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  #11  
Old 4th July 2021, 01:24 PM
Mike O'Pray Mike O'Pray is offline
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Hi, CanonJane, it's dismal Jimmy here (see the rest of my reply but if you needed a car to get across to the cottage for a decent shot, it sounds quite a long way away. How far away from the nearest point for a reasonable shot is it?

Given the limited magnification from MF lenses, might it not be better to use say a 500mm cat lens or 300mm with a converter if required on a 35mm camera.

If it means serious cropping and enlarging as well to get the cottage big enough then the likes of D100 or T grain low speed film such as TMax 100 in a fine grain developer might help

Depending on the distance you might even want to try Adox CMS 20 film which for resolution gets close , some would say, to a 4x5 LF negative. It would be a tripod shot, of course as the speed of CMS is 20 at best in Adox tailored developer and probably nearer 6-10 in most other developers

I hope this introduces other possible avenues for the project

Mike
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  #12  
Old 4th July 2021, 01:45 PM
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CanonJane CanonJane is offline
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Thank you guys, certainly lots to think about!

The crofters cottage wasn’t that far away, lack of parking on a single lane road, with difficult terrain and the field of stroppy sheep with lambs meant I couldn’t just walk closer, so it mean a 4 mile detour down the valley and up around the other side.


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  #13  
Old 4th July 2021, 05:03 PM
John King John King is offline
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Quote:
Originally Posted by alexmuir View Post
There are 150mm and either 200 or 250mm lenses which would get you closer. There is also a 2x Tele converter. There is a 500mm as well, but you would need a mortgage and a Landrover to carry it.
I have the 150 which I like, but as far as getting in closer is concerned, it is only equivalent to 70mm in a 35mm camera system. Buying it, or the 250mm and the converter might be the most economical option.
Check the list of IanB Photo online. He does a lot of Bronica, and is good to deal with. Ffordes also usually have some in stock.
Alex


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Actually nearer to 90mm, or more accurately 93.75mm. That is assuming the prime lens is 80mm. If the prime was a 75mm which is half of 150mm the magnification would equal to a 100mm lens on a 35mm.

Last edited by John King; 4th July 2021 at 05:07 PM.
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  #14  
Old 4th July 2021, 08:28 PM
Michael Michael is offline
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The diameter of 6x6 is 8.485.
The diameter of 2.4x3.6 is 4.32.

(4.32 divided by 8.485) times 150 is a little over 76.
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  #15  
Old 4th July 2021, 09:03 PM
Nat Polton Nat Polton is offline
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Here are a few pages from an old SQA / SQAi Bronica brochure.
I will try and put the whole catalogue of accessories etc. on the appropriate section of the forum tomorrow.





http://www.film-and-darkroom-user.or...1&d=1625432516

http://www.film-and-darkroom-user.or...1&d=1625432516

http://www.film-and-darkroom-user.or...1&d=1625432516

http://www.film-and-darkroom-user.or...1&d=1625432516


There is at photo at the top of one of the pages showing the comparative image size from the different focal length lenses.


Bit more tomorrow.

Cheers.
Attached Files
File Type: pdf SQA PAGE 10.pdf (1.78 MB, 155 views)
File Type: pdf SQA PAGE 11.pdf (1.75 MB, 158 views)
File Type: pdf SQA PAGE 12.pdf (1.91 MB, 157 views)
File Type: pdf SQA PAGE 16.pdf (1.58 MB, 149 views)
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  #16  
Old 4th July 2021, 10:08 PM
John King John King is offline
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Quote:
Originally Posted by Michael View Post
The diameter of 6x6 is 8.485.
The diameter of 2.4x3.6 is 4.32.

(4.32 divided by 8.485) times 150 is a little over 76.
The measurement is calculated using the focal length of the lenses not the size of the film. It is a relatively straight forward task if a 50mm lens gives an image of a certain size double the focal length and the image is twice the size of the 50mm. Can I make it simpler. If a 50mm lens records an object on film as 1/2" tall. Doubling the focal length to 100mm the object would be 1" high

To get the same with a Bronica prime 80mm to get the same degree of magnification a lens would have to be 160mm, but as the comparison is with a 150mm lens the reduction in size of the image is just below that in proportion of the two 35mm lenses and not as small as you suggest.

This was part of the syllabus taught when I was on a course for my City and Guilds exam in 1963. The film size does not come it the equation especially considering the formats are a different shape. Turn a 120mm neg into a similar proportion to a 35mm neg you don't get a larger or smaller image, it just means more is cut off.

Last edited by John King; 4th July 2021 at 10:15 PM.
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  #17  
Old 5th July 2021, 06:58 AM
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Thank you all!


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  #18  
Old 5th July 2021, 07:20 AM
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MartyNL MartyNL is offline
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Here are my calculations for the 35mm film format equivalent of 150mm focal length lens on 6x6 in millimetres.

Film diagonal 35mm (24x36) = 43.2mm
Film diagonal 6x6 (56×56) = 79.2mm

43.2 ÷ 79.2 = 0.545mm
0.545 x 150 = 81.75mm


However, gven that the standard 50mm focal length lens of 35mm is 15% longer than the film format diagonal, the equivalent in 6x6 would be a 94mm lens.
81.75 + 15% = 94mm

In conclusion, scientifically, I don't see how lens focal length equivalents can be calculated without taking the film format into consideration.
And optically, the difference between the 35mm standard 50 lens vs 150mm lens is a multiple factor of x3.
While the equivalent 6x6 standard 80mm lens vs 150mm is only a multiple factor of x1.9.
Therefore, the impact of a 150mm lens on 6x6 could be visually underwhelming in comparison to a 150mm on 35mm film format.
A lens of 250 would perhaps be more satisfying in this respect.
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  #19  
Old 5th July 2021, 08:13 AM
Alan Clark Alan Clark is offline
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It seems from the above posts that there are several ways to calculate the equivalence of 35mm and 120 lenses. Here's another.
Measure the diagonals of each negative. Multiply these by the double-indirect-thorcus of the primary integer. Then divide these figures by the number of times it rained during your last holiday in Wales. If you now have minus numbers, multiply them by the number of times your car was broken into if your Welsh holiday was in Blaenau Festiniog.
This should do the trick.
Alternatively, if, like me, you don't like maths, you could do the following.
Take a 6 x 6 Bronica SQ with standard 80mm lens, and a 35mm Olympus OM1 with standard 50mm lens. From the same position, use them both in turn to frame the same subject. Do they both encompass the same width of view? When I tried this the 80m lens had a slightly narrower width of view. I concluded that a 75mm lens would have the saame width of view, and would therefore be the equivalent of a 50mm on a 35mm camera.
So - a nice easy ratio of 2:3

Alan
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  #20  
Old 5th July 2021, 08:58 AM
Michael Michael is offline
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I wish I could combine irony and the serious point as well as you do, Alan!

Anyway, differences aside, Jane's best bet is clearly to find a way of trying the options out practically rather than theoretically.

[But I would certainly take seriously the last three lines of Marty's post]
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