PDA

View Full Version : Two problems with new Ansco 5x7



brian steinberger
27-Jan-2015, 17:25
I just acquired an ansco 5x7. I'm having two problems which I believe may be related. Here's the two problems:

The first problem I'm having is the bellows getting in the way of movements. I'm using a 180mm lens, so just slightly wider than normal. When I focus at infinity the front and rear standard are only 1" apart, so when I go to use front rise the very stiff bellows don't allow very much front rise at all. I'm thinking my only solution may be bag bellows. Distance from film plane to middle of lens board is about 4 3/4". For a 7" lens this cannot be right.

Second problem, I cannot seem to get a sharp image on the GG. It's so close to being sharp but just not quite. I even tried focussing my loupe at different distances and nothing worked. I had a Wista 4x5 in the past and the GG and fresnel was crisp and sharp. If the GG on my ansco is original could it just be not up to par with modern GG with a fresnel?

Btw.. I'm using a Rodenstock 180/5.6 Sironar-N and a Rodenstock 4x loupe.

Shootar401
27-Jan-2015, 17:46
I just acquired an ansco 5x7. I'm having two problems which I believe may be related. Here's the two problems:

The first problem I'm having is the bellows getting in the way of movements. I'm using a 180mm lens, so just slightly wider than normal. When I focus at infinity the front and rear standard are only 1" apart, so when I go to use front rise the very stiff bellows don't allow very much front rise at all. I'm thinking my only solution may be bag bellows. Distance from film plane to middle of lens board is about 4 3/4". For a 7" lens this cannot be right.

Second problem, I cannot seem to get a sharp image on the GG. It's so close to being sharp but just not quite. I even tried focussing my loupe at different distances and nothing worked. I had a Wista 4x5 in the past and the GG and fresnel was crisp and sharp. If the GG on my ansco is original could it just be not up to par with modern GG with a fresnel?

Btw.. I'm using a Rodenstock 180/5.6 Sironar-N and a Rodenstock 4x loupe.

I had the same camera. The bellows issue is something you have to live with. I just gently pushed them in my fingers when tilting. It won't harm anything just annoying. There is no cure for it unfortunately.

And your second problem might be that the ground glass is installed backwards? Trying flipping it around and see what happens. The smooth side should be facing you. if not you can use some shim steel from a hobby shop to shim the GG if the plan of focus on the film is too close.

brian steinberger
27-Jan-2015, 17:57
And your second problem might be that the ground glass is installed backwards? Trying flipping it around and see what happens. The smooth side should be facing you. if not you can use some shim steel from a hobby shop to shim the GG if the plan of focus on the film is too close.

The GG is in the correct way. Im afraid something is wrong with the lens. The GG to plane of focus on film is off by almost 3". That's why I'm confused.

djdister
27-Jan-2015, 18:04
If your standards are about an inch apart and you are roughly focused on infinity with a 180mm lens, its a problem with your lens. Either the lens is missing one or more elements, or some elements are installed backwards.

Maybe you could post some photos of the lens...

brian steinberger
27-Jan-2015, 18:30
Any part of the lens in particular?


If your standards are about an inch apart and you are roughly focused on infinity with a 180mm lens, its a problem with your lens. Either the lens is missing one or more elements, or some elements are installed backwards.

Maybe you could post some photos of the lens...

djdister
27-Jan-2015, 18:41
Any part of the lens in particular?

Unscrew the front and rear lens groups, and let's try a shot looking at each side of each lens group (four shots).

Shootar401
27-Jan-2015, 18:45
The GG is in the correct way. Im afraid something is wrong with the lens. The GG to plane of focus on film is off by almost 3". That's why I'm confused.

