Custom Center Filters Printed On Clear Gelatin

Old-N-Feeble · Oct 11, 2014

Has anyone tried printing custom center filters on clear thin gelatin sheets... the stuff available in your local supermarket? I'm thinking inkjet. One could make an exposure against a blank wall and adjust in Photoshop to use the fall-off of the lens as a template. One could even make custom CF for use at differing apertures. If the gelatin at a supermarket is too poor optically (I doubt that) then using inexpensive clear or UV gel filters would do nicely unless the inkjet ink diffuses light too much.

wildbill · Oct 11, 2014

Interesting thought with a loss in sharpness (regardless of material used) would be the only issue. OHP film or the mylar sold by Aztek would be my first choice.

Old-N-Feeble · Oct 11, 2014

The reason I suggested gelatin is due to its very pure optical qualities... at least with professional grade filters anyway. Also, the gelatin will probably absorb the wet ink from inkjet printers. I just don't know how a typical inkjet will affect optical quality. I laser printer might be a better option but I don't know if the hot drum would damage the gelatin.

Ian Grant · Oct 11, 2014

Gelatin filters were made (I think a few still are) and there was no loss of sharpness. The polymers used for some filters like Cokin, Hitech etc will absorb dyes - it's how they make the graduated filers.

Incidentally graduated filers have been around for over 100 years. Some filters use a dyed gelatin layer sandwiched between two pieces of glass, these must be squeezed together while wet so there's no air bubbles you wouldn't realise at first they are sandwiched together.

So not such an implausible idea.

Ian

cramej · Oct 11, 2014

The gelatin at your supermarket is not in any way like gelatin filters. Food gelatin has no pure optical qualities and melts in hot water.

You would need a mylar film to make such a thing. Toner from a laser printer is not translucent and at small apertures you would likely see the dot pattern. Light black or gray ink from a high quality inkjet may be translucent enough to work and the dot pattern is much smaller than a toner based printer.

Mustafa Umut Sarac · Oct 11, 2014

If inkjet penetrates in to gelatin , there would be an 3D filter. It would result in nonlinear effect and lots of strange aberrations. Theoratically , you can create lots of painting , pinsieve effects or pinhole effects. The best aberration chaos would if the two sides deeply inked. But if your idea is to correct more of a lens , it will not work IMHO.

M Carter · Oct 11, 2014

What about the wratten filters (like I used to tape to the rear element of my view camera to correct EPP for product shots). I don't know if they made a clear version, but perhaps the lightest grade of correction could then be corrected out in printing or scanning?

Before there was inkjet transparency material, I used to spray mount tracing paper to print paper and run it through a laser printer to make ground glass templates for advertising work (spray 'em with krylon clear and they'd turn pretty transparent). If wratten filters accepted the ink, that could be a way to get those 2" squares through a printer (I'd just make a thin strip adhesive, not the whole sheet!)

Old-N-Feeble · Oct 11, 2014

M Carter said:
What about the wratten filters (like I used to tape to the rear element of my view camera to correct EPP for product shots). I don't know if they made a clear version, but perhaps the lightest grade of correction could then be corrected out in printing or scanning?

Before there was inkjet transparency material, I used to spray mount tracing paper to print paper and run it through a laser printer to make ground glass templates for advertising work (spray 'em with krylon clear and they'd turn pretty transparent). If wratten filters accepted the ink, that could be a way to get those 2" squares through a printer (I'd just make a thin strip adhesive, not the whole sheet!)

Yes, they made completely clear and UV versions. They're not "cheap" but far less pricey than manufacturers' center filters.

Ian Grant · Oct 11, 2014

M Carter said:
What about the wratten filters (like I used to tape to the rear element of my view camera to correct EPP for product shots). I don't know if they made a clear version, but perhaps the lightest grade of correction could then be corrected out in printing or scanning?

Before there was inkjet transparency material, I used to spray mount tracing paper to print paper and run it through a laser printer to make ground glass templates for advertising work (spray 'em with krylon clear and they'd turn pretty transparent). If wratten filters accepted the ink, that could be a way to get those 2" squares through a printer (I'd just make a thin strip adhesive, not the whole sheet!)

It would be e worth looking at Wratten and Wainwright's Patents

After all George Eastman bought the company because they wanted Mees & Shepard's skills. Wratten's was the world leader in this field before WWI.

Ian

ic-racer · Oct 11, 2014

I made one for my enlarger by inkjet spraying onto a transparent sheet. It was pretty crude, however. I only used it between the lamp and diffuser. In terms of a taking lens filter, it would probably be easier to make a hole in a piece of cardboard and do a center burn when printing.

Old-N-Feeble · Oct 11, 2014

ic-racer said:
I made one for my enlarger by inkjet spraying onto a transparent sheet. It was pretty crude, however. I only used it between the lamp and diffuser. In terms of a taking lens filter, it would probably be easier to make a hole in a piece of cardboard and do a center burn when printing.

"Easier" is somewhat evasive. For instance, wouldn't it be easier to use a center filter on your camera rather than always burning the center during enlarging? Then you can concentrate solely on burning in clouds/sky, etc. Also, wouldn't using a CF on your camera be better to avoid overexposing the center of your film images to give enough exposure to the corners?

