Focusing under the dark cloth

[suk_jung_choo]

<p>Hello,<br>

I have just begun getting into Large format photography. My field camera has a fresnel lens. However, when viewing the image under the dark cloth, I cannot see the entire image projected on the ground glass at one go. I have to move around before I am able to see the corners and various parts of the image that is projected. Therefore, to get the entire image, I have to reconstruct the different segments in my head and then imagine what the actual image would be like before deciding to use film.<br>

Is there a better way or is this something that I just have to live with? Do I need additional viewing accessories or should I replace the current fresnel lens with those types of glass that are advertised to give significantly enhanced brightness? I would appreciate any response that would help. Thank you,<br>

SJ Choo,<br>

Seoul, Korea.</p>

 

[dan_south]

<p>SJ,</p>

<p>It would be helpful to know what camera you're using, the size of the film (4x5?) and the focal length of the lens. Also, are you focusing with the lens wide open or stopped down? Wide open will make the task easier.</p>

<p>What you're describing sounds like a problem that happens when using a wide-angle lens (for example, a 90 mm lens on a 4x5 camera). When you begin to use a view camera it's easier to learn to focus with a normal lens or a short telephoto lens (e.g., 150 - 210 mm on 4x5).</p>

<p>Also, are you trying to focus when the light is dim (near dusk, for instance)? Try practicing when the sun is shining brightly. When your skills improve you can try again in a low-light situation.</p>

<p>A brighter ground glass might be available for your camera, and that may help as well.</p>

[brucecahn]

<p>Your problem is characteristic of the larger fresnels. Usually it doesn't happen much with 4x5. There are good screens out there. I always liked the Linhof bright screen if it fits, there is also acid etched glass, boss screens, satin snow and other options.</p>

[frank_menesdorfer]

<p>Yes I agre with Dan more info would be useful but it could be so to that your lens is not covering the entire GG well when focusing with the aperture wide open. The image circle encreases with smaller aperture. If you use a smaller aperture when focusing it could mean that the lens is not covering the entire ground glass. This is a minor problem if you use 6x6, 6x7 or 6x9 film back but give you an underexposed corners on 4x5 which means darker corners on the print.</p>

<p>Good luck to you anyway.</p>

[suk_jung_choo]

<p>Thank you all very much for your replies.<br>

My camera is an Ebony 45 SU - it is a non foldable wooden field camera in 4x5 format.<br>

As Dan pointed out the lens that I am using may be, too wide, i.e, they are 135mm and 90mm lenses. That lens opening may be, too small is a reasonable assessment, but I viewed with the lenses wide opened. I've never taken the camera outside yet, so I'll try that.<br>

I don't know if the fresnel is, too large - I am using the fresnel that came with the camera when originally purchased. Having it serviced to have a Linhof bright screen does sound tempting, but that would entail additional hassel of sending it away (which always makes me nervous) as well as cost.<br>

Would some kind of a device or specially designed cloth that could effectively shut out all stray light solve my problem? <br>

Once again thank you all very much. I now have a better understanding of what my problem is. <br>

SJ</p>

[david_l3]

<p>A fresnel lens has a certain focal length to view the image. Move your eyes back from the ground glass approximately 30 cm and you should see the entire screen to compose the image. 90mm f8 lenses are hard to focus in low light.</p>

[vick_vickery]

<p>Compose from further back, focus close and with a loupe, check all parts of the glass, then move back to see the full view again. It'll get easier with time and experience! :-)</p>

[brucecahn]

<p>The 45SU has a wide angle fresnel. These are notoriously difficult to use. I have the 57SU which is worse. You get used to it after a while and forget about it. If you hate it, change to a ground glass.</p>

[suk_jung_choo]

<p>Hi, I 've carefully gone through all of the replies. David and Vick, thank you for your pointers. I took the camera outside for the first time and did exactly that and you were right. Stepping back and viewing under brighter conditions signficantly improved the situation.<br>

Thanks Bruce for the input. I fully agree that the fresnel that came with the camera is wanting more brightness and better focusing. However, looking back on my limited experience, I think I can work around the limitations. I need more experience.</p>