Help work me through a problem with out of focus negatives

[mbuonocore]

I'm fairly novice when it comes down to shooting LF. I've played around in the past, but have never really gotten results. I'm making a concerted effort to shoot 4x5 right now, as I have a project in mind that was tailor made for it.

I've been getting out of focus negatives, and I can't work out what's going wrong. I'm hoping it's a simple mistake I'm making, and one of you can help me out with.

Here's the setup: I'm shooting with a Cambo studio camera that in good shape. I've got a Schneider Symmar-S 210 lens, and a nice Schneider 10x glass loupe. I have a sturdy tripod, witch the camera attached directly to the legs, no head. I don't really have a head that can handle the weight, so I figured that was a good solution. The legs are very steady, as they're not extended at all. I'm shooting a close up image, not macro, but close - less than 1:2, not 1:1. I'm using a Quickdisc to help get the exposure. I'm focusing on a flat surface, an old wooden drafting table with lots of deep cuts in it. In order to check that the plane of focus is correct, I've got a stainless ruler running through the scene, which I can get sharp from end to end. My eyes are good, and I never encounter problems with judging focus when I'm making enlargements in the darkroom for example. The exposure times are 8s at f16. I've got Fidelity Elite holders.

I understand that when making macro images there's not a lot of wiggle room in terms of focus. I swear I've got the image tack sharp on the ground glass, but when I process the negative, it's significantly out. It looks like it's behind, not in front. I'm using a cable release, and have used them all my life. I've done a lot of long exposures at night, and know the routine. I'm quite certain that neither me or the tripod is moving around.

I read in a book that the act of putting in a film holder can move the camera out of focus, particularly with macro work. So can pressing the loupe against the ground glass. So I set up my camera and really observed if there were any changes in focus when I put in the film holder - I was even a lot more forceful than I usually am - but focus stayed sharp.

Any ideas? How is it that an image can be sharp on the ground glass, but considerably soft on the negative?

Maybe I'm using the wrong developer!

Thanks!

[Vaughn]

The fresnel lens on the wrong side of the ground glass would be the classic problem. You can have the image sharp on the GG, but if the film plane is not exactly where it should be when it replaces the GG, then the sharp focus will be off.

Do you have one? Did you have one than remove it? Shift it around at all?

I bought a Zone VI 8x10 used -- it had a frensel and I do not like them...so I removed it. Turns out it was in the wrong place to begin with (in front of the GG), which may be why the camera was sold in such great condition...the previous owner might have had focusing problems like yours and blamed the whole camera.

[macolive]

Perhaps your loupe is not adjusted to focus on the ground glass' rough side? I'm no expert but I've also read that a 10x loupe is not recommended for focusing...rather a 4x is much better for judging focus on the gg. I don't know if that's true or not as I've only used a 4x.

[Vaughn]

Perhaps your loupe is not adjusted to focus on the ground glass' rough side? I'm no expert but I've also read that a 10x loupe is not recommended for focusing...rather a 4x is much better for judging focus on the gg. I don't know if that's true or not as I've only used a 4x.

With a 10x loupe, if it is focusing on the proper place, than one should see the 'grain' of the GG. If you do not see the 'grain' that might be the problem.

[Liquid Artist]

Perhaps your loupe is not adjusted to focus on the ground glass' rough side? I'm no expert but I've also read that a 10x loupe is not recommended for focusing...rather a 4x is much better for judging focus on the gg. I don't know if that's true or not as I've only used a 4x.

I usually use around a 30x for detailed work, and have never had a problem.
However, like Vaughn says, I focus on the grain.

I'm another one that thinks it sounds like a fresnel or gg issue

[Bob Salomon]

1: ground glass in wrong position. Is the ground side of the gg facing the lens? If so, then you need to have the position of the gg checked by a good technician.
2: your lens is not corrected for ratios greater then 1:10. Are your images out of focus at infinity?
3: optimal aperture for your lens is f22 where it will be diffraction limited.
4: is your loupe focused on the grain of your gg? If not, remove your lens, point the camera at a light source, focus the eyepiece of your loupe till the grain of the gg is sharp. Keep the eyepiece at that position with a piece of tape.
5: get a proper loupe with a focusing eyepiece and an opaque skirt of between 4 to 6 x magnification and save your current loupe for examining stamps, coins and currency.

