using a reversed lens help

[kevindar]

I have looked at several threads here, with excellent inputs from LordV and others as well as threads on FM, and Flickr. However I have a couple of questions remaining.

I have a sigma 150 2.8 on a canon 5d, which I am trying to get better than 1:1. I understand I can use a full set of kenko tubes which will give me 2:1.

However, I also have a canon 50 1.4, which I was thinking of reversing.

questions:
1. as I understand I need a 72mm-58mm coupler ring, which I am finding impossible to find. there are stepdown adaptors. should I just use a 72 to 58 step down adaptor, and a 58 to 58 coupler ring?
2. I understand the working distance will be very short. will this be just a few centimeters? does any one have any idea how little working distance?
3. Will the image quality suffer more than using extension tubes.
4. is there any advantage in using the 150 macro? will this work as well on my 70-200 2.8 lens, but with 4:1 magnification at 200 when coupled with the reverse 50?
5: would the aperture of reveresed lens make any difference 1.8 vs 1.4.
6. Is there any way for me to get more working distance? is this dependat on the mounted lens?

thanks in advance for answering any of the above questions.

[LordV]

I have looked at several threads here, with excellent inputs from LordV and others as well as threads on FM, and Flickr. However I have a couple of questions remaining.

I have a sigma 150 2.8 on a canon 5d, which I am trying to get better than 1:1. I understand I can use a full set of kenko tubes which will give me 2:1.

However, I also have a canon 50 1.4, which I was thinking of reversing.

questions:
1. as I understand I need a 72mm-58mm coupler ring, which I am finding impossible to find. there are stepdown adaptors. should I just use a 72 to 58 step down adaptor, and a 58 to 58 coupler ring?
2. I understand the working distance will be very short. will this be just a few centimeters? does any one have any idea how little working distance?
3. Will the image quality suffer more than using extension tubes.
4. is there any advantage in using the 150 macro? will this work as well on my 70-200 2.8 lens, but with 4:1 magnification at 200 when coupled with the reverse 50?
5: would the aperture of reveresed lens make any difference 1.8 vs 1.4.
6. Is there any way for me to get more working distance? is this dependat on the mounted lens?

thanks in advance for answering any of the above questions.

Reversing the 50 onto the 150 macro lens will you min and max mags of between 3:1 and 4:1 - pretty high mags with correspondingly low focus distances (guessing at about 3 to 4 cms in front of the reversed lens.

Yes you could use a 58/58mm reverse coupler and then a 72 to 58mm stepdown ring.

You will lose more IQ doing this but will be getting higher magnification.

Using the macro lens adds the existing magnification to the reverse lens magnification so using either the 70-200mm at 200 or the 150 macro will give you 4:1 mag. The 70-200mm lens will however give you a zoom macro lens with a minimum magnification of 1.4:1

I don't think the aperture setting on the reversed lens will make much difference as long as it is near wide open.

The only way to preserve working distance would be to use a TC instead ie a 2X TC on your 150 would give you 2:1 with the same working distance as the lens has at 1:1 but of course you will get some IQ loss.

Brian V.

[kevindar]

thanks Brian. From what I have read it seems like the macro lens is not even necessary. it will work on any lens. and I think by mounting a zoom lens as my primary lens, i can better control degree of magnification

[kevindar]

so I tried it out
things I discovered so far:
1: it is best to set the focus to infinity on the revered lens. It seems to give just a slight bit more working distance (and I mean slight)
2: It is best to set the macro focusing distance to 1:1 (minimum) this tends to give the least amount of vignetting, even when shot at f8.
3: As you may expects, dof is super thin. Stopping down to f8 increases it marginally.
4: shooting hand held is extremely difficult. first off, even with a stationary object, slightest movement will push you in and out of focus. seconnd thing is due to degree of magnification, I am looking at 1/500 of a second to get decent hand held results.
5: flash use on hot shoe is not possible. external strobes are necessary if the light is not enough
6:HOLLY CRAP. Its at least a 4:1 magnification, and the detail is crazy. see a whole new world of detail.

[bokchoi]

Good to see you're having fun with the lens reversal; my mind was similarly blown when I first saw the world at 4:1. It really is incredibly challenging to get a good shot, and I was getting about 1 usable shot out of about every 30 or so when I was photographing ants on the peonies in my yard (finding an ant on a peony at 3:1 or higher is like trying to find a moving country on the globe, and even your heartbeat can throw off the DOF).

http://farm4.static.flickr.com/3278/2622210035_b45fefdf87.jpg

For this one, I was reversing a Nikkor 50mm f/1.8 on a Sigma 70-300 zoom lens at 133mm; people tell me that reversing prime-on-prime will yield better results, though I think you're right in that it would make it more difficult to control things like magnification.

For lighting, what I did was take a white piece of paper and create a reflector for my camera mounted 430EX flash so that the light would be reflected downward onto the subject right in front of the lens; this ended up working surprisingly well, and I was able to stop down to f/25 for more DOF and was still able to expose properly. I found that this technique works very well with a 50mm 1.8 / 1.4 and extension tubes as well, or possibly even any situation where you have little working distance. I've since spent a few dollars on one of those flash reflector cards from Hong Kong, and it is a bit more rigid and less susceptible to getting blown away by the wind.

I'd be interested to know if anyone has any tips on how to improve image quality with the lens-reversal method; from the ant photo, you can see that aberrations are really bad on the edges, so much so it looks almost like I applied a rotate-blur to the photo, and there's serious vignetting at any focal length under 100mm. I heard from some people that reversing a macro lens on another macro lens will yield superior results (still not approaching the MP-E, but for less money), but I want to hear what other people have tried before I spring for any new toys...