Macro options study

[Techuser]

This week I got myself a 70-300 IS and a set of tubes, decided then to see what I could do without a macro lens... so far what I've tried was my close-up on the 50mm 1.8, which didnt gave me enough magnification

The problem I have now is choosing the best combination :rolleyes:

Here are my tests, hope they might help anyone looking for alternatives to macro lenses... I dont know the magnification formula but you can have an idea by the ruler. My camera is a 450D so these have a 1.6x crop on the FL


http://img43.imageshack.us/img43/4231/img1192s.jpg
working distance: 13cm


http://img138.imageshack.us/img138/3294/img1193.jpg
working distance: 7,5cm


http://img510.imageshack.us/img510/5226/img1195r.jpg
working distance: 4cm


http://img412.imageshack.us/img412/5951/img1472y.jpg
working distance: 2cm


http://img510.imageshack.us/img510/1221/img1198z.jpg
working distance: 8cm


http://img402.imageshack.us/img402/6954/img1199j.jpg
working distance: 6cm


http://img31.imageshack.us/img31/5080/img1517a.jpg
working distance: 4cm

[Techuser]

http://img510.imageshack.us/img510/3808/img1520p.jpg
working distance: 8cm


http://img402.imageshack.us/img402/9195/img1522c.jpg
working distance: 9,5cm

Some real life shooting examples now

18-55 5.6 IS @55mm (kit lens) + ET12 + ET20+ ET30
http://img138.imageshack.us/img138/1065/img1506.jpg

70-300 5.6 IS @200mm + 8 diopter
http://img138.imageshack.us/img138/8186/img1532.jpg

With the 70-300 you have almost double the working distance, but notice the difference in the background
both were shot at F13

And this next one goes to show you shouldnt underestimate zoom lenses quality
after these tests, just for the versatility I'm not even counting the 50mm as an option anymore


70-300 5.6 IS @140mm + 8 diopter
http://img31.imageshack.us/img31/4605/img1113vy.jpg

http://img339.imageshack.us/img339/6864/img1113copy.jpg

Thats all :)

[Dalantech]

Excellent post!

For the magnification just divide 20.7 (the width of the sensor) by the number of millimeters in the images.

[dicklaxt]

I am not familiar with what you are doing when you mention +8 diopter is this an add on filter or a camera adjust? will someone explain this?

dick

[Techuser]

Its a close-up filter, an add on like a magnifying glass with is strength measured in dioptry, mine is a Raynox DCR250

Dalantech thanks for the formula

[dicklaxt]

Is this a filter that makes a better resultant image for you only or are you saying its a must to create a better view in this experiment/study.The book I have doesn't cover this dioptic thing much but it seems to be leaning to individual preference.

dick

[Techuser]

It adds magnification at the cost of image quality theorically (for the saying of more glass = less IQ), but there is the fly crop to analyse yourself, for me its great
Dependending on the lens its a must, the 70-300 for instance wouldnt come even near the magnification of the diopter if I used a full set of tubes on it

I'd say for short lenses the tubes worked better, but at longer focal lenghts the close-up will give way more magnification than tubes

btw I just realized the first sundew shot (18-55) was done with tubes and not with the close-up

[LordV]

Excellent post!

For the magnification just divide 20.7 (the width of the sensor) by the number of millimeters in the images.

Minor adjustment - 22.5mm for a 1,6 crop camera sensor width.

Dick add-on dioptres are a bit like reversing a lens in front of another lens.

You just need to find the focal length by dividing 1000 by the diopter number - eg +5 dioptre= 200mm focal length.
You can then use the standard reverse add on lens formula to work out the mag. = focal length main lens/focal length reversed lens (or dioptre).
So a reversed 50mm lens is a very powerful +20 dioptre lens.

Simple add-on dioptres suffer a lot from chromatic aberation but the canon 250D or 500D or the raynox add-on lenses are doublet lenses or more which correct chromatic aberations.

[dicklaxt]

So then are we saying that a +1 +2 +4 +10 found on a group of Macro filters is in fact the diopter value and not the power of magnification?

dick

[LordV]

So then are we saying that a +1 +2 +4 +10 found on a group of Macro filters is in fact the diopter value and not the power of magnification?

dick

Yes :)
Brian v.

[dicklaxt]

AHA!!!!! I sure am getting smmmmmmmmmmmartin my old age:DThen that also means the diopter setting on your camera is just matching you up with the view finder.I think

dick

[gmazza]

Just to add info, with the canon 100mm macro in a EOS 500D camera I got:

10,5mm with the Raynox DCR-250 in front of it, when the lens is in the 1:1 focus

4mm with the Raynox MSN-202 in front of it, when the lens is in the 1:1 focus

[orionmystery]

Just to add info, with the canon 100mm macro in a EOS 500D camera I got:

11,5mm with the Raynox DCR-250 in front of it, when the lens is in the 1:1 focus

4mm with the Raynox MSN-202 in front of it, when the lens is in the 1:1 focus

I used both the DCR250 and MNS202 on my D80 + SP90 before...gave me about 1.7X and 3X respectively. You should get a bit more with the 100mm..so these are about right.

