I recently read a book titled "The Nature Photographers Complete Quide to Professional Field Techniques" by John Shaw and published by American Photographic Book Publihsing. In this book, a section of it dealt with fine tuning the light meter in one's camera by assuming the sunny f/16 rule for the northern sky at 45 degrees above the horizon on a sunny cloudless day. However, it did not specify any particular lense. My question is; isn't this fine tuning operation neglecting the fact that different lenses and their respective designs is a variable that is not being considered in this method of calibration? In other words, isn't the type of lens one uses also a factor in determining the amount of light coming in? I tried this test with different zoom lenses and got different calibration results. Any thoughts on this method of fine tuning any camera's meter?
Reply: Joe - Your problem with different lenses is entirely due to manufacturing errors. f8 on one lens is IDENTICAL to f8 on any other lens. In the past, there was a proposal to use T-stops instead of f-stops. T-stops mean 'transmission' stops, which take into account the density of the lens glass, flare factor, efficiency of design etc especially of zooms. A good lens will actually use t-stop markings (Zeiss, Leitz, etc) while cheap lenses just base the f-stop on the physical aperture, not the light transmission.
The calibration procedure is correct, but lenses rarely are!
I shot some Kodak VPL ISO 100 under artificial lighting and when I got it back from the photo lab it was underexposed. I took careful readings and bracketed my shots one Fstop in each direction. The images are dark and they are also quite red--sort of like looking at them under safelight conditions. I have been told that VPL is for natural not studio lighting and that there is no 4x5 studio lighting negative film. I used 100 watt halogen (which I was told is closer to natural light balance than tungsten) and 60 to 150 watt household lightbulbs to light my subject. Will getting higher wattage studio lights get me the light I was missing, do I need to use transparency rather than negative film if I need to shoot indoors (and can I scan transparencies for digital manipulation) or is there some other solution to my problem?
Reply: VPL is for long exposures, but as you say, not for tungsten light. Your domestic bulbs are very yellow-red indeed, probably no more than 2,500K compared to the 2,850K of the 100W tungsten halogen light, but even these are too yellow for tungsten film, which needs lights running between 3,200K and 3,400K - proper tungsten luminaires like 800W Redheads or video lights, or photoflood bulbs (over-run tungsten 275-500W). You can overcome the problem slightly by overexposing the film 1 to 2 stops; this gives enough detail in all three emulsion layers to permit re-balancing during printing. However, normal exposure results in a blue deficiency which can't be corrected by print filtration. Proper correction can be obtaining by using blue A-to-D type 80A filter, but this won't quite cancel the warm cast from household lamps, so you still need to give 1/2 stop extra exposure to give the printer sufficient blue detail to print a neutral result. Even better idea - why not try flash? Even a small flash unit would have to be more powerful than little 60 to 150W bulbs!
I'm involved in a project which aims to use digital cameras and
modems as a low cost way of getting medical X-ray information from
remote locations.
My background is medicine, not computing or photography but I have an
amateur interest in these areas. I would be grateful for any
suggestions re magazines/books that would provide a relatively
painless introduction to the field of digital imaging, manipulation
and transmission. Also are there any newsgroups on the topics?
From Andy Weissman
I'm heading for a summer trip and will be unable to control film
temperature.
I have liked my results with Velvia (I rarely do portrait-type pictures),
but I always read it has temperature sensitivity and I'm concerned high
(e.g. inside of auto on 90 degree day) temperatures could cause problems.
My questions:
Fujichrome Velvia is a professional film and should be kept refrigerated before use and between exposure and processing (freezing is not recommended). Provia is the same, but less sensitive to heat. The best choice for your vacation would be Fujichrome Sensia, which is available in Europe without pre-paid processing, and probably can be obtained the same way in the States. This is identical to Provia but has a different maturity color balance, and does not require refrigeration; it is much less sensitive to heat problems. Provia 400 is pretty grainy by comparison with the 100 speed film, and not ideal for those bright sunny days. Sensia has a 200-speed version. There's a review of the Sensia films in PHOTON, and this includes comments on its suitability for use on extended summer tours.
Unfortunately, Kodak use different names for their films in the USA and Europe. We have Panther (professional) and Elite (retail) E6 non-process paid emulsions in Europe. I do not know which type Lumiere is equivalent to. The 'X' version will probably be the same variant as the 'X' versions in Europe - warmer color balance, hotter contrast, for overcast days or combating blue sky light. You should use the retail, amateur version if your film is likely to be kept for a while after exposure, or exposed to heat. In Europe it is also lower in price and as far as I can see the results are every bit as good.
I recently bought a Canon EOS 5. I like to take the camera out into the mist or rain. I am a bit worried about the moisture getting into my camera. Do you have any tips on how protect my camera from moisture when I take it out in wet conditions? Do you have a book you could recommend which will explain how to protect your camera from rain?
