Multiple lens adaptors

[Thwyllo]

Does anyone have experience of using not one but two lens adaptors connected to each other.....?

I was perusing adaptors to fit a Bronica SQ lens to my Sony a7ii and while I think Fotodiox do one, it only seems to be available in the US and not here in Europe. However one advert that popped up on Amazon in Germany was for what was described as a combo lens adaptor which on closer inspection turned out to be an EOS to NEX adaptor with a Bronica SQ to EOS adaptor plugged into it. The idea appeals because I had already invested in a not inexpensive Bronica SQ to Nikon adaptor, so for the price of a Nikon to NEX adaptor (€25) I could be in business...

Obviously it's all manual focus and exposure although I think the a7ii will take care of the latter, but does anybody know if using two adaptors like that (1) affects infinity focus in any way (the advert said infinity focus guaranteed but I wouldn't trust Amazon any further than I could throw it) or (2) causes any light loss?

I haven't used close-up adaptors since the original days of film but I seem to recall you could lose a stop or two with them but I might be just getting old 😂... would the same be true of a double lens adaptor combination?

 

Any feedback very much appreciated

[XKAES]

Much depends on the adapters.  If neither has any glass in them (i doubt they do). they should be OK,--  and no exposure adjustment would be needed.

You should be able to use you camera in M or A MODES ONLY.

[Thwyllo]

No there's no glass, I think it's probably only Nikon bodies that suffer that issue because of the sensor to mount flange distance.

 

But I'm pretty sure I've used my a7ii with Hexanon glass in P mode as well as A and M... I'll have to pull some lenses out and check.

[tadwil]

I have done that few times with the Pentax, not as much with Sony A7II.  I have 180/2.8 and 300/4.0 Pentacon Six lenses that were part of my Pentax 645 lens kit that I have adapted to Pentax K-5 and the A7II via P6 > P645 > PK and P6 > P645 > PK > Nex respectively.  Having 3 or 4 adapters between a heavy lens and the body makes the kit unwieldy but I found a Pixco brand P6 > Nex adapter on eBay but even with this one piece adapter the kit is still somewhat unwieldy because A7II is a small body to begin with.  None of these adapters have any problems of light drop-off or infinity focus.

And you are correct in being able to shoot in any mode.  The camera still fires whether there is a lens in front of it or not in any mode and with manual lenses the camera defaults to stop down metering and adjust the exposure when you change the aperture setting manually.

[Thwyllo]

Aha that's what I thought. I did a quick bit of research and as I thought might be the case from my (very old!) film days, using extension tubes for macro work does indeed result in one or two stops of lost light, so I expect the longer tube of adaptors might have the same effect. However I think with a tripod, because I mostly do landscape and cloud stuff, I can live with that so I  just need to go and find myself a reasonably priced NIK-NEX to plug the SQ-NIK one into!

 

Many thanks to everyone who responded, much appreciated.

[XKAES]

1 hour ago, tadwil said:

And you are correct in being able to shoot in any mode. 

How can you use S-exposure mode with manually-focusing lenses.  In S-mode the camera needs to adjust the aperture.  Same with P-mode.

[Thwyllo]

16 minutes ago, XKAES said:

How can you use S-exposure mode with manually-focusing lenses.  In S-mode the camera needs to adjust the aperture.  Same with P-mode.

I don't know about S mode but I assume in P mode it simply adjusts the shutter speed accordingly. It certainly works, I was surprised and pleased to find out it did...with both Hexanon and OM glass.

[Thwyllo]

Obviously it can't adjust the aperture which is why you need to compose and focus with the lens wide open and then stop down to the required aperture when you're ready.

[Pieter]

2 hours ago, Thwyllo said:

using extension tubes for macro work does indeed result in one or two stops of lost light, so I expect the longer tube of adaptors might have the same effect.

No, the adaptors don't exactly work like extension tubes (well technically they do, but that's irrelevant here). All they do is bridge the difference in flange focal distance between two camera systems so light is still focussed on the sensitive plane. For example, your Bronica SQ has a flange focal distance of 85 mm. Nikon F has a flange focal distance of 46.5 mm so a Bronica SQ to Nikon F adapter is exactly 38.5 mm thick. Sony E has a flange focal distance of 18 mm, so a Nikon F to Sony E adapter is 28.5 mm thick. Stacked, these two adapters are 67 mm thick, which is the same as a Bronica SQ to Sony E adapter should be: 85 mm - 18 mm = 67 mm. You don't loose light, you don't reduce working distance, everything should be just fine.

Edited March 6 by Pieter

[tadwil]

3 hours ago, XKAES said:

How can you use S-exposure mode with manually-focusing lenses.  In S-mode the camera needs to adjust the aperture.  Same with P-mode.

