Here Is A Quick Tip List On Letters For The HELP! Desk:
Please confine yourself to only one question per letter. Both postal letters and e-mails are fine, although we prefer e-mail as the most efficient form of communication. Send your e-mail queries to with Help in the subject header and your return e-mail address at the end of your message. Although we make every effort, we cannot promise to answer every HELP! letter.
When sending a response or suggestion that refers to a published letter please include the month and page of the original question.

All postal letters to HELP! must be accompanied by a stamped, self-addressed envelope to be considered for reply. We will respond to e-mail queries with an e-mail.

Four-Stop ND?
Q. In his latest publication photographer Bryan Peterson makes frequent reference to his use of a four-stop Neutral Density (ND) filter to get those dreamy images and soft waterfalls. Yet, my local independent camera store does not carry it, nor could they locate one in their catalogs or online. My question: What brand of four-stop ND filter does Mr. Peterson use and where is it available? A clerk at the store suggested using two two-stop ND filters.
Frank J. Bien
via e-mail

A. I have no idea what make of ND filter Mr. Peterson uses. I scoured the web and found a few places where you should be able to locate and purchase the ND filter you seek. At many sizes of screw-in threaded filters are available. At they list many sizes of screw-in filters available in one-stop (0.3), two-stop (0.6), and three-stop (0.9) densities. Other websites you might want to search are and If you cannot locate a four-stop ND filter, you could always use two two-stop ND filters to achieve the same four-stop reduction of light reaching the film or sensor. Several decades ago I purchased a Tiffen Photar Series #8 2.0 ND filter. Since each 0.3 increment in ND filter nomenclature is equivalent to one f/stop, my 2.0 filter reduces light intensity by 62⁄3 f/stops, which allows me to use slower, blur inducing, shutter speeds at ISO 100 in daylight. This means that instead of shooting at f/22 (typically the smallest aperture on most lenses) at 1⁄60 sec in bright light, I can shoot at f/22 at about 1 second.

Canister Codes
Q. A couple of years ago a reader from New Mexico asked about those little metal Kodak film canisters, and what the color coding of the cans meant. Mr. Mayer published the letter and challenged readers to provide the answer. I’ve never seen the answer, but now have many of the little metal beasts. Any news?
Roger Macon
via e-mail

A. I have been waiting to compile more data about this subject. Since you asked, I dug back into my files and here’s what I have on the subject. I called Kodak’s hotline (800-242-2424) but they could not provide any data, however they suggested calling the George Eastman House (GEH) in Rochester where many of the Kodak archives are now located. I did, and an old friend at GEH told me that Kodak started using metal canisters about when Kodachrome was introduced in 1936; they were phased out in the ’70s. The body of most metal canisters was bright yellow (typical for anything Kodak) combined with color-coded screw tops that identified the film inside. This was back in simpler times when there was not the wide range of different emulsion speeds and similar film names that we had in the ’90s and early 2000s. He said that since Kodak film was produced at plants throughout the world the color-coding might vary. Sometimes it might even vary in one factory since they would use parts (colored tops) that were currently available if they ran out of the normal color for any particular film emulsion. This was the era when 35mm film cassettes had removable end caps so they could be reloaded and reused. The color photo of four metal canisters and cassettes provided by reader John Binns several years ago shows the film cassette had the same color-coding as the top of the metal can. Binns further stated that all of the metal canisters he has have yellow bodies with colored caps. He also has some plain aluminum canisters but did not recall what was in them. Below are the color-coding schemes of four different Kodak cartridges and canisters that we are currently aware of.

Super-XX: green
Plus-X: brown or purple
Panatomic-X: blue
Kodachrome (daylight balance): orange

After sending this reply to Roger Macon, I received this e-mail back from him:
“To date, I’ve come up with at least 23 color combinations, and suspect many films had more than one color scheme. I’ve managed to collect six or so, and am working on the others. It’s amazing what they are bringing on eBay these days—sometimes $3 or more per canister. Being the quintessential pack rat, I’ll continue on the quest!”
If this is the situation, there must be many other color combinations that were offered for the wide range of films Kodak offered. If any readers have additional information about Kodak’s film can color-coding and the film type it identified, I would appreciate hearing from them for another follow up on the subject.

Mamiya 6 Lenses
Q. I have a Mamiya 6, a square format medium format camera. I like this format because it does not require any resetting for horizontals or verticals. I have the three lenses that were available at the time of release. I would like to know: 1) Is there anyone who provides an adapter for other manufacturers’ 6x6 lenses? 2) Does Mamiya have any other lenses to fit this camera?
via e-mail

A. The Mamiya 6 and later M6 medium format rangefinder cameras were offered with a selection of three Mamiya lenses, a 50mm, 80mm, and 150mm. I have not been able to determine if any other lenses were offered, or if lenses from other manufacturers could be adapted to this camera. Here is Mamiya’s current contact informatioin: MAC Group, 8 Westchester Plaza, Elmsford, NY 10523; (914) 347-3300; e-mail:; On the website I only found reference to the newer Mamiya 7, which is a 6x7cm rangefinder model.

Power For Bauer
Q. I have a Bauer E 160 Ultrablitz flash unit (serial number: 260108) with a missing power cord for charging the internal power supply. The power cord should have a three-wire connector to accept a 110 VAC or 220 VAC power source. Where can I obtain a replacement power cord for the flash? The unit was made in Germany by Robert Bosch Electronik und Photokino GMBH.
Charles Kung
via e-mail

A. Sorry, I have not been able to locate a source for the power cord you seek for your Bauer E 160 flash unit. I called four major flash repair facilities around the country and none of them had parts for this brand of flash and they did not know who might have the cord. I also spoke with an old friend with a firm that imports several brands of German-made flash units and he was unfamiliar with the Bauer brand. I would imagine the cord you seek would be one that is compatible with other brands of German electronic flash units, but without knowing exactly what the cord looks like I cannot suggest a brand that might be similar. You might want to take a close-up photo of the connection that fits into the charging device and send this to a flash repair firm. They might have a suitable cord that also works on a different brand of German flash. We will ask any readers who know of this brand of flash to get in touch with us if they happen to have a spare power cord, or know of a place where this cord could be purchased.

120 Re-Roll
Q. Please advise of the procedure to re-roll 120 film so it can be used with a 620 film camera.
George R. Sprague
via e-mail

A. If you do a Google search for “rewind 120 film” you will find more than half a dozen suggestions on how to accomplish this. Several are very well illustrated and detailed in their directions so they should provide the guidance you seek. They are too detailed and lengthy to include in this reply. It is a bit tedious to do and requires either a darkroom or light-tight changing bag. Also be aware that metal and/or plastic 620 spools are difficult to locate. If you do respool some 120 film onto 620 spools and send the film out for processing be sure to tell the lab to return your 620 spool so you can reuse it again. If you want to go the easy route to obtain some new 620 film, I just checked the film listings for several major mail-order dealers and found had a number of emulsions available in 620 format. You might want to purchase several rolls to use and get your empty 620 spools this way. Good luck.