Minolta 5400 Scanner Lens and Laowa 25mm f/2.8 Comparison

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Macro_Cosmos
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Minolta 5400 Scanner Lens and Laowa 25mm f/2.8 Comparison

Post by Macro_Cosmos »

I decided to run a comparison between the Laowa 25mm f/2.8 Ultra-Macro lens and the highly praised Minolta 5400 Scanner Lens.

The setup:
I'm using a vertical setup. The resolution target was set on a dedicated filter holder, underneath is a white sheet of paper. The target is lit up using an optic fibre halogen lamp illuminator.

I adjusted focus to find the sweetspots and tallied through the results to find the best looking one.

Camera is a Nikon D810. Shot at ISO 64, 1/30s.

Minolta 5400 scanner lens is set on some M42 extension tubes, which are flocked. Configured to have a reproduction ratio of about 2.6:1.
Laowa 25mm is set at f4 [1], configured to have a reproduction ratio of about 2.6:1.

The 240 lp/mm section was used. Both horizontal and vertical line pairs are photographed, set for the centre and corner respectively. I only used one corner.

The results: (please click on the link for full resolution)

CENTRE:
Image
https://farm5.staticflickr.com/4851/461 ... abf7_o.jpg

CORNER:
Image
https://farm5.staticflickr.com/4821/462 ... e90c_o.jpg

Conclusions:
1. The Laowa 25mm is more resolving. This is true for both centre and corners. For the horizontal lines in the first image, the Laowa was at mid-centre, I focused on the wrong segment.
2. The Laowa wins for corners, but it kind of struggles as well.
3. For the second image, no matter how much I tried, I wasn't able to get the Minolta to produce a good looking result.
4. The next step is to have all 4 corners photographed for a more controlled test.
5. I do not really intend to test for CA. The Laowa 25mm has a fair amount of LoCa, this however was never an issue for me since I focus stack. I might run a test upon request, I don't have a proper chart to test for CA however.

Notes:
[1]: Laowa 25mm f/2.8 Ultra-Macro is the best at f/4. Scanner lenses used for film reproduction are designed to have the best performance as it is (there's no aperture dial).

Pau
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Post by Pau »

I see something weird in your test images:
- In the center crops resolution shown is the same although the LW25 shows more contrast with vertical lines while M5400 shows better contrast in horizontal lines.
- In the corner crops with vertical lines they seem identical while with horizontal lines the M5400 is horrible and both are much less contrasty than at the center...the difference with horizontal-vertical only could be due to the lenses if they suffered lots of astigmatism, likely not the case.

Could you further comment your results? Any real life comparison?
Pau

Macro_Cosmos
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Post by Macro_Cosmos »

Pau wrote:I see something weird in your test images:
- In the center crops resolution shown is the same although the LW25 shows more contrast with vertical lines while M5400 shows better contrast in horizontal lines.
- In the corner crops with vertical lines they seem identical while with horizontal lines the M5400 is horrible and both are much less contrasty than at the center...the difference with horizontal-vertical only could be due to the lenses if they suffered lots of astigmatism, likely not the case.

Could you further comment your results? Any real life comparison?
The constrast is probably due to lighting. In general, the MN5400 is more contrasty. I had to have the chart floating between the lens and a white sheet of paper, shadows were casted and I didn't find a good way to fix it.

Another problem could be the optical axis, I was using cheapo M42 tubes and the adaption method is probably not perfect. Hence why the other 4 should be looked at too.

No real life examples from the 5400 (it's not my lens), I do have lots of Laowa 25mm photos on my flickr. At a pixel level, the Laowa clearly has more resolution, but not by much. I don't think this would matter much for real life examples.

The major challenge with the 5400 lens is hotspot and flare. I put an impromptu cardboard hood on the sample I have and it improved things a bit.

They both are good lenses. For 2.5x and 3x, the MN5400 is still a good choice. Below that it's superb, it was designed for 1.2:1 anyway. The working distance is 58mm at 1.2x whereas the Laowa is 45mm at 2.5x. I didn't measure the WD at 2.5x for the MN5400. Going to run more tests when I get the time.

Hope this clarifies things a bit.

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Post by ChrisR »

Looks like agreement that the upper end of the 5400's mag range is about 2x, then - you found the edge!
Chris R

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Post by Macro_Cosmos »

Fatal Error!!!!
The 5400 lens was mounted in reverse!!!!

This led to general softness in the edges, and thus this test should not be taken as valid.

Sorry for my stupidity.

RDolz
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Post by RDolz »

There is nothing to excuse, nothing happens, making mistakes is part of the process of moving forward.

Are you going to repeat the test in the right direction?

By the way, I can not see the images in this post, have you deleted them?

best,
Ramón Dolz

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Post by Lou Jost »

Macro_cosmos, when I was testing the Nikon 14 element Scanner ED lens against the Printing Nikkor 105A, I accidentally posted the very same photo as coming from both the scanner lens and the Printing Nikkor. I've also made other equally stupid mistakes. The great thing about this forum is that it is full of sharp eyes and errors will eventually be caught and corrected. That's part of the scientific process. Nothing to be ashamed about.

But as in all fields, when we get a surprising result, we should double and triple check it. Seems like that's what you did, and you figured out what was wrong.

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Post by Macro_Cosmos »

RDolz wrote:There is nothing to excuse, nothing happens, making mistakes is part of the process of moving forward.

Are you going to repeat the test in the right direction?

By the way, I can not see the images in this post, have you deleted them?

best,
Yeah those are now deleted. I did a massive purge on my flickr recently due to the 1000 photo limits they introduced. Going to get the pro anyway but I would like the gallery to look neat.

