Re: Extreme WA lens for Whole Plate
Quote:
Originally Posted by
Corran
Last time I mentioned that it "should cover just fine at infinity" but I didn't expressly show it - I only posted an image with a very close focus.
I went back into my archive and found a better example for you. Here is an 8x10 image shot at infinity with the 90mm XL and I have inscribed a rectangle of exactly 6.5" x 8.5." This is accomplished by knowing what DPI the scan was done at and properly sizing the rectangle in PS. As you can see, it covers the rectangle fine. Of course others may tell you the circle of "acceptable definition" is smaller than the actual thrown image.
If you get a 90mm XL make sure you get a newer one with the removable rear shroud. I assume the rear shroud shrinks the IC slightly from mechanical vignetting, but I haven't actually tested this. I always have the rear shroud off when I've put this lens on 8x10.
http://www.garrisaudiovisual.com/pho...wp-example.jpg
Thank you for posting the image. The 90mm XL obviously covers a bit more than the 90mm Nikkor. Edge distortion with the XL looks to be a lot more extended then on the Nikkor. It would be interesting to know what the criteria was for each of the manufacturers for determining the coverage of their lenses, I assume it is based on shooting a line resolution chart, since the image thrown by these 2 lenses far exceeds their mfg's coverage specs.
Distortion in the corners... I just accept it. I use a 5.9” No. 5 Gray Periscope (equivalent around a 15mm lens on FX or 35mm) on my 11x14. Published Mfg. lens specs (late 1800s) say it covers 11x14. Image distortion in the corners absolutely lot of it there, but it just doesn't bother me all that much and I guess didn't bother photographers in the late 1800s. Since I am contact printing the negatives, seems to be even less pronounced in the final prints. Prints made from this optic when displayed in a gallery setting earlier this year... well no one has ever commented on the distortion in the corners of the prints.
Re: Extreme WA lens for Whole Plate
"Distortion"...are you talking about perspective distortion? That can't really be avoided with such enormous angles of view. It's built in.
If you're talking about pincushion or barrel distortion, where straight lines in the subject render as curved in the negative, that's another story. Fisheye lenses are designed to have that kind of distortion. I don't see that in Corran's picture above and I really haven't seen it in my own view camera work, although the widest lens I use is a 75mm on 4x5. Certainly I've had to be very careful with camera position, when shooting kitchens and bathrooms with that lens, to avoid perspective distortion.
Re: Extreme WA lens for Whole Plate
Perspective distortion in the far corners is certainly a fact of life with extreme wide angles. It occasionally disturbs me on certain images but usually it's not too big of a deal. Depends on the subject. I wouldn't be surprised if there are some lenses that also have actual distortion in the corners outside of their prescribed image circles per the manufacturer, but I am not one to photograph test charts to find out.
Re: Extreme WA lens for Whole Plate
A common distortion on UWA scenes would be in interior shooting, where the rooms look stretched/deeper...
Steve K
Re: Extreme WA lens for Whole Plate
I also used to have the 90mm Nikkor which did nicely on my 5x7". I now have a 90mm f8 Ilex Acu-Veriwide (in Copal.0 and often used with a Schneider IIIb). Dim as it is, its a keeper as it has an even larger image circle and excellent definition. Whether it covers full plate I can't 100% guarantee, but it'd be pretty close.
Re: Extreme WA lens for Whole Plate
Is an ILEX Acugon 90mm f/8 the same as an 90mm f8 Ilex Acu-Veriwide?
Re: Extreme WA lens for Whole Plate
Re: Extreme WA lens for Whole Plate
...so, yes, thanks, Dan. http://www.galerie-photo.com/ilex-lenses.html
The optical design across its iterations over the years is said to be identical. They came in a variety of shutters (Ilex, Compur, Seiko, Copal (0 and 1),...) and there are also versions without filter thread (!), so it makes me wonder if they didn't have, even minor, optical updates as well during their run. Another comment: My copy opens up to about f6.8 or thereabouts, both the shutter and the lens are marked f8; so, although noticable, its only really a stop slower than the f4.5 for preview.