A couple macro questions

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KecheMukwa
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A couple macro questions

Post by KecheMukwa »

I'm in the market for a good macro lens, so I've been doing some research lately. I'll be using it more for insects than herps. I have a couple questions about macro equipment/techniques.

First, does anyone have experience using any of the Carl Zeiss Makro-Planar lenses? If so, what are your thoughts on it/them? They look to be high quality pieces of equipment (complete with a high-end price tag), but I've noticed that they only have a magnification up to 1:2, not 1:1.

Second, has anyone used a reverse mounted lens for macro work? I work with very small insects so a magnification greater than 1:1 would be helpful. Trouble is, I shoot Nikon and as far as I know there isn't a Nikon mounted lens with >1:1 magnification on its own.

- Jay

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Re: A couple macro questions

Post by fvachss »

While reverse mounting lenses can be an effective way of increasing magnification on the cheap I'd recommend using extension tubes to achieve pretty much the same effect. That way you can at least retain aperture control from the camera. Most ways I've seen using a reversed lens there is no electrical contact with the camera and you have to set the aperture in advance with the lens mounted normally, remove it to fix the aperture and then remount the lens reversed to take the picture. Also once you have done so the view through the (stopped down) lens at your subject will generally be very dim. This works well enough for static subjects, but I'd hate to try track a moving bug this way.

I have no direct knowledge of the Zeiss Makro-Planars (other than of their sterling reputation), but honestly I think with macro lenses you pay for utility not sharpness - they're ALL sharp, particularly stopped down as is the case in most applications. Utility in this case means things like magnification range, working distance, usability with desired camera bodies, possibly image stabilization, etc. Given that, for insect work with the Nikon platform I'd probably just decide the working distance I required and choose the appropriate focal length Nikon mount macro lens. Then buy tubes or a bellows as needed to get magnification up to the desired level - and spend the remaining budget on lighting (which matters as least as much as lens choice in producing good bug shots).

In fairness, I'm a Canon guy so the Nikon shooters here will probably have much better specific information on lens choice within the Nikon world, but I think my comments are fairly platform-independent.

reptileexperts
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Re: A couple macro questions

Post by reptileexperts »

The biggest thing with macro lenses is working distance, how much do you need, how much do you want. When you work with some subjects, like bugs that sit still, you dont need a 180mm macro lens that is more beneficial when trying to photograph a skittish frog in suto. With the remark to extension tubes, they will get you above the 1:1 mark, but not by much, but its a pretty significant improvement, even on the cheap.

With the Nikon 105mm if you take the 20 and 36 extension tubes from a set of the Kenko, you should effectively get a 1.5x magnification if I'm not mistaken. Meaning that you only need a 2.33 cm subject to fill a full frame sensor, even less on a cropped sensor body. The issue is your working distances changes quite a bit as well, and you will lose focus at infinity. Only an issue if you plan to go back and forth between shooting styles.

If you were on the canon side of things, canon has a 1-5x micro lens that would blow your socks off! But takes a lot of tehcnique and practice to use it effectively.

Cheers

bgorum
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Re: A couple macro questions

Post by bgorum »

Actually you don't need to give up aperture control with reversed lenses if you stack then on another lens. To do this you need a male/male adapter that screws into the filter threads of both lenses. You reverse the shorter lens on top of the longer lens and when the lens on the camera is set to infinity you end up with a magnification equal to the longer len's focal length divided by the shorter len's focal length. Of course you can always focus the lens on the camera closer for more magnification. For example if you stack a 50mm lens on a 100mm lens you get 2x life size, 4x if you stack the same 50mm onto a 200mm lens, etc. In effect you are turning the reversed lens into, (a very high quality), diopter. I have an old Canon 50mm f1.4, that I found laying in the middle of a road once, that I used to use that way. The only problem is it is really heavy and I worry about it damaging the lens I stack it on. Something small and light like a 50mm f1.8 or 28mm/24mm f2.8 is ideal for this technique. The optical quality can be absolutely outstanding too.

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Re: A couple macro questions

Post by fvachss »

bgorum wrote:Actually you don't need to give up aperture control with reversed lenses if you stack then on another lens....
Thanks for describing this. I like this approach better than the bare reversed lens one I was talking about. It also seems to allow for higher magnifications than are easily obtained with reasonable numbers of extension tubes.

Even with this approach though, in the high magnification regime where diffraction effects are typically more pronounced than the usual lens aberrations, I would think that any decent lenses would work and extra money would be best spent on things like lighting and support rather than expensive glass.

