the hyperfocal distance.

Without my glasses, the little black screws look like largish blobs and I have an awful feeling that I mistook the 4m screw for the 12m hyperfocal marker. That would give me a far limit on focus of just over 8 meters ... which rather fits with the result.

So, I'm probably an idiot (well, I've known that for much of the last half-century). But at least it seems there is a fair chance that the camera is OK.

I need to reload it and give it another chance.

I guess the moral of this is that when using an unfamiliar camera it is a good idea to be able to see it properly!

[LucisPictor]

It takes a lot to get images that are better than a 6MPix DSLR, really.
The comlplete chain that has been mentioned here has to be perfect.
If there is just one faulty element, the whole chain brakes.

[Attila]

A Tessar lens must be lot better right, I have one with Pentacon Ercona II.

No idea what is wrong with your camera.

[PaulC]

Probably user error, Attila.

I need to run another test.

Carsten, I reckon a 6x9 folder - if everything is right - should be able to produce results equivalent to a 12MP digital camera. That is about the best I've got from any of them.

[Attila]

[LucisPictor]

[PaulC]

Don't be hard on the Novar, Attila, my 6x4.5 nettar with the Novar lens is absolutely spectacular. I've shown it before but ...




I'm now fairly sure I screwed up the focus settings with the Tessar. I'll probably find out tomorrow. And I really should take the rangefinder accessory with me.

As long as there aren't any light leaks, I don't believe it makes any difference whether it is a Nettar or a Bessa. The tin box, pressure plate and bellows are all much the same. If a Bessa can take top-notch photos, so can a Nettar. As I understand it, the Heliar and Skopar really aren't any better than a Tessar. You've got RF as an extra, that's all.

[Attila]

I guess this cameras have copy variation issue some of them excellent some of them don't as we can see from Novar example.

[PaulC]

A lot can happen to a lens in 60 years. It can get dirty, be taken apart inexpertly, lose its spacing shims, have elements put in backwards.

It would be interesting to know just how varied the original factory output was. Maybe those old Amateur Photography articles would tell us.

[Attila]

[mo]

http://shop.ebay.com.au/sambar_v/m.html?_nkw=&_armrs=1&_from=&_ipg=&_trksid=p4340

there is a seller selling a stack of old photography "books" not sure if that would help.They are mainly 1900-1915 I think was the latest.And a 1936 leica catalogue

[PaulC]

It won't deal with folders but the magazines might be of historical interest to someone, so I'll stick a note in the "cafe"

[mo]

Thanks,Sometimes I wonder if posting these "finds" could be a pain.

[PaulC]

It turns out to be my error.

Here is a shot from yesterday's test:



Here is a 72dpi crop from it after it was sized to 12.8MP:



and here is part of it when resized to 6MP:



So it was user error after all (thankfully). It seems to be a difficult lens though, the light was fading fast and most of my guessed exposures were way out. I need to test it at various shutter speeds against a reliable exposure meter.