Reversing 50mm?

BBbuilder467 wrote:

Just for curiosity, I'd like to reverse a Pentax 50mm SMC-M, all manual lens to my micro 4/3.

I can't remember if I need to reverse directly to the body or reverse to the adapter to get the 1:1 magnification.

Has anyone tried it? With extension tubes, I need to use the adapter to get accurate ratios, so I assume I need to reverse to the adapter. I'd need the reverse mount for Pentax K instead of m4/3?

I know some people love using legacy lenses, both the right way round and reversed, but I've never had much success with them. However, having experimented with them I do have some legacy lenses, adapters and reversers so I just did an experiment.

I reversed a 28mm Minolta lens on to a G80 using a Fotodiox MFT reverse adapter. This reverse adapter has an MFT mount on one side and a 58mm male thread on the other side. I used step rings to marry up the thread on the adapter with the filter thread on the lens. At infinity focus I got a scene width of around 14mm, so slightly more than 1:1, with a working distance of around 30mm, which is very small. Going to closest focus didn't change the scene width but slightly reduced the working distance to around 25mm.

Doing the same with a 50mm Canon FD macro lens I got a scene width of 40mm, so less than 1:2 with a working distance of around 160mm at infinity focus, and at closest focus a scene width of around 38mm with a working distance of around 120mm.

I don't understand what you have in mind for "reverse to the adapter". An adapter (that is, an ordinary, non-reverse adapter) gives you the mount for the lens type you want to attach, with the lens used the right way round. For reversing, whatever lens you want to reverse you use the same reverse adapter and then use appropriate step rings to attach it to the filter thread of the lens you are reversing.

3D Gunner wrote:

gardenersassistant wrote:

I don't understand what you have in mind for "reverse to the adapter".

"Reverse to adapter" provides a different distance (the correct one) between the sensor and the front lens of the inverted optics, than "reverse to body".

How does that work in practical terms? For example, suppose I want to reverse mount an FD lens on to an MFT body. If I put an FD to MFT adapter on the body it presents an FD mount to attach to. Do I then put an FD reverse adapter on to the FD to MFT adapter, and then attach the lens to the reverse adapter?

So, the solution is "reverse to adapter" (and it works very well).

What are the benefits of reversing to adapter rather than reversing to body? Sharper images? Less aberrations? More magnification? A greater range of magnification? With my two experiments the shorter focal length produced the greatest magnification, but changing the focus between infinity and nearest focus didn't change the magnification for one of them, and only changed it a small amount for the other one. Is that normal with lenses that are reversed to body? Do you get a better range of magnifications when reversing to adapter? (Unfortunately I only have the reversers needed for reverse to body and don't have the reversers needed to experiment with reverse to adapter, hence my questions.)

The magnification ratio and the effect on the image captured on sensors of different sizes needs another discussion.

gardenersassistant wrote:

How does that work in practical terms? For example, suppose I want to reverse mount an FD lens on to an MFT body. If I put an FD to MFT adapter on the body it presents an FD mount to attach to. Do I then put an FD reverse adapter on to the FD to MFT adapter, and then attach the lens to the reverse adapter?

So, the solution is "reverse to adapter" (and it works very well).

What are the benefits of reversing to adapter rather than reversing to body? Sharper images? Less aberrations? More magnification? A greater range of magnification? With my two experiments the shorter focal length produced the greatest magnification, but changing the focus between infinity and nearest focus didn't change the magnification for one of them, and only changed it a small amount for the other one. Is that normal with lenses that are reversed to body? Do you get a better range of magnifications when reversing to adapter? (Unfortunately I only have the reversers needed for reverse to body and don't have the reversers needed to experiment with reverse to adapter, hence my questions.)

Lenses are made so they can focus as long as they are at the proper distance away from your camera's image sensor.
So, an m4/3 to Pentax adapter will give you functionality of Pentax lenses on both directions, normal or inverted.
"Inverted to body" may give you a too short distance to sensor, depending on physical lens construction.
But you can use an adapter for "Inverted to body" option plus some extenders.
1. - m4/3 body + Lens adapter + reverse ring + reverted lens
2. - m4/3 body + reverse ring for desired diameter + extension rings with same diameter + reverted lens. Extension rings have the same effect as some short macro tubes.

