7

There are lots of budget cameras (for example about $200) offering 30X optical zoom lens along with 8.0 million pixels of image capture. Definitely, the quality of picture, focus, and depth of field is not comparable with a DSLR camera.

I decided to buy a macro lens for my DSLR camera to take microscopic photos, but the popular macro lens are in the range of 60 - 150mm. For an optical zoom comparable with budget cameras, I would need a macro 720mm lens, which is not common.

With what lens, I can take microscopic photos (with optical zoom 30X or higher) with my DSLR camera?

16

There seems to be some understandable confusion here.

At "ordinary shooting distances"¹ (for want of a better term), it is convenient to think of the focal length of a lens as a sort of shorthand for magnification. From 6 metres away (20 feet), a 600mm lens will make your subject appear roughly ten times larger than it woud have if you were using a 60mm lens. It's not precisely true except at infinity, but you'd need to go digging into the decimal places to notice the fib, and lensmakers usually round the actual focal length of the lens off to a "familiar" length for labelling, so let's call that close enough for government work (or close enough for jazz, if the government thing offends you).

In macro (and micro) photography, we are generally concerned with fixed amounts of magnification. If a 60mm macro lens and a 600mm macro lens are both labelled as having a "1:1 reproduction ratio", then they will both make the subject the same size on the sensor. That is, they will have the same magnification. The difference between the two lenses is that you could get that magnification using the 600mm lens from roughly ten times as far away from your subject as you could with the 60mm lens. In order to accomplish a 1:1 reproduction, though, both the subject and the sensor (or film) need to be the same distance from the optical centre of the lens, namely twice the focal length.² So you can think of focal length as a convenient shorhand for "working distance" in macro photography, but you do need to keep in mind that longer focal lengths mean larger, heavier and more expensive camera assemblies to get what is essentially the same magnification.

Micro photography is the reciprocal, if you will, of "ordinary" photography. That is, your subject will be closer than twice the focal length (but no closer than the focal length plus a smidgen) to the optical centre of the lens, and the sensor will be more than twice the focal length away from the optical centre it sees. And just as the slightest nudge of the focus ring will mean the difference between focusing 15m (50 feet) away and focusing 6m (20 feet) away, with the distance between the sensor and lens hardly changing at all in "ordinary" photography, getting just that much closer to the subject means increasing the distance between the sensor and the lens by a huge amount (relative to the focal length) in micro photography. For this purely practical reason, shorter focal length lenses are used to produce higher magifications. The loss of working distance is more than adequately made up for by the reduction in size (and awkwardness) of the apparatus. It is one thing (and a difficult thing at that) to manage a 12.5mm micro lens on the end of a 30cm-long (12") camera + bellows arrangement to get a particular magnification of a very small subject; it is quite another to manage a 600mm lens on the end of a 14.4-metre-long (48 feet, roughly) camera setup for the same magnification.

For actual photomicrosopy, the sort of microscope eyepiece adapters that have been mentioned in other answers are The One True Answer. They allow you to use very short focal length lenses that have been optimised for high magnifications, as well as a rigid apparatus that will present the fewest number of problems in capturing an image.

If all you want is macro (that is, images where something roughly an inch or 2.5cm in size will completely fill an APS-C- or DX-sized frame), then you want a macro lens. The focal length will determine how far from the subject you need to be to get that 1:1 magnification (though since most modern macro lenses are internal focus designs, you would actually have to check the minimum focus distance and the physical length of the lens to determine what the actual working distance would be). You can achieve somewhat greater magnifications by using extension tubes in conjunction with a macro lens.

For more extreme magnifications without actually resorting to a microscope, you might find that reversing a wide-angle lens will get you where you want to go. Wide angle lenses (these days) are almost all retrofocal, meaning that they have a longer focal length on the "sensor" side of the lens than they do on the "object" side. When you reverse the lens, that means that there is a greater distance between the subject and the lens than the marked focal length would indicate, and that you can project a much larger image onto the sensor by moving the lens only a little bit further from the sensor (using extension tubes or bellows). Even mounting the reversed lens directly onto the camera body will (usually) produce images greater than life-sized.


¹ That is, distances at which no exposure compensation would have been needed to account for "bellows draw" on a unit-focus lens.

² I am simplifying reality here somewhat and using the thin lens version of the truth. With real photographic lenses, especially SLR lenses, it would be normal for the subject and the sensor to "see" the optical centre of the lens as being in two different places. The closest you'll see in the real modern world to true thin lens behaviour on SLRs will be with Tessar and Symmar lens designs. As well, internal focus lenses actually focus closer by "zooming out" to a shorter focal length while keeping the front of the lens anchored in space, so a "60mm macro" would actually be a 40-45mm lens when focused for 1:1.

