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LotusEsp
10-Jul-2016, 04:51
Hi
I'm having a bit of trouble with soft images.

I'm using a Shen Hao 4 x5 with a 90mm rodenstock lens. I have a good solid tripod and am focusing with a loupe on the standard GG

I focus with the aperture wide open, and then stop down (f32) for the shot I want. When I develop and scan in my slides, they are all slightly out of focus, across the entire frame (landscape images) near-far-middle, all slightly soft. There is no sharpness anywhere

I am shooting on Kodak Ektar 100 and developing myself with unicolor C-41 kit

I am troubled by what I think is sharpness on the GG glass not transferring to the negative. Is it a shooting thing or a developing issue at play here?

Thanks
Simon

Jim Jones
10-Jul-2016, 06:08
Perhaps the lens is flawed. Is there a problem with any other lens? At very small apertures, diffraction limits sharpness. However, f/32 shouldn't be quite that small an aperture on a 4x5 camera. A more likely problem is the position of the focusing screen. Sometimes Fresnel lenses have been added or removed between the focusing screen and the camera lens, throwing the focus off by about 2/3 the thickness of the Fresnel. In a 4x5 film holder, the distance from the face of the holder to the back of the film should be 0.197 =/_0.007 inches. The distance from the face of a plain ground glass frame to the ground glass should be slightly less to allow for the thickness of the film. This distance must be adjusted if a Fresnel lens is mounted between the ground glass and camera lens. To check for this, photograph a ruler at an angle. If the image is sharpest at a different mark on the ruler than you focused on, the problem is likely the positioning of the ground glass in its frame. By using standard lens formulae or online calculators, the displacement of the ground glass can be calculated. Remotely possible is a defective film holder.

David Lobato
10-Jul-2016, 07:40
You didn't say if you examined the negatives with a loupe. Are they sharp?

Robert Oliver
10-Jul-2016, 08:41
Using a Cable release?

F32 should compensate for any minor film plane issues.

Is it possible it's a scanning issue? You didn't say if you looked at the negatives with a good loupe.

Can you post a scan?

Bob Salomon
10-Jul-2016, 09:40
Using a Cable release?

F32 should compensate for any minor film plane issues.

Is it possible it's a scanning issue? You didn't say if you looked at the negatives with a good loupe.

Can you post a scan?
F 32 is in diffraction and can't compensate for film plane issues. That would be the depth of focus of the lens. Which is behind the lens and determines where the film plane is. Depth of field changes with aperture and is what appears in apparent sharp focus depending on the chosen CofC and the magnification and the viewing distance.

What kind of loupe are you using to determine focus? Have you adjusted its eyepiece so it is adjusted to focus other grain of the gg?

LotusEsp
10-Jul-2016, 10:47
The loupe is pretty cheap/basic

http://www.bhphotovideo.com/c/product/798855-REG/Kalt_NP10158_8x_AGFA_Style_Loupe.html

Jac@stafford.net
10-Jul-2016, 11:28
The loupe is pretty cheap/basic

http://www.bhphotovideo.com/c/product/798855-REG/Kalt_NP10158_8x_AGFA_Style_Loupe.html

I used to use those. I have two and each focuses differently. I had to use it backwards to focus upon the ground glass texture. Could that be an issue? Can you see the GG texture?

Doremus Scudder
10-Jul-2016, 12:32
Several things could be going on here.

First, check the negative with a good loupe (even your Agfa 8x loupe should be sharp in the center) and see if, indeed, the flaw is with the negative.

If it is not, then it is a scanning problem. I don't scan, so no help from me here :)

If the neg is soft, then look for focus issues. Although Bob is technically correct that f/32 introduces a bit of diffraction, I use that aperture all the time and can make razor sharp 16x20 prints from it. That's not your problem. Camera movement should be obvious under magnification; you will see directional blur, or a double image. If the image is unfocused, than you may have a ground glass misalignment, Fresnel positioning problem or filmholder seating problem, all of which result in the film being in a different place than where you focused.

