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genotypewriter
24-Aug-2013, 21:32
I tried googling (here and elsewhere) but didn't really come across an answer to my particular question:

Long version: From the two f/4.5 Tessars I have, I know they light up far more than their ~60 degree image circles (of "good sharpness") and are sharp for a good part of the extra bit too, depending on what I do with it. But, everywhere I read on the internet (I also have the LCVM), people make it sound as if a Tessar will chop your hands off if you try to shift/raise a bit more than you should.

Finding out this information about Heliars is even more difficult because people tend to use Heliars (and Universal Heliars) mostly for portraits and not at infinity or much for landscapes. Anyone know what the wide open circle of illumination of a 300mm 4.5 Heliar is (at infinity)?


Short version: When wide-open at f/4.5, how do the circles of illumination compare between the Heliars and Tessars of the same focal length? How big is the circle of illumination of a 300 4.5 Heliar at infinity when wide open?


Thanks in advance.

G

IanG
25-Aug-2013, 01:25
My experience with Tessars and Xenars is they do clip the corners quite quickly if you're not careful using movements, I have 135mm, 150mm & 165mm that I use, varying from a 1913 Tessar to a very last production run 150mm f5.6 Xenar. So what you've read isn't wrong.

Can't help withn regards to Heliars.

Ian

ridax
25-Aug-2013, 02:38
I don't own Heliars now, but from memory: I've found sharpness of the rather large central part of the field (equal to the 'official coverage' or perhaps some 2/3 of it) was getting better from a Tessar to a Celor (or Dogmar) to a Heliar of the same vintage and build quality (all f/4.5 pre-WWII uncoated German ones), and the edge sharpness was exactly the opposite; the reason being the character of astigmatism correction in these lenses. So generally speaking, Heliars are about the worst of the lot concerning coverage.

As for the circle of illumination regardless of the sharpness, Tessars still win due to less vignetting. Both Celors and Heliars have longer barrels and thus illuminate less.

And considering current Heliars' prices, I don't think using them as 'fake-wideangles' makes any sense these days.

Sevo
25-Aug-2013, 04:05
The same seems to be true for my more recent coated ones (late fifties Heliar and a variety of seventies to nineties Tessars). The latter have quite a bit more coverage (at least 10 extra). Fully open, the Heliar has a more pleasant centre. But stopped down and within their coverage they are close to equivalent.

Dan Fromm
25-Aug-2013, 05:46
I have one reasonably fast heliar type (105/3.7 Ektar) and a roughly parallel tessar type (101/4.5 Ektar). The 105 barely covers the format, the 101 allows a little displacement but less than a 2x3 Graphic's 19 mm of rise. With no rise the 101 gives better corner sharpness than the 105.

For calculated coverages, usually three stops down, visit www.dioptrique.info. Heliar types cover narrower angles than fast (f/4.5 and faster) tessar types. Slow tessar types (f/6.3 and Schneider's last gasp f/5.6ers) have more coverage than faster tessar types.

The importance of sharpness in the corners is often overrated.

Jason Greenberg Motamedi
25-Aug-2013, 10:31
As others have noted, Heliars have long barrels which mechanically vignette their illumination circle. I find that a Heliar will just cover/illuminate about 40 degrees open wide without a perceptible reduction of light in the corners. So, if you want relatively even illumination in the corners with a Heliar at f4.5 you will need to use a medium long lens, so 210mm on 4x5, 300 on 5x7, 360 for full plate, or 420 on 8x10. Not surprisingly these are pretty close to what Voightlander recommended.

Some Tessars have wider throw than others, which may be a function of their different maximum apertures.

genotypewriter
26-Aug-2013, 01:19
Thanks, everyone, for the replies and the interesting inputs.

By any chance does anyone have an MTF graph of a f/4.5 Heliar or a f/4.5 Universal Heliar? I was thinking about extrapolating the lines to roughly estimate the circle of illumination.

Also I imagine a Universal Heliar being hardly different from a standard Heliar, at least at the "off" setting?

Thanks again.

Sevo
26-Aug-2013, 01:30
Also I imagine a Universal Heliar being hardly different from a standard Heliar, at least at the "off" setting?


It is positively different to later Heliars in being a genuine Heliar design - after WWI they updated all other "Heliars" to the (optically superior, less soft) Dynar design.

genotypewriter
26-Aug-2013, 16:39
It is positively different to later Heliars in being a genuine Heliar design - after WWI they updated all other "Heliars" to the (optically superior, less soft) Dynar design.
I see... so the Universal Heliar and the original Heliar should have the same coverage when the UH's movable element is in the same place? Was wondering if there was something in the way the barrels were made that might reduce the angle.

G