By example, You can use a Macro Reverse Mount Adapter m4/3 to 52mm, and 52mm to any other diameter adapters plus extension rings, to use a lot of inverted lenses made any brand.

To increase magnification with a defined lens, you need to increase the distance from the lens (inverted or not) to camera sensor (solution without any other optical attachments).

I don't honestly know but I recently spoke to a very technical and knowledgeable guy at a top lens manufacturing company.  He told me to install my 50mm on my Nikon camera normally (to keep full control electrically), then reverse a 28mm lens on top of the 50mm  (using a step ring or other adapter) so they end up facing each other.  He said this works great and even better on a 100mm Macro specific lens.  Other have seemed to agree but I have not tried it yet.

I'll even then experiment that set up with my tubes. Trial and error.

3D Gunner wrote:

gardenersassistant wrote:

How does that work in practical terms? For example, suppose I want to reverse mount an FD lens on to an MFT body. If I put an FD to MFT adapter on the body it presents an FD mount to attach to. Do I then put an FD reverse adapter on to the FD to MFT adapter, and then attach the lens to the reverse adapter?

So, the solution is "reverse to adapter" (and it works very well).

What are the benefits of reversing to adapter rather than reversing to body? Sharper images? Less aberrations? More magnification? A greater range of magnification? With my two experiments the shorter focal length produced the greatest magnification, but changing the focus between infinity and nearest focus didn't change the magnification for one of them, and only changed it a small amount for the other one. Is that normal with lenses that are reversed to body? Do you get a better range of magnifications when reversing to adapter? (Unfortunately I only have the reversers needed for reverse to body and don't have the reversers needed to experiment with reverse to adapter, hence my questions.)

Lenses are made so they can focus as long as they are at the proper distance away from your camera's image sensor.

What is puzzling me here is the "as long as", which presumably means the lens can't focus if it isn't at the proper distance from the sensor. However, if your options 1 and 2 put the lens at the right distance from the sensor so it can focus, how is it that the reverse to body option I used also allows the lens to focus, with it being at the wrong distance from the sensor? I used

3. m4/3 body + reverse ring + reverted lens

which puts the reverted lens closer to the sensor than your options 1 and 2.

So, an m4/3 to Pentax adapter will give you functionality of Pentax lenses on both directions, normal or inverted.
"Inverted to body" may give you a too short distance to sensor, depending on physical lens construction.
But you can use an adapter for "Inverted to body" option plus some extenders.
1. - m4/3 body + Lens adapter + reverse ring + reverted lens
2. - m4/3 body + reverse ring for desired diameter + extension rings with same diameter + reverted lens. Extension rings have the same effect as some short macro tubes.

By example, You can use a Macro Reverse Mount Adapter m4/3 to 52mm, and 52mm to any other diameter adapters plus extension rings, to use a lot of inverted lenses made any brand.

This is another solution out of many options.
It works very well.
The magnification ratio is obtained by dividing the value of the long focal length by that of the attached lens inverted.
Using a 100mm lens + a 50mm inverted lens gives a magnification ratio of 2x.

gardenersassistant wrote:

What is puzzling me here is the "as long as", which presumably means the lens can't focus if it isn't at the proper distance from the sensor. However, if your options 1 and 2 put the lens at the right distance from the sensor so it can focus, how is it that the reverse to body option I used also allows the lens to focus, with it being at the wrong distance from the sensor? I used

3. m4/3 body + reverse ring + reverted lens

which puts the reverted lens closer to the sensor than your options 1 and 2.

It's about the minimum distance required between the lens and the sensor.
The adapter between different mounts provides the minimum distance needed (at least).
Using the bayonet-to-lens-thread adapter requires a few extra extension rings to get the minimum distance needed for imaging on the sensor.

3D Gunner wrote:

gardenersassistant wrote:

I don't understand what you have in mind for "reverse to the adapter".

"Reverse to adapter" provides a different distance (the correct one) between the sensor and the front lens of the inverted optics, than "reverse to body".

So, the solution is "reverse to adapter" (and it works very well).

The magnification ratio and the effect on the image captured on sensors of different sizes needs another discussion.

Thank you.  You understood what I meant. I thought that was how it worked to get 1:1 with the 50mm reversed.