Check this with the following test: With the camera in zero position, set up a ruler at a 45° angle to it. Focus wide open on a specific marking (say the 10cm mark). Shoot wide open, develop the negative and see where on the ruler is sharp. If the 10cm part is the sharpest, then no problems. If that's not the case then start checking things. First check if your filmholders are seating correctly. Any gunk or added light-trap material in the seat can cause the film to be positioned incorrectly. If you have a Fresnel screen, make sure it is installed correctly. If it is between ground glass and lens, it may well be the culprit unless it is an OEM screen. If your Fresnel can be removed, take it out and place it behind the ground glass and do the test again.

If none of these are the problem, then the ground glass is likely misaligned. If the sharp focus in your test is at a point farther from the camera, then the ground glass needs to be shimmed back. If a point closer is in focus, the ground glass needs to be unshimmed or moved forward (this latter is rare).

Doremus

Bob Salomon
10-Jul-2016, 12:50
The loupe is pretty cheap/basic

http://www.bhphotovideo.com/c/product/798855-REG/Kalt_NP10158_8x_AGFA_Style_Loupe.html

That's your first problem. Invest in a proper, adjustable, opaque barrel focusing loupe.

LotusEsp
10-Jul-2016, 12:54
any suggestions on a good loupe?

LotusEsp
10-Jul-2016, 12:58
thanks all, I'll recheck my focusing and try a B&W test with a ruler to check the neg/GG alignment

Mick Fagan
11-Jul-2016, 00:33
any suggestions on a good loupe?

In a nutshell, Bob Salomon has nailed the requirements very well.

You will find many different magnification factors of various loupes available. I have used 2x, 4x, 5x, 6x, 8x, and I have some 12x to 18x loupes that are for another industry. The best loupe magnification that works easiest for me on a GG for view cameras is the 4x magnification. I own and have used a 2x magnification loupe often with very good results.

If you start to go much higher than 6x magnification, then things are generally a bit harder to focus the image super clearly. 8x is starting to get a bit hard, above that I have found focusing much harder. Doesn't mean you cannot use a high(ish) magnification, you certainly can, but you are focusing on an increasingly smaller area.

I have a Schneider 4x with opaque and semi-opaque and that is very good. However round loupe bases are a bit problematic for getting alongside the GG edge and especially into the corners.

To that end, I eventually purchased a Peak 4x square based loupe, best thing I have done for focusing, works a treat.

The better loupes all have a dioptre adjustment ring, whereby you adjust the focus so that your eyesight is corrected. That adjustment ring is really a requirement, not a luxury.

Attached is a picture of the Peak loupe that I have.

Mick.

152690

Randy Moe
11-Jul-2016, 01:53
Is it possible to miss focus with any loupe-eyesight combination? If the image looks sharp and in focus on GG with any Loupe is it not in focus? Of course if the GG is out of spec positionly that IS the problem.

I try many loupes and simple bare -7 diopter eye works OK at very close distance, but I have checked GG postion against holder actual and found some issues with some famous gear. Get a depth gauge and learn to use it. Or make a couple go no go sticks. Learn the stack up issue. http://www.sigmetrix.com/tolerance-stack-up/

Jim Jones
11-Jul-2016, 04:35
Randy's link to the stack up issue is particularly applicable to film holders and ground glasses. Consider the linear position of the film within the holder. The "T" distance, between the face of the holder and the septum in a 4x5 holder is 0.197 +/- 0.007". The width of the slot for the film is 0.012". The film I have used varied from 0.004" to 0.010". Assuming the dimensions of the holder and film are barely within specs, the emulsion could be from 0.194" to 0.216" from the face of the holder. Ground glass position error and any deviation from perfect flatness of the film adds to the potential for unsharpness. To further complicate the problem, film may record more detail than can be seen on the ground glass, and it is easier to analyze sharpness on film than on a ground glass.