[mbuonocore]

Thanks everyone for the replies. There is no fresnel, and the ground glass is facing the lens.

Bob, I think you might be on to something. If you'll humour me, I'll answer your questions in order.

1: As I mentioned, the ground glass is facing the lens. This is assuming the ground glass is very matte, and the other side is glossy and shiny.
2: I've used the camera in the past, and I've gotten sharp images with it, at infinity and otherwise. Regarding the lens not being corrected for ratios more than 1:10, where could I confirm that? Also, wouldn't I see that on the ground glass? Like, wouldn't it be out of focus?
3: I can try it at f22; I find it hard to believe that a lens could perform so badly 1 stop away from optimum. I'll give it a shot though, as well as confirm it's working at infinity.
4: The loupe if focused on the grain of the gg. I had already performed the test of removing the lens and focusing the eyepiece. I tape all my loupes and grain focusers.
5. This lens does have an opaque skirt. It's my favourite one in the darkroom, so I thought it would perform well. I can probably borrow a 4 to 6 x magnification loupe from a colleague and compare it.

All in all, point 1 and 2 seem the most likely culprits. Is there any way of verifying the placement of the ground glass myself? It's screwed in tightly, and seems to be facing the right way. Visually, at least, it the appears to be on the same plane as the film holder when I put it in. I wonder how I could confirm that? Sometimes I don't do a good job of thinking outside the box.

I appreciate all the advice!

[Paul Metcalf]

What you see on the GG is what you should see on the film. Forget about all of the lens issues or whatever, if there was a problem you'd see them on the GG (and with a 10x loupe for sure). So your problem is either a change of focus from when you focus on the GG or your film plane is not in the same position as your GG. If your camera has been worked on or screwed with than you need to check that the film holder is in fact putting the film at the same position as your GG. As far as changing focus after focusing on the GG, such as when inserting your film holder, you need to have everything locked down really tight before doing such. But I've used a couple of 100yr old Conleys that move/wave/bend/whatever when inserting the film holder and I don't have this problem (everything comes to rest after the insertion), so I'm going to lay odds on that your film plane and GG plane are not equal. Could be your film holder (try others) but could very well be your rear standard. What's the history on this camera?

Oh, and do your further tests at infinity focus, that will eliminate the "lens issue" comments.

[brucetaylor]

I am not an expert, but I have used 2 techniques to verify gg position. With a vernier caliper using the depth rod through a lens board I can check the distance to the gg, then place a holder loaded with film in place and confirm the depth is the same. Second, I took an old holder removed the darkslides and drilled a pattern of five holes in it. I placed a processed negative of grays in it and checked focus on a focus chart with a loupe, then removed it and checked the gg image. That should confirm the same plane or not.

[Doremus Scudder]

Marco,

Check to see if there is a discrepancy between the position of your ground glass and the film plane. The test is simply and you've got the set up already. Use your drafting table and ruler, but instead of tilting to get everything in focus, focus on one particular point on the ruler in the middle of the scene. Shoot wide open; the object is to make sure only the mark on the ruler you've focused on is in focus and that everything else is out of focus. Develop the negative and check to see if the mark you focused on is the sharp one. If so, you're fine. If the plane of sharp focus is closer to the camera than the mark you focused on, then your ground glass is closer to the lens than your film plane. The opposite if the plane of sharp focus is farther from the camera than the mark you focused on. The latter is rare, but the former is easy to take care of by simply shimming the ground glass out. Shim and test till you get the accuracy you need.

One more thing you should try first, just in case. Stop your lens down to taking aperture and check focus again. Some lenses have a focus shift. Your Symmar-S shouldn't, but maybe something is not quite right with it...

By the way, yes, your focusing loupe will work best if it is focused on the frosted (matte) side of your ground glass. However, if it's not, you'll just see a blurry image; there's nowhere else for it to focus on. If you see a "tack sharp" image through your loupe, you are most likely doing everything right. Personally, I like an 8x-10x loupe for fine focusing.

Hope this helps,

Doremus