MP-4 Tominon lens questions

[Thagomizer]

Hi all;

A few questions regarding the Tominon lenses designed for the Ploaroid MP-4 system. Hoping they are not too daft...

What is the film to flange distance for these lenses? Are they be capable of focusing to infinity with the right amount of distance between lens and sensor? I know that they were designed for close-up work for a fairly large film format. I'm wondering if they could be used for double duty, both as a macro lens (using extension, or reversed and stacked on other lenses) and something for greater distances on a DIY tilt/shift rig? The Tominons, were they to work at infinity, or at least greater than macro distances, would be smaller, lighter and cheaper than medium format lenses on a TS set-up, and more compact (though slower) than #%mm lenses for revrse-stack use.

Any information or suggestions would be helpful.

Thanks in advance!

[ray_parkhurst]

Hmm, I've used these for many years, but only for macro work. Never tried them for infinity focus.

Your film to flange distance question is puzzling. Do you mean at infinity focus?

The MP3/4 system used the lenses at fairly long extensions. Like the Multiphot and other systems, magnification ranges were accommodated by using varying focal lengths. I'd expect the 135mm lens to work very well at infinity, and the 17mm to not work at all. Which focal lengths are you interested in using this way?

I have used the 75mm for as low as 0.2:1 mag. I think it was designed for 3:1, so I'm using it way outside its range, but it covers APS-C well at lower mags. I don't know about FF or larger.

The 50mm appears to be a symmetric design, and works very well at 1:1, even though it was probably intended for 5:1. I would not expect it to work well at infinity though.

So IMO your best bet for a wide magnification range is the 135 and 105, and possibly the 75.

[Thagomizer]

Thanks for the information. Yes, I'm wondering what the flange distance is for infinity focus for the 50 or 35mm lenses. Longer ones aren't going to be as useful for higher magnifications on extension or stacked, and too narrow for the TS play I had in mind...

Thanks again!

[dickb]

What sensor size do you intend to use this T/S system on? For shift you need a lens with a larger image circle than your sensor diameter. For a 35mm lens this may be a challenge, especially when focussed to infinity. It sounds a bit like what in German is called an egg-laying, wool and milk-producing pig -something with an unlikely combination of positive features.

Still, it is nice to tinker with such things. I have a set of Tominons lying around somewhere, I could roughly test image circles and flange distances tomorrow.

[Thagomizer]

What sensor size do you intend to use this T/S system on? For shift you need a lens with a larger image circle than your sensor diameter. For a 35mm lens this may be a challenge, especially when focussed to infinity. It sounds a bit like what in German is called an egg-laying, wool and milk-producing pig -something with an unlikely combination of positive features.

Still, it is nice to tinker with such things. I have a set of Tominons lying around somewhere, I could roughly test image circles and flange distances tomorrow.

I'm shooting APS-C. I've got the accordian bits from a coulple of bellows. Tilting will be much easier than shifting with the way they move.

The Tominon 35mm focal length lens was designed to cover a bigger film format than 35mm, so it should produce a big enough image circle to allow a decent range of movements in relation to an APS-C sensor. Whether or not it would focus to infinity, tilting would still let me get greater subject focus in my macro shooting, which would be useful in and of itself.

Thanks for the offer of testing! That would be very helpful.

[ray_parkhurst]

What sensor size do you intend to use this T/S system on? For shift you need a lens with a larger image circle than your sensor diameter. For a 35mm lens this may be a challenge, especially when focussed to infinity. It sounds a bit like what in German is called an egg-laying, wool and milk-producing pig -something with an unlikely combination of positive features.

Still, it is nice to tinker with such things. I have a set of Tominons lying around somewhere, I could roughly test image circles and flange distances tomorrow.

I'm shooting APS-C. I've got the accordian bits from a coulple of bellows. Tilting will be much easier than shifting with the way they move.

