Yes, microscopes also work like this... i mean i don`t want to talk you out of this, but if i wanted to test lenses to find a good one - i`d also wanted to use the good lens for taking pictures. And i am pretty sure that the aerial image is not as meaningful as a test with film. That`s why i`m remarking here as you wanted to have a mobile lens-tester.
I see about the Contax. Yes, this may be hard to resolve 100ll/mm sharp.
I`m not that into estimating quality of lenses, so if i want to test a neg once in a while i use a handheld loupe or put it in my enlarger - but a handheld loupe is easier and faster.
So you can project 100ll/mm onto the wall to a size of 1mm and hold this still enough?
Oh, if such a film-strip projector is the right thing for you i`m glad! I assumed you to shoot full frame (for the most).
These Dukanes probably will be similar, i just wanted to note that this one was for 500W and i couldn`t find any warning on it. But i have an idea what the warning could be about:
First of course not to put a too strong bulb inside, as this would fry the electronics and the film - second to only use bulbs having a cold-light reflector. A bulb of course does produce heat, being infrared, and these Halogen bulbs having a reflector incorporated usually also do reflect the infrared heat of the bulb - towards the film. Some decades ago special coatings for these halogen bulb reflectors came up which only do reflect the visible part of the light, while the infrared part will be passed.
This means ordinary Halogen reflector bulbs will reflect the heat of the bulb towards the film, while a cold-light reflector will only reflect the visible light towards the film. Of course such a bulb still will throw heat at the film, as the reflector is at the back of the bulb, front is open, but such a cold-light reflector bulb will throw less heat at the film.
Depending on the construction of the projector a non-cold-light reflector bulb may throw too much heat at the film - this could be the reason to only use specific bulbs. 28A33 and 28A55 probably are/were cold-light reflector bulbs.
But if you`d put in a 30W or 50W LED chip, you`re a lot lower in heat production that an original cold-light bulb, so going LED shouldn`t be a problem on these projectors.
Ah, i see. Now this of course does look interesting as this box ain`t big and seems to convert a camera into a projector easily... but i cannot see any opening for the fan. LEDs have a lot of advantages but also one or two disadvantages, one being that they shouldn`t get too warm. If a LED exceeds 100° Celcius (there is some variance, also depending on the manufacturer), it either will break down or will loose light-output and lifespan - they say significantly. It shall not exceed 100° Celcius by just one degree - not even for a second. Apparently its that bad, so LEDs need to be cooled sufficiently. Also for optimum performance the chip needs to be like 60° celcius, at for example 80° there will be a loss in light output.
LED chips up to 10W can be cooled passive by a heat sink, above 10W you need a (bigger) sink and a fan.
Now this box seems a little small for a 30W LED including heat sink and fan and i cannot see air inlets -outlets you`d need for a 30W LED.
So question for me was how good this works - apparently it does work but will the LED produce maximum light output, or is it getting too warm; how long can you project or is there a time limit as the LED would reach 100° celcius, is this battery driven as i cannot see any power cord - making me wonder what would happen to the battery if its being heat up by the LED, respectively the battery heating up the LED which was also possible, how film flatness is achieved as you wanted to use the camera lens wide open, so you need good flatness, what about the camera internals if the LED goes up to 60° celcius or 80° because cooling is too low...
...it looks nice at a first glance, but i had some doubts.
I mean you`re right. Enlarging lenses aren`t optimized for projection - but leaving the cinema hall aside i had a minimalist approach in my mind: Turn an enlarger to the wall and you have a (multiformat-)slide projector. If you wanted maximum performance you had to take projection lenses, but you get the idea.
Regarding the bread slices, Lol.
