Can't mount lens on Bronica ETRSi extension tube.

GRHazelton · Apr 19, 2017

I just received a 28mm extension tube for my Bronica ETRSi. The tube mounts easily on the body, but I can't mount the lens to the tube! All my lenses mount easily to the body; the instruction manual says nothing about mounting a lens to an extension tube. The battery was low, I put in a fresh one, not expecting any effect; there was none.

Does anyone know of a special trick to using this tube? It seems in excellent condition, except for this one little flaw.....

Sirius Glass · Apr 19, 2017

Does the lens have to be cocked like Hasselblad lenses?

GRHazelton · Apr 19, 2017

Sirius Glass said:
Does the lens have to be cocked like Hasselblad lenses?

I don't think so. Lenses can't be removed or mounted unless the shutter and mirror are both "charged," to quote the instruction manual.

Sirius Glass · Apr 20, 2017

So cocked is like charged? Do you only have one lens that will not mount or does any other lens mount on the tube?

wiltw · Apr 20, 2017

Mount the lens on the tube first, then mount the combination on the body.

Make sure cocking pin lines up with green dot on lens; do same on teleconvertor
Mount lens on teleconvertor
Mount combination on both

GRHazelton · Apr 20, 2017

I'll try this later today. Many thanks to all.

moto-uno · Apr 20, 2017

Follow "WILTW"s' instructions , next question will be how to remove them. Peter

wiltw · Apr 20, 2017

moto-uno said:
Follow "WILTW"s' instructions , next question will be how to remove them. Peter

Remove the combination from the body, then remove the lens from the tube by pressing in the fatter chrome pin (opposite side of lens from Green Dot) to release

GRHazelton · Apr 20, 2017

wiltw said:
Mount the lens on the tube first, then mount the combination on the body.

Make sure cocking pin lines up with green dot on lens; do same on teleconvertor

Mount lens on teleconvertor

Mount combination on both

Still doesn't work. The extension tube won't insert far enough into the lens to rotate to engage. It's as if the extension tube is slightly distorted on its male end.

wiltw · Apr 20, 2017

GRHazelton said:
Still doesn't work. The extension tube won't insert far enough into the lens to rotate to engage. It's as if the extension tube is slightly distorted on its male end.

I am certain my written procedure works...I actually verified before writing it up, and then I double checked the procedure against Bronica printed instructions which I dug up! The procedure for mounting the Bronica teleconvertor is identical to Bronica extension tube...and I have both.

Methinks you are referring to the FEMALE end of the extension tube...the lens' mount inserts into the receiving ('female') side of the extension tube. Perhaps you have an extension tube that was damaged when it got dropped?

moto-uno · Apr 20, 2017

Before I say anything else , I only have the tele-converter for my ETRSI. If there's a difference
I hope someone will say so . If it's the same I'll retry to re & re the tele-converter , otherwise "WILTW"
directions I believe are correct . Peter

GRHazelton · Apr 20, 2017

Yup, I meant the female end. I'd imagine that the mounting/dismounting would be identical for the teleconverter. Certainly a drop could distort the mount just enough. Nothing visable, nothing I could fix. Guess I'll return it. In defense of the vendor no one would have noticed it unless they tried to mount it. Thanks to all for the responses. GRHazelton

wiltw · Apr 20, 2017

BTW, unless you are trying to shoot 'macro', the E14 might be better length than E28. With 75mm lens, the E14 permits 0.18x-0.36x with object distance of 39-59cm, while the E28 has 0.39x-0.54x and 35-39mmm object distance.

I own both E14 and E28 but never actually used the E28! But then again, I am not inclined to do much macro work. I finally cannabalized my E28 in order to be able to mount a Bronica ETRSi lens on a large format lensboard!

paul ron · Apr 20, 2017

be sure the lens is cocked and camera cocked.

sounds odd it wouldnt mount.

.

GRHazelton · Apr 20, 2017

wiltw said:
BTW, unless you are trying to shoot 'macro', the E14 might be better length than E28. With 75mm lens, the E14 permits 0.18x-0.36x with object distance of 39-59cm, while the E28 has 0.39x-0.54x and 35-39mmm object distance.