Dan Fromm · Oct 11, 2014

O-n-F, I take it that you're trying to avoid paying the usual high price for a proper center filter for some wide angle lens or other.

I have two such, a 49 mm one to fit a 47/5.6 SA and a 67-86 to fit a 35/4.5 Apo Grandy. I bought each used, delivered prices were around $200 each.

You have to be patient and keep looking. That or find a less expensive way to pass the time.

Old-N-Feeble · Oct 11, 2014

Thank you, Dan. Yes and no... I own four CF for use with Schneider XL lenses. I'm trying to offer an affordable alternative to those who need such filters but can't afford them... and a way to make CF for lenses that none are made for.

AgX · Oct 11, 2014

An alternative would be casting dyed resin/gelatin in an a-spherical form.

Or photographing a printed sample on un-matted, colourless film.

Newt_on_Swings · Oct 11, 2014

I don't have any, even the used prices scare me! I also wish there was a cheap and easy alternative as well.

RalphLambrecht · Oct 11, 2014

Old-N-Feeble said:
Thank you, Dan. Yes and no... I own four CF for use with Schneider XL lenses. I'm trying to offer an affordable alternative to those who need such filters but can't afford them... and a way to make CF for lenses that none are made for.

It sounds to me like an idea well worth trying.clear transparency film and an inkjet printer should work.Give it a try and report. I tried it with magenta ink for local dodging with some successthe results are shown in WBMEd2

Old-N-Feeble · Oct 11, 2014

I haven't owned an inkjet printer for approximately ten years. I'd have to buy one just to experiment with the idea. I have a cheap monochrome laser printer though.

Maris · Oct 11, 2014

Theoretically a centre dark filter could be made this way:

From the optometrist get a +3 dioptre neutral dyed-in-mass ( maybe 20% transmission) sunglass blank and combine it in contact with a clear -3 dioptre eyeglass blank. The optical powers cancel but the combo is dark in the middle and less dark at the edges. Spectacle blanks cost about $20 each here. I think Leitz did something like this years ago by combining a + lens ground from black glass with a clear - lens.

Dan Fromm · Oct 11, 2014

Maris said:
Theoretically a centre dark filter could be made this way:

From the optometrist get a +3 dioptre neutral dyed-in-mass ( maybe 20% transmission) sunglass blank and combine it in contact with a clear -3 dioptre eyeglass blank. The optical powers cancel but the combo is dark in the middle and less dark at the edges. Spectacle blanks cost about $20 each here. I think Leitz did something like this years ago by combining a + lens ground from black glass with a clear - lens.

Maris, this is how the major manufacturers make center filters. Of course, theirs have elements that are ground to fit well and to give the right density gradient. And they're cemented.

Center filters for Metrogon lenses are flat glass with fine dots of metal deposited on them. Denser towards the center. I'd think that flat glass would be a better sort than any sort of film.

ic-racer · Oct 11, 2014

Old-N-Feeble said:
For instance, wouldn't it be easier to use a center filter on your camera rather than always burning the center during enlarging? T

Perhaps if one has access to a center filter, but isn't this thread for those that don't have the filter? Also, the filter makes the lens slower and makes it harder to compose and focus. Almost always a little edge burn is needed anyway, so sometimes one can not have to do anything at all. The widest non-retorfocus lens I use is 100 degrees and there is no need for a center filter.

Dan Fromm · Oct 11, 2014

ic-racer said:
Perhaps if one has access to a center filter, but isn't this thread for those that don't have the filter? Also, the filter makes the lens slower and makes it harder to compose and focus. Almost always a little edge burn is needed anyway, so sometimes one can not have to do anything at all. The widest non-retorfocus lens I use is 100 degrees and there is no need for a center filter.

Focal length and format, please. I ask because on 2x3 my 47/5.6 SA is jes' fine but on 6x12 it really needs its center filter. Depending on the image, my 35/4.5 Apo Grandy sometimes needs a center filter. On 6x12, always and with no doubt.

AgX · Oct 11, 2014

AgX said:
An alternative would be casting dyed resin/gelatin in an a-spherical form.

It must be "spherical form"

And any casting must done without any distortion to the shape during setting.

Jim Jones · Oct 11, 2014

I exposed film through a wide angle pinhole camera and developed it for a gamma of about one. Mounted near the film holder it was good enough for pinhole photography.

RalphLambrecht · Oct 11, 2014

Jim Jones said:
I exposed film through a wide angle pinhole camera and developed it for a gamma of about one. Mounted near the film holder it was good enough for pinhole photography.

I'm not surprised. the quality of pinholes, when measured in lp/mm is better than many expect.

Old-N-Feeble · Oct 12, 2014

ic-racer said:
Perhaps if one has access to a center filter, but isn't this thread for those that don't have the filter? Also, the filter makes the lens slower and makes it harder to compose and focus. Almost always a little edge burn is needed anyway, so sometimes one can not have to do anything at all. The widest non-retorfocus lens I use is 100 degrees and there is no need for a center filter.

Yes, but it's for those who wish to make and use their own CF.

Custom Center Filters Printed On Clear Gelatin

Privacy & Transparency

Privacy & Transparency