Brightness of ground glass

[monochromeFan]

Finally had the time to actually USE my 4x5 camera this afternoon. Indoors as its rather windy out.. I may have over exposed but thats life.

However, with the lens fully open, i was only getting about 1.5" of viewable image on the ground glass, very center. Is this normal, a sign of an issue with the lens or camera itself?

Or do i need to find a replacement ground glass thats rated as being highly visible? Ive seen youtube videos of people taking video images through their ground glass and its like they did it through a window.

[Kino]

Lots of factors to determine the issue; What camera? What lens? How extended are your bellows (lens standard to film plane)?

Maybe you have a lens that will just cover 4x5 at typical focal length, but with enough bellows extension, will only cover a 1.5 inch circle.

Maybe it's not even up to covering 4x5 at all.

More information needed!

[Tin Can]

Most GG need dish soap cleaning

Dry it well

[Doremus Scudder]

Finally had the time to actually USE my 4x5 camera this afternoon. Indoors as its rather windy out.. I may have over exposed but thats life.

However, with the lens fully open, i was only getting about 1.5" of viewable image on the ground glass, very center. Is this normal, a sign of an issue with the lens or camera itself?

Or do i need to find a replacement ground glass thats rated as being highly visible? Ive seen youtube videos of people taking video images through their ground glass and its like they did it through a window.

Kino is right that we need more information. Kino is mistaken, however, that extending the bellows past infinity focus will reduce the image circle; just the opposite, extending the bellows increases image circle.

On to your 1.5" circle in the very center. It's quite possible that in a low-light situation you are just seeing the "hot spot" that the lens projects on the ground glass, especially if you have a Fresnel lens installed. Or, there could be another problem.

So, before we go further with this, we need to know:

Camera
Lens
Type of ground glass (Fresnel or not, if you can figure that out)
Lighting conditions you were working under
Anything else that might be of import in this situation.

Best,

Doremus

[monochromeFan]

hmmm lets see

Omega View 45D

lens my nice wee schnieder tele-xenar 1:5.5 240mm lens

distance between the standards, back of front standard, and front of rear standard, an exact 4".

Was shooting at the kitchen, all lights on, window blinds open.

The negatives have been drying for a while. The entire negative is exposed. Each negative has a spot on each edge where nothing seems to be on it. The stearman 445 leaks heavily.

I made 4 shots. All with aperture at 5.5 a 1 second, a 1/2 second, a 1/5, and lastly 1/10th.

As expected some are better, but i cant put a shutter speed to a negative, things got mixed up with getting them in the tank.


As for getting things focused, i extended the front standard all the way out, and pulled it back until i had an image on the ground glass center and fiddled with the "fine" focus to make it look better.

[Doremus Scudder]

Let's see... There seems to be a 240mm Tele-Xenar telephoto that was designed for the 3 1/4" x 4 1/4" (90x120mm) film format. If that's what you have, it may not cover 4x5 completely; you'll see unexposed corners on the negatives.

If your image was in focus, and there is vignetting of the image (corners unexposed, etc.), then that's likely the problem.

See here: https://www.pacificrimcamera.com/rl/01676/01676.pdf on page 7. The lens was designed for press cameras and probably has pretty tight coverage even on the smaller film format

You can still use the lens and crop the image when enlarging, but you'll likely always get vignetted corners at infinity focus. Working close-up with greater bellows extension will give you greater coverage.

There also seems to be a more modern 240mm Tele-Xenar that covers 4x5 with room to spare. See here: https://www.surpluscameragear.com/schneider-kreuznach-tele-xenar-1-5-5-240mm-large-format-lens-in-linhof-synchro-compur-shutter-mounted-on-linhof-technika-iii-lens-board/

Which one does it seem you have?

Best,

Doremus

[monochromeFan]

black body, silver rim on the front for a filter to screw into, 6 bladed diaphram. max diameter of silver band is almost 2", and it sticks out from front of shutter about 1 3/8".

the defect on the negative is a completely clear strip on the long edge.. like the film moved in the holder. Asa the image itself on two of them seems to be "canted" to one side.

