Modification of focus distance on a Horizon 202?

[ulrich.von.lich]

I'm not sure if I'll ever get an answer but I wonder if there's any Horizon 202 camera user (or of newer models) and if you know there's any workshop that would modify the focus distance, which I believe fixed at somewhere between 10 meters to infinity, to something closer.

Would it be something that an ordinary repairman can do? Or do I have to contact the factory?

 

[t6un]

I doubt it can be done any other way than by placing a weak positive lens element in front of the lens. It could be a DIY job if you have a spare filter mount. It would be unpermanent as well, and you would get two fixed focusing distances instead of just one. A local optometrist could help you with a lens.

Edit: The other way could be by adding a layer of material to the film rails. Sounds simple, but may have some complications...

 

[ulrich.von.lich]

Thanks for the ideas!

I'd prefer to have it fixed at say 2 meters permenantly and use the DOF to cover the rest. But the filter sounds indeed a more doable option. Is it like a close-up lens?

I saw people talking about optimising their Sonnar 50/1.5 to f1.5 or to f2.8 so I thought it'd be something like that to modify the fixed focus distance. If my memory serves right, Leica has also issued some fixed focus lenses for special purposes. I thought they could be adjust at will?

The film rails are not flat in the camera and I don't know if they can be modified.

 

[t6un]

The curved film plane is the reason why one, at least theoretically, can't just focus by moving the lens. It's optical center needs to stay aligned with the pivot in the center of film curvature. Maybe a fraction of a millimeter that you need is doable, but it still sounds like a very complex job to me.

So: either you shorten the focal length of your lens with what is effectively a close-up lens, yes, or you lengthen the radius of the film loop. For the latter I had in mind putting some strips of aluminium tape on the film rails, but as most Horizons already have problems with the friction in the film gate, I'm not so sure...

 

[sig]

http://www.flickr.com/groups/horizoncameras/discuss/72157611958350038/

one step closer but not all the way.....

 

[t6un]

I tried using a lens formula, and it appears that in order to bring the focus of a 28mm lens from infinity to 2m, you need to add 0,39 mm of height to the film rails; or alternatively, add 0,51 diopters to the lens power.

 

[ulrich.von.lich]

So I'll give up the lens modification idea. Had it be possible, it wouldn't be cheap anyway.

It's a pity the website showing the hack is down... I'll try the tape solution first.

t6un, thanks a lot for the information! Care to share how you calculated the numbers? Just in case I may want to have more than one focus distance.

Just out of curiosity, will the filter (diopter) trick bring down the focus distance of any lens? For example, to bring down the minimum focus distance (0.7m) of a Summicron to 0.5m? And I suppose and the infinity side will shilft down more than 0.2m?

 

[ulrich.von.lich]

Sorry if it's a stupid question: as to the film rail modification, why would adding height (so reducing the gap between the lens and the film plane) help focusing closer? Isn't a macro tube there to increase the gap?

 

[t6un]

Ulrich, I cant see where one could add the tape to reduce the distance between the film and lens? Of course you need to increase that distance. In case I wasn't clear before, by film rails I meant the two long shiny stripes besides the film gate in the camera body and not somethig on the back door, if there is anythin (idon't have a Horizon.)

I'll try to explain the calculation later today.

 

[ThomasM]

Why 10 meters? The instruction manual gives the following table (which I found true, based on my limited experience, since I've only shot three rolls with mine):

Depth of Field Table for the HORIZON-202 Camera Lens

Aperture Depth of field, m
2,8 5,5--∞
4 3,9--∞
5,6 2,9--∞
8 2--∞
11 1,5--∞
16 1--∞

 

[ulrich.von.lich]

10m is the focus distance of the camera. The ranges are only "covered" by the DOF. For example while using f16, I can see clearly a difference in sharpness between my subject at 1m and the items at infinity, even if the former falls in the range. Plus sometimes the light simply doesn't allow you to use f16.

So it depends how do you use your camera. In my case, I need to bring down the focus.

 

[ThomasM]

10m is the focus distance of the camera. The ranges are only "covered" by the DOF. For example while using f16, I can see clearly a difference in sharpness between my subject at 1m and the items at infinity, even if the former falls in the range. Plus sometimes the light simply doesn't allow you to use f16.

So it depends how do you use your camera. In my case, I need to bring down the focus.

I see your point now. Good luck.

 

[ulrich.von.lich]

Ulrich, I cant see where one could add the tape to reduce the distance between the film and lens? Of course you need to increase that distance. In case I wasn't clear before, by film rails I meant the two long shiny stripes besides the film gate in the camera body and not somethig on the back door, if there is anythin (idon't have a Horizon.)

I'll try to explain the calculation later today.

Yes of course. I was being stupid. You had been clear and I had understood correctly the film rails. But I forgot it's the other side where you would load the film!!!

I would still like to know how to calculate those numbers though.

