Lens reversal issues

lennon33x · Apr 30, 2013

So I'm experimenting with lens reversal and I've run into a problem. I'm using a lens reversal mount and am using both a 50mm f/1.8 and an 18-55 f/3.5 reversed directly mounted to my Canon T3. I'm losing sharpness and depth of field with both. I know that they will be shallow. Is there a better way to get sharpness and/or increase depth of field? Is using one lens mounted to the camera and having another lens reversed at the end of it more effective in achieving better quality results?
Thanks

HughGuessWho · Apr 30, 2013

You will ALWAYS loose DOF at macro distances.
Do a Google search for Focus Stacking

Josh66 · Apr 30, 2013

Yes, like Hugh said, that's normal. The closer you get, the smaller the DOF gets. At 4:1, DOF can be measured in fractions of a millimeter.

lennon33x · Apr 30, 2013

So is there a benefit to stacking lenses?

Josh66 · Apr 30, 2013

reavesce said:
So is there a benefit to stacking lenses?

It's the cheapest way to get greater than 1:1 macro.

Josh66 · Apr 30, 2013

Also, to figure out the magnification ratio, divide the focal length of the long lens by the focal length of the short lens. I.E. - a 50mm mounted on a 200mm will give you 4:1.

I can't remember where I first read that, or why it's true, but it is - lol.

It doesn't matter which lens is on the front, but I would put the heavier lens on the camera.

480sparky · Apr 30, 2013

O|||||||O said:
Also, to figure out the magnification ratio, divide the focal length of the long lens by the focal length of the short lens. I.E. - a 50mm mounted on a 200mm will give you 4:1.

...........

I don't know....... I reverse my 50 on my 105 and can get 3.7:1.

Josh66 · Apr 30, 2013

Like I said, I have no idea why 'it works', but it seemed accurate from my observations with various lenses. How are you coming up with the 3.7:1 figure? (Seriously, I want to know.)

480sparky · Apr 30, 2013

O|||||||O said:
........... How are you coming up with the 3.7:1 figure? (Seriously, I want to know.)

Simple... I shot a ruler.

Josh66 · Apr 30, 2013

480sparky said:
O|||||||O said:

........... How are you coming up with the 3.7:1 figure? (Seriously, I want to know.)

Click to expand...

Simple... I shot a ruler.

Did you factor in sensor size? Not entirely sure if that matters, but it seems like it might...

480sparky · Apr 30, 2013

O|||||||O said:
480sparky said:

O|||||||O said:

........... How are you coming up with the 3.7:1 figure? (Seriously, I want to know.)

Click to expand...

Simple... I shot a ruler.

Click to expand...

Did you factor in sensor size? Not entirely sure if that matters, but it seems like it might...

Yes. I was able to take an image of about 4/10" of the ruler with an FX sensor.

Josh66 · Apr 30, 2013

I will have to do further testing to prove you wrong. :lol:

Kidding, man. But seriously, I want to do some controlled experiments now.

Overread · Apr 30, 2013

O|||||||O said:
Also, to figure out the magnification ratio, divide the focal length of the long lens by the focal length of the short lens. I.E. - a 50mm mounted on a 200mm will give you 4:1.

It's a good rule of thumb, however its important to remember that focal length (like quite a lot of things with lenses) is measured with the focus set to infinity. Many lenses on the market will actually shift their focal length and be shorter than stated when their focus is set closer than infinity (it varies a lot model to model, some will have very little to no variation others quite abit). This can mean that it will affect the final actual magnification factor that you get.

480sparky · Apr 30, 2013

O|||||||O said:
I will have to do further testing to prove you wrong. Kidding, man. But seriously, I want to do some controlled experiments now.

I revisited my test method, and here's what I came up with: Using a ruler marked in 16th, I was able to get to just under ½". So let's say 0.45"

0.45" = 11.43mm. The sensor on my D600, according to Nikon, is 35.9mm on the long dimension. Last time I went to skule, 35.9 / 11.43 = 3.14 and change. So my puny brain computes that to be a 3.14:1 mag. ratio.

Now, that's putting both the 105 Micro and the 50mm at their closest focus. Move 'em both to infinity, and I get 11/16" of the ruler.

11/16 = 17.4625mm. 35.9 / 17.4625 = 2 and a nickel. 2:1. So we're both right. :hug::

This is one reason I made the 105 and 50D part of my Trinity. Carry the Nifty Fifty for obvious reasons. I can get 1:1 straight out of the chute with the Micro, plus it's a good, sharp medium tele to boot. Reverse the 50 on the 105 and I gain the 2:1 to 3.1:1 range with no more expense, space and weight of a simple reversing ring. And I can open the aperture of the 50D just by unlocking the aperture ring and turning it to 1.8... no need for a BR6.

lennon33x · May 2, 2013

Ok, so now I have more issues.

I tried the lens stacking and I'm getting HORRENDOUS vignetting. I'm able to control the DoF much better, but vignetting is terrible. I am using a 50mm f/1.8, and then an 18-55. I mounted the prime to the camera and then flipped the zoom. Then I switched and had the prime flipped. Vignetting improved, but still terrible. Any advice?

I also have a 12-24 (Tokina) and a 70-300 EF, so if any of these would decrease vignetting, I'd appreciate the help.

Chance