rodeo_joe1

Ermm, that's out by a factor of 1000! There are 1000 nanometres in a micron (= 1/1000th of a mm, 10^-6 metres or 1 um). A nanometre is 10^-9 metres) - blue light has a wavelength of 450 nm for comparison. So, the Rollei's 450 micron spacing is actually 0.45 mm in more understandable units, and pretty close to the 0.5 mm that I measured on the Yashica-mat and Mamiya 645. That still leaves between 1/5th and 1/4 of a millimetre slop between film-rails and 'pressure' plate. However, as Kmac already said, the film wants to stay curved as it comes off the spool. Therefore any bowing will tend to be back toward the restraining plate with a TLR film-path. Not outward toward the lens. The film has no incentive at all to float exactly halfway between rails and plate. This same concave emulsion-side bowing can be seen in processed film when fitted to a glassless negative carrier in an enlarger. In view of which, I'd suggest that any camera focussing check be done at between 0.2 and 0.25 mm (that's common millimetres!) away from the lower guide rails. E.G. by packing a ground-glass or other focussing screen with two thicknesses of 80gm/sq-m copier paper, which I've just measured as being 0.11 mm thick. Cheaper copier paper will be correspondingly thinner at about 0.1 mm.

You wouldn't see any green dots on a T2 screw-thread mount. They're only on Tamron's bayoneted Adaptalls. Adaptall mount aperture rings turn differently depending on the camera make they're designed for. The focus ring is part of the lens, without a mount added. Therefore it might not turn in the same direction as an OEM lens, which is one of the slight drawbacks of 3rd party lenses. Here's a Nikon Ai-S fit Adaptall mount - it's nothing like a crude T2 adapter.

Sadly, yes, it's true and Kmac is right; the film plane location in most rollfilm cameras is a bit rubbish. Here's the inside of my old Yashica-mat - And a closer look at the film guide rails - The 4 outer 'pips' are slightly raised and mate with the 4 tabs on the pressure-plate to prevent it contacting the inner rails - leaving a thin channel for the film to 'float' in. You can see from the film spool width that the film+backing paper fits between those 4 outer raised guides. The rollers either side of the film gate are lower than the film rails, and serve no part in tensioning or positioning the film, apart from preventing it from scraping on the rails and film gate. I measured the relative height of the guide rails with a digital depth gauge, as well as I could, and there's approximately 0.5mm difference in their height. The film-rail arrangement in my Mamiya 645 cameras is very similar, and again I measured a 0.5mm difference in height. I would be quite surprised if a Rollei TLR was much different. Then I measured the thickness of a strip of processed Ilford 100 Delta 120 film; it was 0.12 mm thick and its discarded backing paper measured 0.11 mm thick. However, unprocessed film is a little thicker than when it's processed, so if we say a total film+backing-paper thickness of 0.25 mm, we won't be far off. That leaves a gap of 0.25 mm (about 1/100th of an inch or 10 thou) for the film to float about in. Which is not very precise IMO. But having said that, the Yashi-mat and my Mamiyas have always delivered sharp and in-focus negatives. As has every other make and model of rollfilm camera I've yet used. So the system obviously works, despite its apparent sloppiness. In short, I wouldn't worry too much about film bowing in the gate. It's obviously designed to be a loose fit. Incidentally and FWIW, a focussing screen can be easily made by sticking some Scotch 'Magic' tape to some flat glass or acrylic sheet. The finely-dimpled surface of the tape is perfect for a focussing surface and resembles that of etched glass. Also, glass microscope slides can be easily broken to size after scratching them with a glass cutter. It's a better option than trying to flatten a bit of tracing paper adequately.

I've always found Tamron lenses to be well made and reliable performers. Not always outstanding optically, but very good in their price bracket. Some acheived 'cult' status in their time, and many of Tamron's modern offerings punch well above their weight. Equalling OEM lenses for (sometimes much) less money. Adaptalls allow aperture meter-coupling to most cameras. Something you can't get with a T2. They bayonet strongly onto the lens and lock firmly in place. A good design - as long as you align them properly to begin with. FWIW I bought a used lens where the Adaptall mount had been fitted incorrectly. It was impossible to remove without bending its bayonet and then completely dismantling it. Line up the green dots! Is the watchword.

Some to none at all. It's film for goodness sake! It's flexible and has an emulsion thickness. If you want an absolutely flat, sub-micron thin image-plane, shoot digital.

So, still the sub-category and 'assisted' adjective persists. Surely that's got to be a typo? Otherwise, what the heck is an 'assisted' film camera?? One with TTL? AF? A pistol-grip? Motor drive? It's own set of wheels? What?!