I stand corrected, you cannot shoot in P-Mode because P-Mode with manual lenses is basically M-Mode.  A and P modes works because the shooter takes control of aperture setting aka Aperture Priority.  I shot in P-Mode with manual lenses with Panasonic Lumix G2, G6, Pentax K-5 and currently Sony A7II.  I set the aperture in order to control either bokeh or depth of field and let the camera compensate by changing the shutter speed for proper exposure.

[Thwyllo]

8 hours ago, Pieter said:

No, the adaptors don't exactly work like extension tubes (well technically they do, but that's irrelevant here). All they do is bridge the difference in flange focal distance between two camera systems so light is still focussed on the sensitive plane. For example, your Bronica SQ has a flange focal distance of 85 mm. Nikon F has a flange focal distance of 46.5 mm so a Bronica SQ to Nikon F adapter is exactly 38.5 mm thick. Sony E has a flange focal distance of 18 mm, so a Nikon F to Sony E adapter is 28.5 mm thick. Stacked, these two adapters are 67 mm thick, which is the same as a Bronica SQ to Sony E adapter should be: 85 mm - 18 mm = 67 mm. You don't loose light, you don't reduce working distance, everything should be just fine.

So I'm struggling to get my head around that explanation which sounds perfectly credible; here's why...

 

When you use extension tubes you definitely lose light because the camera lens screwed on the end of it effectively has a smaller aperture. This can be as much as a stop or two with a long tube... All this I remember from my film days and it makes sense because if you think about it if you extend that tube so it's a mile long the light from the lens would be a tiny little pin prick in the distance wouldn't it.

 

And while I can imagine there is minimal impact from a single relatively shallow lens adaptor, in this case as you have correctly pointed out, the lens is moved away from the camera by 67 mm so surely therefore there must be a loss of light - maybe a stop or so - which the camera has to compensate for by increasing ISO or reducing shutter speed (or I have to manually increase the aperture on the lens because the camera can't).

 

In simple terms, we know that old-fashioned extension tubes cause aperture reduction/light loss, so I'm struggling to understand why a different metal tube (because that's all these two adaptors are) doesn't have the same effect?

 

As I said, all this would be moot in the case of a single shallow adaptor but the Bronica one particularly is quite deep.

 

UPDATE: having gone through that thought process, I went away to check something and suddenly there was a light bulb moment - to understand how dim I was being I'll be honest and tell you that I was wondering if there's a point at which a 28 mm lens for example is no longer exactly 28 mm focal length when stuck on the front of an adaptor... I was also confusing myself because of the adaptor-on-an-adaptor scenario.

 

The simple fact is, of course, that regardless of it being two adaptors in this case, it is effectively one Bronica SQ adaptor and of course the overall effect of an adaptor is to make the lens think that it has its original camera sitting behind it, so apart from the crop factor because the Bronica is 6x6, the lens would behave exactly the same, and deliver exactly the same amount of light as it would if it were fitted to its original body. Correct?

 

So now I'm trying to get my head around what would happen if you used two adaptors because you didn't have the right one for the lens you're using? Say for example you put a Canon lens into an EOS/OM adaptor and then plug that into an OM/NEX and into your beloved Sony... I assume in that case you have created an actual extension tube which WILL reduce the effective lens aperture as well as preventing infinity focus?

 

This is 15 minutes of my life I'll never get back 😂😱😱

 

[Thwyllo]

2 hours ago, tadwil said:

I stand corrected, you cannot shoot in P-Mode because P-Mode with manual lenses is basically M-Mode.  A and P modes works because the shooter takes control of aperture setting aka Aperture Priority.  I shot in P-Mode with manual lenses with Panasonic Lumix G2, G6, Pentax K-5 and currently Sony A7II.  I set the aperture in order to control either bokeh or depth of field and let the camera compensate by changing the shutter speed for proper exposure.

Is it me or have you slightly contradicted yourself? 😂 I think what you meant to say is what I explained earlier, that you CAN use P mode but it just doesn't function as it would with an OEM lens... In other words as you say, you have to set the aperture manually but the camera then sets the exposure for you in terms of shutter speed and ISO.

In M mode of course you've got to set all three, either using a light meter, Sunny 16 or trial and error until you get the correct exposure. Correct?

[XKAES]

Regarding exposure mode, if you use P Mode with older, manual-focus lenses, the camera will try to set the correct exposure by changing the shutter speed -- that's all it can change (although depending on the camera and settings, it might try to change the ISO too).  However, it can only adjust the shutter speed (and ISO) withing the limits of the camera.  If it were if FULL P-mode -- which it can't be -- it would adjust the f-stop as well.