I've had the lenses, adapters and extension tubes for years. I just couldn't remember about that reverse mount.

3D Gunner wrote:

gardenersassistant wrote:

What is puzzling me here is the "as long as", which presumably means the lens can't focus if it isn't at the proper distance from the sensor. However, if your options 1 and 2 put the lens at the right distance from the sensor so it can focus, how is it that the reverse to body option I used also allows the lens to focus, with it being at the wrong distance from the sensor? I used

3. m4/3 body + reverse ring + reverted lens

which puts the reverted lens closer to the sensor than your options 1 and 2.

It's about the minimum distance required between the lens and the sensor.
The adapter between different mounts provides the minimum distance needed (at least).
Using the bayonet-to-lens-thread adapter requires a few extra extension rings to get the minimum distance needed for imaging on the sensor.

I just mounted a Canon EF-S 18-55 reversed directly on to a reverse ring on a G80. Both have 58mm threads so no extension rings were needed to make the physical connection. It focused fine all the way through from 18 to 55mm. I then did the same with a Panasonic 14-140mm (the only other lens I have with a 58mm filter thread). It too focused fine without the need for any extension rings.

gardenersassistant wrote:

3D Gunner wrote:

gardenersassistant wrote:

How does that work in practical terms? For example, suppose I want to reverse mount an FD lens on to an MFT body. If I put an FD to MFT adapter on the body it presents an FD mount to attach to. Do I then put an FD reverse adapter on to the FD to MFT adapter, and then attach the lens to the reverse adapter?

So, the solution is "reverse to adapter" (and it works very well).

What are the benefits of reversing to adapter rather than reversing to body? Sharper images? Less aberrations? More magnification? A greater range of magnification? With my two experiments the shorter focal length produced the greatest magnification, but changing the focus between infinity and nearest focus didn't change the magnification for one of them, and only changed it a small amount for the other one. Is that normal with lenses that are reversed to body? Do you get a better range of magnifications when reversing to adapter? (Unfortunately I only have the reversers needed for reverse to body and don't have the reversers needed to experiment with reverse to adapter, hence my questions.)

Lenses are made so they can focus as long as they are at the proper distance away from your camera's image sensor.

What is puzzling me here is the "as long as", which presumably means the lens can't focus if it isn't at the proper distance from the sensor. However, if your options 1 and 2 put the lens at the right distance from the sensor so it can focus, how is it that the reverse to body option I used also allows the lens to focus, with it being at the wrong distance from the sensor? I used

3. m4/3 body + reverse ring + reverted lens

which puts the reverted lens closer to the sensor than your options 1 and 2.

So, an m4/3 to Pentax adapter will give you functionality of Pentax lenses on both directions, normal or inverted.
"Inverted to body" may give you a too short distance to sensor, depending on physical lens construction.
But you can use an adapter for "Inverted to body" option plus some extenders.
1. - m4/3 body + Lens adapter + reverse ring + reverted lens
2. - m4/3 body + reverse ring for desired diameter + extension rings with same diameter + reverted lens. Extension rings have the same effect as some short macro tubes.

By example, You can use a Macro Reverse Mount Adapter m4/3 to 52mm, and 52mm to any other diameter adapters plus extension rings, to use a lot of inverted lenses made any brand.

I think the simple logic is to reproduce the register distance of the original body for the lens.

I want the same effect as reversing the lens on a K-mount body, so I need to the m4/3 to PK adapter. When  I reverse mount the 50mm, I expect 1:1.

BBbuilder467 wrote:

I want the same effect as reversing the lens on a K-mount body, so I need to the m4/3 to PK adapter. When I reverse mount the 50mm, I expect 1:1.

I assume you understand that what the 1:1 magnification will contain on the m4/3 sensor image is equivalent to what a 2:1 magnification would contain on the FF format image.

3D Gunner wrote:

BBbuilder467 wrote:

I want the same effect as reversing the lens on a K-mount body, so I need to the m4/3 to PK adapter. When I reverse mount the 50mm, I expect 1:1.

I assume you understand that what the 1:1 magnification will contain on the m4/3 sensor image is equivalent to what a 2:1 magnification would contain on the FF format image.

Yes. I want the actual 1:1. I have a dedicated macro lens, and have used extension tubes with the 50mm to reach 1:1.

