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Pete Andrews wrote:

> Most scanners could, in fact, see a higher density, simply by winding up the intensity of the lamp

This is untrue for most scanners, unless you're willing to allow the...

Deviating a bit into scanner-land...

Pete Andrews' point (that Dmax for EPN is fairly low) is technically correct, but from a practical standpoint I think that Paul Schillinger's advice is still...

A comment to Sal:

Be VERY CAREFUL about how you measure timing accuracy at the faster shutter speeds. The reason is because if you measure at small apertures (i.e. looking only at light rays which...

One additional comment: My favorite testing method is to put a light source on one side of the lens and a photocell on the other, and hook an oscilloscope to the photocell. Focus an image of the...

Hi Bill;

I think that a lot of the concerns people have about shutter accuracy stem from the many older, used shutters on the market. I've tested my new Copal shutters fairly extensively (using...

Hi Rob;

If it's a 90 f/8 (you didn't specify the F.L.), and you shoot slide film, and you plan to use substantial movements, then the answer is probably "yes".

I have a Nikkor SW 90/8, and I...

Voightlander made a lens called the "zoomar". Could that be what Sean refers to (it had a horrible reputation, IIRC).

-- Patrick

Hi Bill;

Are you dividing by the enlargement factor squared?

Line pairs per millimeter is a linear measure of resolution (i.e. it measures resolution along a single axis rather than the amount...

Hi All;

Great thread!

One apology/clarification: Glenn Kroeger rightly points out that I got my estimates of diffraction-limited resolution wrong. Specifically, I used a relation (the Rayleigh...

This is a reply to Bill Glickman's comments:

In my experience, resolutions higher than about 60 lp/mm are pretty much mythical beasts in ANY film format. One reason already pointed out is the...

A comment to Sean Yates: I'm not sure I see why the existence of the Technikardan in particular should have any effect on the market for yaw-free, base-tilt only cameras like the VX-125 or the Cambo....

Hi;

I've moved the (tangential) discussion of perspective manipulations into its own thread because it really doesn't belong here...

Thanks,

--P

Hi;

This is a continuation of a tangential discussion from the "Pros and cons of fie ld cameras" thread. In that thread, I wrote:

"Consider the simple manipulation of using front rise to...

fw wrote thusly:

"One last thing - the movements on the camera do not control perspective, they enable you to control where a plane of sharpness will lie in the image. Only physically moving the...

Hi Doremus;

Julian's web page says "scale focussing", which implies that you focus by estimating the subject distance and then racking the focussing mechanism in or out until the focussing...

Hi;

I think that there's a serious lack of accuracy in this thread regarding effects of filmplane to groundglass misaqlignment.

One poster has stated that the effects are worse for long lenses...

A few clarifications:

1. I'm not the person who posted the URL for the Polaroid data sheets, but like Daniel I'm eternally grateful to the person who DID do so...

2. The groundglass on both my...

Hello;

Has anybody here tried exposing (NOT developing) Polaroid Type 55 in a Fuji Read yload holder? Did it work?

The reason I'm asking is that I'm REALLY getting sick of the Polaroid 545i's...

Regarding Michael Biggs' comments about light falloff: The cos^4 rule is derived from thin-lens theory, and isn't necessarily a very good predictor of the behavior of real lenses. The Nikkor SW...

Hi Paul;

I'm intrigued by your comment about being "somewhat limited on my favorite long lenses" with a monorail. The Technikardan has a maximum extension of 48 cm (19"), which is more than a...

"Astigmatism" is an optical aberration wherein the tangential and sagittal axes of a lens focus on different planes. Consider the circle of coverage of a lens. Now imagine a point near the edge. If...

Hi Rob;

Given the set of simultaneous requirements that you've listed, and your aversion to excess weight, I think that your budgetary expectations may be a bit unrealistic.

I doubt that you're...

Hi Darron;

"Noise floor" is a commonly accepted term for what you were trying to describe in the image capture world.

High-end drum scanners use photo multiplier tubes as their capture...

To Bob Salomon;

You might note that I said "using" instead of "fitting" in my post. I did that for a reason ;-).

Given that my LF experience is with a Linhof Color Kardan (uses Technika boards,...

The Super-Symmar 110 XL's rear O.D. is ~60 mm. You shouldn't have any trouble using one on a Technika-style lensboard.

--P

Hi David;

The presence of a fresnel on the inside of the ground glass shifts the plane of sharpest focus by about 1/3 of the thickness of the frenel. If you believe what Ron Wisner writes on his...

Hi Todd;

The way I like to think of this is:

- Front tilts and swings are for correcting focus

- Rears tilts and swings are for editing perspective (though they do change focus as well...)
...

I wanted to comment a bit on Robert Zeicher's method for evaluating DOF. Measuring the range of focussing bed positions at which the image is in-focus, putting the standard in the middle, and then...

A correction to what Bob Solomon wrote: An unfocussed loupe WILL make the groundglass image look blurry, and therefore difficult to focus. It WILL NOT under any circumstances cause the apparent...

Hi Paul;

As a general rule, only things which lie along the tilt axis of your camera will stay in focus when you tilt. Thus, ANY rule of thumb, such as "focus far, tilt near", is specific to...

The traditional way to approach this is to determine the impulse reponse of the system (taking lens plus film plus scanner) and derive a convolution mask which as nearly as possible inverts it, such...

Hi Bob;

With regard to filtration for specific films and situations, I'll defer to others (such as Ellis) with more experience.

With regard to your color meter problems, the short answer is...

Hi Mark;

One thing to watch out for with chromogenic films such as T400CN is grain structure.

While the amount of grain produced by chromogenic emulsions is low, the pattern that it forms (the...

Hello;

I've searched Polaroid's web site and the archive, and can't find an answer for this one:

Where can I find a listing of recommended reciprocity corrections as a function of time for...

Hello;

I've stumbled across an older camera in my local shop, and wanted to know if any body out there is familiar with the design or knows its market value; It's a Lin hof Color Kardan. It apears...