8x10 Ground Glass Focus is Crap

[dasBlute]

so, what do you mean by "I've used two different types today..."
Are you swapping GGs into a single camera, or are these from two 8x10s
that have worked well in the past?

[AtlantaTerry]

So, back to shooting 8x10 after a break. I don't remember it being so hard to focus on the GG.

Maybe it is time to have your eyes checked by an ophthalmologist.

[Vaughn]

Well, I would suggest having someone else see if they can focus it.

[Lachlan 717]

Start by eliminating variables - starting with the lens.

Was it the same one on both cameras? If so, was it a similar optical result on both cameras? If so, check the lens.

Contrary to the slightly acidic suggestion of Luis-F-S, I would start with the things that you can do for yourself, rather than starting with getting your eyes tested... This approach requires more effort than checking the lens.

Additionally, it seems a strange theory to blame vision/glasses if you haven't had any issues with your vision prior to looking at a ground glass.

[Keith Pitman]

A couple of years ago I was having trouble focusing and finally tied it to a change in my eyeglass prescription. When I refocused my loupe, focusing on the GG got back to normal. Make sure your loupe is focused.

[Jerry Bodine]

I know I've posted this before, but it's been awhile. Decades ago, my backpacking buddy had been complaining about his Linhof trannies not being as sharp as they used to be. I asked him if he'd had his vision checked lately; he said his eyes were fine. Then we were on our way to Wyoming for a vacation trip to the Wind River Wilderness; he was driving and had left his sunglasses in his pack in the back of the car but didn't want to stop to get them, so I offered him my prescription sunglasses and said I wanted to nap anyway. He put them on and was aghast "OMG!! I can see every tree on that ridge. Everything is so SHAAAP" (he was from Boston). When we got back home he had his eyes checked; it turned out we both used the same optometrist to make our glasses, and when I went in to pick up my new lenses, the optometrist started telling me about this guy who ordered BIFOCALS but wanted the close distance part placed in the TOP of the lenses so it'd be more comfortable for him when working under the darkcloth since he had to lean forward to see the groundglass. I said I think I know that guy.

[Pawlowski6132]

Ok. Thanx for the helpful suggestions.

Again, the issue is that the image on the GG doesn't get sharp or appear in focus. At least not to the degree that I would expect.

At 50 years old, my eyes are not good but, I can focus on everything else (books, phone screen, prints, negatives, etc.) and also the ground glass. That's how I know the image on the GG is not sharp. As I rack the bellows in and out, I can see details (say in a tree) begin to come into focus, get to the "most" sharp it gets on the screen and then leave that point and move to out of focus again as I continue to focus the bellows.

I don't think it's the lens. It's a Nikkor 450 M. It works because I can get negatives that are perfectly sharp.

I replaced the ground glass using two different examples - same problem on each.

When I look at the GG just using reading glasses it looks sharp from about 6 or so inches away.

But when I use a higher power loupe, it's impossible to focus critically on a minor detail (say eye lashes for example).

In conclusion, I'm chalking this up to:

1) Quality of the Ground Glass
2) Expectations

I wont continue to worry to much about it. I will continue to feel my way to optimum focus.

[Jac@stafford.net]

I wish you good luck with this issue and hope you share a conclusion if there is one.

I had a loupe that went out of whack due to heat (standing in sunlight too long) and tested it by placing it on my LCD screen laptop. Sure enough it could not possibly resolve. It is more likely a loupe problem rather than your eyes suddenly changing.

Best,
Jac

[Colin Graham]

I've had a similar problem with homemade screens if I grind them with a grit too fine. For me things seems to pop into focus a little easier on a coarser ground glass. But it's also harder to resolve very fine details on a coarser screen, and they are a bit dimmer as well, so it's a trade off.

[Bob Salomon]

Ok. Thanx for the helpful suggestions.

Again, the issue is that the image on the GG doesn't get sharp or appear in focus. At least not to the degree that I would expect.

At 50 years old, my eyes are not good but, I can focus on everything else (books, phone screen, prints, negatives, etc.) and also the ground glass. That's how I know the image on the GG is not sharp. As I rack the bellows in and out, I can see details (say in a tree) begin to come into focus, get to the "most" sharp it gets on the screen and then leave that point and move to out of focus again as I continue to focus the bellows.

I don't think it's the lens. It's a Nikkor 450 M. It works because I can get negatives that are perfectly sharp.

I replaced the ground glass using two different examples - same problem on each.

When I look at the GG just using reading glasses it looks sharp from about 6 or so inches away.

But when I use a higher power loupe, it's impossible to focus critically on a minor detail (say eye lashes for example).

In conclusion, I'm chalking this up to:

1) Quality of the Ground Glass
2) Expectations

I wont continue to worry to much about it. I will continue to feel my way to optimum focus.

Are you using a loupe with a focusing eyepiece or one without? If you are have you adjusted it to be in focus on the grain side of the ground glass? If not, or if your loupe does not have an adjustable eyepiece then your loupe is not focusing on the image plain.