Chamonix H-1 and Imagon 250mm

[olk]

Hi,
I'm confused because I got an Imagon 250mm and I've ordered a Chaminix H-1 (not shipped yet).
The previous owner of the Imagon told me that he was forced to buy an extension for his Sinar F2 - otherwise he couldn't get in focus.

My intention was to use the H-1 with the Imagon for portaits (2,5m - 3m distance to the subject). I've calculated that the focus plane will be at 273mm.
Is that correct?

At the H-1 the bellows can be extended up to 340mm. So I see no reason why it shouldn't work. Maybe the standard rail length of the Sinar F2 is too short?

Oliver

[Tin Can]

Try it and come back

I could test combo. but I am one handed right now

[drew.saunders]

Ebony Camera, before they closed up, had a great page called "Lens Compatibility" that you can still get through the Wayback machine. Here's a good version: https://web.archive.org/web/20161215...es/lenses.html

Anyway, the flange focal distance, or Flange Back in that chart, of the 250mm Imagon is 276mm. That means to get to infinity, you have to be racked out to 276mm, not 250mm as you might expect for a 250mm lens. If you look at that page, you'll see that most lenses have a Flange Back a bit shorter than the focal length, but the Imagon has all its elements behind the shutter, so needs more extension. What this means is that your bellows are effectively 26mm "short," so to focus at 2500mm, which requires 278mm of bellows extension for a 250mm lens, but with the 276mm flange back of the Imagon, means you have to rack the bellows out to 304mm. With 340mm of bellows, your minimum focus is around 1.22m.

That's a lot of math to say: It should work just fine.

I had both my 250mm Fujinar and 250mm Imagon with me recently, and composed an image with the Fujinar, then decided to try it with the Imagon, and was surprised at how much I had to rack the bellows out to get the same image back into focus.

[John Brady]

If you find you need more extension than your camera allows you can get an extension board to mount the lens to, assuming you don’t have to extend too much.

[Alan Klein]

Check with Hugo, Chamonix's rep.
hugo zhang <hugoz_2000@yahoo.com>

[olk]

If you find you need more extension than your camera allows you can get an extension board to mount the lens to, assuming you don’t have to extend too much.

Unfortunately the H-1 can not be extended.

[olk]

Anyway, the flange focal distance, or Flange Back in that chart, of the 250mm Imagon is 276mm. That means to get to infinity, you have to be racked out to 276mm, not 250mm as you might expect for a 250mm lens. If you look at that page, you'll see that most lenses have a Flange Back a bit shorter than the focal length, but the Imagon has all its elements behind the shutter, so needs more extension. What this means is that your bellows are effectively 26mm "short," so to focus at 2500mm, which requires 278mm of bellows extension for a 250mm lens, but with the 276mm flange back of the Imagon, means you have to rack the bellows out to 304mm. With 340mm of bellows, your minimum focus is around 1.22m.
That's a lot of math to say: It should work just fine.

Thank you - I missed to take into account that the lens is mounted at the back of the shutter.
I'm wondering because with f=276mm I get a little bit different distances (312,5mm for 2.5m distance). I used the simple lens formula: 1/b + 1/c = 1/f (b: distance subject, c: distance image, f: focal length).

[Bernice Loui]

What are the image goals?

Single image ratio case calculations apply to one specific image making example, which will vary LOTs with each and every other image making endeavor.

If the 250mm Imagon is used at infinity focus, those calculated numeric values for camera extension/bellows apply for one specific image case (infinity).
If the 250mm Imagon (or virtually any 250mm lens) is used for head/shoulder portraits, the camera/bellows extension could easily exceed the capability of 340mm. If the 250mm Imagon is used for close-up life-size aka 1:1 camera/bellows extension will exceed 500mm.

The mind-set of camera first, lens and all much less significant appears to be a carry over from fixed lens box type cameras (makes zero difference with brand or model or style or etc) does not apply to the view camera world.

If the image goals are to use this 250mm Imagon for head/shoulder portrait images, not gonna work. Images at infinity should be ok. Slight increase in camera/bellows extension can be had by using a "top hat" lens board.

These are some of the very real limitations of a lightweight field folder view camera.


Sinar F2, F, P, Norma or ... can be camera/bellows extended as needed. Adding a rail extension costing about $50 can add 6" to 18" of rail extension, adding more rail extension results in Sinar set up like this.


Or



Bellows are simply added with a front standard or "aux" standard as needed.

The "forced" of adding rail/bellows extension is completely lens dependent, camera serves this need. If the camera is unable to serve the needs of lens and image ratio needed, image goals cannot be met.


Bernice

Hi,
I'm confused because I got an Imagon 250mm and I've ordered a Chaminix H-1 (not shipped yet).
The previous owner of the Imagon told me that he was forced to buy an extension for his Sinar F2 - otherwise he couldn't get in focus.

My intention was to use the H-1 with the Imagon for portaits (2,5m - 3m distance to the subject). I've calculated that the focus plane will be at 273mm.
Is that correct?

At the H-1 the bellows can be extended up to 340mm. So I see no reason why it shouldn't work. Maybe the standard rail length of the Sinar F2 is too short?

Oliver

[Tin Can]

I will trade a 4X5 Norma for that piece of junk H1

Really

[olk]

If the 250mm Imagon (or virtually any 250mm lens) is used for head/shoulder portraits, the camera/bellows extension could easily exceed the capability of 340mm.

Is this a guess or did you calculate that more than 340mm bellows extension is required for the Imagon (focal length nominal 250mm but as Drew mentioned it is actually 276mm) for head/shoulder portraits?

Oliver