Solution to 39mm to 52mm Macro Coupler?

MacM545 wrote:

Besides getting a 52-52mm coupler then a 39-52mm step up ring, is there any other method for mounting the 52mm threaded lens onto a 39mm thread lens?

You need a special adapter made to order by a specialized company (or an experienced lathe), to reduce the distance between the front lenses by ~ 3mm vs the formula with two rings. (eMachineShop - for example)

MacM545 wrote:

Besides getting a 52-52mm coupler then a 39-52mm step up ring, is there any other method for mounting the 52mm threaded lens onto a 39mm thread lens?

Before you might say that I should use a different lens/lenses- I did seriously consider that, but I've also read that the diameter and/or aperture (or maybe it was the exit pupil size) of the wider angle lens should be greater. If this is certainly true, then if I can get this to work with a single adapter, there's no better way that I'm currently aware of, except my own unless perhaps I might be able to be successful with a manual vintage lens. at this point, I'd need to spend about several hundred dollars for a more modern setup. If got the 7artisans 60mm F/2.8 along with the Viltrox 23mm F/1.4 to couple with. I know, there are almost certainly better options of lenses that I could've used, but it's what I've got and hopefully I might not need to use a different lenses for the macro coupling. The distance between the lens elements should be as small as possible- which is the main reason why I don't want to use a step-up ring.

That's the most practical way to reverse mount a lens face to face.

The front lens acts as a diopter and a couple mm shouldn't show up. You might need the space to clear the outer surface of the lenses.

If I machined one, I'd do a mock-up with step-rings anyway.

FWIW, a lot of old slr primes had 52mm threads.

BBbuilder467 wrote:

If I machined one, I'd do a mock-up with step-rings anyway.

If you have a lathe and you can help MacM545, I can offer you a solution with less distance between the front lenses than with any adapter ring on the market (using two commercial adapters, ~ $15 together).

3D Gunner wrote:

BBbuilder467 wrote:

If I machined one, I'd do a mock-up with step-rings anyway.

If you have a lathe and you can help MacM545, I can offer you a solution with less distance between the front lenses than with any adapter ring on the market (using two commercial adapters, ~ $15 together).

My point is the need for a functional mock-up for the OP. I'm not going to design it for him. If the mock-up works, use it. I have a $125 minimum fee.

BBbuilder467 wrote:

My point is the need for a functional mock-up for the OP. I'm not going to design it for him. If the mock-up works, use it. I have a $125 minimum fee.

I can help him for free, just for fun, but I'm still not sure if it's worth the effort (in terms of the quality of the result) for a ~3mm gain in distance between the lenses.

I should order the parts, cut them at a lathe that is in another location and make an international shipment (more expensive than the parts themselves)...

He could do some tests to see if it's worth the effort or not. The technical solution exists.

So, we're waiting for his opinion.

................................................

I just did some measurements. The difference would be ~7mm, not ~3mm. 7mm may have some influence on quality, but still need some tests.

Using a 52-52mm coupler and a 39-52mm step up ring, you will have ~6-7mm distance added between the fronts of the objectives (not between the fronts of first optical lenses, which are situated deeper).

With my solution, you will have ~1+mm "negative" distance between the fronts of the objectives (like the front of 7artisans will go ~1+mm inside the Viltrox's front filter mount). Because of this, can have a gain of about 7+mm.

The combination does not have to be used at the maximum magnification level of the 7artisans lens, so the magnification level will be variable, with some differences in the area photographed.

c h u n k wrote:

Yeah, I wasnt thinking, I wouldnt be so sure the distance added by the step up would be problematic. The only experimentations Ive done with coupling vs just reversing with an adapter/reversing with tubes/adapter, I used step ups. I often use a Raynox, which I know isnt quite the same, but when I use my front mounted twin flash it pushes it out more than just a few mm and I havent noticed any difference. Id be more concerned about it increasing vignette than anything probably.

My understanding is that a lens that is reversed on to a normally mounted camera lens acts as a close-up lens. And as far as the distance between a close-up lens and the camera lens goes I have used a configuration with a close-up lens (Raynox 150/250) mounted on the end of a fixed tube, within which the camera lens extends and contracts (this is with a fixed lens bridge camera). The distance between the camera lens and the close-up lens varied from not much to two inches or so. I wasn't aware of any problem.