That sounds like an ongoing process, rather than a finalised resolution. Even if it was nearly two years ago. Is there a more recent statement from Kodak-Alaris on the subject? And obviously, Kodak are farming out their products to 3rd parties, so they have no direct Q.C.

Colour films all have the same developing time, since both the C-41 and E6 colour processes are rigidly standardised. OTOH, B&W film developing times can easily vary by 50% or more between different types in the same developer. Film exposed 24 years ago and stored without refrigeration? You're actually lucky to get a usable image at all. There's a thing called 'latent-image regression' where the undeveloped image fades over time. The least-exposed areas (shadows) disappear first, effectively resulting in under-exposure. That's in addition to the aforementioned age and/or storage-related fog. That's the reason for the advice on the box that says 'Develop promptly'.

That sounds like 'cinch' marks caused by winding the film too tightly. If film is subjected to creasing or stress, it puts enough energy into the emulsion to effectively expose it and cause black marks when developed. A polished mark on the pressure-plate might indicate the spring pressure is too heavy. Maybe someone has bent or replaced the leaf springs? Or not slotted them back onto the retaining pins properly? 1956 is nearly 67 years ago. That's an old camera! They don't last forever. Especially ones built down to a budget price.

+1 to Kmac's diagnosis. Long before the current 'film revival' most of those old folders were dilapidated and past their use-by date. I've seen many of them, and years ago, with rust-spots or missing chrome on the transport rollers and with rollers that barely turn. Those old wrecks aren't going to get any better without a big dose of help and TLC - no matter how 'desirable' they become.

OK, you asked for it! First we have to look at how lenses focus, and where the conjugate focii formula comes from. For the sake of depth-of-field it's always assumed that focussing is done by changing the distance between lens and film, or lens and sensor - the 'focal plane'. Conventionally, the distance between lens and focal plane is designated the letter 'v', and the distance between lens and subject is called 'u'. The focal-length of the lens is assigned the letter 'f'. In order for very distant ('infinite) subjects to be in focus the lens needs to be nearer to the focal-plane than for closer subjects, and vice-versa. That is; to be in sharp focus, near subjects require the lens to be further away from the focal-plane than for distant subjects. v is always => f, the focal-length of the lens. Now, (and here's where the trigonometry comes in), we can imagine the light projected by the lens from any point on a subject as a perfect cone, i.e. an isosceles triangle rotated through its vertex. And conversely we can treat the cone of light as a 2 dimensional isosceles triangle. So if we zoom in on the focal plane shown in the diagram above, and with the lens focused on an intermediate distance subject, we get this 2 dimensional model - We already know the physical size of the lens aperture from f/n, where f is the lens focal-length and n is the relative aperture (f-number). While the circle-of-confusion diameter is got from a look-up table. The aperture diameter divided by the C-O-C diameter gives us the values of delta-v, and hence v1 and v2, by similar triangles The distance of the focal-plane from the lens, v, is got from using the conjugate focii formula and the subject distance. So, that's all the information we need to work out delta-v, and from there the values of v1 and v2. When v1 and v2 are plugged back into the conjugate focii formula we get u1 and u2, which are the limits of far and near 'sharp' focus. Some of the maths cancels out and there are a few shortcuts that make the calculation(s) easier. One of which is to know that the subject 'magnification' is given by v/u. Well, my head's spinning now, going over all that again. Good luck getting your own head around it!

Just 5 days ago I spotted a Minolta SrT101 in a charity shop with a £50 price tag on it. It was fitted with a 58mm f/1. 4 MC Rokkor P-F lens. The camera body I couldn't care less about, but I'm always a sucker for a lens I haven't used before. The lens was hiding behind a filthy old skylight filter, but looked pretty clean underneath. However, the aperture was stuck open, and I haggled the price down to £40 because of that. Long story short, the aperture was completely unstuck for about an hours work, plus an egg-cupful of lighter fluid, methylated spirit and a few cotton buds. The camera body cleaned up nicely as well and has a pretty accurate shutter. Oh, and the meter works fairly accurately as well. So, yes, there are still cameras and lenses in good order out there. You just have to look past the dust, dirt and general neglect to find them. With maybe a little input of repair. FWIW, it turns out the lens ain't that hot - despite many glowing (literally) reviews online. IMO the 6 element design is basically an f/2 lens that's been 'stretched' to f/1.4 for the sake of a brighter viewfinder image, and to heck with the image quality. Whatever, I now have a camera and lens that'll easily get my money back... plus a little profit for my trouble.

