Polaroid Sharpness

Ok im taking test shots with my polaroid back. In the polaroid, the subject looks sharp and

the same thing thru the view finder. I scanned the polaroid to test the sharpness. I

scanned it at 3200 DPI. I zoomed in on the area and its blurry, Its not sharp at all.

 

Is this because its a polaroid and the actully negative will be much sharper? Or is

something screwed up with my lens?

 

Please help cause Im flippin out!

 

Thanks.

I do not think Polaroid has that much resolution. You are blowing up details that are not there, which is why you get that unsharp look. Take some other print, scan it at the same resolution and the zoom-in will likely give you similarly unsharp result.

 

The film will definitely have better sharpness, but small details (like foliage on far trees) can be easily unsharp if you scan at 3200dpi.

 

The customer will not be zooming into the picture at 3200dpi, they will look at the whole photo at once, just as you are looking at your polaroid (admittedly the 'oid is smaller).

 

Relax, print from the negative (or scan the negative) and make the final judgement then. I'm not discounting the possibility that there is something wrong with your camera, but most likely you are trying to judge the resolution of negative from resolution of Polaroid and that's not gonna work.

Based on my experience, the first thing is to check the optical resolution of your scanner. No, not the highest resolution the software will let you ask for (which I suspect is the source of your 3200 ppi), but the actual maximum resolution of the sensor. It's common for it to be a lot less than the "maximum scanning resolution" which higher figure is arrived at by interpolation -- that is, by letting you blow up the picture, and making what should be the edges of the pixels blurry instead of sharply defined (like defocusing an enlarger to reduce the appearance of grain in a large print).

 

When you scan beyond the optical limits of your scanner's hardware, the resulting scans get fuzzier, not sharper, because instead of adding information, you're just spreading out the same information over a larger piece of screen.

 

So, though my Arcus 1200 will let me scan at up to 9600 ppi, the actual resolution is 1200 ppi optical, with 2400 ppi vertical resolution via microstep scanning. If I scan at anything above 2400 ppi, I'll get a larger image with the same amount of actual information, and the spaces between filled in by what amounts to a mathematical version of focus blur.

 

Now, if you have a flatbed scanner that actually scans at or beyond 3200 ppi (and I'm not sure such a thing exists, much less at a reasonable price), then the questions will revolve around whether the film plane in the Polaroid back is in the same position as the ground glass -- because the other thing is that you may be "magnifying" an existing blur that's too small to see with your eye. Does the print look sharp under magnification? A 28 mm lens for a 35 mm SLR, reversed so you're looking in at the object end and have the mount toward the photo, makes a nice improvised loupe. My experience is that Polaroids aren't as sharp as comparable conventional prints, especially contact prints the same size as the Polaroid, but that could be because I've never used a really good camera with Polaroid film.

 

So, two things, and most likely (IMO) you have at least some of both -- scanner resolution limits with unadvertised interpolation, and high resolution magnification of existing blur that your eye can't detect due to scale. Probably nothing wrong with your lens, possibly even no problem with your focusing technique -- but the only way to be certain is to shoot conventional film and compare against a known good negative.

Taras

 

Examine the Polaroid with a loupe or other magnifier. The act of scanning introduces

another generation of image degradation. Remember that the Polaroid back has a glass

window which is to bring the image to focus on the Polaroid, as it can not be held at the

film plane of the roll film backs, The image on roll film passes through one less piece of

glass than the image on a Polaroid, so I would assume the Polaroid image wouldn't be as

sharp as the image on roll film.

 

Another thing could be that the Polaroid wasn't held flat in the scanner. Also, is the

scanner interpolating pixels?

 

Taras

Thanks fellas. it must be that then.

 

Heres my situtation. Im taking shots of a PC CARD being inserted into a laptop. The PC

CARD it self needs to be in perfect focus. This is not a paying gig for me, Im doing it at

work. They asked me at the last minute so I had to use whatever I have. The problem is

that the 80mm lens on my Hassy doesnt allow me to get closer than 3 feet for the card. Im

just worried that the card itself wont be sharp. Maybe Im just being an idiot.

Polaroids do have a blur to them...I have scanned a few with relative success though.

 

If you look in my portfolio, there is a shot of Henry Rollins that I unfortunately ONLY got

on a Polaroid (6x6 Hassy). I scanned it and

had it enlarged to an 8x10. It looks OK....though the applied Sharpening is visible.

 

Polaroids survive enlargement MUCH better when the Film is bigger (3x4 or 4x5)

 

Sometime you should try p/n (positive negative) Polaroid Film. I have done a lot of

enlargements from the Polaroid Negs and they look great.

 

jmp

John the polaroids dont have to be sharp cause Im just using them for testing. What Im

wondering is if my negatives will be sharp.

The Polaroid print is made by transfering the image captured on the negative

(which except for type 665 is unusable and pretty much unviewable) through

chemical gel which activates the emulsion in the print.. That is a long way of

expalining why a Poalroid print is inherently "soft". Assuming that your

camera back and camera are in perfect alignment your real film should be in

focus if it appears to be so on your cameras groundglass.

I'm not very knowledgeable about polaroid emulsions in general, but the Type 79 that I usually shoot limits out around 400 dpi. Negative film will be about 5-10 times sharper than that, depending on lens SQF, film alignment, etc.

The Polaroid film Im using is Fuji FP-100C.

Antonio:

 

"I scanned the polaroid to test the sharpness."

 

Polaroids are inherently NOT sharp. Sometimes, that's the appeal of them. When used

for proofing purposes, one generally is judging exposure and composition. Also, to

make sure sync/lenses/shutters/apertures are working properly. You cannot scan a

Polaroid and expect it to reflect the sharpness of your film.

 

If it is "blurry," as you say, and not just a bit soft, i would check to ensure that your

focus is on the mark, AND that you have sufficient depth of field. If you are shooting

small products as close as your 80mm will allow, with only natural light, you may be

using wide apertures which may not be keeping your product in focus. Lock the

mirror up, use a cable release for longer exposure times and stop down, if focus is

the problem.

 

If you have to do similar projects (small product shots) with only the 80mm, consider

buying a Hasselblad Proxar filter/lens. It will get you much closer, for only about

$100. Of course, you will have to stop-down even further, because the Depth of Field

shrinks even more with close-up attachments.

Antonio,

 

If you want to get closer with your 80mm lens, you can use an extension tube. Or you can

use a Proxar lens to get closer as well.

 

You can get some information from From Hasselblad's web site: http://

www.hasselbladusa.com/Archive/documents/Downloads_files/Information/Closeup.pdf ,

the 8mm tube gets you an field width between 10.5" and 22", a 16mm tube from 7.1" to

11", and a 32mm tube allows a field width between 4.3" and 5.5". An old 21mm extension

tube might be the right amount for something the size of a PC card.

 

A great source of info for close up are the old Hasselblad theme books. These can often be

found at used camera equipment dealers or on ebay. Also, Wildi's The Hasselblad Manual

has all the needed tables.

 

see also http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=0085FI

 

Taras

Polaroid films rely on diffusion transfer of the image from the negative, through the 'goo' and onto the reciever paper to form a positive image. That is quite a distance in terms of a film image.

 

This diffusion process results in a very unsharp image. This is the nature of diffusion and is inherent in the very word 'diffusion'.

 

Ron Mowrey

Antonio,<br><br>I'll add another confirmation of what has been said many times now: Polaroid sharpness is very, very, very bad. It's by no means a meassure of how sharp an image will appear on film.

Thanks everyone. I had another shoot this weekend and the Polaroid back was very help

ful. It was worth every penny.