Which Macro lens?

[J.Davis]

Am about to buy a macro lens for my D60 and was wondering which is a preference;-
Tamron 90, or Sigma 150.
Is there a major difference or is just an 'either or' situation?

[big pix]

Both are very good macro lens......the 150mm Sigma will enable you to shoot subjects without chasing them off by being too close....... if I had the same choice, 150 Sigma

[gstark]

I would go with the Tammy. it's a legendary lens, and that can never be said about any Sigma.

And it will double as an excellent portraiture lens too; the Siggy is too long, with the crop sensor.

I'm not sure if either of these lenses will auto focus with the D60. For macro photography, that would be a moot point, but for general photography, that might be something to be aware of.

[ATJ]

Advantages of shorter macro lenses:
* Greater depth of field for a given magnification and f/stop
* Easier to light the subject (artificially) because the camera is generally closer
* Lens is lighter (and usually cheaper)

Advantages of longer macro lenses:
* Great distance from the subject for a given magnification - helps with skitty subjects
* More pleasing backgrounds (because of the shallower depth of field)

[sirhc55]

Sigma all the way, whether it be the 105, 150 or 180. Great optics and a great price.

[aim54x]

I vote the tamron 90mm (the current version will AF on the D60 as it has a micro motor). I own a Sigma 180mm but would also like a Tamron 90mm but I cant justify it.

Anyone want to swap Tamron 180mm for Sigma 180mm??

This is an interesting article that I read AFTER I bought my Sigma, but it is a good read
http://www.nnplus.de/macro/Macro100E.html

[J.Davis]

I have just thought of throwing in the Nikon 105 micro? is it worth the extra $?

[colin_12]

I have not tried the other leses but I really like my Nikon 105 micro.
It is on my camera most of the time.

[shakey]

For immobile subjects the tamron is excellent. For bugs the longer sigma will at least get you some shots. I've got the 90 mm tamron, but for bugs I've got a Canon 500d closeup lens to stick on my regular zoom.

[aim54x]

I have just thought of throwing in the Nikon 105 micro? is it worth the extra $?

I have used this lens, and i would say that it is worth the cost unless you are considering either of the Tamron or Sigma 180mm lenses (similar pricing). I have heard that the older AF-D version is sharper but I cannot confirm this as I have only used the AF-S 105 VR.

[ATJ]

I love my 60mm. It is compact and easy to use. The DOF is quite amazing, even at 1:1. It works well with tubes. It is easy to light (with DIY softboxes). Despite the short working distance, I have still managed to get some good shots of butterflies, dragonflies, damselflies, wasps. flies, etc.

I've had my 200mm for a week now and I know I'm going to love it. I get the extra reach I was missing from the 60mm (in some circumstances) but also have a new challenge of lighting and very shallow DOF.

Maybe one day I'll get a 105mm, too.

[kiwi]

I have just thought of throwing in the Nikon 105 micro? is it worth the extra $?

I have used this lens, and i would say that it is worth the cost unless you are considering either of the Tamron or Sigma 180mm lenses (similar pricing). I have heard that the older AF-D version is sharper but I cannot confirm this as I have only used the AF-S 105 VR.

oh, it's sharp as. Very slow AF

[DaveB]

Advantages of shorter macro lenses:
* Greater depth of field for a given magnification and f/stop [WRONG]
* Easier to light the subject (artificially) because the camera is generally closer [yup]
* Lens is lighter (and usually cheaper) [yup]

Advantages of longer macro lenses:
* Great distance from the subject for a given magnification - helps with skitty subjects [yup]
* More pleasing backgrounds (because of the shallower depth of field) [yes, but not because of DOF]

This is a common misconception about DOF. If you look at the depth-of-field formulas you will see that it's dependent on focal length, aperture, and subject distance. But if you look closer you will see that together the focal length and subject distance values can be grouped together as "magnification".

The DOF at a given magnification depends only on aperture. NOT focal length. If you're using a 200mm macro lens at 1:1 magnification, it will have the SAME DOF as a 50mm macro lens at 1:1. The focal length is different, but the change in subject distance to achieve the same magnification cancels out the difference in the DOF calculation.

What IS different about a longer macro lens is that you will have a narrower view of the background. This makes it easier to select a background free of annoying highlights for example, just by moving the camera sideways slightly. But the DOF will be the same.


The optical quality of the Tamron 90mm is reportedly very good, but my own preference is for a longer macro lens. I use a Sigma 180mm, but if I was buying one now I think I'd go for the 150mm. Sigma do make some "dogs" of lenses, but I've been very happy with my Sigma 180mm (FWIW, most of my other lenses are Canon 'L').
I think both the Sigma 150mm & 180mm lenses are HSM in the Nikon mount, which means they should AF with a D60.

[ATJ]

The DOF at a given magnification depends only on aperture. NOT focal length. If you're using a 200mm macro lens at 1:1 magnification, it will have the SAME DOF as a 50mm macro lens at 1:1. The focal length is different, but the change in subject distance to achieve the same magnification cancels out the difference in the DOF calculation.

Hmm... this suggest that depth of field calculators have errors - and serious ones at that. Plus many photography texts.

For my 60mm lens, I get 1:1 with a focusing distance of 21cm. For the 20mm lens, focusing distance is 51cm for 1:1. If I plug these numbers into this calculator, DOFMaster Online Depth of Field Calculator, I get...
For the 60mm at f/16:

Code: Select all

Subject distance      21 cm
 
Depth of field
Near limit     20.7 cm
Far limit     21.3 cm
Total     0.56 cm
 
In front of subject     0.28 cm (49%)
Behind subject     0.28 cm (51%)
 
Hyperfocal distance     1131 cm
Circle of confusion     0.02 mm

For the 20mm f/16:

Code: Select all

Subject distance      50 cm
 
Depth of field
Near limit     49.9 cm
Far limit     50.1 cm
Total     0.24 cm
 
In front of subject     0.12 cm (50%)
Behind subject     0.12 cm (50%)
 
Hyperfocal distance     12520 cm
Circle of confusion     0.02 mm

i.e. the 60mm is supposed to have twice the DOF as the 200mm for the same magnification and the same f/stop.

Bob Atkins Depth of Field Calculator gives the same results.

Nikon stick the hyperfocal distance in the Exif when you take a shot. If I use that to calculate the DOF for each lens at f/16 I get 0.79cm for the 60mm and 0.40mm for the 200mm.

BUT...
If I take a photograph of a ruler at a 45º angle with each lens, it is difficult to discern any difference in DOF:


60mm


200mm

[gstark]

i.e. the 60mm is supposed to have twice the DOF as the 200mm for the same magnification and the same f/stop.

But at what subject distance?

In your test images, the subject distance is the same. In your calculations, you're using different subject distances, but working towards the 1:1 reproduction ratio.

What happens if you refactor the calculations for a common subject distance?

[DaveB]

Some DOF calculators use simplified formulas. I think the simplified formulas don't work so well at small distances.

Also keep in mind that many lenses actually change focal length as they focus closer (due to the way the internal focussing mechanism has a side-effect of changing the lens design). For example I think from memory that the Nikon 105mm macro actually ends up closer to 80mm at 1:1 (despite not reporting that to the camera). This is also going to throw out any calculations.

There does seem to be a slight difference in DOF in those two sample shots. Not sure where that's coming from. I might be working on an approximation and there might in fact be a difference in DOF, but I don't think so.
Are you sure you took these images with exactly the same angle towards the tape measure? If the 60mm shot had a steeper angle that would increase the apparent DOF along the tape (and in fact the distance between the tips of the 9cm and 11cm marks is slightly longer - although the change in angle of view of the lenses complicates measurements like that).

[ATJ]

Are you sure you took these images with exactly the same angle towards the tape measure?

Yes. Positive. I had the camera mounted on the tripod and did not change anything other than the lens.

[ATJ]

In your test images, the subject distance is the same.

Um, no. Not even nearly. The subject distances (from focal plane to subject) are the same as in those calculations. i.e. 21cm for the 60mm and 50cm for the 200mm.

[DaveB]

Are you sure you took these images with exactly the same angle towards the tape measure?

Yes. Positive. I had the camera mounted on the tripod and did not change anything other than the lens.

But you must have changed the distance to the subject, no? Which bits of the setup moved?

[gstark]

In your test images, the subject distance is the same.

Um, no. Not even nearly. The subject distances (from focal plane to subject) are the same as in those calculations. i.e. 21cm for the 60mm and 50cm for the 200mm.

So, there is no relationship between the measurements as displayed in the images (the targets), and the actual subject distances.

Cool!

[ATJ]

In your test images, the subject distance is the same.

Um, no. Not even nearly. The subject distances (from focal plane to subject) are the same as in those calculations. i.e. 21cm for the 60mm and 50cm for the 200mm.

So, there is no relationship between the measurements as displayed in the images (the targets), and the actual subject distances.

Exactly. I just chose to centre on 10 cm for ease of comparison.

[ATJ]

Are you sure you took these images with exactly the same angle towards the tape measure?

Yes. Positive. I had the camera mounted on the tripod and did not change anything other than the lens.

But you must have changed the distance to the subject, no? Which bits of the setup moved?

Well, yes.

What I did was as follows...
* Set up the tripod so that the head was angled down at 45º
* Mount the camera on the tripod and the 60mm lens on the camera
* Set the 60mm lens to its closest focusing distance (21cm which gives 1:1)
* Adjust the height of the tripod using the centre column* so that the point of focus was as close as I could get to the centre of the lens
* Adjust the ruler so that the 10cm mark was at the centre and the ruler was straight
* Take a series of photographs from f/4 through to f/57
* Take the 60mm lens off the camera and put the 200mm lens on the camera
* Set the 200mm lens to its closest focusing distance (50cm which gives 1:1)
* Adjust the height of the tripod using the centre column* so that the point of focus was as close as I could get to the centre of the lens
* Adjust the ruler so that the 10cm mark was at the centre and the ruler was straight
* Take a series of photographs from f/4 through to f/45

I have taken another series of shots this time using 1mm graph paper. I went for a lower angle that 45º. The contrast in the images has been increased significantly to better show up the differences. These two shots were taken at f/11.





They appear to show little difference in DOF.

* Yes, I know it is not a good thing to raise the centre column but I was not after rock solid stability but simply consistency in the shots. Plus I was shooting with flash so it would freeze any camera movement.

[ATJ]

By the way, I was chatting with Cameron just yesterday (at Minnamurra) about the problems I was having reconciling the theoretical depth of field of the 60mm and 200mm lenses (based on what the books and DOF calculators say) versus what I was actually getting with my test photos. The test photos have been suggesting that the difference in DOF between the lenses was not much at all (if anything).

[DaveB]

It turns out most DOF calculations include some approximations/assumptions.

This web page goes into a lot of detail, and my conclusion after reading it is that for my purposes the approximation that "DOF in macro does not depend on focal length" is valid.
The rate of "in-focusness" outside the DOF does change though, along with other subtleties.

[ATJ]

This web page goes into a lot of detail, and my conclusion after reading it is that for my purposes the approximation that "DOF in macro does not depend on focal length" is valid.

Thank you for this. It was very informative. It also explains why I was having difficulties showing a difference in DOF at the same magnification (1:1) and f/stop between my 60mm and 200mm lenses.