I just want to verify what you get when reversing the lens. It's more of a test than anything else.

After getting the reverse ring, I found that I had to add 25mm of extension to the adapter to reach 1:1. Only got 1:2 without the extension tubes and the PK to m4/3 adapter using the same Pentax 50mm f/2 SMC-M.

It's about 50mm from the body itself to the lens. I didn't expect that.

BBbuilder467 wrote:

After getting the reverse ring, I found that I had to add 25mm of extension to the adapter to reach 1:1. Only got 1:2 without the extension tubes and the PK to m4/3 adapter using the same Pentax 50mm f/2 SMC-M.

It's about 50mm from the body itself to the lens. I didn't expect that.

Some interesting facts about Reverse Macro, and what the different focal lengths provide in terms of magnification when reversed.

I originally wrote the article before Laowa came out with all their cool lenses, but it is still applicable today.

If you're on of severe budget, and can't afford even Laowa glass, probably the best budget optic you can buy for reverse-macro is the Zoom Nikkor AI-S 28-85mm f/3.5-4.5 AI-S:

Zoom Nikkor AI-S 28-85mm f/3.5-4.5 AI-S

It's only about $125, and oriented correctly, you obviously get between 28 and 85mm — and up to .25x magnification. Reversing it, you can get from .25x to 2.9x magnification.

• Unlike the Canon MPE-65, and Laowa 25mm 2.5x-5x macros, this lens can focus to infinity. Unlike either, it's also a zoom lens oriented correctly.
• Unlike the Laowa 100 1-2x Macro, this lens goes almost up to 3x magnification, and it also zooms, from 28-85, so you can take wide-angle shots of habitat if you like.

It's one of the single most versatile field lenses you can select, it's dirt cheap, and it takes fairly decent macro images too. (Note: these are with a flash, and the EXIF is wrong).

That's the bad thing about reverse-macro (and most Laowas): No EXIF info.

You have to manually change the settings in your camera, and if you forget to do so, like I did, the camera just remembers the last lens that you used.

The same 50mm lens that reaches 1:1 with 50mm extension tubes, requires 25mm extension tubes to reach 1:1 reversed. Plus, it's attached to a 25mm adapter.

Simply reversed to the adapter, it's only 1:2.

BBbuilder467 wrote:

The same 50mm lens that reaches 1:1 with 50mm extension tubes, requires 25mm extension tubes to reach 1:1 reversed. Plus, it's attached to a 25mm adapter.

Simply reversed to the adapter, it's only 1:2.

Interesting.

Not sure what is all involved between the optics of different brands.

I know that I've personally measured the image-dimensions taken by my 50/1.2 AI-S, with a mm ruler, and the magnification is exactly 1.1x. There is also this worksheet from Nikon directly, concerning the magnification of reversing their lenses on their reverse-ringmounts:

Nikon's Own Lens Specs on their own reverse rings.

I don't think anyone's older glass is used more frequently than Nikon's, because they can usually be adapted to any brand, reversed. The lenses highlighted in green are MF lenses. I highlight those, because you can use a manual aperture, whereas the AF lenses require auto-aperture, which is sub optimal.

Anyway, if you'll note, their 50/1.2 AI-S (which I had) achieves 1.1x magnification. However, their 50/1.8 AI-S is only 0.5x.

Perhaps there's something to do with the aperture or the specs of your brand?? What was your aperture?

Here is a stack I did on a male Green Lynx spider, years ago, stacked with the 50/1.2 AI-S @ 1.1x:

Green Lynx ♂ Stacked @ 1.1x w/ Nikkor 50/1.2 AI-S, reversed.

Here is a female Green Lynx spider, stacked with the 28/2.8 AI-S @ 2.6x:

Green Lynx ♀ Stacked @ 2.6x w/ Nikkor 28/2.8 AI-S, reversed.

The quality of these older Nikkor optics is pretty darn good, and they're very small and very light, and again they can be reversed on almost any camera brand.

Not sure about the specs of what you're using, since it's a different brand, but I'm absolutely certain about the specs of what I'm using.

I'm trying to establish that you need the adapter from PK to m4/3 to get the magnification. I need the 25mm adapter just to reach 1:2 with the lens reversed.

I don't think I'd get any magnification at all with the lens reversed directly to the body.