Improbable Lens Reversal

[snakeroot]

Did I waste $25? Just ordered 72-77 mm step up ring, planning to

attach my 70-200 F/2.8 IS EF lens backwards to my 180 3.8 EF Macro to

try to image the hairs on spider ears.

 

Am I being ridiculous or experimental? I know reversing two EF Zoom

lenses are a no-no from previous discussions on the forum, but

doesn't my 180 macro qualify as a prime lens?

 

By the way, I only plan to shoot straight down on a tripod with the

physics envisioned.... I might just nail the tripod to the floor too.

 

Merry Christmas (I'm working...sigh)

[neild]

If I tried this at all, I wouldn't be using a zoom lens in either case: they have more glass elements and the total glass may degrade your image overall. Try it with two primes.

[stephen hazelton]

Just hold one lens in front of the other, and you should be able to approximate the effect well enough to see if the assembly vignettes, or if working distance is unreasonably small, etc.

 

I assume you already have a 77mm macro coupling ring? (I would think that would be scarce!) Anyway, the step up ring wouldn't be wasted, lets you use filters on the other lens, if you need to.

[jimstrutz]

Besides the regular step up ring, you will need a reverse adapter ring. It's got male threads on both sides. Either a 72mm or 77mm should work.

 

Before you do it though, why not mount the macro on camera and just hold the lenses together the way the adpater would. You should tell if it will even focus. Some of these combinations focus somewhere in the middle of the reversed lens. That's not good. If you can focus it, look to see how much vignetting you will have. None is good, but often there is some, and this will have to be cropped out. Not always such a bad thing anyway, as the effective magnification appears to be increased.

 

If your combination doesn't work, try it the other way around, with the zoom mounted on the camera and the macro, or some other lens reversed. When you find a combination that seems to work hand held, buy the adapers for it. Two primes together seem to work best, but not all combinations make it.

[jnicholson]

Michael, everyone's still asleep in the house here so I can't get to my photography books to check but it seems to me that these two lenses are not a good choice for reversal. I thought a good rule of thumb for determining magnification when reversing a lens was to divide the shorter focal length into the longer focal length. So, reversing a 50mm lens on a 200mm lens would give you approximately 4X magnification. If that is correct, and I wish I could check before I write this, then it seems like the best you can hope for is about 2.5X. And I'd guess the image quality will suffer.

 

I know you say you'll be pointing the camera straight down but please be sure that 70-200 is securly attached.

 

Merry Christmas to you too! (I'm waiting for the festivities to begin).

[jess_lee]

I think you would want to use a wide angle to achieve greater magnification

[eric_bell]

Michael,

This seems like an improbably cumbersome rig. Just the lenses will be over 15" long and weigh about 6 Lb.. I predict that lighting the subject properly will be very difficult to impossible. As alternatives, The very nice Canon M65 macro is capable of about 5X and is only 4" long and about 2 Lb.. If that is not enough, the 20mm f2 Olympus Macro attached to the Telescopic Auto Tube will go to around 9X (would require Cameraquest's OM to EF adapter). BTW, you probably are already aware that a powerful ring flash is a must at these magnifications.

Regards and good luck, Eric

[wolver]

Your 70-200 plus the 180 macro reversed should work good together. Below is a 100% crop of the pixels of a CRT monitor done with a Canon 70-300 and a reversed Canon 50mm. So you should get a fair decent magnification with your set up. <br><br>

[peter_houtmeyers]

If you really want to destroy one or both your lenses please continue with what you are trying to do. I can assure you that the filterthread is not made to hold that kind of weight.What you can do to get more magnification is to add a shorter focal lenght lens in reverse like a 50mm1.8( very light and cheap but good ).The shorter the focal lenght of the reversed lens the more magnification you'll end up with. The limit is about a 20mm lens because the workdistance will become to short. A set of extension tubes can get you beyond 2,5:1 without the loss of sharpness from the very good 180 macro. Both the options are not that expensive( 100$ each) and they will work a lot easyer with better results( sorry for the bad English)

[snakeroot]

Thanks Peter, but I'm from Maine and think I can rig up some duct tape to support it....

 

I got my 72-77mm step up today from B&H and ordered a 77mm male to male macro ring from Image Gallery in Michigan (great people there, Adorama didn't have them...)

 

I will experiment when it arrives and post results here, I know the physics are against me, but if I point both lenses downwards and use just enough duct tape......

[stephen hazelton]

"I think you would want to use a wide angle to achieve greater magnification"

 

I think when I tried this (wide angle on front), it just vignetted terribly. It seems the absolute aperture size on the front lens is important, and that is very small on short focal lengths.