[Doremus Scudder]

black body, silver rim on the front for a filter to screw into, 6 bladed diaphram. max diameter of silver band is almost 2", and it sticks out from front of shutter about 1 3/8".

the defect on the negative is a completely clear strip on the long edge.. like the film moved in the holder. Asa the image itself on two of them seems to be "canted" to one side.

The former seems to indicate that the bellows may have blocked the light, or maybe some other obstructions. The image canted on the film indicates that the film was improperly loaded in the holder, not under both hold-down rails in the holder and fell out diagonally a bit when the darkslide was pulled.

The former should be visible if you remove the back and look at the configuration. The latter you can fix by being sure both sides of the film make it under the rails when loading. Feel with your fingers and pull up on the corners to make sure.

Doremus

[jnantz]

All is not lost. You can still use the lens on your camera form”macro” work. Rack the front standard out at least 2x the focal length get a ruler and go to town.
in case you are befuddled by how to figure out the exposure here's some reading to get you started https://www.largeformatphotography.info/forum/archive/index.php/t-147740.html
Have fun!

[added later]. you can also expose your film so the image circle is inscribed edge to edge inside the rectangle of your film. some people love circle-images very KODAK ( and religious icon ).

[maltfalc]

are you sure the gg is installed and not just a fresnel on it's own?

[Doremus Scudder]

are you sure the gg is installed and not just a fresnel on it's own?

Good question. A photo of the set-up in action would help.

Doremus

[rdenney]

Many setups use a plastic fresnel sandwiched with ground glass. What you describe sounds like there is no fresnel, or the fresnel is not suited to this telephoto-design lens.

A tilting loupe will help, too.

If you like that focal length, keep on the lookout for a non-telephoto lens of that length. For example, Caltar marketed the 240 Type Y, which is a Rodenstock Ysarex of Tessar design. These are decent lenses that are not expensive. You’ll need more bellows draw, but you’ll have more movements.

Telephoto designs on view cameras were a compromise for cameras of limited bellows or bed length, like press cameras. You shouldn’t need it for your Omega.

Rick “doubting Omega supplied fresnels but not sure” Denney

[BrianShaw]

Rick “doubting Omega supplied fresnels but not sure” Denney

Surprisingly, they did... optional

[Doremus Scudder]

Rick makes a good point. If there is a Fresnel screen of a focal length not well-suited to the lens focal length, there would be a definite hot spot.

The OP, however, has what look like loading and bellows sag defects.

I'm waiting for photos of the negatives (on a light box or white computer screen) and of the ground glass with an image projected on it.

Those would help us get to the bottom of this.

Doremus

[monochromeFan]

ive had issues at home, spent a whole day getting screamed at because i dared CLEAN THE SILVER WARE DRAWER.

[BrianShaw]

Sorry to hear this and don’t think you are alone. Sometimes the most thoughtful acts can get misconstrued in a marriage. Whatever you do, don’t even think about rearranging the clothes in the closet.

[Kino]

Kino is right that we need more information. Kino is mistaken, however, that extending the bellows past infinity focus will reduce the image circle; just the opposite, extending the bellows increases image circle.

Doremus

Yes, I wasn't thinking too clear there. Anyway, be interested in hearing the final verdict.

[Drew Wiley]

Fresnels might help with wide angle lenses in dim light. But they can be counterproductive with longer lenses like a 240 for 4x5. I don't like them at all.

[Tin Can]

Ditto

and I have tried many

Horseman 8x10 even made it in front or rear

I have both

nobody believes me

FTW

[Vaughan]

schnieder tele-xenar 1:5.5 240mm lens

That lens has an image circle 141mm, will not cover 4x5 (152mm) at infinity.

[Mal Paso]

Fresnels might help with wide angle lenses in dim light. But they can be counterproductive with longer lenses like a 240 for 4x5. I don't like them at all.

Fresnels help with telephotos if you use a monocular viewing hood. The lens on my hood is very close to the GG and with a 600mm is fairly even, with a darkcloth not so much. There are different focal length fresnels too, one company listed 2, one for wide, one for tele, not much hard info though.