Comments on: I live 20 miles at 65 mph outside New York ..

By: Alberto

Alberto — Sat, 29 Nov 2008 17:29:12 +0000

Thanks for your input guys… Ed, I’ll take a look at that LL video you suggested… and I think I’ll try that test image too. I’ll let you know how it goes. Regards, Alberto

By: Brian Patterson

Brian Patterson — Thu, 27 Nov 2008 21:57:01 +0000

Thanks, Kurodo – glad you added your comments.

The DX Dilemma has been a rats nest since Day One. Since someone can put a DX lens on an FX body, it needs to be labeled at its optical spec, even though it isn’t going to present that field of view on its intended (DX) DSLR body. Just confuses a lot of people – always wished they had put both focal length representations on them.

By: Ed

Ed — Wed, 26 Nov 2008 19:51:18 +0000

Nice clear explanation Neil – thanks!

Alberto – the boys from Luminous Landscape have a video on printing which discusses exactly your question. They suggest that if your native resolution is between 180 ppi and 480 ppi you should send the native pixels (ie not resampled) to the printer. However in your case for the size you want your ppi drops (slightly) below 180ppi.

Their opinion is that in that case you can easily upsample to 200% with CS3 provided that the image you use is good to begin with (ie tack sharp and well exposed) and properly sharpened.

There is lots of detail in the LL video but Jeff Schewe also wrote an article about this in Digital Photo Pro magazine – The art of up-res. See http://www.digitalphotopro.com/technique/software-technique/the-art-of-the-up-res.html

In your case I’d do a simple experiment. Create the cropped 20″ image with native pixel resolution of 178ppi. Then create another copy where you resample to the required 300ppi. Then after you have upsampled, you need to resize to the desired 20″ (untick resampling).

Finally create one last image with the left or right halves of both test images and send that off to your online printing service. You then have one 20″ test where you can see the effect of both settings side by side.

Heck I may just do this myself on my new Epson printer – sounds like fun for a rainy day! Let us know what worked for you!

Cheers,

By: kurodo

kurodo — Wed, 26 Nov 2008 13:40:22 +0000

Tam, I don’t really agree with what you want to demonstrate ?

you say : “And seems like everyone is made to believe that its a 27-105mm equivalent” and you say “Its still a 18-70mm (cause it was specifically designed for an APS-C sensoer camera)” and “The multiplication factor comes into play only when you stick a (non-DX) lens of a APS-C sensor camera.”

I totally disagree:
Your 18-70mm IS a 18-70mm because of its optical specifications, even when not mounted on a camera. BUT because of the sensor size of APS-C cameras, your 18-70mm field of view matches the field of view of a 27-105mm zoom with a 24×36 size sensor.

And if it is a DX lens or not doesn’t matter:
a 18-70 DX and a 18-70 non DX zoom will project the same image on an APS-C sensor. The image from the non DX zoom have a wider field of view, but the borders are lost outside of the APS-C sensor. In both cases the captured image matches the field of view of a 27-105 on a 35mm camera.

Hope this help

By: William Rodriguez

William Rodriguez — Mon, 24 Nov 2008 08:26:54 +0000

I have always taken my files to a printing service lab and requested a 12×18, which is the size I usually enlarge to.
I shoot with my 4 megapixels D2H but many times, the file comes from the D70S that has 6 megapixels. Both files, when enlarged, have looked great. I leave resampling the image to the service lab.
When “resample image” is not checked the photographer can add the size he wishes to print, like my 18 inches in the widest dimension of the print. Photoshop will add the height and the ppi. The ppi could be much less than the usual 300 and still, if not under 100, the print will be fine simply because, by not checking resampling, the quality of the original has not changed.
If something I have learned from this method (taught by Scott Kelby) is that we do not need high ppi images to have an excellent print.

By: Daniel

Daniel — Fri, 21 Nov 2008 22:50:14 +0000

Ok, I just realized I spelled “calculus” wrong. Do you have a “genius” book for spelling that I can borrow?

By: Daniel

Daniel — Fri, 21 Nov 2008 22:48:54 +0000

Wow Neil! It looks like you’ve been reading that “Advanced Calculas for Genuises” book again! Thank you for this post, but it still leaves me with one question. What do you save your images as when you convert from RAW? I use Canons DPP (as do you) and I usually put ppi at 300 and change the size to 6″x9″. Sometimes I have to compromise between resolution and file size. Is this any different than choosing 100 ppi @ 18″x27″? Thanks

By: Alberto

Alberto — Thu, 20 Nov 2008 04:36:08 +0000

Great post… which reminds me of something I’ve been thinking for the last couple of days…

I’m planning on sending some of my 12MP pictures to an online printing service… they accept anything from 100ppi, being 300ppi their recommended resolution. I’d like to test some 20″x16″ printing which means my original pictures will have to be cropped (from 4288×2848 to 3560×2848) giving me an efective 178ppi resolution on the 20″x16″ paper.

Now, I’m wondering… do you think 178ppi is enough for a casual observer not to notice the lack of resolution?… and also, should I just crop the image and send it with 178ppi or should I crop and resample the image up to 6000×4800 so the resolution becomes 300ppi?… I was just thinking that maybe CS3 resampling is something I could trust (or not?)

Anyway thanks for the reply and keep up the good work!
Alberto

wonder

By: Stefanie

Stefanie — Thu, 20 Nov 2008 01:19:43 +0000

Thanks Neil! I often point people to your blog when they ask questions like this on forums and this is just another in a long line of extremely well written, informative pieces from you. Keep up the good work!

By: Neil

Neil — Thu, 20 Nov 2008 00:48:52 +0000

Sean .. thanks for the info. I wasn’t aware of that. :)

Neil vN