Macro Question

Hi guys,

With macro lenses offering 1:1 ratio, am I right in thinking that a 5mm insect would look the same size on the sensor for all lenses from the 1:1 focal distance? So would appear the same size in the frame?

The insect should appear the same size for both a 60mm 105mm and 180mm lens if the 1:1 focus is obtained

My doubt is that from a perspective point of view, the insect would be further away from the lens on the 180mm therefore would appear smaller as 1:1 from 30cm on a 5mm bug is not the same as 1:1 from 10cm

Not sure I explained myself properly but hope you can clear this in my head

Thanks
Shane

Yes, the insect would appear the same size on the sensor (and thus the frame) with each of the lenses you mention at 1:1. The difference is the sensor's physical distance to the insect, and as a result, you do have to watch your dof which is shallower the closer you are physically to the subject.

Thanks a lot for the clarification. So what is the limitation on the focus distance? Any reason it cannot go any further than 1:1 or is this just up to the manufacturer of the lens?

That's the way they are made. The focussing goes from infinity to 1:1. To get any closer physically you need either extention tubes connected to the lens, or an even more specialized lens such as the MP-E 65mm lens (for Canon).

Ok thanks. I just find that with small insects the 1:1 is not enough to fill the frame and the images require a bit too much cropping. Will look at the extension tube option.

Not sure which lens you have, or plan on having, but for insects you would be better off with a longer focal lenght such as 150mm or 180mm to get you further away. I have a 100mm macro lens and although I love it I find lots of insects just get spooked by being so close.

Thanks for pane #6 Daniel. I learned a bit reading that one.

I have the Nikkor 105mm VR micro. But sometimes would like to be able to magnify real small insects without having to crop the image too much.

I have read about both extension tubes and teleconvertors and not sure what would be my best option.

Quote:

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Originally Posted by shane shacaluga

I have the Nikkor 105mm VR micro. But sometimes would like to be able to magnify real small insects without having to crop the image too much.

I have read about both extension tubes and teleconvertors and not sure what would be my best option.

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Hi Shane,
You can use both (even at the same time). However, as you push magnification, lens aberrations become more of a problem as you are going beyond the lens design. This includes spherical aberration, field curvature, and diffraction. As magnification gets larger than 1:1, it gets more difficult to push with extension tubes or TCs. For example, with a 180 mm macro, a 1.4x helps OK, but a 2x does not give much more detail than a 1.4x. The canon MP-E 65 mm goes to 5x, and pushing with a 1.4x works ok, but 2x does not give much more detail. This also ignores the shallowing depth of field with increasing magnification. Another option is to mount a microscope objective into a tube and attach that to the camera. For example, buy a 1.25-inch T-adapter, then a 1.25 inch plumbing sink trap extension, paint the inside black and make a plug with the microscope objective mounted in it. Of course a microscope objective means you have to get really close (might be OK for dust mites).

Roger

Quote:

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Originally Posted by Daniel Cadieux

Yes, the insect would appear the same size on the sensor (and thus the frame) with each of the lenses you mention at 1:1. The difference is the sensor's physical distance to the insect, and as a result, you do have to watch your dof which is shallower the closer you are physically to the subject.

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If the subject is the same size in the frame (in this case all 1:1), then you will have the same DOF at any given aperture regardless of focal length.
The fact that you need to be closer to get 1:1 with the 60mm compared to the 180mm is cancelled out by the difference in focal length along with the corresponding difference in distance to the subject.
But there is a difference in working distance as Daniel pointed out and I agree that longer is probably better for insects.

Thanks for all your tips

I was more inclined to get the TC as it would then also be able to use it on my birding lens (still thinking which to get)

The final option I had considered was adding a Raynox adapter to the front of the glass as its easy on and easy off and would only be required on very specific subjects.

Will post some pics later

An important extra point that hasn't been mentioned yet is that the lenses with different focal lengths will also give you a different angle of view, which will affect the way your BG's will turn out. I own the 200mm Nikkor Micro, with which it is very easy to get a nice smooth background, simply because less of it is included in the frame compared to shorter focal length lenses. The downside is that sometimes you get a completely even colored BG, which can look a little unnatural. But the extra working distance of these long lenses is great as Daniel already mentioned.
Adding a front lens works well, I've seen many great results with it. You can also add it to non-macro lenses.

Thanks for that extra bit of info Jerry.

Think I will go for the Raynox then as its cheap and can be carried about quite easily

Hi Shane,

All macro images in my BPN albums were taken with a Panasonic bridge camera with a cheap screw on 4+ front lens, which I used before I switched to a DSLR. This setup enabled me to get much higher magnification than my current 1:1 macro lens. As a comparison, the non cropped image of the spider in the album called "RAW excercises" is a full frame 1:1 image of a wolf spider, which will probably be somewhere around 0.5 cm in size.
I was quite happy with the results with the screw on lens. You will find some quality differences with a normal macro lens, increasing existing lens abberations as Roger mentions being the most common. With my rig I especially had problems with color fringing.

Thanks for that Jerry. I was planning to buy a Raynox to use on my Panasonic FZ100 but a pitbull headbutted my camera and bent the part where the entension tube screws on so I could use it.

Now that I have the DSLR and the dedicated macro lens, i still feel the need for higher magnification so deciding on which to get

So could we post the pros and cons of the following 3 options for my 105mm macro lens:

Extension tubes (would like to be able to use AF on these as the D7000 AF is very good)
TC - also to use with AF and if so which is best 1.4x, 1.7x or 2x (I plan to buy a bird lens soon so this may put some extra weight on this option)
Raynox 250 or 150

Thanks

Hi Shane, the Nikon TC compatibility chart states that you will not have AF with any of the Nikkor TC's on the 105mm Micro. Not sure about third party TC's.
But I wouldn't worry too much about AF. At magnifications of more than 1:1 the limited DOF will put extra weight on a very exact focus to get good and appealing images, so you'll probably don't want to rely on autofocus and only use manual focus an/or a macro focus rail anyway. I use the Nikkor 200mm Micro on the D7000 and find that the AF hardly ever does what I want at 1:1. Having said that, the AF system on the 200mm is completely different (as in old fashioned and slow) compared to the 105mm. At magnifications of more than 1:1 the limited DOF will put extra weight on a very exact focus to get good and appealing images.
Since you are going to buy a bird lens also, I'd go for the TC. With the D7000 the extra loss of light is less of an issue. Because of the small pixel size and relatively good high ISO performance, you can easily shoot at somewhat higher ISO levels without losing too much detail and compromising IQ too much (but don't push it).
I have no hands on experience with any of the options on a DSLR with macro lens, so let's hear what the others chime in.

I stand corrected on the DOF issue I mentioned, but different focal lenghts do tend to affect the BG...that is where I confused the two :-)