My bad. I read through it too quickly

brian steinberger
27-Jan-2015, 19:29
Here are some shots of the lens:

First the entire lens:
128584

The Front element:
Front: 128585
Back: 128586

The Rear Element:
Front: 128587

brian steinberger
27-Jan-2015, 19:29
The Rear Element back:
128588

Joe Smigiel
27-Jan-2015, 20:04
Can you determine the individual focal lengths of the front and rear groups by themselves by holding them away from a wall and seeing at what distance infinity comes into focus? I would assume the Sironar-N is a 180mm plasmat and would have element groups of roughly 420mm and 315mm if anything like a convertible Symmar 180mm. That might help you narrow the problem down and tell you if one of the groups is bad.

William Whitaker
27-Jan-2015, 20:15
Quite a conundrum you've got there, Brian-lad!

djdister
27-Jan-2015, 20:17
The Rear Element back:
128588

So ... nothing immediately jumps out. There are two possible avenues to explore:

1. the inner element of each lens group could be reversed. You would need a reference lens to use as a guide.
2. the entire rear lens group is not matched to (not meant to be part) the front lens group. Are there any markings on the lens rear grouping such as serial number or other information that matches it to the front lens group? Although the rear lens group fits in the shutter, that doesn't prove that it is the proper rear lens group for a 180mm Sironar-N. Because the effective focal length of that assembled lens is so different from marked, it is a good bet that the whole rear lens group is from a different lens.

brian steinberger
27-Jan-2015, 20:30
Quite a conundrum you've got there, Brian-lad!

Yea tell me about it! At least I have a 14 day return policy!

brian steinberger
27-Jan-2015, 20:45
There is no markings on the rear element whatsoever.


So ... nothing immediately jumps out. There are two possible avenues to explore:

1. the inner element of each lens group could be reversed. You would need a reference lens to use as a guide.
2. the entire rear lens group is not matched to (not meant to be part) the front lens group. Are there any markings on the lens rear grouping such as serial number or other information that matches it to the front lens group? Although the rear lens group fits in the shutter, that doesn't prove that it is the proper rear lens group for a 180mm Sironar-N. Because the effective focal length of that assembled lens is so different from marked, it is a good bet that the whole rear lens group is from a different lens.

brian steinberger
27-Jan-2015, 20:48
Joe, do you mean to look through each element at a textured wall and see at what distance away from the wall it becomes sharp?


Can you determine the individual focal lengths of the front and rear groups by themselves by holding them away from a wall and seeing at what distance infinity comes into focus? I would assume the Sironar-N is a 180mm plasmat and would have element groups of roughly 420mm and 315mm if anything like a convertible Symmar 180mm. That might help you narrow the problem down and tell you if one of the groups is bad.

William Whitaker
27-Jan-2015, 20:59
Yea tell me about it! At least I have a 14 day return policy!

I don't see that anyone else has asked, but do you have another lens you could try? That would at least narrow it down to the lens. Or not.

How much time is left on the clock?

brian steinberger
27-Jan-2015, 21:02
Will, no I don't have another LF lens. Nor do I know anyone near me to borrow one. I have until next Friday to return, so plenty of time. If it's something I can fix I will, but if it's something like a Frankenstein lens then I'm sending it back!


I don't see that anyone else has asked, but do you have another lens you could try? That would at least narrow it down to the lens. Or not.

How much time is left on the clock?

Joe Smigiel
27-Jan-2015, 21:47
Joe, do you mean to look through each element at a textured wall and see at what distance away from the wall it becomes sharp?

No. Hold the element group (or combined lens) in hand so that it projects the light coming from a window on the opposite side of the room onto the wall. Move the lens group manually towards and away from the wall and notice where the projected image comes into sharp focus on the wall. If the lens is configured correctly and has a combined focal length of 180mm, that's the distance away from the wall where the image ooutside the window should come into focus when the lens is assembled and both front and rear groups are present.

