digital to slides

[John Camp]

Most digital projectors throw away a good part of a camera's resolution when projecting digital photos. Has anyone tried on of the digital to (film) slide services? I've still got an old Kodak slide projector, and I suspect the slides would be much sharper than a digital projection...but I don't know for sure. Anyone? Anyone? Bueller?

[stamper]

John it would be helpful to state what country you live in, either in post or in your profile. If it is the UK then I used to use this company.

http://www.microquiz.eu/

Very good processing  imo.

[PhotoEcosse]

Perhaps have a wee think about the basic premise you are using, John. I am not sure that it is entirely valid.

If I want to enter a PDI into a digital image section of one of my camera club's competition, I have to resize it to a Jpeg not larger than 1400x1050px to suit the club's projector. Additionally, the rules limit me to a 1Mb file.

Now, you would think that making a 1½Mp Jepg from a 36Mp Raw file would suggest a huge reduction in resolution. But that premise fails to take account of the viewing mode. In our club, that "wee" 1½Mp image file is being projected on to a screen approximately 10 feet by 7.5 feet and the front row of seats is at least 15 feet from the screen.

At that viewing distance and projected image size, the resolution/sharpness/detail of the viewed photograph is every bit a good as a 35mm Kodachrome 25 trannie projected to a similar size.

The same would apply at smaller screen sizes and correspondingly lesser viewing distances.

So, I guess what I am saying is that I am not sure if you would actually gain anything, in terms of viewed image quality, by converting from a digital file to a slide for projection purposes.

I'd be interested in what others think.

[BJL]

My gut feeling is that the curvature and such of most projector screens causes focusing errors and distortions that limit the resolution of what you can see from them, and that this sets a far lower useful resolution limit than modern digital cameras are giving. I suspect that 4K and beyond will only ever be worthwhile for projection if the screen is a good rigid professional grade cinema screen.

On the point made by PhotoEcosse, the vertical resolution of most current projectors is limited to 1080 (unless you have a "4K projector budget"), and the suitability of that is described by this somewhat self-interested Sony white paper: http://pro.sony.com/bbsccms/static/files/mkt/digitalcinema/Why_4K_WP_Final.pdf  One conclusion from there that seems reasonable also for the more demanding viewing of still images is that with an image 1080 lines high, the threshold for seeing the limitations of its resolution is a viewing distance between about 2.3 and 3 picture heights for people with reasonably good eye-sight. The camera club example of PhotoEcosse has a viewing distance of twice picture height and 1050 pixels vertically, so people with 20/20 vision might notice some small degree of imperfection ... but I suspect that most camera club members no longer have 20/20 vision! (I am old enough to be allowed to say that.)


P. S. Moved here; somehow it got posted as a new thread.

[Alan Klein]

I like showing my photos (medium format and 35mm) on an HDTV at 1080.  I do it as a movie with music background and sometimes voice.  I think they're pretty good although many think that projecting the film is better.   

One advantage of showing on HDTV's is that with the "old" projection method,  you had to work quickly setting everything up before your guests would jump up, feign some illness and race home skipping the dessert.  With HDTV, they think you're putting on Sunday football and then it's too late for them to bail out once your slide show starts.

[John Camp]

Thanks everyone.

Let me set a few parameters here -- I didn't give enough information in the original post.

I want to be able to clearly see very small detail -- like electric wires on between poles.

I will be projecting at 8-10 feet to a very white, rigid, absolutely flat screen, absolutely perpendicular to the line of projection. I haven't done this yet, because it's inconvenient at the moment, but I have found a couple of on-line companies in the US who offer to print to high-resolution slides. One of them says, "All 35mm slides are imaged at 4K resolution (meaning 4096 pixels in the long dimension.)"

Would that be any different than a 4k projector?

[BJL]

... I have found a couple of on-line companies in the US who offer to print to high-resolution slides. One of them says, "All 35mm slides are imaged at 4K resolution (meaning 4096 pixels in the long dimension.)"

Would that be any different than a 4k projector?

Maybe a bit better and vastly cheaper when you consider current 4K projector prices --- unless you make a _lot_ of slides. 4K projectors tend to be in very wide "cinematic" aspect ratios, so about 4000 pixels wide like those slide scans, but less pixels high.