The Silicon Wafer Test Chart

[MGrayson]

It's hard to test a 300mm lens indoors. I mean, pixel pitches being what they are, you need an extremely detailed test chart or an extremely long hallway. But if you want to test at home and want detail down to ridiculous levels, get a silicon wafer from the 1980's (available inexpensively on eBay, last time I checked). More modern ones are etched too fine to use, unless you're doing X-ray photography.

Here's what I get from a few feet away with an X2D and XCD 120/3.5 Macro. This is a 100% crop.


Viewed at 800%, you can see that the detail is at pixel level. Any printed chart that I have can't get near pixel level detail from this close. (Well, I do have an inexpensive USAF 1951 scanner target.)

Here's what the center looks like at about 2:1 with an enlarger lens and a bellows.


PLENTY of detail left.

Matt

 

[rdeloe]

If you like silicone wafer pictures, you have got to visit Robert O'Toole's fantastic site, Closeup Photography. https://www.closeuphotography.com/

 

[MGrayson]

If you like silicone wafer pictures, you have got to visit Robert O'Toole's fantastic site, Closeup Photography. https://www.closeuphotography.com/

That’s actually where I first read of the idea, but had forgotten the URL! I’m glad that we can now give credit where it’s due.

 

[MartinN]

I have used MTFmapper. A very nice and automated piece. However, to get camera sensor parallel to the target is not my best skill, but that software is not for macro, though.

 

[MGrayson]

I have used MTFmapper. A very nice and automated piece. However, to get camera sensor parallel to the target is not my best skill, but that software is not for macro, though.

I used Imatest for a while. Not easy, but very informative. MTFmapper seems unavailable on my platform, alas.

This is not going to provide information like MTF, but rather give a quick comparison of similar focal lengths. I fave a number of 300mm-400mm old medium format telephotos ("Why?" is a very good question. I blame @jng ). Some are 1/3 the weight and 1/20th the price of other similar spec optics. How visible is the difference? That's the kind of thing I'm after. A Siemens Star chart works well for, say, a 50mm. At 200mm, though, I'm getting 40 feet away before I can see aliasing. A 400mm lens is hopeless without a higher detail target. Those pixels are tiny, and there are a LOT of them.

 

[rdeloe]

I used Imatest for a while. Not easy, but very informative. MTFmapper seems unavailable on my platform, alas.

This is not going to provide information like MTF, but rather give a quick comparison of similar focal lengths. I fave a number of 300mm-400mm old medium format telephotos ("Why?" is a very good question. I blame @jng ). Some are 1/3 the weight and 1/20th the price of other similar spec optics. How visible is the difference? That's the kind of thing I'm after. A Siemens Star chart works well for, say, a 50mm. At 200mm, though, I'm getting 40 feet away before I can see aliasing. A 400mm lens is hopeless without a higher detail target. Those pixels are tiny, and there are a LOT of them.

I don't use the wafer test, but I'm on board with the idea of having a common test subject for quick and dirty comparison, especially when I no longer own a lens that I want to compare with another lens. Like you, I run out of space to use it with long lenses.

 

[buildbot]

That’s actually where I first read of the idea, but had forgotten the URL! I’m glad that we can now give credit where it’s due.

They also inspired me to get some test wafers!

Focus stack from 1:1

Cropped in:

 

[MGrayson]

Well, interesting stuff.

Front row, from left to right, the Mamiya 300/5.6 ULD (710 grams, $), the Pentax 67 300/4 ED-IF (1650 grams, $$), and the Zeiss 350/5.6 Superachromat (1800g, $$$$). Second row, Soup (7718 grams, priceless).



Everything shot at 36' AKA 11 meters. X2D, Gitzo 5, 2 second delay, etc.
This is the Center at 300%. Each cell on the wafer is about 5mm wide.



I did notice that the magnifications imply different actual focal lengths than those on the lens barrel. The Mamiya is half way between the Pentax 300 and the Zeiss 350. So is it really a 325?

And here's the upper right corner.


The Zeiss is pretty fantastic everywhere, AND wide open. At that price....
The Pentax is notably soft wide open, but does a pretty good job from f/5.6 out. In the corner, f/8 is best - matching the Zeiss. At f/11, everyone is getting diffraction blur. I did nothing to try to sharpen the f/11 images. Bad Matt!
The Mamiya is better than the Pentax in the corners at f/5.6. Everywhere else, it is no better or slightly softer.

So you sort-of do get what you pay for. The Mamiya is small and light enough to get carried around just in case. It is easy to hand-hold, and with IBIS and peaking on the X2D, easy to focus. I wouldn't carry the larger lenses without a car.

And if you find looking at 300% images depressing, here they are at f/5.6 in the center at 100% That's 4" across at 36 feet.
Mamiya
]

Pentax


And Zeiss


Matt

 

[Ray Harrison]

My wife doesn't particularly get involved with my photography interests, but gosh, she does enjoy Soup (as do I). Happy wife, priceless .

 

[jng]

Well, interesting stuff.

Front row, from left to right, the Mamiya 300/5.6 ULD (710 grams, $), the Pentax 67 300/4 ED-IF (1650 grams, $$), and the Zeiss 350/5.6 Superachromat (1800g, $$$$). Second row, Soup (7718 grams, priceless).



Everything shot at 36' AKA 11 meters. X2D, Gitzo 5, 2 second delay, etc.
This is the Center at 300%. Each cell on the wafer is about 5mm wide.



I did notice that the magnifications imply different actual focal lengths than those on the lens barrel. The Mamiya is half way between the Pentax 300 and the Zeiss 350. So is it really a 325?

And here's the upper right corner.


The Zeiss is pretty fantastic everywhere, AND wide open. At that price....
The Pentax is notably soft wide open, but does a pretty good job from f/5.6 out. In the corner, f/8 is best - matching the Zeiss. At f/11, everyone is getting diffraction blur. I did nothing to try to sharpen the f/11 images. Bad Matt!
The Mamiya is better than the Pentax in the corners at f/5.6. Everywhere else, it is no better or slightly softer.

So you sort-of do get what you pay for. The Mamiya is small and light enough to get carried around just in case. It is easy to hand-hold, and with IBIS and peaking on the X2D, easy to focus. I wouldn't carry the larger lenses without a car.

And if you find looking at 300% images depressing, here they are at f/5.6 in the center at 100% That's 4" across at 36 feet.
Mamiya
]

Pentax


And Zeiss


Matt

Tele-Superachromat (and Soup) for the win!

P.S. Thatsalottacat!

 

[MartinN]

My 300 Mamiya seems to be a bargain for the modest price. Thanks. Btw, in my hallway I think I tried MTFmapper A3 chart with the 300 and that was just about possible. And no, I don’t have a long hallway

 

[MGrayson]

My 300 Mamiya seems to be a bargain for the modest price. Thanks. Btw, in my hallway I think I tried MTFmapper A3 chart with the 300 and that was just about possible. And no, I don’t have a long hallway

Slanted blocks are a great (and extremely clever) way to measure MTF. I can't find any (affordable) software to do that on a Mac, and I don't want to write it (talk about a rabbit hole with teeth!).

 

[MartinN]

Slanted blocks are a great (and extremely clever) way to measure MTF. I can't find any (affordable) software to do that on a Mac, and I don't want to write it (talk about a rabbit hole with teeth!).

Virtualbox and Windows install, pretty secure and clean ? I have installed Windows 2000 on a Virtualbox, but it is indeed pretty old and limited. Most of the problems arise with programs needing special ports and so on. I don’t know what is minimum requirement for MTFmapper, but I happen to have an old PC, now somehow running Windows 10, and that is convenient for PC software.