This may sound discouraging, but photographers have managed to achieve sharp 4x5 negatives for more than a hundred years. Some even dare to use Aero Ektars wide open, although an acceptable depth of focus may well be smaller than the above worst case film position error. It's ironic that sheet film with all of its potential for error has almost completely replaced the more precise glass plates in vogue when typical lens apertures were smaller and contact printing was the norm.

LotusEsp
11-Jul-2016, 05:16
Randy's link to the stack up issue is particularly applicable to film holders and ground glasses. Consider the linear position of the film within the holder. The "T" distance, between the face of the holder and the septum in a 4x5 holder is 0.197 +/- 0.007". The width of the slot for the film is 0.012". The film I have used varied from 0.004" to 0.010". Assuming the dimensions of the holder and film are barely within specs, the emulsion could be from 0.194" to 0.216" from the face of the holder. Ground glass position error and any deviation from perfect flatness of the film adds to the potential for unsharpness. To further complicate the problem, film may record more detail than can be seen on the ground glass, and it is easier to analyze sharpness on film than on a ground glass.

This may sound discouraging, but photographers have managed to achieve sharp 4x5 negatives for more than a hundred years. Some even dare to use Aero Ektars wide open, although an acceptable depth of focus may well be smaller than the above worst case film position error. It's ironic that sheet film with all of its potential for error has almost completely replaced the more precise glass plates in vogue when typical lens apertures were smaller and contact printing was the norm.

Thats a very good point. All the talk of tolerances yet people have been getting sharp images for many years before I came alone with my fat fingers.

I did another loupe test last night, and found that I was looking at the ground side (closest to the lens) of the GG, not the smooth side. There are black lines etched into the ground side and these focus up with the grain

When I get time I will burn some B&W and try the ruler test. I should also check my scanning process.

Jac@stafford.net
11-Jul-2016, 06:39
I did another loupe test last night, and found that I was looking at the ground side (closest to the lens) of the GG, not the smooth side. There are black lines etched into the ground side and these focus up with the grain.

That is the correct method. If you want to make life a bit more complex, but get accurate focus, consider aerial focusing. You can have the GG drilled to make it so.

LotusEsp
11-Jul-2016, 08:09
thanks Jac
are there any walk through of aerial focusing? I've been searching but can only find vague referencing to the process, drilling holes, using thin wire etc. Nothing comprehensive

Doremus Scudder
11-Jul-2016, 10:18
Is it possible to miss focus with any loupe-eyesight combination? If the image looks sharp and in focus on GG with any Loupe is it not in focus? ...

Randy, I think you're right here. I've used cheap loupes turned backward, magnifying glasses and all sorts of other focus aids. As long as you are focusing on the frosted side of the ground glass, as sharp as it gets with the loupe is the correct focus. My current favorite "loupe" these days is a small pull-out 8x magnifying glass with one aspheric element (exactly the one that Sherlock Holmes uses in the "Sherlock" series). It has no skirt; I just hold it the right distance from the gg.

There is a problem if you focus on the image in a different place than on the frosted side of the ground glass. This would seem to me only possible with the aerial image, but I'm not sure.

... I did another loupe test last night, and found that I was looking at the ground side (closest to the lens) of the GG, not the smooth side. There are black lines etched into the ground side and these focus up with the grain. ...

This is exactly correct, so it's likely not your loupe or your focusing that's the problem.

Best,

Doremus

Jim Jones
11-Jul-2016, 12:10
thanks Jac
are there any walk through of aerial focusing? I've been searching but can only find vague referencing to the process, drilling holes, using thin wire etc. Nothing comprehensive

My first choice would be to polish out the ground glass texture in a small spot for aerial focusing rather than drill a hole, although I've never had to use aerial focusing.

Pere Casals
13-Jul-2016, 08:44
any suggestions on a good loupe?

Peak brand, Schneider...