I give you a quote from an article about "Extreme Macro":

"You maybe tempted to try using a macro lens as the rear lens (ie the longer one), but be aware that this is not necessarily a route to success. Macro lenses tend to have the front element recessed into the body of the lens, and you really want the front element as close to the reversed lens as possible. And with macro zoom lenses as the rear lens, the front pupil might be too far back. Both of these will lead to vignetting."(Johan J Ingles-Le Nobel)

For the lenses in this discussion, the front elements are not too recessed into the body of the lenses, so -+few millimeters may not influence the optical system.

Longer distances between reversed lenses can induce vignetting at high apertures. I can confirm that for some situations.

Vignetting usually does not occur with close-up lenses used on lenses with normal or long focal lengths, because they have a large open surface, but may occur if used on wide-angle lenses.

3D Gunner wrote:

I give you a quote from an article about "Extreme Macro":

"You maybe tempted to try using a macro lens as the rear lens (ie the longer one), but be aware that this is not necessarily a route to success. Macro lenses tend to have the front element recessed into the body of the lens, and you really want the front element as close to the reversed lens as possible. And with macro zoom lenses as the rear lens, the front pupil might be too far back. Both of these will lead to vignetting."(Johan J Ingles-Le Nobel)

For the lenses in this discussion, the front elements are not too recessed into the body of the lenses, so -+few millimeters may not influence the optical system.

Longer distances between reversed lenses can induce vignetting at high apertures. I can confirm that for some situations.

Vignetting usually does not occur with close-up lenses used on lenses with normal or long focal lengths, because they have a large open surface, but may occur if used on wide-angle lenses.

In the setup I described I certainly got severe ("looking through a porthole") vignetting at the widest angles (lowest magnification), but having got past that I didn't notice any issues. (This was all at f/45 full frame equivalent btw.)

MacM545 wrote:

3D Gunner wrote:

BBbuilder467 wrote:

My point is the need for a functional mock-up for the OP. I'm not going to design it for him. If the mock-up works, use it. I have a $125 minimum fee.

I can help him for free, just for fun, but I'm still not sure if it's worth the effort (in terms of the quality of the result) for a ~3mm gain in distance between the lenses.

I should order the parts, cut them at a lathe that is in another location and make an international shipment (more expensive than the parts themselves)...

He could do some tests to see if it's worth the effort or not. The technical solution exists.

So, we're waiting for his opinion.

................................................

I just did some measurements. The difference would be ~7mm, not ~3mm. 7mm may have some influence on quality, but still need some tests.

Honestly, I'm not sure what to say right now, although that really is appreciated! I did some test by basically holding the front lens in front of the telephoto. The front lens I set to F/4 while the distance between lenses was likely 8-11mm. I was able to get excellent image quality. I might need to do something to be able to get the lenses closer together, safely, which I should be able to do here soon, in order to see what difference it's able to make. Even with the somewhat large gap, it seemed to me that there was good image quality although I might need to see if that's true with the smaller apertures.

You're main concern was vignetting and you've proven it works. The reverse lens is the diopter. You can't stop it down or the main lens will see it.

A 23mm lens should be a +44 diopter when reversed. How will you even measure the image size to see if the adapter length is accurate. If the adapter and step-ring work, just use it.

gardenersassistant wrote:

In the setup I described I certainly got severe ("looking through a porthole") vignetting at the widest angles (lowest magnification), but having got past that I didn't notice any issues. (This was all at f/45 full frame equivalent btw.)

Up to a point, the close-up lenses can be equated with objectives, but are not the same thing from the multiple points of view.
Let's see a practical example.

In the two images, I put a 50mm lens (at f/2.8) with extension tubes to get a 1:1 magnification, over which I inverted a 23mm lens at f/4 (maximum for this lens).
In the image on the left, between the lenses is just a 52 to 52mm coupler, in the image on the right I added an additional 9mm extension.
As you can see, in the first image the vignetting is small, but at a distance of only 9mm more it is already significant, and at +5mm it is also visible, but smaller.
You can also see less magnification as the distance between the lenses increases.
So, with the basic 60mm f/2.8 lens (instead of 50mm f/2.8) and with the inverted 23mm f/1.7 lens, at apertures wider than f/4 it is expected that vignetting will not occur using the 52-52mm coupler + 39-52mm step up ring, but at apertures smaller than f/4 I think vignetting can occur.