DCR250 is +8 diopter and MSN202 is +25 i think.

[Dalantech]

...It adds magnification at the cost of image quality theorically (for the saying of more glass = less IQ)...

I'm one of the few people I know who disagree with that: Adding extension tubes moves the aperture blades further from the image plane, and that increases diffraction. A good dual element diopter won't hurt your image quality more than a 25mm extension tube...

@ Brian: Thanks for the clarification! I Googled for the width of an APS-C sensor and the numbers were all over the place...

[gmazza]

I'm one of the few people I know who disagree with that: Adding extension tubes moves the aperture blades further from the image plane, and that increases diffraction. A good dual element diopter won't hurt your image quality more than a 25mm extension tube...

As opposite to the repeated mantra in macro forums (more glass more distortion... ) I have seen very good results from the dedicated macro lens with adapters (my setup is this, mostly because I already owned the two Raynox before the 100mm) But wondered if could or not improve changing to ext tubes....but the images are acceptable actual way, but could be better with ext tubes, revolving thought, nooo.... noooo......

There always will be a trade of increasing magnification, push the optical system to limits, need a good lens to support the increased magnification, and, as you said, increase the diffraction, I'm not sure, but to a point the ext tubes steal more light than a adapter with good coatings, longer flash times equal less quality.

About the Raynox if I'm not wrong the DCR-250 is a 3 element 2 group and the MSN-202 is a 4 element 3 group.

[LordV]

Just to add a thought on the diopter vs ext tubes. It would appear that for any set magnification (no matter how you achieve it) you always reach the same DOF/diffraction relationship so ext tubes are no better or worse than add on diopters from that respect but you are not adding glass with ext tubes.
You can of course get excellent results with both but the tendency is to use dioptres on longer lenses and ext tubes on shorter lenses to gain the max magnification benefit.

Brian v.

[Dalantech]

There always will be a trade of increasing magnification, push the optical system to limits, need a good lens to support the increased magnification, and, as you said, increase the diffraction, I'm not sure, but to a point the ext tubes steal more light than a adapter with good coatings, longer flash times equal less quality.

Always trade offs my friend -I'm always balancing things out...

From my experience you won't lose any light with a diopter, but you will with tubes.

[Dalantech]

Just to add a thought on the diopter vs ext tubes. It would appear that for any set magnification (no matter how you achieve it) you always reach the same DOF/diffraction relationship so ext tubes are no better or worse than add on diopters from that respect but you are not adding glass with ext tubes.

According to John Shaw, in "Closeups in Nature", reversing one lens onto another will give you sharper images than using extension tubes because the tubes put more distance between the aperture blades and the image plane.

Diffraction doesn't just cause light to bend, it causes light rays to spread out in a cone. Noticeable diffraction is defined as that cone becoming large enough so that light rays that should only strike a single pixel are bleeding over half way into adjacent pixels. Adding more room between the aperture blades and the image plane would make diffraction worse cause the cone would have more time / distance to expand. You can see a similar effect by simply standing next to a wall with a flash light in your hand and observe how the light spreads out as you back away from the wall.

Last, but not least, diffraction is just one piece of the image quality puzzle. The sharpness of the glass, and even motion blur, are more important factors than diffraction. The problem is that they all have a synergistic effect on image quality; add too much diffraction to an already weakly focused image, or motion as little as the width of half a pixel, and presto instant diffraction limited photo even at relatively small Fstops...

Even the gap-less micro lenses that Canon keeps advertising as a feature of their new sensors could be a potential problem. Light that would have bled over into the gap between pixels is now hitting adjacent photosites due to the micro lenses touching each other...

Keep in mind that all of this is coming from me, someone who routinely stops his lenses down to get more depth :D

[Alarm]

This is an amazing post !!! Thank you . It made me understand about what i can get with those setups. Too bad there was no reversed included and their working distances .

Thank you ! :)

[Alarm]

So if i understood right, my Tamron 70-300 at 300mm with +8 diopter would give me 2.65:1 magnification with a working distance of 10cm about.

This sounds really great if by just reversing the 50mm lens would give me about 1:1 and a working distance less than 5cm. Plus i do not lose aperture settings.

Am i right? If yes, then why most of the people use the simple setup of just revering a prime on the body?

Unfortunately the 50mm reversed on the 300mm would give a really high magnification which i will be almost unable to use. But what if i would use set the tamron at 100mm and used the 50mm reversed? Thats a magnificaction of about 2.25X , and the new working distance would be ? How can i calculate this ?