Originally posted by normhead ....Tony is actually a printer. If he tells me that with a 600 DPI printer you need two rows of lines to make one line, making it effectively a 300 DPI printer, I'll be happy to go with that. Sometimes stuff just doesn't make sense.
Thank you normhead. As a printer and photographer (would be for the latter for the last 12 years - personal reasons) {Pedant mode:
ON} I cannot actually tell you precisely that {Pedant mode:
OFF} , but you are certainly in the right direction. And, yes sometimes it is hard to make sense of stuff and once we think we have made sense then someone throws new or contradictory information into the barrel and off we go again!
Please take the following in the manner it was intended that is informing. I am not here to try to teach or preach, I do not try to tell people what they should see or do and I do not always follow my own advice or suggested best practice
. I have learned a lot from this and other fora and generally have taken away more than I have contributed. So my contributions are really trying to help others based on my working experience and if it is just theory or guesswork I will endeveour to make sure I mention this.
Ok, so I am picky and try to make sure we are talking like for like and comparing apples to apples. To make sure of no confusion I try not to use the catch all DPI my first photographic mentor and boss beat this into me! I know that this may be teaching granny to ...
When referring to scanners for instance I use SPI (samples per inch). Inkjet printers have two resolutions one that is declared to the OS which is its requirements measured in PPI and the only thing that our editing programs are interested in.
The second and least appreciated (IMO) is DPI. A printers dpi specification is pretty meaningless in relation to the ejaculation (I have a dislike of the misuse of the word Giclee quite affected again IMHO!) of ink onto paper. The dpi specification is merely the pitch of the stepper motor usually seen as two figures in the specs. I do not think in terms of dots either because the printer 'squirts' ink onto paper and that volume of ink does not have a fixed size it will spread according to variable such as substrate absorption paper surface type and many other factors...It can take many DPI to form 1 PPI
So to finally arrive back at your first statement the only change I would make is that generally there is a hidden agenda within your print driver and although 300/600 PPI and 360/720 PPI quoted as declared to OS the actual max is probably double this. I have two main printers an everyday Canon TS 8000 series and Epson P800 the actual maximum resolution is 1200 PPI for the Canon and 1440 PPI for the Epson. So as you said 1/2 the maximum resolution brings us back to 600 PPI Canon and 720 PPI Epson. I have never seen any IQ improvements printing over 720 PPI my own or others work. However I have until recently limited myself to outputting from either LR or PS. Results may well be different via another specialised printing application either RIP or something I have but rarely use Qimage. Mike Chaney has showed some advantages to IQ for certain images printing at the higher PPI. I am well aware of viewing distance and how it should or may not matter if you are far enough away - still if you do get close you may see what your capture system is capable of.
On the matter of Dr Clark well he came or was brought to my attention many years ago when I was researching digital imaging sharpening and optics.
Dr Roger Clark PH.D Planetary Science MIT 1980
Over 300 scientific papers posted
Team member of certain NASA bodies
Team member on the Cassini mission to Saturn
Lead the USGS environmental assessment of the World trade Centre diasaster
Lead the 2010 Deepwater Horizon Gulf of Mexico oil spill.
Hirsch citation index: H-index= 72 (2017)
I have faith in Dr Clark judgment and assessment as do many others including those that pointed me in his direction many years ago. Does he know what he is talking about photographically, optically visually I would say yes he does. Regardless of this I would and have proven and demonstrated to myself and others some of the points he covers.
Perhaps his choice of image last updated in 2009 could have been better, that is his call and nearly 10 years on he is unlikely to add more? What he published and what I linked to cannot by any means be considered junk. With the benefit of hindsight I could have pointed to another learned article and author – his just came to mind.
The image depicted is a small section from a 5x4 film.
I will try and comment on at least some of the points you made in an earlier post on this thread at least to the best of my knowledge and understanding - there may be controversy
. Hope that did not come across as pompous
EDIT: Just to prove I do take photos and print them my table with recent test prints and a restoration work from finished B&W to hand coloured for a project I am working on with a client. Nothing wonderful but the image with rhe rule on top is going to be a 60"x17" print to go in a spare bedroom (to hide the poor plaster repair I made prior to painting). I may post something more on this image - from a photographer that really hates the fact that he cannot hold his iPad or Android phone steady!!