9.5", 24cm, 240mm HELIAR MEASUREMENTS

**Tracy Storer** · 26-Mar-2015, 21:57

Hi guys. I just got cells for a 9.5" HELIAR, but no barrel. Looking for some barrel measurements so I can make adapters to mount it in a shutter.
Who's got one and some calipers ?

**Steven Tribe** · 27-Mar-2015, 01:29

Cameraeccentric says - mount in a compur IV no. R.9!

**Emmanuel BIGLER** · 27-Mar-2015, 04:57

Hi !

I do not have anything directly related to the 9.5" / 24 cm Heliar, but you'll find below the prescription and a paraxial simulation for 100 mm original Heliar, data taken from the original US patent # 716035, the original 1902 Heliar design, and computation is done with Oslo-EDU (free software, but deals only with a maximum of 10 surfaces)
Acknowledgement: I got the Oslo file from Richard Knoppow, and I thank him very much.

From the lens prescription for a 100 mm lens, one should in principle multiply all dimensions by 2.4 to get what is applicable for your 24 cm = 240 mm Heliar.
The computation yields the following distances for a 24 cm original Heliar.

- Between surface #5 (the vertex of the negative single lens in the middle, surface #4) and the iris (aperture stop, AST, #6): 2.4 x 2 mm (actually = 1.99 below) = 4.8 mm.
- Distance between the iris #6 and surface #7: 3.6 x 2 = 7.2 mm
- Total distance between surf #5 and surf #7 = 4.8 + 7.2 = 12 mm.

Additional info:
- Back focal distance = distance between the last lens vertex (image surface #9, IMG) and the paraxial focus: 85.4 x 2.4 =~ 205 mm.

With those data you should be able to mount your lens without being to far from the proper requirements. Of course if your Heliar complies with patent # 716035, and one never knows, unfortunately, the Heliar brand applies to various designs, the lens was still manufactured in the fifties, but a focal length engraved in centimeters indicates a pre-WW-II lens, usually.
At least those values should help you to have your lens cells not grossly offset from their ideal position.

See the attached pdf file below to identify various surfaces as defined in the Oslo file.

===============================
*LENS DATA

Heliar 1902

U.S.Pat# 716035

SRF RADIUS THICKNESS APERTURE RADIUS GLASS SPE NOTE
OBJ -- 1.0000e+20 3.6397e+19 AIR

1 40.952608 1.598150 13.391628 LV1
2 25.730217 3.595838 12.232451 LV2
3 -583.123363 8.090636 12.232451 AIR

4 -44.708247 1.598150 9.365994 LV4
5 44.708247 1.997688 9.221742 AIR

AST -- 6.092948 3.728073 AS AIR

7 583.123363 3.595838 12.232195 LV7
8 -25.730217 1.598150 12.232195 LV8
9 -40.952608 85.419837 13.308923 AIR

IMS -- -- 36.397023 S

*PARAXIAL SETUP OF LENS

APERTURE
Entrance beam radius: 4.545455 Image axial ray slope: -0.045455
Object num. aperture: 4.5455e-20 F-number: 11.000000
Image num. aperture: 0.045455 Working F-number: * 11.000000
FIELD
Field angle: * 20.000000 Object height: -3.6397e+19
Gaussian image height: 36.397023 Chief ray ims height: 36.397023
CONJUGATES
Object distance: 1.0000e+20 Srf 1 to prin. pt. 1: 14.580163
Gaussian image dist.: 85.419836 Srf 9 to prin. pt. 2: -14.580163
Overall lens length: 28.167399 Total track length: 1.0000e+20
Paraxial magnification: -1.0000e-18 Srf 9 to image srf: 85.419837
OTHER DATA
Entrance pupil radius: 4.545455 Srf 1 to entrance pup.: 18.351919
Exit pupil radius: 4.380242 Srf 9 to exit pupil: -10.945498
Lagrange invariant: -1.654410 Petzval radius: -241.417787
Effective focal length: 99.999999

**Tracy Storer** · 27-Mar-2015, 09:23

Thank you Stephen and Emmanuel ! Stephen, I am not familiar with the R9 designation, will that give me overall ("barrel") length and aperture placement from one or both ends?

EDIT: FOUND some C-IV, 9 data here, but thnk I still need more
http://www.largeformatphotography.in...-shutter-sizes

**Emil Schildt** · 27-Mar-2015, 11:44

don't know whether this helps - I have one in a Compound shutter - but I don't have the right mesuring tools - and no digital camera...

So I tried to scan (!!) the lens and make some approx mesurements in PS...