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Advanced Questions
by Chuck McKern

With over 12 years of retail and professional experience Chuck thought he'd heard it all - until he took this job.

Send us your questions for either the Beginner or Advanced columns by clicking HERE.  Please include as much detail about the technique, camera, lens, or film as you can so Chuck can answer your questions.

Sigma AF 50-500mm f4-f6.3 EX APO RF HSM. Bought one, and its a nice lens. Also bought the Sigma 1.4 teleX and the images are totally USLESS. All images with the teleX are so soft as to be throw-aways. Used on Manfrotto Tri. Slik ballhead, Nikon D100 and cable release. Any quick and dirty thoughts as to possible problems? Or do I just have a bad adapter? Accept that there will be some loss, but extreme overall softness is unacceptable.


I can only speak for the lens/teleconverter we used (for the test we had a Kenko 2x converter). In the article we stated that the lens should work better with Sigma's converter as manufacturers generally optimize their lens/converter combinations.

I'm assuming that the lens without the converter is producing good images. If the combination is as soft as you say something is wrong. Try contacting Sigma's tech support department at (631) 585-1144 between 9AM & 5PM Eastern Standard Time and ask if there are known problems with this combination. If so ask what they can or will do for you. I'd also check with your dealer on this one (where you purchased the converter) to see if they've had any complaints on this combination. One question Sigma will probably ask is how the converter works with other lenses.

By the way the number I provided is for Sigma Corporation of America. I noticed that your email address is Canadian. Since Sigma doesn't list a separate contact number for Canada I'm assuming that this is the number for all of the Americas. The number is located in Ronkonkoma New York.

One last thing. Before calling check the manuals that came with both the converter and the lens. It's reasonable to assume that the pair would work together as they're both made by Sigma. But teleconverters are funny animals. Some combinations are notoriously bad no matter who the manufacturer is. You may even find a note in one or both of the manuals recommending against this combination.

Please let us know how you make out.

Is this really the correct way to read my studio lights? I took a portrait photography class and was taught to read each light separately -- that is, to turn off the background and fill light and read the main light, then turn off the main light and read the fill, then making sure the main and fill are turned off, to read the background light. My pictures seem to be overexposed. (It seems to me that, for example, when I actually take the picture that the fill and the main lights will spill over to the background and change my desired light ratio.) I am using a Sekonic light meter and adjusting my lights to get exact readings. My pictures look perfectly nice when the exposure is adjusted at the time of printing but I would like to get it right in the camera.

Thanks for your help on this, 
Jan Barlowe

The technique you described is correct for determining the lighting ratios. But when you're determining your final exposure you should take a reading with the main and fill lights both on. The background light shouldn't matter since it shouldn't be spilling onto your subject.

If the problem is light spilling into unwanted areas you may need to use a flag or barn doors to control where the light goes. If you need more information on accessories for controlling light in the studio see my article on the topic in our March 2002 issue at

When taking your readings make sure nothing is blocking any of the light from reaching the meter. This is a common mistake we've all made at one time or another and it will throw off your readings.

I have an Epson 1280 printer and have difficulty in establishing what maximum size the printable can be for a given size of paper. Working with 11x17 size and attempting to get max print size and going to view print on Photoshop I come out with a print that keeps clipping part of the print. How can I print max size prints on any size paper? I have Photoshop 7 and do use constrain proportions. 

Neil Wollpert

I'm not quite sure what you mean by clipping. If you're using a U.S. standard B size paper and you're sizing to 17 inches on your longest side, than the opposing side would actually be 11.3 inches and would cause some clipping along that edge. You can compensate for this by cropping the 11 inch side or by setting the longer side to 16.5 inches. This assumes the proportions of a 35mm negative. If you're using Epson's A2 paper you can print this image unconstrained and it's just a matter of trimming the matting when you mount the image.

If the clipping is only occurring in the preview window in Photoshop chances are the paper size hasn't been correctly set. Click the "Page Setup" button on the right side of the dialog box and choose the exact paper that you're using to print.

Finally the problem could be in the initial resizing. Make sure that "Constrain Proportions" is indeed checked. For resolution we normally recommend 300 dpi as a catch all for inkjet printers, but I know that the Epson 1270/1280 models print well at 240 dpi (which provides a smaller image). After setting the resolution set the image proportions, then go to preview. If you paper size is correctly set there should be no clipping other that the small amount dictated by the image proportions mentioned above.

There's one final thing to check. The 1280 does full bleed printing, meaning it prints right to the edge of the paper, but you may have to enable full-bleed printing in the print driver. To get to that screen click on "page setup" in the preview window, then click on "printer", click on "properties" and finally click on "paper".

In the December, 2002 article "Get Ready to Print," Gary Stanley suggests to "use the scanner's highest resolution...rely on the scanner to get as much information as possible [into Photoshop]." I infer that he prefers to do most of the editing in Photoshop after the scan, as opposed doing significant editing in the scanner software before the scan. I use Silverfast software with my Nikon LS-4000, and consider Silverfast to be far superior to the NikonScan software. Do you have experience with Silverfast, and if so, do you still prefer to do most of the editing after the scan?

Richard Lieberman

To some extent it's personal preference. Jim probably does a little more in the scanner software than Gary but both do the bulk of the adjustments in Photoshop. We've heard good things about Silverfast but we don't have it installed on our scanners here.

A guy at the local camera shop recently showed me a trick to get depth of field preview with my N70. Set the aperture with the aperture ring then you press the lens release and rotate the lens slightly which causes it to stop down so you can see the depth of field. It seems to work OK but I'm wondering if it can hurt my camera or lens.


Only if you drop the lens! This is an old trick used by Nikon shooters for some time on bodies without DOF preview. It works great but you need to make sure you have a firm grip on the lens and that you reseat it completely to avoid a dropped lens.

I just read your article on luminosity. Thanks for the insight. What I was wondering was if you ever heard of anyone using lacquer on ink jet prints. If it makes traditional exhibition prints look good why not a similar technique for digital? Perhaps the ink will run or some other problems will arise. I don't think I can try it for myself and not get tossed out of my apartment for the stink. My wife may not like the over spray either.

I have never read anything about after the printing process for ink jet prints. What about mounting and coating? Do you have any resources available? Articles etc.?

Just wondering, 
Charlie Loeven

Gary Responds: The only protective spray specifically for inkjet papers that I know of is called Lumijet ImageShield from the folks who make inkjet papers, Liminous Photo.

It is a fast drying spray that seals the surface, is non-yellowing, makes the inks wetfast, has UV inhibitors and is fade resistant. One can will do up to sixty 8-1/2x11 coats (3 coats each). It is not cheap, at around $18 a can, but seems to work real well and I cannot see any visual difference when compared to the original. Give it a try!


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