  • There is another confusion left unresolved here: The result will probably not be VIEWED as a sensor-sized print, so there is magnification inherent in the means of displaying it too.... – rackandboneman Oct 9 at 19:28
4

You cannot do what you are asking to do. There is no lens which will give you the desired magnification combined with minimal focal distance to perform microscopic photos. Even if you took something like the Canon MP-E 65mm F2.8 1-5x macro and added a zoom element inbetween: you wouldn't be there.

If you could somehow manage to get enough magnification: I cannot imagine how you would get enough light.

To do microscopic photos on a DSLR generally requires a microscope adapter. Here's one chosen relatively at random to illustrate: http://www.amazon.com/gp/product/B005OZ5NXU/ref=as_li_ss_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B005OZ5NXU&linkCode=as2&tag=bryanmirafpho-20

3

You seem to have a fundamental misunderstanding of how lenses and microscopy works. Typical photographic lenses, including macro lenses have a minimum focal distance. That is the minimum distance from the lens at which they can focus. This means that the actual meaningful magnification of such a lens is not actually all that high.

Microscopes are designed with radically different construction to provide high magnification. To take photos of microscopic things you will need to use a microscope that will allow use of a DSLR/Microscope adapter. Typically, such adapters go in place of the eyepiece, so they don't provide as high of magnifications as you would normally see looking in the microscope, but will still use the main element of the scope. (A typical microscope uses a magnifier in the eyepiece plus the magnifier near the subject.)

3

You could reverse stack two lenses, which can give you an effective lens length of 2000mm (that's the right number of zeros) or more.I recently did this with the only two lenses I have - a 55-250 mounted on the camera, and a 18-55 reverse mounted onto that:

My setup

The trade of with using this method is that the focusing plane of the finished setup will be paper-thin: around 1 mm. Also, this configuration will only be able to focus on something that is less that around an inch from the end of the lens. If you are using your DSLR as as a true microscope, then neither or these matter.

Another trade off with this method is that you will need lots of light to photograph much of anything without blurring.

If you have two lenses, then try this method. It may work way better than you expect it to. Here is an example photo (not cropped, directly from camera):

My Finger!

  • Great answer! The names of the adapters you used to reverse-stack the lenses would be very helpful. – Pranab Dec 21 '18 at 10:13
2

I have a consumer camcorder which gives 32X optical zoom and after using it for a year I wanted a DSLR which would do the same thing. For a DSLR lens to offer the same zoom range is unheard of and I was disappointed to learn how the DSLR makers aren't making such lenses. I have a 10X zoom lens for my DSLR which all by itself is larger and heavier than the entire camcorder combined with its lens which gives 32X. I've seen a 5200mm lens for a DSLR, but using it every day would be like like a case of the tail wagging the elephant.

If you only want macro with 30X THAT can be done, but not with the macro set ups generally shown.

You can use a microscope objective lens on your DSLR without spending big bucks for a commercially manufactured microscope adapter. There's probably half a dozen ways to make an adapter yourself - if you have - or know someone with basic shop skills.

https://www.youtube.com/watch?v=dj6Y1SDnQJQ is a link to a youtube video showing one way to accomplish what you're asking.

Recently I researched buying an adapter like the one shown in the video which is used to quickly and easily exchange one microscope objective for another. A high quality microscope is expensive and even the adapters shown in the video are prohibitively expensive for many part time hobby photographers. It is very easy to avoid that cost by just putting the desired microscope objective in place of that adapter and leaving the objective installed on the pipe cap permanently. PVC fittings are dirt cheap compared to the cost of the chrome adapter shown. If you don't want to risk repetitively straining the objective over and over to make several changes while experimenting - simply use a different PVC fitting for each objective you want to use.

Different diameters of PVC pipe can be fitted together using freezer tape so the pipes can slide for coarse focus adjustments or a UPS telescoping mailing tube can be had for free from the post office. Just paint the PVC flat black inside and out and allow the paint to cure before using. There is a certain kind of paint commonly available in spray cans which is made so that the paint fuses with PVC pipe. If that kind of paint is used the chance of paint flaking or peeling is significantly decreased.

If you prefer a more professional looking and more convenient approach than PVC pipe you can use a camera / lens bellows. The advantage of using the bellows is much greater focus precision.

As with telescopes - many beginning microscopists make the mistake of attaching their most powerful eyepiece first and then giving up because nothing could be seen. That frustration could be avoided by installing the least powerful ocular first, then next adding a more powerful magnifier. It is much the same when using a microscope. It might be wise to begin by using a 4X microscope objective for finding objects then substituting the next more powerful objective.

A 4X microscope objective can give powers in excess of 4X by moving the objective further away from the camera lens in the same way higher magnification can be had by adding longer extension tubes to a prime lens used for macro shooting. After gaining experience with the 4X microscope objective, then add a more powerful objective after gaining experience.

As with any home brew or DIY project the performance you enjoy may vary with the skill, patience and accuracy of the builder and user.

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