Does anyone know of a 4x5 resolution target?

[Steven Ruttenberg]

I am looking for a 4x5 film transparency target to use when I adjust my scanner focus with a variable height wet mount holder. I see 35mm format, but don't think it would work well to really set focus. I could be wrong though, but working with a target the same size as what I shoot would make me feel better and I think would work better.

Any thoughts on a 4x5 focus/resolution target and where to get? I can't find them, just the 35mm ones.

[Steven Ruttenberg]

I suppose I could order acalibrated target of choice and photograph on 4x5 with my camera. Assuming I get everything right, then I would have a target that I can use to set focus on my scanner.

[Steven Ruttenberg]

I was looking at this NBS 1952 Resolution Test Target, 3" x 3" from https://www.thorlabs.com/thorproduct.cfm?partnumber=R3L3S6P while it is 1.5mm thick and I would need to be a tad creative to wet mount, I could shimm glass in betterscanning holder to put the target at the right distance (so it ends up in the same spot/distance from the scanner glass as a wet mount piece of film would. Or I can photograph it, develop and use that as my target.

Lasersoft is looking into seeing if they can make a 4x5 target for me. Sales thought so, but is checking with main office in Germany so won't know till tomorrow.

[Leigh]

Have you checked with Edmund Optics?
They have over 100 different targets, from $6 to over $1200, and sizes from microscope slides to 8"x10".
https://www.edmundoptics.com/search/?criteria=resolution%20target#

- Leigh

[Oren Grad]

Is there a reason you need a resolution target, rather than just taking a good negative you have and adjusting for maximum scan quality? Are you trying to quantify the performance of your scanner?

[Steven Ruttenberg]

Yep, I looked and they have a target I am interested in https://www.edmundoptics.com/f/high-precision-ronchi-rulings/12727/ in either 3x3 or 4x4 like 100 lpl/mm. Would be same issue, mount to ANR glass, shim ANR to proper height and go from there. I suppose I could mount target backwards to to get close to actual slide position without shimming ANR glass.

The film target has the advantage in that I can wet mount it for focus adjustments and have that based on the same optical as an actual 4x5 film sheet when mounted.

[Pere Casals]

Steven, you can DIY your own 4x5 resolution target.

You need a USAF 1951 glass slide, and a sheet of ADOX CMS 20. Then you make several contact copies of the slide in several places of the CMS 20 sheet. The film emulsion side in contact with the printed side of the slide...

CMS 20 is in fact microfilm material, so it can outresolve anything (until 800 lp/mm). $159 for 50 Sheets, 4x5". You can develop the contact copy with any common developer, as you need no greys.

What's for the slide you may find cheap ones at ebay (search USAF 1951 glass slide), mine it's good until some 250 lp/mm, it was not reaching what was said, inspected with a microscope, but good enough for what I wanted it, most of the cases you can make an offer, try offering the half, some $40...

At the end you may need a resolving target sporting under 60 Lp/mm for the scanner, both the cheap slide and the CMS 20 are able for that. And you will also have 49 sheets of CMS to get some fun...

[Leigh]

Would be same issue, mount to ANR glass, shim ANR to proper height and go from there.
Huh?

The emulsion side of the original should be in contact with the scanner glass.
That shouldn't produce Newton's rings.

- Leigh

[Steven Ruttenberg]

Is there a reason you need a resolution target, rather than just taking a good negative you have and adjusting for maximum scan quality? Are you trying to quantify the performance of your scanner?

I tried using a well focused image, but the results were not as good as I wanted. Using a target that is calibrated and of known quality i can more accurately set the focus. In some respects I can fi d the best scanner resolution that will also give the sharpest image. More importantly it is just something I want to do.

[Steven Ruttenberg]

Huh?

The emulsion side of the original should be in contact with the scanner glass.
That shouldn't produce Newton's rings.

- Leigh

I use a better scNning fluid mount set up and wet mount my film to the anr glass film faces scanner glass. It is several mm abo e the scanner glass as that is wbere the focus point is set. G Epson for scn i v 5x7 and smaller formats.

[Steven Ruttenberg]

Steven, you can DIY your own 4x5 resolution target.