If you use S-mode, the only thing the camera MIGHT be able to adjust is the ISO -- and only within the limits of the camera.

As to any lens used with adapters (without glass), the important thing is the flange focal length of the lens.  The adapter simply needs to total to the length of the flange focal length of the lens, as Pieter has pointed out.  It makes no difference if it is one adapter or five stacked together.  It only becomes an extension tube when the length is LONGER than the flange focal length of the lens.  With a medium format lens with a long FFL, and a mirrorless camera with little FFL, multiple adapters can easily be used -- but only in A and M exposure modes because the S and P modes can't adjust the f-stop.

[Pieter]

9 hours ago, Thwyllo said:

in this case as you have correctly pointed out, the lens is moved away from the camera by 67 mm so surely therefore there must be a loss of light - maybe a stop or so - which the camera has to compensate for by increasing ISO or reducing shutter speed (or I have to manually increase the aperture on the lens because the camera can't).

As Xkaes and I have already pointed out, all that matters for your old Bronica SQ lenses to work properly on a Sony E-mount camera is that the distance from the mount flange to the photosensitive plane (flange focal distance) is exactly similar to your Bronica SQ setup, which is 85 mm. Since in an E-mount camera, the distance between the mount flange and the sensor is 18 mm, the Bronica SQ lens needs to be moved outward by 67 mm for it to be able to focus properly. Be it 1 or 2 or 3 adaptors and/or extension tubes or bellows stacked together makes no difference, they just need to be 67 mm in total height. Any more and you loose light intensity and reduce working distance (loose infinity focus, gain close focus). Any less than 67 mm and you gain light intensity and increase working distance (loose close focus, gain focus beyond infinity).

9 hours ago, Thwyllo said:

the overall effect of an adaptor is to make the lens think that it has its original camera sitting behind it

The adaptor does not make your lens 'think' anything, all it does is move the lens to the exact position from the photosensitive plane as it was designed to work at.

Edited March 7 by Pieter

[XKAES]

The only question remaining is "Is there really a market for putting LARGE format lenses on SMALL cameras?

[Thwyllo]

1 hour ago, XKAES said:

The only question remaining is "Is there really a market for putting LARGE format lenses on SMALL cameras?

When they're as good as a 40mm Zenzanon PS absolutely. And it's not about a "market"; we do these things because we can and it's enjoyable.

[Thwyllo]

1 hour ago, Pieter said:

The adaptor does not make your lens 'think' anything, all it does is move the lens to the exact position from the photosensitive plane as it was designed to work at.

No offence but you're being pedantic. You know exactly what I meant.

[Pieter]

20 minutes ago, Thwyllo said:

No offence but you're being pedantic. You know exactly what I meant.

Not being pedantic at all: there's a distinct difference between 'smart' adapters, which 'tell' your lens all sorts of things, and 'dumb' adapters, which are nothing more or less than an extension tube with different mounts on both ends. I merely tried to convey the message that the adapter in your case is of the 'dumb' type.

[XKAES]

I'll add that those asking questions (dumb or smart), and those providing answers (correct or incorrect) are not the only ones reading the threads on this FORUM.  But we learn from each other.

For example, I've learned that I should check out to see if I can get an adapter (or two) to attach my 37mm f4.5 Mamiya RB67 Fisheye lens on my Sony DSLR.  Sure, it weights five times as much as the camera, but "we do these things because we can and it's enjoyable."

Edited March 7 by XKAES

[tadwil]

12 hours ago, XKAES said:

-- but only in A and M exposure modes because the S and P modes can't adjust the f-stop.

No, it works in PAM modes.  All you need to do is mount a manual focus lens with an aperture ring on your Sony DSLR and shoot in P mode.  You will know for certain you can shoot in P-Mode with proper exposure throughout the aperture range.

[Thwyllo]

On 3/7/2024 at 8:52 PM, Pieter said:

Not being pedantic at all: there's a distinct difference between 'smart' adapters, which 'tell' your lens all sorts of things, and 'dumb' adapters, which are nothing more or less than an extension tube with different mounts on both ends. I merely tried to convey the message that the adapter in your case is of the 'dumb' type.

Well to be fair you are... Everyone knows that a basic adaptor with no electrical connections can't possibly "know" anything.... All I was trying to say in a very simple manner was that, as far as focal length and so on are concerned, the lens functions as if it's original camera was sitting behind it.

 

 

[Pieter]

You're the one asking for help and info about the use of adapters. Since some of your questions were pretty basic stuff, I didn't dare to assume anything about your knowledge level. I'm just trying to be as informative as I can here.