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hpulley
01-02-2011, 08:20 AM
May just have been 35mm defenders but the old adage was always that 8x10 lenses didn't need to be that sharp as they weren't enlarged 10-20x on printing like 35mm needed to be for anything more than the 4x6" snapshot developing plus prints option at the lab.

Which 16 and 25mm lenses cover 8x10" sheets and have good close focus characteristics?

Q.G.
01-02-2011, 08:35 AM
Zeiss Luminars, Olympus bellow head lenses (they were/are 20 mm and 38 mm in focal length), Leitz Photar lenses. I'm sure Nikon and others make the same type 'micro'-lenses as well.

Mind you, they only cover large formats at high(ish) magnifications. But then, that's what they are made for.

Different focal lengths are not chosen to get a different field of view, but are optimized for different magnifications (or rather, ranges of magnifications), so are chosen to match the magnification you're after.
As a rule, the higher the magnification you are after, the shorter the lens that's best suited. (For instance: the 16 mm Zeiss Luminar is best for 10 - 40 x, for a bit less, 6 - 25 x, the 25 mm Luminar would be better.)

hpulley
01-02-2011, 08:54 AM
Same as enlarger lenses. Thanks.

Diapositivo
01-02-2011, 09:39 AM
Well, just to split my half hair, if the spheric seed is opaque, you cannot see from any angle more than half of it, so you only need half inch of depth of field :whistling:

The question of the OP I think can be generalized beyond the macro field. If you use a 200 mm lens, on whichever camera, to take a shot of a landscape, and there is a certain bell tower in this landscape, the absolute size of the bell tower on the film will be the same regardless of the dimension of the photogram. On an APS, 135, 120, or LF film, given a certain focal lenght, the dimension of the object is the same, and the DOF is the same.

We have the "impression" 200mm is more a tele in a small format because we don't get, and don't print, all what would have been "around" the bell tower.

So if you use a 200 mm with a 4"x5" and with a 135, if you only print a 24x36 portion of your 4"x5" film, you have the exact same results.

The same applies to macro photography. So, strictly speaking you need a larger format than 24 x 36 only if you need a 1:1 reproduction, on film, of a subject that is "bigger than 24 x 36". (Or you need LF because you need movements and it is easier with LF).

At the end of the day, you can always use LF with movements, take a LF picture, and only print a 24x36 portion of it, but you will have used the Scheimpflug law.

Post #3 seems to suggest that maybe the OP deems that the actual f/value of 44 has an influence on the DOF. If this is the case, I'd like to say that to my (quite imperfect) knowledge, it has not. The light fall caused by extension tubes, bellows, or teleconverters, is not accompanied by a correspondent DOF increase, nor by a correspondent diffraction increase, because DOF and diffraction, as far as I know, depend on diaphragm aperture.

Fabrizio

Q.G.
01-02-2011, 03:13 PM
Same as enlarger lenses. Thanks.

But quite different thingies.

Galah
01-03-2011, 07:39 PM
Recently I have been trying to photograph a small round seed pod at about 1:1 with my Olympus OM1 and 50mm Macro with extension rings. I put the lens on f/22 which is probably an actual f/45 or so at 1:1. The 8x10 proofs I made aren't impressively sharp, and I think I have eliminated camera/subject motion as a cause.

Effective Aperture=Nominal Aperture x (magnification +1)

So, in your case (above) EA=22(1+1)=44 :)

Nathan Potter
02-14-2011, 12:01 AM
The Z stacking is superior but as David points out this is an analogue site, so instead the OP could use a psuedo stacking technique developed long before digital shenanigans. That would be all analogue scanning photomicrography. The idea is simple and obvious but devilishly difficult to execute. The trick is to illuminate the subject with a sheet of light of a thickness equal to approximately the depth of field of the lens while simultaneously focusing the lens at that illuminated sheet. The subject is then moved thru the sheet of light while the shutter is open, exposing the entire subject during its transit thru the plane of best focus and illumination. Since the shutter is open during the extended exposure time (typically 10 to 30 sec.) the room needs to be darkened to avoid extraneous light fogging the film. The key advantage is that if the plane of light can be made as thin as the depth of field of the lens at a moderate aperture - say f/8 or 11 - pretty decent resolution can be realized over a large distance. The subject needs to be translated thru the focus plane at a uniform velocity to avoid banding of the lighting uniformity. One can use either a stepper motor or even gravity thru a dashpot connection for translation. I have done this in a vertical setup with translation in Zaxis and dual slit illuminators horizontally positioned in an X and Y plane. Lots of setup here but it gets the job done with superlative results.