I like this one I like:

http://www.bhphotovideo.com/c/product/40720-REG/Peak_1302044_8_16x_Zoom_Loupe.html

but I'd prefer to buy 20 8x10 Velvia sheets : )

I use this one, same of the above link, but AP branded... http://www.bhphotovideo.com/c/product/798855-REG/Kalt_NP10158_8x_AGFA_Style_Loupe.html

It is said that 4x is better, but for me 8x also works perfect, well you see less area and ground glass grain is perceived to much, but I check focus perfectly.

Just one thing, if one needs glasses to read, and most of 40+ years old people do, then one needs something that can be adjusted, same like the diopter of DSLRs...

...I have to rise the AP loupe some 4mm from ground glass to sharpen the image, this can be confusing, I've to add an spacer to adjust the loupe to my eye !!

I made the barrel near opaque with a permanent marker. Yes... a good loupe is a great thing if one shots a lot !!!

Jac@stafford.net
13-Jul-2016, 08:57
any suggestions on a good loupe?

I second the suggestion to try a few, if possible.

I'll leave this thread with just a couple things - greater magnification is not always better, the coarseness of the GG is important and relates to magnification. I have a couple of the late Satin Snow screens and it was just too fine for my eyes (but so very well made). Finally if you use a GG with a hood as some field cameras have, be sure it reaches into the area properly. :) The later point is why I had to swing away the hood on mine, a real PITA. I lucked out in finding a used Wista loupe, the long, collapsible one; no longer made, I think.

Good luck!

brouwerkent
13-Jul-2016, 09:09
Sounds to me like a ground glass misalignment...that would be consistent as you describe. Loupes should not even be necessary except in very low light or with a really slow lens.

Peter Collins
13-Jul-2016, 09:23
Wow! WOW!!! That Peak loupe is priced to perfection. Just a little less than another lens.....

Pere Casals
13-Jul-2016, 09:24
I think is sharpness on the GG glass not transferring to the negative.

Suposing that there is no camera shake...

You have to spend a sheet or two to diagnose the thing.

Place a metering tape on the floor, the camera can be some 3 metres far and 1 meter higher, well, it depends on the bellows you have to focus on near objects...

Then write in a paper the DOF: first and last numbers in focus of the metering tape, so you have the center focus reference.

Shot wide open and develop... You'll know if the focus center has shifted, by looking in the neg if the same numbers of the metering tape are in focus.

Is a shift there ? It can be:

1) Film holder plane inside Graflock clamp has to match the same plane than the ground glass.

2) Tripod !!!! Be careful !!! if it has some jog... if you make a tilt and after inserting the film holder it moves just a bit... then the focus plane will move a lot !!! impossible to retain the focus in the eyes of the subject !!!

a tripod can be "elastic", this is it can move away when you make force to insert the film holder, but it is imperative (absolutely) that the camera returns exactly to the same position after you stop making force !!!!!

3) Some weird glasses have "focus shift", the focus plane moves when you close diafragm, an example is old Symmars in converted configuration, this can be stated by closing diafragm and cheking focus again, this may be done in a dark place and with a subject strongly illuminated with a close light source.

To know if it is the tripod or the glass plane, repeat the shot but with some tilt movement, and perhaps making a little of force down at the lens (hang some 200grs weight). If problem appears with the shot made with the shift movement, then it's the tripod !!!

This is what I know... I don't remember other factors...

djdister
13-Jul-2016, 09:59
Shooting a 90mm lens stopped down to f/32 should be a lock on a sharp negative - diffraction should be minimal. Assuming that you are able to focus the image on the ground glass visually (again, should be easy enough for a landscape without using a loupe), to summarize the three most likely sources of this problem:

1. The ground glass is not positioned correctly, or could even be installed backwards. The "ground" side should be facing the lens, not the back of the camera. Also, check to see if someone inserted a Fresnel lens next to the ground glass (if so, where is it placed?).

