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gma
06-22-2004, 12:31 PM
I have an idea to use my Pentax 55mm SMC Takumar for some macro photos on a 4x5 view camera. I plan to mount the lens backward and use long calculated exposures with controlled studio lighting. Any reason this is not a valid method? Any comments appreciated.

glbeas
06-22-2004, 12:54 PM
Sounds like you have the technique nailed to me. Got a darkroom handy to check the bellows and reciprocity compensation?

Eric Rose
06-22-2004, 01:19 PM
just make sure you have enough coverage from the lens.

Tom Hoskinson
06-22-2004, 01:50 PM
At high magnification you should have adequate coverage with the 55mm, but the working distances may be too close to allow proper lighting. I like to use at least a 110mm and usually a 150mm for macro work with a 4x5.

Eric Rose
06-22-2004, 01:52 PM
Tom, is that a 110 or 150 normally used on 35mm?

Tom Hoskinson
06-22-2004, 02:04 PM
No Eric,
I generally use my 110mm Super Symmar XL and either my 150mm Apo Ronar or my 150mm Apo Sironar for LF macro work. All of these lenses cover 4x5 at infinity and all are in Copal shutters. I also use these same lenses (bellows mounted) for Medium Format macro work.

However, at high magnifications 100mm and 150mm 35mm lenses will work - no shutters, of course.

gma
06-22-2004, 02:37 PM
If my calculations are correct for a two inch lens I will have a lens to subject distance of 2.9" and a lens to film distance of 6.4" for a magnification of 2X plus with adequate 60 degree cone coverage for the 4x5 film. I want to make some macro photos of plant structure. My wife has some interesting specimens in the garden window. Since the lens to film distance is 3X focal length that means the exposure compensation is 3 Squared or 9X, right? So if I read 1/10 second on the meter it will really be 1 second plus reciprocity effect.

glbeas
06-22-2004, 02:42 PM
You might want to make a white card reflector with a hole in it to put the lens through to bounce light onto the subject for more even lighting. A ringlight would be even better.

gma
06-22-2004, 03:53 PM
Thanks for the suggestion of the white card with a lens cutout. I'll try that. Also some side lighting with one side brighter than the other. I am not a big fan of even ring lighting for 3-dimensional objects. I can see that it is very useful for photographing coins or stamps or other more or less 2-dimensional items.

gma

glbeas
06-22-2004, 06:26 PM
I wouldn't discount ring lights entirely. If you want some modelling simply cover half the ring. The main thing is to get the light between the camera and the subject but not shining into the lens. A ringlight does that. You can make a homemade version with a cheap bundt pan by cutting a hole in one side and pointing a small flash into it. The light will bounce around the shiny insides and out, you can shoot through the hole in the middle, though the hole may have to be enlarged for some lenses. It's a fairly cheap experiment.

gma
06-22-2004, 07:12 PM
I like the idea of flash into a bundt cake pan. I might try that and also some variations on the white card - maybe aluminum foil. I will photograph some very small cactus plants with tiny hairlike "spikes" that I think will benefit from side/backlighting against a solid black background. I know the result that I am after. Now I have to figure out the procedure to make it happen. When I get the first few done I will post in the experimental gallery with 2 or 3 different lighting setups on a single subject.

David A. Goldfarb
06-22-2004, 07:28 PM
It should work. Lenses for smaller formats often have plenty of coverage at macro distances. If you reverse the lens, though, be particularly careful to shade the exposed rear element. Reversed lenses are very flare prone.

You might also consider reversed enlarging lenses. They usually work quite well for macro, and you don't have to worry about blocking the aperture pin and such, as you might for a 35mm SLR lens.

gma
06-26-2004, 09:33 AM
A quick update on this project. I found that I already have a reversing adapter for Pentax screw thread mount with 49 mm male thread filter threads on the other side. I have epoxied the ring into a lens board in a position that will place the f/stop ring to the top side of the lens I intend to use to make it easy to set. Also the auto/manual dial is up. The lens focus can be used as well. All I need to do now is make some sort of lens shade and I will be ready to test tomorrow.

glbeas
06-26-2004, 07:22 PM
If you have an extension tube for the pentax it might do for a shade if it's not so deep it vignettes.

gma
06-27-2004, 07:36 AM
Great suggestion, Gary. I should have thought of that - so obvious now that you mention it. I do have extension tubes of various lengths.

gma
06-27-2004, 07:30 PM
I set up using some very small house plants. At greater than life size they are too three dimensional even stopped down to f/16. I set up some household product boxes and they are very bright and easy to focus with the 55mm f/2 lens. I know now that the concept works as I thought it would. I need to test using some individual leaves approximately parallel to the film plane.

ThomHarrop
06-28-2004, 10:07 AM
I set up using some very small house plants. At greater than life size they are too three dimensional even stopped down to f/16. I set up some household product boxes and they are very bright and easy to focus with the 55mm f/2 lens. I know now that the concept works as I thought it would. I need to test using some individual leaves approximately parallel to the film plane.

At the kind of magnifications your are looking at depth-of-field will be measured in millimeters. You might consult Al Blaker's book "Applied Depth of Field" to see what sort of apertures you will need. I can say without much hesitation that f/16 isn't going to do it. You will end up stopping all the way down meaning you will need a lot or light or a very stable subject.

gma
06-28-2004, 12:00 PM
I am using a reversed 55mm lens that only closes to f/16. I think I will be able to shoot only flat leaves, feathers, etc. and they will have to be parallel as possible to the film plane. My first test was with some tiny cactus plants that have spikes that are waaaaay to deep to focus.