billkantor

Hi Bob,

 

Thanks for the response.

 

The 165 Super Angulon and the 155 Grandagon are nearly the same. Is there a center filter for the 165 Angulon still available? Do you know if the center filter for the Super Angulon would work on the Grandagon? After all these things are not that precise. The fall off (using cosine^4) is closer to 2 stops whereas the filters are only 1.5 stops Moreover, I am not taking photos of blank walls.

 

Bill

The camera is an 8x10 Deardorff. I am shooting landscapes with near/far compositions and find that if I am careful I don't

run out of room with either lens.

 

FWIW, both lenses have about comparable coverage. But this is a center filter question.

Shooting with 155mm Grandagon and 210 Angulon.

 

Ok, I am ready to concede that I am tired of underexposed corners and trying to pull detail out of my chromes. This

is a bigger issue with the 155 Grandagon. I see that the formerly-available-but-very-expensive Rodenstock center filter

for the 155 seems to be no longer available. Ebay has been a wasteland for this kind of optic for some time. On the

210 Angulon I have never seen a recommended center filter.

 

My questions.

 

1.) Does anyone know if there are any other alternatives for the 155 Grandagon? E.g., would any of the Schneider

center filters (like the size 6 for the 210 XL) work?

 

2.) What are the center filter options for a 210 Angulon?

For those size files I think that the iMac will do fine. There is another issue which Arthur mentioned.

 

The screen brightness of the (at least the 24 inch iMac) is too bright even when turned down to lowest to do a successful

calibration. Although I have not tested the new 27 inch models I suspect they work the same. Ask or test it at the store.

This makes a color calibration impossible and leads to the "prints too dark" problem--the image looks perfect on the

screen but way too dark in final print form. I bought a 24 inch iMac and found this too frustrating. Installed a third party

application that allowed me to adjust the monitor brightness lower but Apple/my color calibration vendor wouldn't support

this configuration. In the end I traded up to the Mac Pro for the color calibration support and more expandability. The

newer models today come with more in them so expandability may not be as much of a concern for your application.

 

If I were doing it today, I would seriously look at the iMac and get a second screen for precision color work. Apparently

you already have this second monitor. This setup works very nicely in PS. You can have your tools on one screen and

the image on another.

 

Food for thought.

 

Cheers,

Bill

Paul got a great deal.

Sara,

 

The camera looks good. The lens is probably quite functional although I see spots on the photo so I can't be sure. I would

not worry about "old" provided that it is all functional mechanically and that the bellows does not leak light. (You can test

this by putting a light inside it to see if there are any pinholes shining out.) This isn't a DSLR with 6 month life cycles. Many

of the LF folks here will tell you they are shooting on 50 -100 year old glass and cameras with fine results.

 

I am not up on the latest values but from my perspective it looks to me like a fair to favorable deal but the question is what

do you want to use this for? If studio then a monorail camera is very practical. If for field use then you might find it a bit

bulky. If you plan to go hiking... Well you see it depends.

 

Bill

.<div></div>

James,

 

I feel your frustration. The lenses should come with the center filter. What a novel idea? But I bet the manufacturers get

a lot more $ by unbundling them.

 

As for the "faulty" product question... it's not that they designed them that way intentionally; it's physics. Most people

don't worry about or notice the falloff. Personally, I find it a real pain in the butt when your corners lose shadow details due to

falloff.

 

Here's a good article. http://www.kenrockwell.com/tech/center-filters.htm.

 

Read that and then decide if it is a faulty product or just the way things are. In any case you will have to pony up some

money if you want to solve this problem.

 

Bill

Thanks Kelley,

 

I'll try setting up my a digital back and running some tests of my own at different apertures.

 

Cheers,

Bill

Bennie,

 

Great educational question to discuss with your class.

 

There is another difference worth noting. You asked about B&W film but with color film there is another consideration. The

spatial color resolution is much greater than digital. With most digital sensors, the pixels are either red, green, or blue; while

color film produces all three at each location. Most digital sensors use an interpolation method to invent the missing two

colors at each pixel. It's a great trick and it works well but this is another difference that works in favor of (color) film.

 

Best,

Bill

Hi Bob,

 

I meant what can you say about the optimum aperture for this very old lens?

 

I own a nice Grandagon 155 which I love becasue it's field of view fits my "seeing" well. As you point out it is optically

superior to an Angulon and I've been using the 155 for years but, as you know, the weight can be an issue. The 210 focal

length also fits my way of viewing the world. Wondering what the optimum aperture is.

 

Bill

<p>Bob,<br>

What can you say about the 210 Angulon (which I presume you would characterize as a modern lens)?<br>

Bill</p>

<p>Just put my 210 Angulon to a field test with some real photos. I am very pleased with the results -- mostly shooting at f16.5 to 32. The lens appears to be quite sharp and versatile with plenty of coverage. I notice a little softness in the corners but that is to be expected. Can anyone tell me the optimum (sharpest) shooting aperture for this lens?</p>

<p>Nathan... Brilliant! (Except for the 30% thing.) Somehow I want to believe that a modern shutter on a DSLR is better than 30% but then Bob is the expert.<br>

So Ivan are you going to share the plans for your $20 tester?</p>

<p>Best,<br>

Bill</p>

<p>Thanks everyone for the explanation/confirmation.</p>

<p>Friedmann,<br>

So if the scale is log then where would the 1/3 and 2/3 stop marks fall (on a linear basis)? (I know I can calculate this but it sounds like you probably know.)</p>

<p>Agree. I am not so worried about this up to f/32. Up to this point I can even reasonably guess at 1/3 stop positions. But after this things get very close together. I can't set 1/3 stops between 32 and 45. (OK, I can work around that.) But I am wondering what those mysterious dots after f/45 are intended to represent.</p>

<p>Attached is a close up of the aperture scale on a Copal 3 housing my 210mm Angulon.<br>

Question is where do you place the aperture pointer to achieve the desired settings? I have been using the midpoint of the numbers. E.g., if I want f/22 I set the pointer in between the first 2 and the second 2. This is only possible up to f/32. Then it appears that for f/45 there is a marking with a line showing where the pointer should lie. Mysteriously there are two unlabeled dots after f/45. What do these mean? f/64, f/90.<br>

Can anyone clarify?<br>

Thanks,<br>

Bill</p><div></div>

<p>Technically, you can't get closer than the focal length of a lens. But to get as close as the focal length would require infinite bellows. So practically, Sheldon is right.</p>

<p>Donald,<br>

Most interpretations of a scene aim to preserve shadow details; you are trying to obliterate them. So you have an easy problem to solve here. As has been suggested, just measure the highlights with a spot meter and expose at 2.5 stops over what the meter (calibrated for 18% gray) tells you. The incident meter technique will work well too.<br>

Bill</p>

<p>Jack Welsh,<br>

Preexposure... very interesting. I have tried this successfully with B&W and agree it works quite well. Have you used it on color transparencies?<br>

Bill</p>

 

<p>When you are ready to make the exposure; pull out the dark slide, hold it to shade the lens, trip the shutter, replace the slide. You will see the shadow of the dark slide on the lens so you will know when it is just right. Don't move the slide any more into the scene than you need to produce a shadow covering the front glass on the lens. If the slide is in the picture then you are out of luck. Try recomposing.</p>

<p>As I see it...<br>

The difference in the DOF calculation has to do with the acceptable circle of confusion (a subjective figure in any case) which is based on the amount of magnification, and the viewing distance you are assuming. Smaller formats need to be enlarged more so the acceptable circle of confusion at the film/sensor is much smaller (it gets enlarged more after all) and the corresponding distance you can diverge from the ideal plane of focus is smaller. Does that explain it?<br>

See here<br>

http://www.dofmaster.com/dofjs.html<br>

And notice that the circle of confusion changes when you change the format size.</p>

<p>As for cropping... A large format image cropped to a 1.6x sensor (D40) size and enlarged to the same final output size as the 1.6x sensor image will produce the same kind of depth of field in both cases; with one caveat. There will be a difference in overall sharpness. The smaller format will be sharper because the large format lens will probably have a lower resolution than the equivalent focal length lens designed for a smaller format. For this reason the apparent DOF might actually appear shorter on the LF crop than on the smaller format. If you are going to crop, you should use a lens that is optimized to cover the cropped area.</p>

<p>As for the bigger covering power of the LF lens yielding a bigger DOF that's just not true. I have heard (maybe more accurately -- I've speculated,; I'm not well enough educated on this to know) that the reason a LF lens does not resolve as much as a 35mm lens is that physics dictates there is an inverse relation to the image size thrown (the coverage of the lens) and the resolution. Although bigger coverage generally means lower resolution, this is a tradeoff that works in favor still of larger formats since they are not enlarged as much.<br>

Bill</p>

<p>You would get a shorter focal length if your lens were a pinhole. But I have never seen a minimum flange focal distance for a pinhole lens. ;-) <br>

Otherwise your results will be as stated.<br>

Cheers,<br>

Bill</p>

<p>Thanks Charles. I got it all to work. Appreciate the help.</p>

<p>Regards,<br>

Bill</p>

<p>Wow!<br>

Thanks for the explanation. <br>

My unit has a dust cap covering screw 2 and over the other axis (to the right of item 3). I can't get the main platform to break loose and am afraid to give it a wallop because I worry that it is held in on the right side with a screw like item 2. How do you remove the dust cover to check?<br>

Bill</p>

<p>My Gitzo G1570M head has started to bind. I am wondering if anyone here has seen this and knows how to fix this. </p>

<p>I noticed that the side-to-side tilt clamp was sticking when rotating to loosen or tighten it so I unscrewed it all the way and found the grease had hardened. A little paint thinner and some new grease did the trick. Now I notice that all the movements (except the pan) could use this treatment. No problem on the other tilt clamp but the rotating bearings on the forward and side to side tilts are not easily accessible and definitely need help. Any suggestions as to how this comes apart and the appropriate grease to use? I'd hate to put the wrong grease on this and find that I have to do this again. (Take note please Gitzo.)</p>

<p>Thanks,<br>

Bill</p>