Relationship between ground glass and lens

[swmcl]

My most recent photos with the lens turned out badly so I scrapped them. I can recall comparing them to the same shots with the 180 Sironar and a Heliar and not believing the results. (I blamed myself for not checking focus properly.)

I'd have to go searching for the actual image that I'm thinking of that was sharp (IIRC). Now that my ears have pricked up on this one I've remounted the lens about 5 times ! I'll be devastated to hear it is the lens. I paid good money for it and it is my special lens used on the odd occasion.

Leigh the off-axis abberations here are gross. Not even close to other lenses. The far trees are just a blur whereas other lenses are showing some leaves at least.

Cheers,

ps. I've sent an email to Schneider in California. Unfortunately for my impatience they are only open on Mondays, Wednesdays and Fridays so I'll have to wait a little longer.

[Leigh]

Leigh the off-axis abberations here are gross. Not even close to other lenses. The far trees are just a blur whereas other lenses are showing some leaves at least.

OK. There's something seriously wrong.

My first guess is that the lens originally had one or more shims (front and/or rear) that were somehow lost during mounting or cleaning.

Shims, if present, are very important since they set the internodal spacing.

- Leigh

[genotypewriter]

My most recent photos with the lens turned out badly so I scrapped them. I can recall comparing them to the same shots with the 180 Sironar and a Heliar and not believing the results. (I blamed myself for not checking focus properly.)

Not sure if you missed my question earlier but what range of f-stops do you end up shooting at usually?

Now that my ears have pricked up on this one I've remounted the lens about 5 times ! I'll be devastated to hear it is the lens. I paid good money for it and it is my special lens used on the odd occasion.

I don't call a lens a special one until it performs the way I want it to perform

[swmcl]

Geno,

I won't have been shooting at even f11. I would normally shoot at f16 or f22 or so.

Rgds,

[genotypewriter]

A couple of things have left me (and I'm sure some others) confused in isolating the problem. This is what I've gathered from what you've said:

1. On the GG, the image is sharp in the center but it's difficult to determine focus off-center.
2. The taken image, even at ~f/16-22 is also blurred all over.
3. There might be one image that came out sharp.

#1 is normal behaviour as we have established. #2 and #3 are contradictory. If we pair #1 and #2, the question is how the image became softer as the lens was stopped down. If we pair #1 and #3, it suggests that the GG and lens are fine but there's something else that blurs things up.

For me, going with 1+3 make a lot more sense than going with 1+2. Check to see if your camera shakes easily or if you have involuntarily applied a bit of tilt or swing.

For what it's worth, here's the 110 SSXL @ f/5.6 on a "Chinese" Shen-Hao 8x10
http://www.flickr.com/photos/genotypewriter/9719316020
(Note the link in "see original size")

[swmcl]

Sorry if there is confusion.

At no point is focussing straightforward. There is glow at the centre and at the edges. Focussing a distant tree at the edges of the image is impossible. The relatively recent results I had at f16 or f22 were blurry all over. The 'one sharp' image would've been shot 2 to 3 years ago. My thinking is that the lens has deteriorated somehow sitting on a shelf. Sounds weird but how else did the problem evolve over time like Oren Grad's post would indicate? Perhaps an internal element is held in place with an O-ring or something organic ?? Perhaps a coating breaks down with time ? Dunno.

Anyway, lots of packaging and big costs later and the lens is on a plane. I suspect we'll see whether it is the operator or the lens !

[genotypewriter]

My thinking is that the lens has deteriorated somehow sitting on a shelf. Sounds weird but how else did the problem evolve over time like Oren Grad's post would indicate? Perhaps an internal element is held in place with an O-ring or something organic ?? Perhaps a coating breaks down with time ? Dunno.

Wasn't aware that you had the lens for several years and that it worked back then. In that case you might be right about the possibility of something deteriorating. I'd still expect to see some tell tale signs. E.g. separation of elements might be visible and maybe one side could be worse than its opposite, etc.

Guess you'll find out and do let us know of the outcome too, if you don't mind.

Good luck!

[Doremus Scudder]

Sorry if there is confusion.

At no point is focussing straightforward. There is glow at the centre and at the edges. Focussing a distant tree at the edges of the image is impossible. The relatively recent results I had at f16 or f22 were blurry all over. The 'one sharp' image would've been shot 2 to 3 years ago. My thinking is that the lens has deteriorated somehow sitting on a shelf. Sounds weird but how else did the problem evolve over time like Oren Grad's post would indicate? Perhaps an internal element is held in place with an O-ring or something organic ?? Perhaps a coating breaks down with time ? Dunno.

Anyway, lots of packaging and big costs later and the lens is on a plane. I suspect we'll see whether it is the operator or the lens !

Steve,

Any fogging, fungus, coating degradation, etc. will be easily visible if you open aperture and shutter and look through the lens.

If the lens has been dropped or bumped hard enough, a lens element may be displaced, causing your focusing problem.

Even if the ground glass is in the wrong position in your camera in relation to the film plane, you should still be able to focus a sharp image on it from a lens in good working order, even if the resulting neg is out of focus due to misalignment. If you cannot get a sharp image on the ground glass with just one lens, then likely the lens is at fault. Do some more focusing and changing lenses and compare image sharpness in the center. A lens like the 110XL should perform superbly in the center. If it isn't, there's definitely something wrong with it.

Best,

Doremus

[swmcl]

Back again to fill in ...

I've heard back from Schneider. Apparently, there is an element in the rear cell that is out of alignment. They'll repair and clean the lens for a fair price.

Has anyone experienced this ?

I swear to you there were no bangs or bumps put onto the lens. Nor was there anything loose when it was shaken. I'm thinking the only way for this to occur must be through the expansion and contraction of metal. Could this be possible ?? Is it possible for a lens to lose its alignment by being left in the sun and then shade etc over time ?? How else could a retaining ring or whatever is used to hold the elements in place become loose ? How do I prevent it in the future ?!

Is it possible that there was a seal of some sort that has degraded inside the lens cell ?? Schneider wouldn't use an O-ring of sorts to hold anything in place would they ? I thought the insides of cells were just paint, metal and glass.

Anyway, I'm hoping it all goes well and that I'm glad I sent it to Schneider.

Hope this helps anyone in the future.

Cheers all.

[Leigh]

I would not attempt to second-guess the manufacturer.

The defect might be known, as they described.

It might be known but something they don't want to admit, so they're feeding you a bunch of smoke.

Who cares??? You just want the lens to work right, and they've agreed to make it right.

- Leigh