2. The film holder is not seating properly at the back of the camera. What type of film holder are you using?

3. The film is not inserted into the film holder correctly. Is it loaded emulsion side out, slid all the way under the film rails?

LotusEsp
13-Jul-2016, 10:46

I am not using a fresnel at all - only the GG
The ground side is facing the lens
I am using a mixture of film holders, Lisco Regal, RITEWAY etc
I am not sure what (if any) adjustments can be made to the GG position- it's pressed flush into the recess on the back of the camera and held in by 2 clamps to a sprung mounted plate. This sprung plate is then flush against the main camera body. So the only possible movement available would be to bring the GG it further away from the lens by putting a spacer of some sort inbetween it and the mounting board. I assume that would happen if I placed a fresnel in front of the GG anyway?

Pere Casals
13-Jul-2016, 11:58
I will try

One thing else... in case you can measure the focus shift by focussing a reference point in the "metering tape" and looking at the negative where the focus moved on the metering tape, then you can calculate the shift error (correction_to_be_done) from the ground glass to the film plane by the formula:

1/F = 1/D + 1/B

where F = focal length, D = distance to object, B = Bellows Draw

Then you have a system with two equations, all in mm

1/F = 1/D1 + 1/B

1/F = 1/D2 + 1/(B+correction_to_be_done)

D1 the distance from lens board to the point focused in the ground glass.

D2 is D1 plus the focus shift in mm found in the negative.

Note: It is considered that a common lens has its principal point at lens board plane aprox, (in case of a Tele it is a bit forward)

Jac@stafford.net
13-Jul-2016, 14:29
[snip needless maths]
Note: It is considered that a common lens has its principal point at lens board plane aprox, (in case of a Tele it is a bit forward)

The nodal point is usually close to the diaphragm regardless of the lens board position, and telephoto lenses can have it not a bit, but far in front of the first (front) element.

So much for desktop impressionistic optics. Thanks. NOT.
.

Jim Jones
13-Jul-2016, 14:56
If the Shen Hao was originally provided with a correctly installed Fresnel between the ground glass and frame, and the Fresnel has been removed, the ground glass will be displaced forward by about 2/3 the thickness of the Fresnel due to the index of refraction.

R.K
13-Jul-2016, 15:31
If the Shen Hao was originally provided with a correctly installed Fresnel between the ground glass and frame, and the Fresnel has been removed, the ground glass will be displaced forward by about 2/3 the thickness of the Fresnel due to the index of refraction.

This is not possible with Shen Hao cameras.

Pere Casals
13-Jul-2016, 15:38
The nodal point is usually close to the diaphragm regardless of the lens board position, and telephoto lenses can have it not a bit, but far in front of the first (front) element.
.

First is that there is not a single Nodal Point in a real glass, but two, but this is not much significative for that calculation as it is related to a 3000mm magnitude for the case, and distance D and bellows' draw B resists a measuring error of 10mm. This may affect the calculated correction of 1/20 mm that cannot anyway be fine adjusted with the standard's gearing.

For the Tele points displacement, I'm not sure how the formula must be applied, yes ...Fuji 300T needs only 195mm at infinity, so a 105mm displacement is there...

Pere Casals
13-Jul-2016, 15:42
If the Shen Hao was originally provided with a correctly installed Fresnel between the ground glass and frame, and the Fresnel has been removed, the ground glass will be displaced forward by about 2/3 the thickness of the Fresnel due to the index of refraction.

This would be possible, but it looks that Shen Hao fresnel are after market, 3rd party, to be placed in the exterior. So it would be rare...

DrTang
14-Jul-2016, 09:56
is it in the neg ?

maybe the scanning is the problem

LotusEsp
14-Jul-2016, 17:34
I took some measurements with the lens out. From the ground glass to the lens board, and then the same measurement with a burnt negative in a holder. The film is 2mm further back from the lens than the ground glass.

could this be the source of my problems?