Nate Potter, Austin TX.

Philip Taylor
04-24-2013, 07:16 AM
Ok guys, lets get it right. It's Photomacrography not Macro Photography.

Right, now...since we're on an analog forum....
Forget Z stacking & look up "light scanning photomacrography". Simple.
Yes, you need to find, or build the equipment, but the results can be stunning...especially on LF.

Sorry, should have read the previous post first :D
Nice to see someone else has enjoyed this technique Nate!

E. von Hoegh
04-25-2013, 11:03 AM
Recently I have been trying to photograph a small round seed pod at about 1:1 with my Olympus OM1 and 50mm Macro with extension rings. I put the lens on f/22 which is probably an actual f/45 or so at 1:1. The 8x10 proofs I made aren't impressively sharp, and I think I have eliminated camera/subject motion as a cause.

I use a Nikon 55/3.5 at that ratio quite a bit, and keep the lens at f:4 which means f:8 working aperture. You're working at f:45, and diffraction is giving you mush. Your lens is limited to 33 lp/mm at that stop (assuming the film is recording everything the lens gives it), when you enlarge it to 8x10 that becomes about 4 lp/mm on the print.

polyglot
04-25-2013, 08:02 PM
The Z stacking is superior but as David points out this is an analogue site, so instead the OP could use a psuedo stacking technique developed long before digital shenanigans. That would be all analogue scanning photomicrography. The idea is simple and obvious but devilishly difficult to execute. The trick is to illuminate the subject with a sheet of light of a thickness equal to approximately the depth of field of the lens while simultaneously focusing the lens at that illuminated sheet. The subject is then moved thru the sheet of light while the shutter is open, exposing the entire subject during its transit thru the plane of best focus and illumination. Since the shutter is open during the extended exposure time (typically 10 to 30 sec.) the room needs to be darkened to avoid extraneous light fogging the film. The key advantage is that if the plane of light can be made as thin as the depth of field of the lens at a moderate aperture - say f/8 or 11 - pretty decent resolution can be realized over a large distance. The subject needs to be translated thru the focus plane at a uniform velocity to avoid banding of the lighting uniformity. One can use either a stepper motor or even gravity thru a dashpot connection for translation. I have done this in a vertical setup with translation in Zaxis and dual slit illuminators horizontally positioned in an X and Y plane. Lots of setup here but it gets the job done with superlative results.

Sounds interesting, but I'm slightly confused. Surely if you're moving just the subject (with illumination plane, camera and focal plane all stationary) then you're just going to get a smear unless the shape of the subject is extremely constrained so that no two parts at different depth image onto the same part of the film?

Wouldn't it be more accurate (obviously more difficult) to slide the focal plane and the illumination plane through the subject while keeping the subject/lens distance fixed? It'd mean that the light and film back go in the same direction but at different speeds unless the magnification is 1:1 and doesn't vary much through the depth of the subject.

Philip Taylor
04-26-2013, 06:23 AM
then you're just going to get a smear unless the shape of the subject is extremely constrained so that no two parts at different depth image onto the same part of the film?

You're still making a 2 dimensional image of a 3D object, so as you say, no two parts of the object are exposed onto the same piece of film. If light hits a part of the object underneath another which has already been imaged, the first piece is blocking the now illuminated part (from lens viewpoint), so it is never imaged.

There are some issues with the technique:

Because camera, light sheet (& focus) are all set, and the image is only made at that plane as the object passes through it, magnification is constant, and therefore perspective doesn't work as it normally would. "Leading lines" no longer exist, and objects look a bit flattened.

A sphere would lose it's expected shape, I imagine.

To create a light sheet, often two boards in the shape of a donut are sandwiched 1 or 2mm apart from each other (we used brass spacers), then 3 lights are placed 120deg from each other around the edge, directed into the centre.
This works well, but if the object has holes or depressions in it, they may not be illuminated as it passes through the sheet - the end result is an object with a deep shadow in the said depressions.

But, for a sphere, this isn't an issue.

Not sure if that makes things any clearer or worse.

polyglot
04-26-2013, 07:21 AM
Yeah, that helps; thanks. As you say, there is a loss of the perspective and my concern is that the change in projection could cause overlaps. Can't as I know for sure though.

DREW WILEY
04-30-2013, 03:15 PM
My Sinar 4x5 has 28 inches of bellows, so I'd just grab the thing and be done with it. It would faster than reading thru all the foregoing.

