hyoro
I have to say: I haven’t tried it yet...
But I did notice the following yesterday in the darkroom: the greater the distance between the enlarger head and the paper, the
closer I have to bring the lens to the negative in order to focus. With my older Opemus, however, the bellows are already fully compressed on the base plate even when enlarging large sections. So how can I achieve even larger formats (floor and wall projection) if – logically? – I can’t focus any further? Is this down to my enlarger, which is probably intended more for medium format, or is this feasible with a different focal length, for example?
Best regards,
Henning
Urnes
Hello Henning,
That’s right – if you want to make larger prints with 35mm film and have been working with an 80mm lens up to now, you’ll need a 50mm lens, which, on my Magnifax, is fitted by rotating the lens plate to get closer to the negative. There are also so-called WA lenses from Schneider and Rodenstock (40mm for full-frame), which allow for even larger images.
Regards, Sven.
Roman
Hello!
As the previous speaker has already hinted at: when using a 50mm lens, the lens plate must be positioned on the enlarger so that the curvature faces upwards/inwards/towards the negative. Rest assured, it is still possible to focus even when the enlarger head has reached the end of the column; with an 80mm lens (where the plate should face downwards, towards the base plate), you won’t have these problems anyway; it’s just that, at maximum column extension, only smaller images are possible compared to the 50mm...
hyoro
Hmm – well, firstly, I have a 50mm Rodagon, and secondly, the plate is also curved towards the bellows; that’s actually why I bought the custom-made version from FOTOIMPEX :-)
Perhaps the bellows is actually a bit ‘less short’ than on a standard 35mm enlarger...
Or, and this question is for Mirko, is your plate, for technical reasons, curved a tad less deeply than the original one?
A longer focal length results, I think, in smaller image dimensions. That means I could only make tiny enlargements on the base plate with an 80mm, but large ones on the floor or on the wall – or have I got that wrong? (Wouldn’t an even shorter focal length require the bellows to be shortened even further?)
So would an 80mm lens solve my ‘problem’?
Thanks and best regards,
Henning
Gast
Hi Henning,
It might be that the problem isn’t as bad as it seems.
Basically, this is down to the law of projection. Therefore, the amount of adjustment required for the lens gets smaller and smaller as the magnification increases. In theory, the Opemus should be able to focus almost to infinity; only then should the bellows be at its limit. Magnifications above 1:10 (where even a 50 cm lens-to-image distance corresponds to a 50 mm focal length) require very little extension adjustment. So give it a go first.
Basically, an 80mm lens will of course give you some leeway; you can also fit this one with the plate curvature facing inwards. The distances (lens/image) will naturally increase by a factor of 8/5.
Regards
Martin
hyoro
@max: Yes, that sounds plausible!
However: if I hardly need to focus anymore, that also means I can hardly do it anymore (!), as the mechanism of my Opemus doesn’t exactly run ‘like a dream’. I’m already turning the wheel ‘all the way’ to catch that point just before it (sometimes I end up with proper pressure marks on my hands afterwards). Is it possible to make the friction gears run more smoothly with lubricant?
Thank you all for your advice!
Best regards,
Henning
kessler
Hi Henning,
I’ve got hold of the fine-focus knob for the Opemus. It doesn’t cost an arm and a leg here at FOTOIMPEX, and it really does make focusing easier. Lubricating it with silicone? That made the mechanism run much more smoothly. You just have to be careful not to get the silicone stuff everywhere, as it’s quite difficult to remove from rough surfaces.
Best regards,
Martin
hyoro
Hello!
To sum up: I put it to the test today – and it DOESN’T work!
I placed the enlarger on a chair, turned the column upside down and projected a slide onto a white sheet of paper on the floor. With the ‘top stop’, the focal plane is about 10–15 cm above the floor at full aperture! You could now argue about depth of field... well.
So the base plate is either significantly too flat for this purpose – but for technical reasons it cannot be made any deeper (the Rodagon fits in there absolutely perfectly), so please don’t take this as a criticism of FOTOIMPEX! – or the Opemus bellows is reaching its limits with these dimensions – it could be, but I can’t judge without a comparison.
So the only options left are: a different lens (slimmer than the Rodagon) that fits into the original plate, or a longer focal length with a corresponding enlargement of distances.
Or else, and this is slowly dawning on me, a new enlarger in the medium term $-(
Many thanks to everyone who helped clarify this – and perhaps it has ‘helped’ someone else too.
Best regards,
Henning