Pere Casals
15-Jul-2016, 04:14
I took some measurements with the lens out. From the ground glass to the lens board, and then the same measurement with a burnt negative in a holder. The film is 2mm further back from the lens than the ground glass.

could this be the source of my problems?

It is, I think it's a lot, but effect depends on the lens focal and the selected aperture.

Easy to know...

Take the loupe and fine adjust focus to your subject's eyes, then move the back 2mm away and see what happens.

For the moment (until you solve it) you can focus as always and once you place el film holder you have to move the "camera rear" excactly 2mm, that's to place the film where the GG was when you were focussing.

These 2 mm cannot be a manufacturing error, may be a fresnel was between glass and wood frame.

Just make a 2mm frame that fits in the wood frame with a 4x5 square hole inside, this will move the ground glass to the same plane the film lays, and solved, check again. (you can also glue 4 wood strips on the original wood frame (2mm thick) to make that spacer frame)

The other thing you can do is to place a fresnel, in the middle, but it should match the thikness and the optic effect... So to nail the solution just make that 2mm thick frame. If you later want a fresnel place it in the outside, it works nearly the same in practice, and no complication.

And, again, to check the solution, take that shot of the metering tape on the floor to be sure, film vs GG matching is critical, too many things can go wrong in LF, so not being sure about film/GG matching is not an option.

R.K
15-Jul-2016, 14:05
Simon,
It is hard to believe that you got a camera with manufacturer defect.
For you information. The Shen –Hao cameras designed the way that the Fresnel lens, if it is made for those cameras shall be installed below the ground glass with the grooved side facing the ground glass. With Shen-Hao cameras the ground glass will not be shifted from its original position no matter the Fresnel installed or not (of course if it is a Fresnel made for this camera). If you like to have a bit more information on the subject see this two treads:

The size of the 4x5 Shen-Hao ground glass shall be about 101mm x 127.5mm or very close to this, let say 100mm x 126mm. if you ground glass not original and having at list one dimension about 5mm smaller that the problem. In that situation ground glass may slip deeper in to the wooden frame and take a place what manufacturer originally allocate for the Fresnel lens. And as a result the ground glass will be on about 2mm closer to the lensboard then the film. But if ground glass original, I can’t imagine that it may happens.

Another famous deferens between Shan-Hao and other cameras is a very strong springs. It takes a much more effort to shift the film holder in place on the Shen-Hao then on any other cameras I used. So check it again if you pushing the film holder in its place in full. On the Shen-Hao you will hear the click when the folder will get in place.

Bill_1856
15-Jul-2016, 18:28
I took some measurements with the lens out. From the ground glass to the lens board, and then the same measurement with a burnt negative in a holder. The film is 2mm further back from the lens than the ground glass.

could this be the source of my problems?

Probably yes. It would have my my first thought.

rdenney
16-Jul-2016, 08:32
Loupes should not even be necessary except in very low light or with a really slow lens.

You must either be young or near-sighted.

I use a 6x tilting loupe made by Seagull, I think. It is focusable and it's easy to focus it on the ground surface of the ground glass.

Without loupe, even with trifocals, I can't get close enough to ground glass to focus the lens.

Rick "neither young nor near-sighted" Denney

Jac@stafford.net
16-Jul-2016, 08:54
Speaking to brouwerkent: You must either be young or near-sighted. [...]

Oh, I'm so glad that you wrote that. I'll be several of us had the same thought. Good for brouwerkent.

To add something, as a tri-focal guy, I'm thinking of experimenting with one of those loupes that swings down from my glasses frame, over the dominant eye. My optometrist is willing to work with me, but gads he's expensive. I suspect he's a Leica junkie.

Has anyone tried such a thing?

rdenney
16-Jul-2016, 12:25
I tried it but the dark cloth and the camera kept bumping them and pushing them out of alignment. I've stopped using them for my clock and watch hobby, too, except casually, in favor of proper eye loupes, like these:

But eye loupes tend to fog up in steamy conditions.

