petrochemist

I've used manual lenses with every interchangeable lens camera I've ever had. That's 8 Digital bodies & a few film ones too. Focusing is not as good on a DSLR as my original film SLRs, but mirrorless cameras are generally better for adapting, and the focus confirmation options in the viewfinder are better... For my most recent body purchase (an old NEX6) I don't have any AF lenses & have no plans for getting any. I have over 150 lenses I can adapt to it, all of which can also be used on my micro four thirds systems, but only about 50 on my K5ii... Thinking back I've actually used at least 15 lenses on the NEX6 so far this year (some only for very quick coverage check - 5 failed to cover the full sensor)), and should be trying another possibility at lunchtime. My favourite to date being an LTM mount 'Industar 61', though the tiny Pentax Auto110 lenses have also been fun. When it gets to motorsports/airshows and wildlife AF does have an advantage, but for most other subjects MF is quite good enough & often better. Despite the advantages of AF I'll often still use manual lenses for long focal lengths, as I have options that are significantly lighter. To get AF at 750mm equivalent I have to carry a 1.9kg lens, but I have manual options half the weight that can get me closer - A significant factor when I don't know if long lenses will be wanted! :) The oldest lens I've used has been a 1930's Kodak 12cm astigmat, which can still give good results when adapted via bellows. bellows IMGP2838 by Mike Kanssen, on Flickr

No sign of a optical trigger so probably not a simple slave, they look too small for radio triggers & I cant see any other connectors (PC etc). Both connectors appear to be of the same type so they're probably not adapters between different standards (Sony proprietary to standard, or having pins in different places...) I suspect they serve a similar purpose to the Wein models a multimeter should confirm this if a voltage >6V is put on the flash side & the camera side only reads 5V. They COULD just reverse the voltage polarity of the trigger pins but I don't think that actually effects usage of flash. Again testing with a multimeter will indicate.

I recently got a few ZWB2 filters but not tried them out yet. I haven't tried shooting UV in a darkened room, that should help a lot if my UV torches are bright enough. Apparently copper sulphate solution is quite effective at blocking NIR so I plan on making my own IR block filter at some point - I work in a lab so can get hold of the chemical easily :)

Film IR was unusual but not all that rare - I've had a few people comment (on seeing my IR shots at club exhibitions) that they'd shot some IR on film. I guess adding the mark would have been a fairly inexpensive extra :) Most film IR shooters would probably have used a R72 or equivalent which typically starts transmitting about 700nm & reaches max transmission around 740nm. So I'd expect the IR mark to correspond to something around 800nm. The insensitivity of film to IR was also a factor in trying to shoot UV. All the old UV pass filters leak considerably in NIR, making them unsuitable for UV on converted cameras. There are now some specially coated UV pass filters available, but they cost more than my last camera, and that's without getting the special lenses!

Thank heavens none of that applies to mirrorless cameras! I'd guess I've used between 10 & 20 lenses on my converted body. Three of them AF with no issues, the others are mainly adapted lenses so no chance of AF. Two of the AF lenses are zooms. Even with my DSLR I had no issues using multiple lenses, simply focus using visual light, add the filter & shift the focusing ring to the IR mark. BINGO! If your lens doesn't have an IR mark it's generally not too difficult to add one (a pen mark on a bit of tape). wrt Cokin filters I've never used one for IR but I've found light leaks (round the back of the filter between it & the holder) to be a serious issue with dark ND filters & would expect the same with IR unless special care is taken to block them. FWIW my pre-converted MFT body cost less than getting a conversion for my old DSLR at least until you add in the optional EVF I brought 6 months later.

There are a VERY wide range of factors involved in hot spots. Aperture certainly can be a factor. I've had hot spots at all f-stops using a lens on one (non converted body) but with the same lens never any on my converted body. Other times just turning round & shooting the opposite way (into the sun) has introduced a hot spot Then I've seen bad hot spots when shooting close-ups, but not at normal/infinity (without adding extension tubes etc) both these within minutes same hardware and at similar orientation to the sun.

The first camera I had (back in the mid 1970's) was a 120 roll film camera which would have been practically indistinguishable in features from models available in the 1920s. A well preserved print from 20 years previous certainly could look like one from only a year or two back. As Dustin mentioned labelling on the negative might date the film used but I know people who have recently used 35mm film from the 1970s with good results, so old film COULD have been used anyway. In aging photos it's often the clothing that gives things away more than other aspects, though the processes used before 1900 did look quite different - they are still used occasionally but went out of regular use fairly rapidly once film became available.

With the exception of rather long exposures you should have got good results from the D70 (it has a weak hot mirror, so is reasonably sensitive to IR) the biggest problem perhaps being focus shift. I used a Pentax K100d for IR which is fairly similar & had no issues as long as I focused manually with lenses with an IR focusing mark. These days I tend to do quite a bit of the false colour stuff you don't like. I only use mirrorless cameras for IR now as that gives me liveview in the viewfinder. Focus with these is done just the same as in visual light. LV should be similar, most cameras use contrast based focus in LV though a few have phase detect built into the main sensor. with both of these I believe there's no issue with AF shift. I've no experience of the AR coated conversions but the reviews I've seen do look promising. Deep IR should be sharper than standard IR (720nm) but will be noticeably less sensitive - probably over a stop. A few of my lenses have a significant drop in transmission above 800nm. In the desert IR should be plentiful so I doubt either will be an issue.

Sounds a better solution than the cruder corrected adapters, but switching to mirrorless is much easier & doesn't change the FOV... If you've done the FF 2xTC, is there any point in doing the 2x cropped version as well?

Wind power - old & new by Mike Kanssen, on Flickr

I have to admit I now use mirrorless cameras for practically all my lens adapting. I still manage to find one or two that get tricky, but I can get infinity focus with nearly 99% my photographic lenses - 15+ mounts work, the CZJ Werra (rangefinder, with aperture in the body) lenses being the only problems. Most of my lenses can be used with multiple special adapters too (focal reducing/helicoid/tilt as well as normal) FD, SR, Minolta/Sony A & Auto 110 are my only SLR lenses that don't fit the fancy adapters. Non photographic lenses such as microscope objectives & microfilm lenses can be a bit more restrictive, but they're generally only wanted for macro anyway.

Minolta lenses don't adapt well to Pentax either. SR mount lenses need to sit about 2mm closer to the film, so you either get an adapter with a teleconverter element built in, or you loose infinity focus.

Bee in infra red by Mike Kanssen, on Flickr