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chrish
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Re: A couple macro questions

Post by chrish »

I used to own a Zeiss Planar T Macro lens that I used to use with a bellows unit. It did give me very sharp photos, or at least as sharp as I could get within the limitations of using an extension bellows. I have a couple of shots somewhere that were taken at around 11:1 of butterfly wings, etc. But are they noticeably sharper than modern Macro lenses? Not that I could tell.

There are also specialized lenses like the Minolta - AF 3x-1x 1.7-2.8 Macro (Minolta/Sony mount) or the Canon Macro MP-E 65, but these have the same issues you will have with a bellows. The subject distances are so small that lighting becomes a real issue and they are just about worthless for unrestrained live critters. You have to focus the MP-E 65 by moving the whole camera!

I have used reversed lenses as well. It is a pain in the rear.

I think you need to realistically calculate how high a magnification you would really want. If you have a APS-C type sensor, a 1:1 magnification is going to fill the frame with something 23mm across. Crop down to 25% of that and you are talking about an image of something that is less than 6mm across. And you could do that from 50cm away with a longer macro lens (e,g, 180mm).

With today's modern optics, I can get a good shot with a 50 macro lens and extension tubes. Sure I have to crop a bit in the final image, but with today's better sensors, cropping down to 25% of the original frame size (or even less) still produces excellent images. With a 50mm macro lens and 100mm of extension you could get to 3:1 full frame theoretically. (With extension tubes, shorter macro lenses give you higher magnifications).

The beauty of using extension tubes for macro work is that you can use them with cheaper sharp lenses and still get decent magnification. Every camera manufacturer makes good, sharp, cheap 35mm or 50mm (non-macro) lenses that can usually be bought used for under $100. Put a $100 set of 3 extension tubes behind those $100 lenses and you can get magnifications in excess of 2:1.

Here's a quick grab shot I made from my desk just now to show the potential. This is uncropped, using a cheap but sharp 50mm lens, 68mm of extension tubes (36mm, 20mm, 12mm). $200 worth of lens/tubes.

Image

Here's about a 10% crop of that shot. This date on the penny is a little smaller than a small ant. The whole field here is about 5x7 millimeters.
That's plenty of magnification. And it was handheld, shot as I sat at the desk typing this (OK, I did stop typing for a minute to put the tubes and lens on and take the shot ;) ). The whole process from thought to shot to LR to pbase took about 3 minutes. You could clearly get a sharper shot by making ANY effort at all (like using a tripod!).

Image

Do you need more magnificaiton than this?

KecheMukwa
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Re: A couple macro questions

Post by KecheMukwa »

Thanks for all your responses guys! I really do appreciate it. They've all been super helpful.

The kind of thing I'd like to shoot is say, a 5mm bug eating a 8mm or so caterpillar (something that happens regularly in my lab and field site). My camera has a cropped sensor, so realistically I think 2x would do a fine job. If I'm doing the math right, a 50mm lens with 50mm of tubes should make this happen, ya? So chris, that would make the answer to your question: no, I wouldn't need more magnification than what you just used. I guess my new question is what would the working distance be with a setup like that? Would it be realistic for field use?

- Jay

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Re: A couple macro questions

Post by bgorum »

KecheMukwa wrote:so realistically I think 2x would do a fine job. If I'm doing the math right, a 50mm lens with 50mm of tubes should make this happen, ya?
No. To get 2x life size with a 50mm lens you would need 100mm of extension. 50mm of extension will only get you to 1x

KecheMukwa
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Re: A couple macro questions

Post by KecheMukwa »

Aye, but what if it was a 50mm macro and already at 1x?

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chrish
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Re: A couple macro questions

Post by chrish »

Yes, the total extension is what matters.

The theory says that If the lens goes 1:2 by itself, you will have 25mm extension in the lens + another of 50mm extension tubes will be 75mm extension therefore giving 1.5x total magnification.
If the 50mm lens already goes 1:1, then adding another 50mm of extension will bring you to 2:1.

Of course, most extension tube sets come in 12, 20, and 36mm options. So all three of those on a 50mm 1:1 macro will give you 50+68 = 118mm of extension. That should theoretically give you 2.36:1 total magnification. With a 1.5x crop sensor (you didn't tell us what brand you have, so the sensor size might be different), you can fill the frame edge to edge with an object 9.7mm across. But you will have to be almost touching the subject with the lens.