Dan Fromm
04-30-2013, 09:51 PM
My Sinar 4x5 has 28 inches of bellows, so I'd just grab the thing and be done with it. It would faster than reading thru all the foregoing.

Drew, there's no way that either of us, with our antiquated gear, can get the infinite depth of field at any magnification that confocal techniques do. That said, confocal techniques can't be used in the situations where I've shot at high magnification.

Around the turn of the century, one of my collaborators who was also chairman of a college biology department, scraped up $250 k and bought a shiny new confocal microscope. He remarked to me that his professors had better get a lot of good publications with it.

DREW WILEY
05-01-2013, 01:06 PM
What you need Dan is a scanning electron microscope - no good for color, however. I don't think a mere
250K will buy one of those, however ... perhaps a used one.... And confocal techniques per se won't resolve critical diffraction issues. Apochromaticity at high magnifications requires a very specialized kind
of hybrid correction, way out of my $ league. I'd be happy just to have one of those Zeiss research microscopes like I used in college, along with a sheet film holder. They're common, but still in demand
enough to be expensive. The Polaroid holders could be adapted to standard sheet film I think. Or the
Sinar system itself can be adapted to high magnifcation work - you just need a very stable base column
and a lot of rail sections and bellows. I don't really understand all this fuss, however ... unless someone needs 1:1 or some other fixed scale of reproduction, the larger film at smaller aperture will
give better results, and in something printed small like publication, it won't matter anyway. Sometimes
it's fun to look at images on Nikons "Small World" site. Most are false color and taken with expensive
gear from their medical imaging division.

Dan Fromm
05-01-2013, 01:31 PM
Drew, I got into photography to take portraits of unconstrained live fish in my aquariums. I'm not aware of anything that will beat an SLR (film, digital, who cares?) with flash illumination in that application. Studio and lab photography are one thing, shooting mobile subjects is another entirely.

I also shoot small preserved fish, with emphasis on the bones in their fins. For this transmitted light is preferable to reflected and an SEM is pretty useless. This hasn't stopped some nut cases I know who had access to an SEM from trying, though. The shots they published weren't informative.

DREW WILEY
05-01-2013, 02:29 PM
Do it like they do butterflies - freeze the fish first! You can always eat them afterwards (just kidding). The other day I bought my wife an amphibious 35mm because she likes to snorkel. Yeah, I know I guy who does bugs with an 8x10 ... but either dead or more often stuffed into the fridge a little while first. I've done macro with 8x10, and once enlarged, have had a few precisely-focused live bugs come to view, which I wasn't aware of when the shot was made. Wish I could find an underwater housing for
my P67, but I don't do it enough to warrant the expense, and all the gaskets for those things have to
be replaced at this point in history - probably been three decades since Pentax stopped making them.

Mark_S
08-23-2013, 12:16 PM
Coming to this thread late, but I have been working on a project where I have been doing close-up photos of tattoos, looking at the interplay between the pattern of the ink and the texture of the skin. The subject is usually curved, and the total magnification to the final print is generally on the order of 10X. I have used 35mm, 6x6, and 4x5 and have gotten decent images from all 3 formats, but depending on the particular subject sometimes one system works better than others.

If my subject is relatively flat (for example, a tattoo on a back), then I tend to prefer the 4x5 where I can adjust the plane of focus to have more control over what I have in focus vs what is thrown out of focus. Otherwise, I have tended to like using one of the smaller formats where more of my total magnification is coming during the printing stage.

One of the other considerations that I have is the exposure time - since my subjects are alive, and don't remain completely still, faster shutter speeds are better, and when I am using L.F., because of more magnification to the negative, I am forced to longer exposures.

KenS
08-23-2013, 12:46 PM
I've been photographing some small but round objects, and running into DOF limits.

I'm not sure how I missed this when it was first submitted... but... there is a means whereby one can reach the objective of 1:1 (and over) magnification of half of a spherical (or non-spherical subject) and have a 'sharp' image of the whole that is observed.

Scanning slit photomicrography where the subject passes through a narrow beam of light from (usually) at least three light sources where the beam is horizontal 'flat and narrow' (via slits between two vertical "barn doors"that control the 'height' of the light beam) and the subject is raised up through the light beam at a predetermined speed (the room 'should be 'in the dark) with the shutter open (time exposure). The results can be 'magnificent'

There should be information on 'the net'... but I'll see if I have a copy of the paper originally published in the Journal of Biological Photography... (Or may time to visit "JStor"... again).

Ken

realart21
12-05-2013, 05:57 AM
Well, Firstly gain complete knowledge about subject. Then Carefully use of Camera and macro.