The definition of focal length is where an object at infinity (i.e., the bright area outside the window in this case) comes into sharp focus at the focal plane (i.e., the wall). Plasmat lenses like a Sironar-N or Symmar or old convertible lenses have a front and rear group that differ slightly in focal length but are approximately around twice the focal length of the combination. For the 180mm combined lens, the rear group is probably about 315mm focal length and the front group somewhat longer at 420mm (at least for the calculation I have for my Symmar 180mm). So, combined, the sharp image should appear around 180mm or 7" from the wall, with the rear only at 315mm or about 12 1/2" away, and with the front group only at about 420mm or roughly 16 1/2" away from the wall.

If the rear group only focuses at a considerable deviation from 315mm, as someone suggested earlier it may be an unmarked mismatched group from a different lens that just happened to fit the shutter and one that somebody mixed up in the past. Or it could be missing an element in the group, or have an element reversed, etc.

brian steinberger
27-Jan-2015, 22:04
No. Hold the element group (or combined lens) in hand so that it projects the light coming from a window on the opposite side of the room onto the wall. Move the lens group manually towards and away from the wall and notice where the projected image comes into sharp focus on the wall. If the lens is configured correctly and has a combined focal length of 180mm, that's the distance away from the wall where the image ooutside the window should come into focus when the lens is assembled and both front and rear groups are present.

The definition of focal length is where an object at infinity (i.e., the bright area outside the window in this case) comes into sharp focus at the focal plane (i.e., the wall). Plasmat lenses like a Sironar-N or Symmar or old convertible lenses have a front and rear group that differ slightly in focal length but are approximately around twice the focal length of the combination. For the 180mm combined lens, the rear group is probably about 315mm focal length and the front group somewhat longer at 420mm (at least for the calculation I have for my Symmar 180mm). So, combined, the sharp image should appear around 180mm or 7" from the wall, with the rear only at 315mm or about 12 1/2" away, and with the front group only at about 420mm or roughly 16 1/2" away from the wall.

If the rear group only focuses at a considerable deviation from 315mm, as someone suggested earlier it may be an unmarked mismatched group from a different lens that just happened to fit the shutter and one that somebody mixed up in the past. Or it could be missing an element in the group, or have an element reversed, etc.

Joe, this is great information. Thanks. I will try this experiment tomorrow when there's light.

brian steinberger
28-Jan-2015, 13:35
So I tried the wall trick. The lens as a whole focused at infinity measured 5 3/8" from the wall.

Front group only - 11 1/2" to center
Rear group only - 5" to center

This was holding the groups with larger side toward the window. Is this correct?

djdister
28-Jan-2015, 14:04
So I tried the wall trick. The lens as a whole focused at infinity measured 5 3/8" from the wall.

Front group only - 11 1/2" to center
Rear group only - 5" to center

This was holding the groups with larger side toward the window. Is this correct?

By larger side you mean you were pointing the lens towards the window as if taking a picture of the window, then yes, that was correct. I'd say the results of this test show that the rear lens group is not the right match for a 180mm lens, and is a mismatched set of elements.
Keep the camera, get another lens.

Joe Smigiel
28-Jan-2015, 14:10
I'd agree. It would seem the rear group is not in the expected range.

Jim Jones
28-Jan-2015, 14:19
A diagram of the Sironar-N http://www.prograf.ru/rodenstock/largeformat_en.html#Apo-Sironar-N suggests that it is fairly symmetrical. Thus, both the front and rear group should have somewhat similar focal lengths as Joe Smigiel says. The rear cell may well be missing one of its elements, or may be the wrong cell. Oops, two others replied while I was seeking information. I agree with them.

brian steinberger
28-Jan-2015, 15:39
Thanks guys for all your help! I will return the lens. In the meantime I will look for another lens. I may go with a 210mm to give me even more room for movements.

Liquid Artist
28-Jan-2015, 22:04
Has anyone mentioned getting a Recessed Lens board. It may correct problem 1 anyways.

graywolf
30-Jan-2015, 15:42
Actually, from the description in the original post, I thought he had a 180mm telephoto lens for a 6x9 camera; but his photos show a Sironar. Any chance it has a telephoto rear element on it?