Just for "fun", I put my 90mm macro on the 68mm of extension tubes and photographed the same penny at maximum magnification.

Image

Here's another ~10% crop. This is something like 4:1 total magnification.

Image


The benefit of using the 90mm macro was that the lens was nearly 2 inches from the coin.

I think the decision you make depends on the answers to several questions:

1. How much magnification do you really need? If you have a APS-C type DSLR, you have a sensor that is approximately 23 mm across. Therefore at 1:1 macro setting, your 8mm caterpillar would be approximately 1/3 of the width of the frame. But you could easily crop down to make it occupy more space in the frame. You could easily crop to 2:1 or 3:1 or higher.

2. How much money do you want to spend? Buying a cheap 50mm lens will get you some magnification with tubes, but a proper 1:1 macro lens will be a lot more practical. If you are shooting insects or the like, having a lens like a 150mm macro lens that goes to 1:1 will allow you to get more, better shots that using a 50mm with extension tubes because you will be able to autofocus more quickly and won't have to get as close to the subjects. And you could always put some extension behind the 150mm lens to get you near 1.5:1.

Subject distance may be more important than total magnification in your ability to get the shot.

The last shot I posted was taken with a 90mm macro (which is a great length for herps in general) and 68mm of extension. That would probably be enough for almost anything you needed, IMHO.

And don't underestimate the problem of trying to light really high magnification macro shots. The lens often has to be so close to the subject that you can't use anything other than ambient light or specialized macro flash units or ringflashes.

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Re: A couple macro questions

Post by bgorum »

KecheMukwa wrote:Aye, but what if it was a 50mm macro and already at 1x?
That's different. In that case you would be close to 2x. You cant really predict exactly what the magnification will be because in all likelihood your 50mm macro uses some amount of internal focusing, possibly in addition to extension.

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chrish
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Re: A couple macro questions

Post by chrish »

bgorum wrote:
KecheMukwa wrote:Aye, but what if it was a 50mm macro and already at 1x?
That's different. In that case you would be close to 2x. You cant really predict exactly what the magnification will be because in all likelihood your 50mm macro uses some amount of internal focusing, possibly in addition to extension.
As far as I understand it (and I might not) that doesn't really matter. If the 50mm gets to 1:1 using extension or internal movement of lens elements, the effect is the same. Add another 50mm extension and you are at 2:1. Of course, IIRC, this only applies at the lenses maximum focus point (i.e. not up close).

The net effect is roughly the same. Somewhere right around 2x. It would be easy to test - simply take a photo of a ruler marked in millimeters. If you get a frame that includes roughly 11.5 mm, you are at 2x.

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Re: A couple macro questions

Post by fvachss »

You guys probably already know all this, but here are a couple of fun math facts about macro photography:

1. Depth of field decreases like 1/(M*M) where M is the magnification. That squared factor is very significant since it means that DOF gets smaller even when scaled to the size of the body in question. In other words getting a picture of the entire body of a horse all in focus is easy, getting one of grasshopper is doable though sometimes tricky, getting one of a sub-mm mite is almost impossible (at least at visible wavelengths using a single image). This is one of the big reasons many of us find extreme macro of live bugs in the field challenging.

2. Once you're in the diffraction limited regime (where most extreme macro photography takes place) there's a fundamental relation between image resolution and depth of field: dz < (dx*dx) / wavelength (where dz is the DOF, dx is the minimum feature size in the scene you can resolve in the image and wavelength is the wavelength of light being used to form the image).

The power of this relationship is that it means once you set the minimum resolved feature size you want the sort of equipment you use almost doesn't matter. FF, crop body DSLR, compact digicam, whatever - macro lens, tubes, diopters, whatever - use enough magnification to achieve a feature resolution of dx (typically imaged onto the size of 1 pixel on the sensor) then stop down enough to get a DOF of dz and the image will look pretty much the same. Stop down any more and dx goes up, stop down any less and dz goes down.

This isn't to say that using good equipment is entirely irrelevant. I still use a FF DSLR and dedicated macro lens for my high magnification macro work - but I do it for the control the equipment gives me and the total amount of image information I can record, not for any significant advantage in minimum resolved feature size compared to a properly set up compact.

PS. A quick caveat here: the diffraction limited DOF equation used here is really an approximate relationship that is valid only in the high magnification, high f number limit and depends somewhat on how DOF is defined. That said, the qualitative results I describe based on it are all things I've run into in practicing macro photography.

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