Cheers

 

[t6un]

Yes of course. I was being stupid. You had been clear and I had understood correctly the film rails. But I forgot it's the other side where you would load the film!!!

🙂

And here's my math homework:

This is the "thin lens equation," copied from Wolfram Alpha:
1/i+1/o = 1/f
where
i | distance between image and lens
o | distance between object and lens
f | focal length

In the case where the lens is focused at infinity, 1/o is zero, consequently i=f=28mm.
Focused at 2m (2000mm) 1/o = 1/2000. 1/i = 1/28 -1/2000. i = 28,397...
So the distance between the lens and image (focal plane) has to be increased by ca 0,4mm.

To calculate the close-up lens we need to:
1) Find a focal length that will be focused at 2m, while image to lens distance is 28 mm.
2) Convert that focal length into dioptres: "dioptre is a measurement of optical power which is equal to the reciprocal of the focal length measured in metres," D=1/f(m).
3) Convert the nominal(28mm) lens into dioptres, and find the difference between the two lenses (in dioptres)
4) That's the measure of the close-up lens we need.

 

[jmanivelle]

Hi, just bought some spare uv filters for my horizon 202 hoping to test a diopter glued over the round uv filter .
I could use an eyepiece correction glass, basically a + 0.5 diopter ( 17 mm square or of a diameter of 13mm up to 17mm).
Just had a quick look at the round eyepiece of my R4A, it might do the job but it's from the 19mm Nikon size and a bit large.
Anyone knows of a smaller diameter eyepiece glass? Canon? Minolta? Olympus?
Cheers
JM

 

[europanorama]

Close up shots-The solutions

Close up shots-The solutions

1. forget the official DOF-table. its not true.
2. i have multiple instructions/solutions in my panorama-forum-login needed.
http://forums.delphiforums.com/n/lo...%3dstart%26prettyurl%3d%252Fpancams%252Fstart

3. add eighter a dymo-tape or contact-lens to en empty filter.

 

[rxmd]

1. forget the official DOF-table. its not true.

Or rather "it was calculated on the assumption that prints would be really small", like the DOF scales on older Russian or Zeiss lenses.

 

[jmanivelle]

3. add eighter a dymo-tape or contact-lens to en empty filter.

Hi europanorama,
I believe you wrote as well in the following link http://forums.delphiforums.com/n/main.asp?webtag=kievreport&msg=1146.12
about adding contact lenses.
Have you done it yourself?
I've been seeking infos about fitting 0.2 contact lenses but all the mentioned links are dead.
Cheers
JM

 

[europanorama]

Making closeup-filters using horizon-filter-mounts

Making closeup-filters using horizon-filter-mounts

I have printed instructions from the dead links. some in digital form somewhere deeply on one of my hdds or cds.
We should ask the panorama-community in yahoo-tech-groups.
My scanner is not ready. Maybe i can make copies and send to you.
pls PM your adress. maybe at the end you could offer filters for us.

Rainer K.Lampinen(Technopan-the luxery Horizon with 8 exp. times) once made closeup-lenses for the old horizont. they were not cheap. I could use it together with a matching camara. he said its delicate to position it.
Dymotape-the quick solution
I was using black dymotape 6.3mm wide, 0.2mm thick most ideal to have sharpness at infinity at about 5.6/8 but being closer than without.
glueing this tape to the film-rails is not easy, above all at the side where the film must go. one must be very careful perforation does not hang there. Results are perfect. We also glued metallic tape(from rainer k.lampinen). my repairman said to do this perfectly camera must be heaten up....My 202 is now perfectly working. Went defective during sitting inactive...Material is living. shutter-opener is now fixed by loctite.
One can change lens-position. if i dont err its 0.25 turning outside-increasing distance to film.
Since i have very little time you must wait until end of february until i can take more actions. we must then publish electronic informations in the panorama-group.
I could not find anyting on jan-willem markerinks site and files. maybe ask him.

I have in mind asking an optician to build a lens. or using contact lenses. 0.2 diopter.
btw: i have actually added 0.5m distance to spinner 360. its easy. this is only for very closeup-situations. Maybe i will try it out for the first time on carnival in 10 days. but i dont have the motor yet 1/4 sec.(14 sec rotation)
good to know now how to calculate diopter. i couldnt find my old calculations anymore.
BTW: If someone can tell me about a save place i will reupload my testimages about unsharp lens on s3pro at f16. comparison with h202.

 

[ulrich.von.lich]

good to see this old thread again.

i still use my horizon 202 at times and still try to live with the focus distance. in fact i've never found any filter to start the idea of going to see an optician.

does Mr. Rainer K.Lampinen still make close-up lenses? when he said it's delicate to position it, he meant to position the lens into the filter frame?

i believe the camera is still being made and commercialised under the name horizon perfekt or something (lomography). it'd be interesting to get in touch with the factory to see if there's a chance to have such a close-up filter made or to get the focus permanently adjusted.

cheers