The Tominon 35mm focal length lens was designed to cover a bigger film format than 35mm, so it should produce a big enough image circle to allow a decent range of movements in relation to an APS-C sensor. Whether or not it would focus to infinity, tilting would still let me get greater subject focus in my macro shooting, which would be useful in and of itself.

Thanks for the offer of testing! That would be very helpful.

It's tough to mount the 35mm to get low magnifications due to short FFD required. As I remember, lowest I could get on a bellows (Pentax) was ~2:1 on Canon APS-C. If you get rid of the bellows, and have a mirrorless, then you can do it with right adapters.

I expect the image circles to be pretty small at infinity focus. The lenses were designed for macro mags, and the image circle expands as mag is increased. Will be interesting to see what dickb comes up with.

Note that for tilting, if you tilt the lens, you need a large image circle. This is because tilt at the lens also causes shift. If all you need is tilt, better to do it as close to the sensor as possible. In theory if you could tilt at the sensor plane, you would get no shift, and thus no need for large image circles. Of course if you have both tilt and shift available you can shift back so there is only tilt. I use one of the cheap tilt adapters that tilt just in front of the lens mount. This type still causes significant shift, and because it doesn't have a shift function it can't be compensated, but it's the best I can do on my system. Mirrorless again has advantage here since the shorter the flange register distance, the less inherent shift.

[dickb]

OK, as expected the 17mm is a challenge. There may be more than one version of these, but I have the one with a rather long barrel. Without any added extension, on my Sony A7 I get over 2:1 magnification...

With the 35mm I need 6mm extension to reach infinity, so it has a ffd of 24mm. Looking at my lens you may be able to remove the M40 mount and gain a few mm that way.

With the 50mm I need 29mm extension to reach infinity, therefor the ffd is 47mm.

With the 75mm I need 52mm, so the ffd is 70mm.

Next I had a look at the image circles. On my Sony A7 it was a bit tricky to determine, as my set of adapters introduced some vignetting in certain combinations, but the 35mm, 50 and 75mm all have image circles large enough for full frame. Using an old ground glass I estimate the image circle to be about 45mm for the 35/4.5 and say 60-65mm for the 50/4.5.

You do have to take into consideration that this doesn't say anything about the quality of the image on the edges of these image circles. As a quick and dirty example of the Tominon 35mm at f/4.5 shows these are not designed for flat field at infinity..

[Thagomizer]

OK, as expected the 17mm is a challenge. There may be more than one version of these, but I have the one with a rather long barrel. Without any added extension, on my Sony A7 I get over 2:1 magnification...

With the 35mm I need 6mm extension to reach infinity, so it has a ffd of 24mm. Looking at my lens you may be able to remove the M40 mount and gain a few mm that way.

With the 50mm I need 29mm extension to reach infinity, therefor the ffd is 47mm.

With the 75mm I need 52mm, so the ffd is 70mm.

Next I had a look at the image circles. On my Sony A7 it was a bit tricky to determine, as my set of adapters introduced some vignetting in certain combinations, but the 35mm, 50 and 75mm all have image circles large enough for full frame. Using an old ground glass I estimate the image circle to be about 45mm for the 35/4.5 and say 60-65mm for the 50/4.5.

You do have to take into consideration that this doesn't say anything about the quality of the image on the edges of these image circles. As a quick and dirty example of the Tominon 35mm at f/4.5 shows these are not designed for flat field at infinity..

Thank you very much for that. Good to know. I'm shooting Pentax, so my flange focal distance is 45.46mm, which means I'm snookered for using the Tominon 35mm for any non-macro TS work. Oh well. If I get one, it will be macro only then. Thanks again!

[dickb]

It depends, is your Pentax a DSLR or a mirrorless camera? Pentax made some weird mirrorless camera with a regular K mount IIRC..

If it a mirrorless camera, you could mount the lens behind the lens mount plane, perhaps connecting it to the 27mm filter thread. With a DSLR, this would mean hitting the mirror.

Although, in my experience using tilt is only useful when combined with an EVF or liveview, the optical viewfinders of autofocus cameras are optimised for brightness, not critical manual focussing.