# 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


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## HughGuessWho (Apr 30, 2013)

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


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## 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.


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## lennon33x (Apr 30, 2013)

So is there a benefit to stacking lenses?


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## 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.


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## 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.


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## 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.


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## 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.)


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## 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.


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## 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.)
> ...



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


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## 480sparky (Apr 30, 2013)

O|||||||O said:


> 480sparky said:
> 
> 
> > O|||||||O said:
> ...



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


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## Josh66 (Apr 30, 2013)

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


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## 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.


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## 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.


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## 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


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## 480sparky (May 2, 2013)

Start by mounting the longest focal length lens you have to the camera, and if it's a zoom, zoom to the longest FL.  If that doesn't eliminate the vignetting, it will at least reduce it as much as possible.  You'll just need to crop your images in post.


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## jowensphoto (May 2, 2013)

I've never used the reverse mounts but I do a lot of free lensing/reverse macro. I'm going to guess no, but I'm assuming that you have no aperture control with the reverse mounts? With Canon, you can lock the aperture by first setting the aperture to what you need/want, then hold down the DOF preview while taking the lens off. Aperture is then locked!


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## Judobreaker (May 2, 2013)

Depends a bit on the lens. 
With my Nikon 50mm D lens I can set aperture manually using the aperture ring it has. ^^


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## 480sparky (May 2, 2013)

When you reverse one lens onto another, you want to have the reversed lens wide open.


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## Judobreaker (May 3, 2013)

Yes, that be true.
I forgot we're talking about stacking here.


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## Helen B (May 3, 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 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.



The basis for that guide is so simple you will kick yourself.

It applies when the rear lens is set to infinity, which means that the light from an in-focus object is arriving at the rear lens in parallel. That means it left the front lens in parallel, so the object must be where the front lens' image plane would be if the front lens were mounted normally on the camera and focused on infinity. 

Therefore, in this particular case:

Object distance = focal length of front (reversed lens)

Image distance = focal length of rear lens

but

Magnification = image distance / object distance

Therefore

Magnification = focal length of rear lens / focal length of front reversed lens.

As already mentioned, the magnification will be higher when the rear lens is focused closer.


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## jowensphoto (May 3, 2013)

480sparky said:


> When you reverse one lens onto another, you want to have the reversed lens wide open.




Ooooooh! Ok. I see what you guys are talking about now.


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## 480sparky (May 3, 2013)

jowensphoto said:


> 480sparky said:
> 
> 
> > When you reverse one lens onto another, you want to have the reversed lens wide open.
> ...



There are two 'reversing lens' methods.

One is to reverse ONE lens around on the camera:







Using a lens that has no aperture ring is near impossible......you'll need a way to control the aperture.  Since the electronic and mechanical connections between the camera and lens are broken, you must control the aperture manually.  I've heard Canon will let you use your DOF Preview button to 'set' the aperture of a lens before you remove it, but then when you reverse the lens you're looking at a dark viewfinder.  Not very practical if you're stopping down to f/8 or smaller.  

Nikon users can enjoy the benefit of a BR-6 (shown mounted on the lens above), which is an adapter that mounts onto the rear of the lens and has both a lever and a cable release connector to allow you to frame, compose & focus with the lens wide-open, then actuate the adapter manually just before shooting.  However, this works best with lenses that have an aperture ring.... newer G-class lenses can only be utilized with any accuracy at their minimum apertures.  This may not be ideal due to diffraction.

To buy an adapter like this, you'll just need to get one that has both your lens mount system and the size of the filter for the lens you want to reverse.  Mine is a Nikon F/52mm.



The other method is to get a filter-thread reversing ring, sometimes called a _macro coupler_.






It's basically a ring with two filter threads, each sized to the two lenses that are used.  You can buy these adapters for a couple dollars on ebay.  Just find the two filter sizes of the lenses you want to use and order one.  Mine is a 52/52.

This basically turns one lens into a high-end close-up filter.  You'll want to use the reversed lens wide open, as you will be using the aperture of the lens mounted to the camera to control exposure (and DOF) as you normally would.  This method favors Canon as you can 'open' the aperture of the reversed lens using the DOF Preview trick mentioned above to it's largest (smallest f/number), and control the exposure as your would normally.  Nikon users, if using a G-class lens, will either need to manually hold the aperture control tab of the lens open manually, or can use a BR-6.  Since I have D-class lenses, I can just unlock the aperture ring and open my 50 to f/1.8.


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## jowensphoto (May 3, 2013)

Thanks for the explanation of the two differences! Re: dark view finder on Canon using the DOF/lens removal aperture control method. I've never had issues with a dark view finder. I've used my 50 1.8 at f/22.