Yes, and that spherical aberration is aperture-dependent. I.E. it resides in the peripheral part of the lens. Therefore attenuating the peripheral rays by any means will cut the spherical aberration and reduce the soft focus along with it. That's how the soft-focus control 'colander' disks work. I thought all that had been beaten to death in 2014.

Apart from the low contrast and flare! The lens is filthy with dirt at the very least, and who knows what permanent damage lurks beneath? Bin-worthy? Maybe not, but until the crud is cleaned off it the jury's still out.

And it's taken them three and a half years to announce!? With no product recall? Plus Danac's 'chocolate brown' seems a bit beyond a slight contamination. I never rated Dektol much anyway and I don't know why they ever dropped D-163.

I never use a pre-rinse with my inversion SS tanks. It was 35mm film in this instance, but 120 comes out the same. Ilford Delta films do bleed a little green colouration into the developer, but not FP4plus or HP5 - well, not last time I used them anyway. What tank are you using? Many metals react badly with developer. Copper and aluminium are a definite no-no.

What? Not even my old Praktina that's had the silvering eaten off the mirror by fungus/corrosion? That's kind of mirrorless.

I think it's supposed to be "assorted" film cameras.

Here's Kodak's spectral curve for T-max films - (Ilford's published response curve for FP4plus is useless, because it's tungsten light biased - the idiots!) The CdS response given in Glen's post above is at 60% between about 480nm and 700nm. So the film and CdS sensor response aren't too mismatched. Here's the response curve of a BPW-21 photodiode, fairly typical of the optically filtered SPDs around in the 1970s - It also peaks sharply at around 550nm - the yellow-green region of the spectrum. Neither of those sensors are as sensitive to blue as the film is. And it's a toss-up as to which would give the most accurate exposure readings without further filtering. However, due to its extended response any stray IR component is going to affect the 'corrected' SPD far more than the CdS cell. Matching an exposure meter response to the human eye response is a pointless red herring, IMO.

It doesn't look like fungus, but it doesn't look good either. Those light-coloured streaks and blobs on the lens might clean off, or they might be permanent coating damage and scratches. Caveat Emptor!

Just a guess, but it might be meant to indicate when the sensor is triggered - I.e. has sufficient light. Another total guess: With the shutter open and light-source in place in front of the lens; is there a position of the Cal knob where the Ind LED lights? Because I had to incorporate a triggering Indicator in my homemade shutter tester. It makes it easier to tell when you have enough light and good alignment through the lens. Incidentally, measuring an FP shutter properly really needs the light source to be sharply focused on the sensor. Something that's not easy to do unless your lamp is at some distance from the lens. Hence the indicator LED to check alignment of the light. Having said that, many commercial shutter-testers just use an opal diffused light screen in front of the camera. Good enough I suppose, if you're not too fussy. FWIW, my homemade tester was just a front-end to enable a digital storage oscilloscope to capture the shutter pulse cleanly. However I independently arrived at the design of a 35mm by 60mm sensor plate that would fit across the film rails of either a 35mm or 120 camera.

If it's like this one, it looks pretty straightforward, with very few controls to master. Having built a DIY shutter tester, they're not very complicated once you have the pulse-width counter sorted. There's a light sensor in the black plate that's positioned in the film plane of a 35mm/rollfilm camera, or has an LF lens+shutter placed over it. It looks as if an external light-source must be provided that's shone into the lens. Notice the desk-lamp shown on the cover of the instruction book. The 'Cal' knob looks as if it adjusts the sensitivity threshold of the sensor. I surmise that you just 'twiddle' it until the pulse-counter triggers reliably when the shutter is fired. So, in summary: 1. Fit the sensor plate behind the shutter. 2. Shine a light source into the lens. 3. Fire the shutter and see if the millisecond counter triggers and counts. 4. If no triggering, then adjust the sensitivity with the Cal knob. The thing can be tested by just obscuring the sensor with opaque card or the like, and seeing if it starts counting when the card is removed. I don't know if it's auto-ranging or not, but I can see no range switch. The evenness of transit of an FP shutter can be checked by moving the position of the sensor plate across the film-plane. You should get the same time-reading, +/- about 10%, at both ends of the shutter travel. P. S. Best not to use a mains LED bulb as the light source. Some have a deep flicker characteristic that could easily affect the count. That thing looks as if it predates the use of mains LED bulbs, so best to use a 'period correct' filament bulb.

FWIW, here's the colour of Kodak T-max developer after having 1 roll of T-max 100 developed in it immediately previously.

Maybe Thomas and Christian are no longer looking for the items after 19 and 11.5 years respectively? Especially since they last visited this site just days after they posted.