You need a USAF 1951 glass slide, and a sheet of ADOX CMS 20. Then you make several contact copies of the slide in several places of the CMS 20 sheet. The film emulsion side in contact with the printed side of the slide...

CMS 20 is in fact microfilm material, so it can outresolve anything (until 800 lp/mm). $159 for 50 Sheets, 4x5". You can develop the contact copy with any common developer, as you need no greys.

What's for the slide you may find cheap ones at ebay (search USAF 1951 glass slide), mine it's good until some 250 lp/mm, it was not reaching what was said, inspected with a microscope, but good enough for what I wanted it, most of the cases you can make an offer, try offering the half, some $40...

At the end you may need a resolving target sporting under 60 Lp/mm for the scanner, both the cheap slide and the CMS 20 are able for that. And you will also have 49 sheets of CMS to get some fun...

Cool. Since I have never done a contact image what all do I need to do it properly? Hold glass slide hold glass slide in place, make exposure etc.

[Pere Casals]

Cool. Since I have never done a contact image what all do I need to do it properly? Hold glass slide hold glass slide in place, make exposure etc.

On the enlarger easel I placed a 4mm thick mirror with the reflecting surface down, becasue mirrors are very flat compared with regular window glass, on both sides of the mirror I sprayed some 3M Re Mount glue (only a little, uniformly from far) to keep the things in place.

on it I placed the film sheet with emulsion side up, on that I placed the glass slide (printed side down) that had attached a black carboard mask. I was holding the glass slide (+ attached mask) in place by pressing steadly with fingers on the slide borders while exposing. Nothing moved...

IIRC I exposed with 10 Lux during 1s. CMS 20 it's very contrasty if processed with a regular developer (for pictorial usage it requires an special low contrast developer), and this helps to obtain nice bars, well, this comes from the microfilm nature (monodisperse, crystals all of similar size).

Using a regular contact printing frame can be difficult because the glass slide has a remarkable thickness compared to film and this may end in undesired deformation in the sheet, I not tried it but perhaps it can be used by making a bkack frame for the slide, having same thickness.

... and we have to add that we have to do all in darkness, so I used the procedure I described because that. Another choice would be using Rollei Ortho ISO 25 sheets, this allows to work under red safe light, that film is not as sharp/suitable than CMS 20 for that, but still it can be good enough to test flatbed scanners.

[Steven Ruttenberg]

Cool. Thanks for the info! Time to get that enlarger. What about sandwhiching between two pieces of glass or like the mirror and a piece of anr glass exposing it to the sun for 1 second? Some how use say a 4x5 film holder put in camera and expose by opening shutter for 1 second without a lens or with it pointing to a white light source?

[Pere Casals]

Cool. Thanks for the info! Time to get that enlarger. What about sandwhiching between two pieces of glass or like the mirror and a piece of anr glass exposing it to the sun for 1 second? Some how use say a 4x5 film holder put in camera and expose by opening shutter for 1 second without a lens or with it pointing to a white light source?

You don't need an enlarger at all, you can do it with a bare tungsten bulb or LED;: https://www.rapidtables.com/calc/light/watt-to-lux-calculator.html

A 20w tungsten bulb throws 10 Lux at 1.5m

182489

But you also can manage to have the glass slide at the test height on the bed of the scanner, and you save making the target, for you only need some platings of desired thickness separating the slide from the bed.

but if you want the 4x5 target then you have that way.



It's good that the illumination source if a bit far (1.5m) because in that way rays come more "parallel", it's also better if the illuminator is small.

[Steven Ruttenberg]

You don't need an enlarger at all, you can do it with a bare tungsten bulb or LED;: https://www.rapidtables.com/calc/light/watt-to-lux-calculator.html

A 20w tungsten bulb throws 10 Lux at 1.5m

182489

But you also can manage to have the glass slide at the test height on the bed of the scanner, and you save making the target, for you only need some platings of desired thickness separating the slide from the bed.

but if you want the 4x5 target then you have that way.



It's good that the illumination source if a bit far (1.5m) because in that way rays come more "parallel", it's also better if the illuminator is small.


Thanks for the help and suggestions. I think I will make a 4x5 target, but will try the offset of glass target as well.