http://www.cameraeccentric.com/html/info/kodak_1.html
(for the kodak lens) describes focusing on the nose instead of the eye catchlights. Russ young told me there was something wrong in this manual, but got on a rabbit trail and didn't say what. I would suspect the cooke has similar focusing traits, but I don't have personal experience with that lens.
If David is focusing at taking aperture, this doesn't make sense to me. It would seem to me that what one sees on the ground glass ought to exactly match what one sees on the film, warts and all. A focus shift when stopping down makes sense, but I don't see the possibility of a focus shift solely on the basis of the surface being focused on, assuming both are flat and in the same place. Was this lens intended for use on press cameras with rangefinder focusing? That may also explain the instructions.Originally Posted by jp498
A 2" focus error at still life and portrait distances seems like a large error to me.
Rick "what am I missing?" Denney
I asked Guy at ZGC who are the folks who Cooke to repair their lenses. He said that to his knowledge, there is no special focusing technique to use with this lens and he is unaware of any problems with back-focusing or front-focusing.
The lens is not intended to be used on a press camera with rangefinder focusing. The Cooke Portrait PS945 f/4.5 229mm lens is a replica of the Pinkham & Smith Visual Quality Series IV Soft Focus Lens. It is made for portrait photography on a 4x5 camera. For more info, go to: http://cookeoptics.com/cooke.nsf/pro...rgeformat.html
As far as distances are concerned, I did tests at 52", 75" and 150" from the front of the lens to the LensAlign testing set-up. The lens, gg and testing surface were all in perfect alignment. The film from all distances showed roughly the same amount of back-focus. The same held true with both still lifes and portraits, which I shot in the 52" to 75" range. Most shots were taken at the 75" end of the range.
Thanks for everyone's responses,
David
Your loupe should be focussed on the grain in the ground glass. Check it is focussed properly.
If your loupe does not have a focus ring then look at the GG from both sides. If the grain of the GG is sharp when looking at it from the ground side, then your loupe is no good as it needs to be sharp when looking at it from the plain glass side.
And if it has diopter adjustment, make sure its set correctly for your eye.
Oh, yes, I knew that. But someone had referenced a Kodak soft-focus lens that provided special instructions for front focusing, and I wondered if that Kodak lens and its instructions were aimed at a rangefinder-focused press camera.
Rick "thinking GG focusing ought to always give you what you see" Denney
My Rodenstock 6X Aspheric Loupe has a diopter adjustment. When the grain of the ground glass was in focus, I gaff-taped the adjustment ring, so it wouldn't move. I made sure the grain of the gg was still in focus.
I'm not sure why the Kodak lens thing keeps being brought up. I have never had one and know nothing about them. I am using a Cooke lens, made in England. The Cooke lens is a soft-focus lens, so perhaps that is why the Kodak soft focus was mentioned, but there are a lot of soft focus lenses out there.
Rick,
The plane of focus on the gg is crystal clear, but when I get my film back, the plane that is in focus is about 2" behind what was clearly in focus on the gg.
Thanks everyone for their suggestions. Keep them coming. User error is usually the first thing to look for. I just can't seem to find mine, yet. if I (with all of your help) haven't figured it out by the time I get back in February, I will test the camera with both 210mm and 75mm lenses to see if the problem is consistent or not. If I find that it is consistent. I will send my camera and lenses to Marflex.
David
By the way, I have tried these tests using 20 different film holders, and the results are consistent.
David
But if it doesn't have a focus adjustment then it will likely be focussed to whatever it is resting on and not the two or three milimiters further away to compensate for the thickness of glass. Setting the diopter alone is not correct (I think) and the diopter should be set to whatever your last eye test said and not what puts the GG in focus (I think). I may be wrong but someone will correct me if so.
If the GG is in crisp focus it doesn't matter.(I know)
It seems that his GG is in the wrong plane. I wouldn't expect this on a brand new $8000 camera.
One man's Mede is another man's Persian.
I mentioned it because of how soft focus lenses can have unusual focusing techniques.
This lens interests me, but it's beyond my present budget, having spent too much $ filling my freezer with film.
http://cookeoptics.com/cooke.nsf/dow...PS945_v1.4.pdf
page 7 says under the section "uncommon optical behavior" that the focus needs adjusting in the way you seem to describe.
Posting Permissions
Reply With Quote
Bookmarks