ETRS1 and focus

[graphicaone]

<p>Hi All,<br>

I recently acquired a Bronica ETRSi with a metered prism viewfinder. However I am unable to get clear focus. I took the camera in to Teds yesterday and the fellow there said it worked perfectly for him :) I assume therefore that the eyepiece is the standard -1.5 diopters.<br>

I took the camera to my optician this morning and he measured the eyepiece as +9 dioptres. When he placed a +1.5 diopter correction lens between my eye and that eyepiece all became clear.<br>

Does anyone know how I work out what eyepiece I need to buy?<br>

Many thanks in anticipation.<br>

Robin</p>

<p> </p>

[SCL]

<p>I'm not sure how your optician arrived at +9 diopters - that is so strong that it is like looking thru several coca-cola bottle bottoms at once.</p>

<p>There were 2 metered prisms which fit on the ETRSi body.</p>

<p>If you mean the AEIII metered finder which was designed for the ETRSi, there is a diopter adjustment located on the finder provides a range from -2.5 to +0.5 diopters; there are two additional accessory eyepiece lenses, a plus which makes the range go from 0 to +3 diopters , and a minus which makes the range go from -2 to -5 diopters. </p>

<p>If you mean the AEII finder, which is smaller in size and was designed for the ETR, rather than the ETRSi, body, the standard eyepiece lens is -1.5 with diopter correction lenses available from -4.5 to +1.5 diopters. Your optician should have removed the existing eyepiece (to determine its strength - unless it was a custom job it couldn't have been a +9), and then placed various diopter correction lenses in its place to determine what worked for you. My guess based on what you related is that you need a 0.0 diopter replacement correction lens (assuming the one in place was a -1.5 and you saw fine with an additional +1.5). However I don't think Bronica made one, I think they came close, so perhaps a +0.5. OTOH, if you can stack one on top of the other, then you should get a +1.5.</p>

 

[david_henderson]

<p>I don't think you can use more than one dioptre lens in the finder. So its not a case of correcting what's there, its a case of replacing it. If I recall right, Bronica sold eyepiece dioptres at 0.5 intervals, so whether 9 or 0.9 doesn't seem quite right. I suspect that its a +1 which the optician has measured to be a little off. The standard fitted when new was indeed -1.5 but it may well have been changed, and I'm not at all sure that you yet have a useful and accurate description of what's in there now. It is however easy to find out by removing the rubber eyepiece and unscrewing the "lens" that forms the eyepiece. It'll take a minute.</p>

<p>I had the same issue in the 1990s with SQ-Ai cameras and prisms and the then UK distributor's technical people were able to translate my opticians prescription into a required dioptre. That's not an option now available I'd guess. IIRC it wasn't just a question of applying the usual opticians prescription - something to do with the fact that the looking through the prism finder was equivalent to seeing your subject from a range of 26" as I recall. I think this was dealt with in a post 10-15 years ago but I can't find it</p>

<p>Whatever your prescription, you are likely to have a problem finding it. The camera/finder has been discontinued for quite a few years now and the days of calling up the main dealer for your country and simply ordering one are long gone. It'll be a case of isolating Bronica repairers and those carrying used Bronica equipment to see who's got what. </p>

[graphicaone]

<p>Stephen and David thank you both very much for your replies.<br /><br />Stephen I have linked to a couple of photos below which might help identify it. Neither of the adjustment wheels on either side seem to have any effect on focus though.<br /><br />I agree about the +9 ! Given that the fellow in the camera shop could focus it correctly I suspect it is in fact the original -0.5 and therefore yes a subtraction of 1.5 would seem logical. If that is the case I may have to make do with a +0.5<br /><br />I don't think there is an option to stack though.<br /><br />David I agree - a replacement eyepiece would be the only option. I was advised that the strength of the eyepiece should be stamped on it somewhere but there is nothing I can see on either side :(<br /><br />There is someone over here in Australia that does have eyepieces for sale and I believe there is a company in the US that still has spares available. Once I identify exactly what I need I can then go about finding one :)<br /><br /><br>

http://www.graphicaone.com/Bronica/</p>

 

[david_henderson]

<p>Robin</p>

<p>All the Bronica eyepieces I've seen have the dioptre visible on them. </p>

<p>I wonder whether the company in Australia that sells eyepieces would consider sale or return over a period of say a week so you could get what you needed by trial & error and send the remainder back for refund. If your eyesight is OK uncorrected I wouldn't ignore the possibility that a bronica -1.5 is the answer.</p>

[graphicaone]

<p>Oh - maybe it is a home made eyepiece :(<br>

I wear graduated bifocals normally. I have no problems with my 5D but that has an adjustment to vary the eyepiece.<br>

I have used Pentax 35mm cameras in the past and the Bronica would be a similar age so I am hoping there will be a resolution.<br>

That's a thought - I can ask the person selling them over here :)</p>

 

[tom_chow]

<p>Diopter is an optical measure of inverse focal length (1/meter), thus a +1 diopter lens has a focal length of 1meter.</p>