I will do another test in the right direction. Currently preparing to go overseas. It will probably be completed after I come back to Australia, some time end of next month-ish. In the right direction, I'd say they will be pretty much neck-in-neck. I did run two stacks at similar magnifications with some interesting discoveries.

Non-reversed on the left.
Centre
Image

Corner
Image

Magnification is slightly different. For the centre, the image quality isn't too different. The corners are appalling, I wouldn't even call the non-reversed "great", it's just alright.

This is what a Laowa 25mm stack looks like:
https://flic.kr/p/2cGtLX4

When reversed, less extension is required for the same magnification. If only the centre is concerned, reversing this little thing could be preferable. However in non-reversed orientation, there isn't any weird hot spot issues. I wouldn't recommend reversing it though.

Lou Jost wrote:Macro_cosmos, when I was testing the Nikon 14 element Scanner ED lens against the Printing Nikkor 105A, I accidentally posted the very same photo as coming from both the scanner lens and the Printing Nikkor. I've also made other equally stupid mistakes. The great thing about this forum is that it is full of sharp eyes and errors will eventually be caught and corrected. That's part of the scientific process. Nothing to be ashamed about.

But as in all fields, when we get a surprising result, we should double and triple check it. Seems like that's what you did, and you figured out what was wrong.
Yeah, I agree. Making mistakes is just the fundamental process of learning :D
I might get the PN 105 as well, it's rated at 1:1 and should be great even at 1:2 and 2:1, might be a good replacement for the tiny Minolta. The Minolta has the advantage being small and portable. I do have a big collection of those Kuboptek "rayfact" lenses waiting for me in China though, hope those turn out to be great. Haven't seen them being tested yet anywhere. A friend got them from some factory thingo undergoing upgrades. Will let the forum know and sell them at breakeven if that's okay. Better let people who use them have it than collectors.

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Post by Lou Jost »

Macro_cosmos, there is a lot of info available on the PN105, and it is not great at 2x. It is a very highly optimized lens, almost unbeatable at 1x. For 1.4x, my tests on this forum show it is better to use it with a good 1.4x Nikon teleconverter rather than on extension. The same seems to apply for higher m.

About those Kubotek lenses, I have tested it a few months ago (after cleaning out the fungus) but haven't had a chance to post the results. It is pretty good but I am not sure I have found the best way to use it. I want to use it in reverse for around 2x, which is where I think it should do well compared to our usual options. Since there are other good m=0.25 to m=1.0 options, I don't care so much about its performance in its normal orientation.

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Post by Macrero »

Mistakes happen... Looking forward to seeing the comparison with the Minolta in the right direction.

I finally got one, and yeah, it works fine in one direction only, not stacked, reversed, etc.

I went further and removed the internal f/stop. As I should expect, IQ dropped, CA, poorer coverage and a foggy image. A really nice lens for 1 - 2X (or a tad more), but not a fun to play with :evil:

- Macrero
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light

RDolz
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Post by RDolz »

Macrero wrote: I went further and removed the internal f/stop. As I should expect, IQ dropped, CA, poorer coverage and a foggy image. A really nice lens for 1 - 2X (or a tad more), but not a fun to play with :evil:
Macrero, I would never have thought of that idea. :o

Please, could you explain the procedure to remove the internal f?

I showed in a post to convert it into telecentric

https://www.photomacrography.net/forum/ ... light=5400

Given the small diameter of the front lens, possibly removing the internal f can help to achieve telecentricity with this lens.
Ramón Dolz

Macrero
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Post by Macrero »

RDolz wrote:
Macrero, I would never have thought of that idea. :o

Please, could you explain the procedure to remove the internal f?

I showed in a post to convert it into telecentric

https://www.photomacrography.net/forum/ ... light=5400

Given the small diameter of the front lens, possibly removing the internal f can help to achieve telecentricity with this lens.
Ramón,

I did not do it myself. That was done by friends of mine, who have a workshop in my city, guys have been repairing lenses and cameras for more than 40 years.

They said locking ring was glued with loctite-like glue and it was not easy to disassemble the optics.

Bear in mind that the f/stop makes also for a spacer, so by removing it you alter the optical design even further.

I honestly very much doubt that the telecentricity makes up for the loss in IQ.

- Macrero
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light

RDolz
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Post by RDolz »

Hi Macrero:

Thanks for the information, ... I did not understand how you could have removed the f, ... now it is clear that we should not try to disassemble the lens.

What luck to have in your city people with that experience !! ... that kind of company is very difficult to find.
Ramón Dolz

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Post by Macrero »

Hi Ramón,

disassembling a lens is not a good idea, unless you know perfectly what you are doing, or say it is a cheap one and needs cleaning. I have disassembled (and reassembled :lol:) quite a few simple design lenses (as enlarging lenses) for cleaning, but I would not take the risk of taking apart a good, clean lens just for an experiment.

Yep, I feel lucky to have the repair shop 500 meters away from my house.

Here is a test stack at 1.25X:

https://images2.imgbox.com/d8/c5/PTmYJBcN_o.jpg

And this is a test at 2.1X with the f/stop removed:

https://images2.imgbox.com/a1/11/w0Q1quWK_o.jpg

The drop of quality is obvious. As the Spanish proverb says: Los experimentos, con gaseosa... :lol: Sorry, no literary translation, "the proof's in the pudding" might be close.

- Macrero
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light

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Post by Pau »

Macrero, at your second test image the only issue I see is glare. Adjusting levels in PS it looks good, resolving more detail likely due to the higher magnification (and maybe NA)
Pau

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