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## jowensphoto (May 3, 2013)

On second thought, probably because I free-lens rather than use an adapter... so that probably has something to do with it.


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## 480sparky (May 3, 2013)

jowensphoto said:


> Thanks for the explanation of the two differences! Re: dark view finder on Canon using the DOF/lens removal aperture control method. I've never had issues with a dark view finder. I've used my 50 1.8 at f/22.




I don't get it.... how can you NOT have a dark VF with your lens stopped down to f/22?


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## jowensphoto (May 3, 2013)

It's not dark. I'm tellin' you lol I will take some this weekend and report back.


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## 480sparky (May 3, 2013)

jowensphoto said:


> It's not dark. I'm tellin' you lol I will take some this weekend and report back.



Look through the lens when it's off the camera.... are the aperture blades closed down?  If not, you're not shooting at f/22.


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## jowensphoto (May 3, 2013)

I'm totally sure. When I first started trying the techniques, I liked the shallow DOF of using 1.8 while doing RM/Free lensing but quickly found it limiting. So I researched how to set the aperture and began closing it up more.

I only have the Minolta 35mm with me today, but I'll try to take something interesting at the truck pull this evening lol


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## 480sparky (May 3, 2013)

jowensphoto said:


> I'm totally sure. When I first started trying the techniques, I liked the shallow DOF of using 1.8 while doing RM/Free lensing but quickly found it limiting. .......



If your VF is just as bright with your freelens set at f/22 as it is set at f/1.8, you've somehow managed to violate the laws of physics.  

I'm gonna report you the the Optics Police, and Isaac Newton will be along shortly to arrest you.


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## jowensphoto (May 3, 2013)

LOL Gahhhh I swear I'm right. Even if I'm not I'm just going to lie to you. 

But really, with the freelensing, wouldn't it make sense? the light leaks in from all sides since I hold the lens a bit aways from the mount.


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## 480sparky (May 3, 2013)

jowensphoto said:


> LOL Gahhhh I swear I'm right. Even if I'm not I'm just going to lie to you.
> 
> But really, with the freelensing, wouldn't it make sense? the light leaks in from all sides since I hold the lens a bit aways from the mount.



If you're seeing light that's leaking in between the lens & body in the viewfinder, that will show up in the image as well.


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## Judobreaker (May 3, 2013)

If there would be light leaks because of freelensing that would indeed make the viewfinder (and the photos you shoot) brighter. However I suspect it would also make you lose a lot of contrast, you'd definitely know if it was a light leak by the contrast.

It's simply not possible for the viewfinder to be as bright at f/22 as it is at f/1.8 (without extra effects because of light leaks), no matter how you look at it.


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## jowensphoto (May 3, 2013)

Well yeah, but it's not dark either. I'm going to do this tonight and hopefully post soon after


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## Temma (May 18, 2013)

480sparky said:


> This basically turns one lens into a high-end close-up filter.  You'll want to use the reversed lens wide open, as you will be using the aperture of the lens mounted to the camera to control exposure (and DOF) as you normally would.  This method favors Canon as you can 'open' the aperture of the reversed lens using the DOF Preview trick mentioned above to it's largest (smallest f/number), and control the exposure as your would normally.  Nikon users, if using a G-class lens, will either need to manually hold the aperture control tab of the lens open manually, or can use a BR-6.  Since I have D-class lenses, I can just unlock the aperture ring and open my 50 to f/1.8.


I've got a couple of 35mm SLRs that I no longer use, a Vivitar and a Minolta XG1.  The 50mm lenses from these are perfect for stacking, since they have manual aperture controls.  Likewise, most camera stores have used 50mm manual lenses for very reasonable prices.


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## Photographiend (May 18, 2013)

reavesce said:


> So is there a benefit to stacking lenses?



I don't think we are stacking lenses. Just images. That is how you can get a broader focal range. Never done it my self. Maybe one day but it takes a bit more planning. 

Also, you should know your lens isn't meant to be mounted backward so using a lens mount for ring reversal is going to strain your equipment. I do ring reversal for my Macro shots but I just have to hold it in place. 

Please explain how you are controlling the fstop with this technique as mine seems to be controlled by software and it doesn't do anything when the lens isn't properly attached.

Edit: Never mind... hadn't read far enough... *insert foot in mouth smiley here*


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## 480sparky (May 18, 2013)

Photographiend said:


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



The thread title is "Lens Reversal issues......"


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## Photographiend (May 18, 2013)

I know. The very basic flipping your lens around was covered in a book I read. Otherwise this is all new to me, lens stacking and what not... Feel free to ignore me I have no clue what you guys are talking about. Or what I am talking about for that matter.


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