I own both E14 and E28 but never actually used the E28! But then again, I am not inclined to do much macro work. I finally cannabalized my E28 in order to be able to mount a Bronica ETRSi lens on a large format lensboard!

Well, the 28mm was what was available. Guess I'll look for some achromat plus lenses. Good luck on that!

wiltw · Apr 20, 2017

GRHazelton said:
Well, the 28mm was what was available. Guess I'll look for some achromat plus lenses. Good luck on that!

No such beasts made to fit the ETRSi that I am aware of.

moto-uno · Apr 20, 2017

My experience with the 105 mm macro lens has been very positive , it is however one heck of a big lens . Peter

GRHazelton · Apr 20, 2017

wiltw said:
No such beasts made to fit the ETRSi that I am aware of.

I wonder if Edmund Scientific would have such. Of course I could use 35mm with the Vivitar 100mm macro on my Pentax LX, or the 120mm macro on my 645n. But the interchangeable backs of the Bronnie are so appealing.

wiltw · Apr 20, 2017

GRHazelton said:
I'll look for some achromat plus lenses.

Can you more fully explain what you mean by the term 'achromat plus lenses'? I am now guessing you mean what are commonly referred to as 'close up lenses'...in that case there is no such thing as what I said 'made to fit ETRSi'...they fit anything of the right diameter (or with a thread size adapter)!

GRHazelton · Apr 21, 2017

wiltw said:
Can you more fully explain what you mean by the term 'achromat plus lenses'? I am now guessing you mean what are commonly referred to as 'close up lenses'...in that case there is no such thing as what I said 'made to fit ETRSi'...they fit anything of the right diameter (or with a thread size adapter)!

Wiltw, you're right. Plus lenses is a perhaps older term for "closeup filters," or "close up lenses," the positive meniscus lenses which enable closer focusing when mounted on a camera lens. Achromats are, IIRC, lenses comprised of two elements of differing refractive indices cemented together. They furnish some correction of lens abberations, but not as much as triplets or 4 element lenses, like the Tessar.

An achromat plus lens would degrade the image less than the single element plus lens. I have a Vivitar/Consina/etc 100mm f3.5 macro lens for my LX and other K mounts which will focus to 1:2 from infinity. Add its matched achromat plus lens and it goes to 1:1 with no apparent image degradation.

I don't know if anyone markets these in standard sizes for camera lenses. One possibility would be a Series filter adapter, then an achromat of the appropriate focal length and diameter from, perhaps, Edmund Scientific. Might be a kludge, but it might give good results.

Again, many thanks to those who came to my aid! I guess I'll send it back and watch for another opportunity. If it were dropped even a little out of round could make it impossible to mount.

wiltw · Apr 21, 2017

GRHazelton said:
Wiltw, you're right. Plus lenses is a perhaps older term for "closeup filters," or "close up lenses," the positive meniscus lenses which enable closer focusing when mounted on a camera lens. Achromats are, IIRC, lenses comprised of two elements of differing refractive indices cemented together. They furnish some correction of lens abberations, but not as much as triplets or 4 element lenses, like the Tessar.

An achromat plus lens would degrade the image less than the single element plus lens. I have a Vivitar/Consina/etc 100mm f3.5 macro lens for my LX and other K mounts which will focus to 1:2 from infinity. Add its matched achromat plus lens and it goes to 1:1 with no apparent image degradation.

I don't know if anyone markets these in standard sizes for camera lenses. One possibility would be a Series filter adapter, then an achromat of the appropriate focal length and diameter from, perhaps, Edmund Scientific. Might be a kludge, but it might give good results.

Again, many thanks to those who came to my aid! I guess I'll send it back and watch for another opportunity. If it were dropped even a little out of round could make it impossible to mount.

I am only aware of TWO 'achromat' product offerings, one from Canon and one from Nikon to fit their lenses. Canon has 58mm and 77mm. Nikon has 52mm and 62mm...sounds like the Nikon is the way to go! Nikon offers 1.6 and 3.0 diopter strengths.

Can't mount lens on Bronica ETRSi extension tube.

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