Print Size Confusion!!

H Folks
Pentax 35mm film user here, but getting VERY close to taking the plunge with *istD. I have done a fair bit of digital imaging and printing at home by getting my 35mm slides scanned but there is something that I cant quite work out ( I have to admit I am a NOVICE and so am probably completely missing something!).

My 35mm slides are scanned at 4000dpi resulting in a digital image size of around 5425 x 3550 pixels. So if I want to print this image at a minimum output of 300 dpi I reckon this will give me a max print size of around 18" x 12". Following the same equation, surely the maximum print size (output 300dpi) from the istD largest available image (3008 x 2008 pixels) is around 10" x 6"? In which case how are we achieving larger print sizes from 6mega pix cameras?

Sorry if the answer is obvious but I am on something of a learning curve here!

By resizing and letting the computer interpolate - that is, make up some more pixels. So, set your 300 ppi, set your required print size and let Photoshop sort out the pixels. The file size will alter accordingly.

Some photographers find that Genuine Fractals enables larger prints to be made without pixelation, but I found very little advantage to this and I let Photoshop do what it will...

I find 6MP to be very satisfactory for architecture and portraiture, but I'm not convinced that it is good enough for highly detailed landscape work.

Hey johnriley
Thanks for your reply. So basically its like upsampling? In other words if I wanted to let my 4000 scans (nominal print size @300dpi o/p 18" x 12") print at say 24" x 16", the image would have to be resampled from 4000ppi to 7200ppi.
Presumably trial and error here will show us how far we can go with this before image quality is poor.
Regards JohnMD

The ppi will stay the same, but the number of pixels will be increased or decreased to produce the size of print you want. As you say, there is a limit, but this will depend not only on the size of the print but also the distance from which the print is to be viewed.

300ppi should yield a print that can be viewed holding the print normally. If the print is to be mounted on a wall and viewed from further away in theory you might find 150ppi acceptable. The upshot of this is that in this example you could make a much bigger print.

John

Thanks for you advice. I think I'm getting the 'Picture'(!)

Regards JohnMD

Hi John/s,
I have a *ist D and find with landscape, especially with long exposures, the images can be very grainy/noisy if they are increased too much beyond A4. Even with professional labs, they cannot get a large size such as 16x20 or 18x22 out of the image without it breaking up. The interpolation is too much To increase beyond th 10x6 at 300 dpi, you are doubling the pixels and stretching the originals to create 20x12. So even bigger creates a bigger stretch. This has caused some problems when an image of mine had to be enlarged to this type of size and ended up not being able to. The professional lab ended up leaving it smaller with a larger white area around within the mount. They expressed the fact that a transparency is better for quality if it is intended to be large.

However, I still like the *ist D and will continue to use it as well as my transparencies. I find that an 8x12 image is really good with good detail and clarity. Some images can go beyond this and some can't.

I have found that if taken with higher shutter speed and good lighting, for close up type subjects. Such as architure, people, etc. when greater dof is not needed, the image can be expanded a lot more. for landscape type images, you can also use noise reduction software, which is relatively good, but the fine details and sharpness is often lost. Other photographers I know, would take sections of the landscapes and join images together, to give more pixels which works as well.

Originally, I guess I was looking and hoping to be able to have very sharp, detailed images which could be increased to A3 plus, but have been slightly disappointed. This also could be my expectations as well. I have come to the conclusion that if I want a professional image with clarity and sharpness without losses of quality when printing very large images, that the transparency wins hands down. I also have decided that big also does not necessarily mean good. A lot of images can be smaller and still have impact.

It does very much depend on the degree of fine detail present, but most of the digital photographers at ADAPS are producing very good A3 prints that stand up well against traditional photography. The cameras they are using generally produce 6 MP images.

If you are losing detail then I would certainly turn off the noise reduction, and also ensure the lowest possible ISO setting is being used. Then the print needs to be viewed from a normal viewing distance - if we look very closely at a large print we will see the defects.

If quality is still an issue, there is still the Pentax 67!

While I don't want to take away from what Anne has said, (because generally it is true) I have easily enlarged to A3, there are a few tricks involved though... I shoot with the best possible lens I can, continually I'm finding the genuine Pentax ones are better although the sigma EX ones have good writeups lately...I'm finding my manual lenses are sharper although don't have the colour (which can be boosted in PS). The other trick you can try is shooting in the MTF mode which uses the sharpest possible aperture at a given focal length (reads it from a chip in the lens...only AF lenses). Sharpening helps a lot...I'm currently trying to get a hint from Fred Miranda as to which of his sharpening tools would be best for the *istD...he has one for the D60 which is apparently pretty close to the *istD needs. (These tools are specifically designed for the camera and I haven't found anything better yet)
Hope this helps...I do a lot of stitched images too, once you get the hang of them they don't take that long. Then you can have as much detail as you want. I recently shot a 48 exposure panorama at 300mm for each shot...that outdoes 4x5 IMO. Obviously only suits certain styles of photography.

Have fun, it's a great camera and you wont regret it.

I have had the istD only a short while having only used medium format for some years but dug out my 35mm Pentax manual focus lenses has I was rather dissapointed witrh the zoom purchaced with the camera. I was amazed at the improvement in quality particually from my 50mm 1.7 partically good at 2.8 with the iso at 400 for available light shots even 800 was satisfactory