Rick "resigned to having to remove his glasses to focus" Denney

Doremus Scudder
18-Jul-2016, 09:47
FWIW, I focus with glasses and a loupe all the time. The glasses are the 4x diopter glasses I use for rough focusing and the loupe is either an 8x peak held backward (skirt toward the eye) so I can tilt it to see the corners or the aforementioned aspherical magnifier. I do have to hold the loupe in my hand, though. I could do it with my regular glasses as well, but these are always stowed when I don the 4x readers.

Best

Doremus

LotusEsp
23-Jul-2016, 09:37
so I went out to do a quick test this morning - no need to crit the image, it was a guesstimate exposure :)
This is the full frame:
153197

and here you can see far, mid and mid/close crops, they are all out of focus.
153198

153199

153200
Ektar 100 film, f22

LotusEsp
23-Jul-2016, 09:39
am I expecting too much from my images/film/camera ? I was expecting to resolve a lot more detail , particularly in the rocks and trees than I appear to be getting

djdister
23-Jul-2016, 10:00
am I expecting too much from my images/film/camera ? I was expecting to resolve a lot more detail , particularly in the rocks and trees than I appear to be getting

No you are not expecting too much from your camera, something is still wrong in that you are not achieving critical focus. I would suggest finding a LF shooter close to your location (perhaps on this forum) and have them troubleshoot your entire setup in person.

cowanw
23-Jul-2016, 11:21
Do the ruler test!

Ari
23-Jul-2016, 12:30
Do the ruler test!

Yes, the ruler test shows you the problem and the solution immediately.
If you rule out your camera back, move on to the film holders.

Jim Jones
23-Jul-2016, 13:44
The distant crop covers about an 8mm square on the negative and the thumbnail is about 40mm square on my monitor. That's a 5x enlargement. The full negative enlarged 5x is close to a 20x24 inch print, and the thumbnail looks fairly sharp. Clicking on the crop gives a 210mm square image, about a 26x enlargement, and similar to a 100x125 inch print. Of course at a normal monitor viewing distant it is unsharp. There is a faint hint of grain in the sky, while I would expect to see more. This suggests the scanning technique or equipment is compounding the apparent problem. If you can see more detail in the negative than either the thumbnail or its full image, this limits our ability to analyze the problem at a distance. Note that apparent unsharpness due to diffraction increases with image magnification. In theory, an image of a point source of light at f/22 and enlarged 26x might have about a 0.5mm diameter.

LotusEsp
23-Jul-2016, 14:13
thanks Jim

I tried a ruler test (not sure if I did it right) although the sun has blown out the top 1/2 of the ruler - I wanted to get it in a bright environment to maximise my GG view

I focused at 9 inches

153203

153204

LotusEsp
23-Jul-2016, 14:16
and a closeup:

I used Ilford delta 100, and f/8
153205

djdister
23-Jul-2016, 20:24
Since you've checked many things to this point, I'll refer back to Jim Jones in post #2. Maybe there's a problem with the lens. Have you shot any tests with a different lens? Getting a small area in the scene that is somewhat sharp while the rest of the scene is not, even when stopped down could be a symptom of a lens problem. An inner lens element could be in backwards. Inter-element lens spacing could be incorrect. A 90mm lens could have 6 or 8 elements, and you won't know if one of the inner lens elements is inserted correctly until you disassemble the front and rear lens groupings (very carefully). A lens element could be screwed in too far, or not far enough. Shoot another test with a different lens.

LotusEsp
24-Jul-2016, 04:01
thanks
unfortunately I don't have any other lenses. I only got a 90mm because I wanted to go for big landscape work on LF, I use MF for everything else.

cowanw
24-Jul-2016, 05:30
What do you think is the sharpest number line on the test. Looks like a 9.5 or so but it is hard to tell without the Over lit side and with such depth of field. wide open makes the depth of field tighter and easier to read. Looking at your hub on the top of the tripod your sharpness looks good. Do you think so?