Also, image sharpness seriously deteriorates outside the central area if the distance between the lenses increases!

BBbuilder467 wrote:

The reverse lens is the diopter. You can't stop it down or the main lens will see it.

A 23mm lens should be a +44 diopter when reversed. If the adapter and step-ring work, just use it.

The inverted lens is not just a diopter. The optical assembly of two lenses is more complicated than that of a lens plus a diopter.

The center of the combined lenses is actually shifted to the center of the reversed lens, so for aperture alterations, the apertures on the reversed lens must be used!

The inverted lens aperture must be closed as long as necessary to obtain an optimal ratio of sharpness and depth.

VILTROX 23mm F/1.4 inverted and at aperture 1.4 I don't think it can provide a usable image.

But I agree with the idea that if it works with the respective adapters, it should be used. It only takes $8 to take the test.

3D Gunner wrote:

gardenersassistant wrote:

In the setup I described I certainly got severe ("looking through a porthole") vignetting at the widest angles (lowest magnification), but having got past that I didn't notice any issues. (This was all at f/45 full frame equivalent btw.)

Up to a point, the close-up lenses can be equated with objectives, but are not the same thing from the multiple points of view.
Let's see a practical example.

In the two images, I put a 50mm lens (at f/2.8) with extension tubes to get a 1:1 magnification, over which I inverted a 23mm lens at f/4 (maximum for this lens).
In the image on the left, between the lenses is just a 52 to 52mm coupler, in the image on the right I added an additional 9mm extension.
As you can see, in the first image the vignetting is small, but at a distance of only 9mm more it is already significant, and at +5mm it is also visible, but smaller.
You can also see less magnification as the distance between the lenses increases.
So, with the basic 60mm f/2.8 lens (instead of 50mm f/2.8) and with the inverted 23mm f/1.7 lens, at apertures wider than f/4 it is expected that vignetting will not occur using the 52-52mm coupler + 39-52mm step up ring, but at apertures smaller than f/4 I think vignetting can occur.

Also, image sharpness seriously deteriorates outside the central area if the distance between the lenses increases!

Thanks for the informative examples. That is very helpful. Here are some examples from the setup I was referring to.

For reference, the focal length of the camera lens (Panasonic FZ200) varies from 4.5mm to 108mm. The close-up lens is mounted on a fixed tube and the camera lens extends/contracts behind the close-up lens as the camera lens focal length changes. The maximum distance between the camera lens and the close-up lens is around two inches at the minimum focal length of 4.5mm.

First, the "porthole" vignetting.

With a 58mm Canon 500D. (The tube has a 55mm thread and a 55-58 step up ring.)

With a Raynox 150 (which has a significantly smaller diameter than the 500D).

With the 500D, the hard vignetting disappears somewhere around 16mm. Here it is at 14.5mm.

Here at 16.9mm the hard vignetting is gone. The top left to bottom right dropoff looks more like uneven lighting than vignetting to me. This was all very "quick and dirty": I was using a single table lamp for illumination and the lamp and camera were at (different) large angles to the piece of paper, and the angles varied from shot to shot as I was doing these shots hand-held.

Here it is at 35mm. It was similar at larger focal lengths.

With the smaller diameter Raynox 150, there was vignetting all the way out to 108 mm. Here it is at 108mm.

Here it is at 50mm. As you can see from the different corners being affected, this is partly an issue with the close-up lens not being exactly centrally mounted. I was using the clip-on adapter, which has a bit of slack as to positioning. Step ring mounting would be better in this respect.

As to image sharpness deterioration outside the central area varying with the distance between the camera lens and the close-up lens, in this case we need to be a bit careful with interpretation for a couple of reasons: close-up lenses tend to be softer in the corners; and here we are comparing across different magnifications. With those qualifications in mind, here are four examples using the Raynox 150. The distance between the camera lens and the close-up lens gets smaller as the focal length gets larger.

These were done with the camera on a table, using a 10 second timer.

35mm

56mm

93mm

108mm

It looks to me as though the behaviour of the two different setups we are illustrating differs significantly.

gardenersassistant wrote:

It looks to me as though the behaviour of the two different setups we are illustrating differs significantly.

Yes, this is the point.