<p>A +9 dipoter eyepiece has a focal length of 11cm (4 1/3 "), which is about the optical path length from the Bronica eyepeice to the focus screen - and if this is the case, +9 dipoter eyepeice would allow someone with neutral vision to focus on that screen. So the optician's measurement of that eyepeice is probably correct.</p>

<p>When you buy eyepeice corrective lenses, they are "dipoter corrections" which add to or change the exisiting eyepiece. I'm not sure how the ETR prism works, whether you remove the existing eyepeice or slide a correction lens over it. If you slide a correction lens over it, a -1 diopter correction lens would actually measure -1 diopter. If you replace the existing lens, then the replacement lens would actually measure +8 diopter (but would be marked -1x).</p>

<p>PS: A quick search indicates that early Bronica ETR prisms take a corrective lens that slide over the existing eye peice....</p>

[SCL]

<p>Hi Robin - I just checked the finder manual (you do have the older AEII finder, according to the picture link you supplied above) on www.butkus.org. - where you can obtain a free copy of the manual. On p. 16 it discusses <strong>exchanging</strong> the eyepiece lens for other diopters, and shows pictures of what the eyepiece lens looks like, and how to replace it. According to the picture, the strength of the eyepiece lens is printed on it. The manual cites 6 replacement lenses as follows: -4.5, -3.5, -2.5, -0.5, +0.5, and +1.5. I hope this helps.</p>

[david_henderson]

<p>I still have my Bronica Hove guide and it refers to <strong>replacing</strong> the dioptre with another rather than adding a corrective lens for your prism, and others from a similar generation. I agree with Stephen that you seem to have the AE11 finder and indeed I had the SQ version of this finder myself and I certainly had to replace the dioptre in that.</p>

[tom_chow]

<p><img src="http://www.rockycameras.com/ekmps/shops/rockcameras/images/bronica-etrs-1.5-diopter-2.49-14132-p%5Bekm%5D500x375%5Bekm%5D.jpg" alt="" width="500" height="375" /><br>

<img src="http://www.graphicaone.com/Bronica/_MG_7944.jpg" alt="" width="800" height="533" /><br>

... it looks like you unscrew the ring above the eye peice and replace it with the above...</p>

 

[graphicaone]

<p>Thanks Tom - that's encouraging news and would explain why the fellow in the shop could focus my camera :) I think replacing the eyepiece would be necessary in this instance. Thanks for explanation of the optics :) :)<br>

Stephen - there was nothing printed on the existing eyepiece which makes me suspicious. Looks like I need a 0 diopter eyepiece which apparently doesn't exist :( Thanks for confirming what I have and the link to the manual.<br>

The person who has some for sale in Australia has +0.5 so I guess that's the nearest I'll get. He has asked me to make an offer <sigh><br>

Thanks David - yes replacement is needed I think :) It is a simple one screw operation as you would know :) - that's how I removed the existing one for the optician to measure it - I hope the replacement goes back on the same way :) I look forward to getting some film through this camera - it's been a long time since I used film. Did it for 35+ years though :)</p>

<p> </p>

[graphicaone]

<p>Ah - excellent - thanks for the photos Tom :) <br>

I couldn't work out how to embed photos myself :(</p>

[tom_chow]

<p>Robin, the unmarked existing eyepiece is probably the "0 diopter" stock lens. Prisms optics are constructed such that the focus screen is sharp when your eyes are focused to somewhere between 1m or infinity. (it varies with manufacture, and by model in the same manufacture). They often do not mark this eyepiece as it is "universal".</p>

<p>If you slightly near sighted, and the stock prism optic is set for infinity, then a -1 dipoter eyepiece (which simply means your eyes focus closer to see the screen - about 1m in this case) makes a big difference. You really only need to mark they eyepiece that is not standard.</p>

[mwmcbroom]

<p>According to my ETRSi manual, the standard eyepiece has a diopter strength of -1.5, which I've always felt was rather a lot for a standard eyepiece diopter. And it is not marked, either, so the unmarked one you reference is likely -1.5. Bronica also made a -0.5 one, which is more like the standard diopter strength found on most other cameras.</p>

<p>Me, I've lucked out. My right eye sees at -1.5 diopters, so the stock ETRSi eyepiece is exactly what I need. A while back I was in a conversation with someone else about diopters and the inability to find what I needed. This guy suggested cutting up an existing set of old glasses. Because glasses these days are almost always plastic, this is not difficult to do. You should be able to do the final shaping with a file, then pop out the existing one and cement the new one in place. But I'm thinking you'll want to cut up a set of fixed diopter glasses and not progressives.</p>

[david_henderson]

<p>I have had - don't have it now- a Bronica prism with a std eyepiece with -1.5 stamped on it. I was told by the Bronica technical manager of the then European Distributor that their prisms required a dioptre that would allow the user to see perfectly at a range of 26". I have a feeling that these two facts may not be disconnected.</p>