Reply: I have tested the EOS-1n in heavy rain, complete their 300mm f4 USM apo telephoto, and it continued to function perfectly when wet. The EOS 5 probably needs more protection. One simple method is to find a suitable polythene bag, a UV filter, and an old filter rim. Fit the UV filter to the lens. Put the camera in the bag so it is well covered, and polythene can be stretched over the filter. Then screw the old filter rim (with no glass in it) on to the UV filter, through the polythene. It will cut the polythene but grip it firmly enough to secure it. Remove the circle of polythene. A more robust version of this idea is the Ewa-Marin Rain Cape for SLRs from German company Ewa. It has a glass front and plenty of space to allow operation of the camera, and protects the operator as well.
From Paul McDonald:
Is there a trick in photographing stain glass windows, what is the best film - negative or reversal? Is natural light better, if available? Any suggestions would be helpful. P.S. I use a 2 1/4 format and have access to photo lamps.
Reply: the exposure does often need to be less than a TTL reading will indicate, and is best obtained by taking a close-up reading from a yellow pane viewed at the same angle you will shoot (avoid red or blue panes). Because stained glass is lit by skylight, using a perspective control lens and close position can avoid darker areas at the bottom of the window which may appear if you move right back (a close viewpoint means you look up at the window, with sky behind it, not nearby trees or buildings). Reversal film is much better than negative, if only because a slide conveys the brilliance of a trans-illuminated subject so much better when projected. The ideal 'print' from such a shot is a Duratrans mounted on a light box! Photo lamps will do you no good unless you have a specific interest in recording stonework details, and use blue filtration on the lamps to balance them with incoming daylight.
From Stefan Deisz:
I have a Sigma SA300 and have problems with filmcartridges I
load with a bulk film loader. Since these cartridges are a little
smaller (yes, they really are) than "normal" cartridges, the film
does not come in and out of the cartridge very smoothly.
I am sure I have correct cartridges, and suspect this is an error
in the design of the Sigma body. (I have no problems at all with
other cartridges).
Reply: I suspect that you are using RADIAL type cassettes, in which the lip thru which the film exits points towards the spool (not exactly on a radius, but nearly). Many reloadable cassettes were made this way. Radial cassettes were found to be causing problems with motordriven cameras about ten years ago, mainly when the film is left unwound for a few days and develops a slight kink. Some also admitted light thru film cassette inspection windows. All the major makers switched to TANGENTIAL cassettes, in which the lip is arranged at a tangent to the circumference, and the film exits without any kinking. You can buy reloadable tangential cassettes. I find some of the best are the plastic ones with slotted spools which come filled with Eastern European film like EFKE.
Followup from Stefan: Unfortunately I do not use the radial type,
but the tangential type.
(I say unfortunately because otherwise it might be the solution to
my problems).
I did the following test:
Insert the cassette in the body, and press it slightly in its place with
your left thumb, then try to pull out the film. (I think this closely
resembles what happens in the camera). The "manufacturer-made" film came
out smoothly, but with the film I loaded
myself, I had to use a lot more force. (Not very much, but a lot more than
the other one). With a piece of paper, I managed to make the "bad"
cartridge fit as good as
the "good" one, and after this there were no more problems. A friend of
mine uses a Canon EOS 5 with the same cartridges, and has no
problems, so I am afraid that the Sigma body is the problem.
Followup reply: well, I think you have your answer - the Sigma body is clearly less tolerant of slight variations in cassette size, and possibly the lip position. We'll leave the whole of this correspondence in place, as the radial/tangential cassette changeover has almost been forgotten today, and may help other readers who load an old film (or one produced in a country using old cassette machinery) and experience problems. For now it looks as if you will have to stick paper on all your reloadable cassettes...
From Henk Jan Spanjaard, the Netherlands:
I've got a Nikon F90 camera, and I have been for some time in search of
someone who can provide the technical specifications of the 10-pin
connector on the body. It is possible to use a Sharp organizer to get
certain settings out of the camera, and to make custom settings in it as
well. The problem is that this organiser and the Nikon card & cable which
you need with it are very expensive, and I wopuld have no other use for
this Organizer (I'm a bit chaotic, and like it that way... :-)... ).
The
"data-link" interface will use some kind of asynchronous protocol for
communications between Nikon & Sharp, so why not connect a PC to the
camera? (didn't Nikon think of this ???) Hopefully a PHOTON reader will
know the
specs or have figured them out (maybe even written a small
application for the F9?).
Reply: Henk, we are going to look for info from our Nikon UK contacts, as we know that similar programs have been written for the Canon T90 and PC. As you say, someone will have figured it out. In the meantime, any reader with this info may like to e-mail you and echo it to our own e-mail at the same time.
From Jim Stone, USA:
I have seen a short article about a UK-made camera called the Corfield Wide Angle 67 that is not yet available here in the US. There was no mention of price and no address (for more information) of the manufacturer. Can you help?
Reply: Jim, the Corfield 6 x 7cm wide-angle camera is now available from: