Low magnification test

Written by Administrator. Posted in Comparative

On this occasion I wanted to make a test involving relatively long focal length lenses and I have done it through different magnification ranges.

The good thing about this long focal length lenses is their good working distances ( WD), these lenses are supposed to become part of my field gear but they can also be used in the studio, of course. I forgot to measure their WD but as an example the Rodagon-D 75/4.5 has around 10cm WD at 2X.

The following lenses were tested:

Olympus MC auto 1:1 macro 80mm f4; a good reputation bellows lens, optimized for 1:1 work and a useful working range from 0.5X to 2X.

Rodenstock APO Rodagon-D 1X 75mm f4; a specialized enlarger lens (in fact it is a duplicating lens) optimized for 1:1 work, it's probably use was film duplication. Its optimum working range goes from 0.7X to 1.5X in 35mm cameras.

Rodenstock APO Rodagon-D 2X 75mm f4.5; other version from same series optimized for 2:1 work, one of its designed tasks may be copying 16mm film to 35mm.

Its optimum working range goes from 1.2X to 2.5X in 6x7 film; as this lens has not got a symmetrical design reciprocal values may apply when reversed so it is also optimized for 0.5X work, having a working range of 0.4 to 0.8X in 6x7 film(It is used at 2X when reversed and at 0.5X when in normal position) I have not found its optimum working range in 35mm cameras but I guess it will have a pretty well balanced behavior from 0.3X to 3X.

I run several stacking sequences at different magnifications: 0.6X (minimum I could get with Olympus 80mm), 1X, 2X and 2.6X (maximum I could reach with Rodagon-D 75/4); at different apertures like f4 (f4.5 for the Rodagon-D 75/4.5), f5.6 and f8.

The test subjects were a couple of old pc cards; a graphics card and a Ethernet card.

I used office paper around the subjects for light diffusion, light source were three ikea led lamps. Stacks were automatized with stackshot (great help for these repetitive tasks) on a EOS 5D mkII in live view silent mode mounted on a nikon PB-6 bellows.

The only post processing applied to the pictures was recovery 20 on Camera raw; images were stacked on Zerene stacker Pmax mode.

0.6X test

imagen 01

Three stack sequences were run for each lens, clicking on the f number you can see them full size. Next to each of them you can see the number of steps, their size and the exposure time.

All lenses were used in normal position.

Rodagon D 75/4

f4           16 shots with 1mm steps       1/6

f5.6        11 shots with 1.5mm steps    0.3"

f8           8 shots with 2mm steps         0.6"

Rodagon D 75/4.5 Normal

f4.5        14 shots with 1.2mm  steps   1/5

f5.6        11 shots with 1.5mm steps     0.3"

f8           8 shots with 2mm steps          0.6"

Olympus 80/4

f4           16 shots with 1mm steps        1/6

f5.6        11 shots with 1.5mm steps     0.3"

f8           8 shots with 2mm steps          0.6"

Let's have a look to those crops; all three lenses are pretty similar, maybe  the Rodagon-D 75/4 struggles a little more in the corners but it also shows better resolution in the center wide open. The weird thing is that it works better at f4 than at f5.6. 

Thinking about it I realized I made DOF calculations based on 0.5X magnification (I got confused), so probably this is what is wrong.

However I think that there are enough areas completely focused on the full size pictures

Clicking on the image you will see it original size (100% crops)

imagen 02

 Test a 1X  FOV 36mm

Here the full image showing the crop areas, same as before.

Imagen 03

On this occasion I did three stacks per lens, but I used the Rodagon-D 75 /4.5 both in normal and reversed position. The reason for that being the Rodagon has an asymmetrical lens design and at 1X is in theory out of its optimum magnification range; I wanted to see which way it works best.

Once again next to the f number you have the number of pictures, step size and exposure time.

Rodagon D 75/4

f4           20 shots with 0.35mm steps  1/13

f5.6        13 shots with 0.55mm steps   1/6

f8            9 shots with 0.80mm steps    0.3"

Rodagon D 75/4.5  Normal

f4.5        17 shots with 0.42mm steps   1/10

f5.6        13 shots with 0.55mm steps   1/6

f8            9 shots with 0.80mm steps    0.3"

Rodagon D 75/4.5 reversed

f4.5        17 shots with 0.42mm steps  1/10

f5.6        13 shots with 0.55mm steps   1/6

f8            9 shots with 0.80mm steps    0.3"

Olympus 80/4

f4           20 shots with 0.35mm steps  1/13

f5.6        13 shots with 0.55mm steps  1/6

f8            9 shots with 0.80mm steps   0.3"

Let's examine those crops; again all three lenses have very good performance. In my opinion the Rodagon-D 2X works better reversed rather than in normal position. Probably the Rodagon-D shows a little more detail in the center of the image but the difference is not as big as I would have expected before running the test. The Olympus also performs very well at this magnification. Do not forget that this is a full frame test; 21mpx seem a lot but pixel density is well below what we find in APS-C cameras.

Imagen 04

 2X test      FOV 18mm

test 2X

We get now to the 2X test, here the Olympus is still in is designed working range, The Rodagon-D 2X is in its optimum range (in reversed position) and the Rodagon-D 1X is well outside of its designed working range. I had seen some tests of these Rodagons which suggested the Rodagon-D 1X had better resolution at 2X, this did not make sense to me; how can a lens designed to work at 1X be better than a lens designed for 2X work, specially when both lenses were designed by the same maker. It is true that those tests were always APS-C tests.

On this stack series I overexposed the shots a little bit, which caused some haloing around the bright white areas; as this is just a test it does not bother me much, as long as we use other areas for the comparison.

Rodagon D 75/4

f4           28 shots with 0.18mm steps  1/6

f5.6        22 shots with 0.25mm steps  0.3"

f8            15 shots with 0.35mm steps  0.6"

Rodagon D 75/4.5 reversed

f4.5        26 shots with 0.2mm   steps    1/5

f5.6        21 shots with 0.25mm steps  0.3"

f8           17 shots with 0.35mm steps  0.6"

Olympus 80/4

f4           26 shots with 0.18mm steps  1/6

f5.6        22 shots with 0.25mm steps  0.3"

f8           15 shots with 0.35mm steps  0.6"

Once we look the crops first thing we can see is that the Rodagon-D 2X is very well optimized for 2X work; it was designed with balance in mind, offering almost same performance wide open than with aperture closed 1 or 2 EV. We can also see that both the Olympus and the Rodagon-D 1X struggle in the corners, specially wide open. The rodagon-D 2X is superior even on borders. However the Rodagon-D 1X does show more resolution in the center of the image, which is the reason it seems to be superior in APS-C tests I have seen before.

test 2X recortes

2.6X test      FOV 14mm

Taking the results we saw at 2X we can expect them to be similar on this last test; the Rodagon-D 2X (reversed) still will be in is designed working range, not like the other two lenses.

test 2_6X

Rodagon D 75/4

f4           48 shots with 0.09mm steps  1/6

f5.6        30 shots with 0.15mm steps  0.3"

f8           25 shots with 0.20mm steps  0.6"

Rodagon D 75/4.5 reversed

f4.5        45 shots with 0.10mm steps 1/5

f5.6        30 shots with 0.15mm steps 0.3"

f8           25 shots with 0.20mm steps 0.6"

Olympus 80/4

f4           48 shots with 0.09mm steps 1/6

f5.6        30 shots with 0.15mm steps 0.3"

f8           25 shots with 0.20mm steps 0.6"­­­­

On this last crop series we can see similar results to those on the 2X test, maybe both the olympus and the Rodagon-D 1X got a little worst, starting to show some mild CAs. The Rodagon-D 2X probes to be very well balanced and in my opinion is best choice for high magnification shots. 

test 26X

After reviewing test results we can see that when makers design a lens it is difficult to make it work well at different magnifications, they have to make choices. APS-C and 4/3 users may think the Rodagon-D 1X is best choice because of the superior resolving power in the center of the frame; however I do prefer the Rodagon-D 2X as it is a very well balanced  lens, for me this is an more important aspect than center resolution.

 What about the Olympus? Well; a very good quality lens, showing very good performance more similar to that of the Rodagon-D 1X. Its only con it that it is a rather difficult lens to adapt.

 On a OM bellows system  with this lens and the 38/2.8 you would have all you need from 0.5X to 6-7X. If your bellows system uses a different mount it can be a problem, it is quite difficult to find M42 or Nikon adapters.

You can always put together some pieces and make your own, problem being it also adds some extension; this can be a problem or not, depending on your needs.

 OM to M42 DIY adapter

montura OM