$17 Plan Achromat Surprise Objective

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RobertOToole
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$17 Plan Achromat Surprise Objective

Post by RobertOToole »

Back in April I came across a objective that really surprised me not just with its performance but also for its $17 price tag.

Before I could share information on the forum, within a day of posting the findings on my site, the objective sold out. After some time with the original still out of stock, and with the help of another PM.net member we found very similar barreled 4X from an Ebay seller in China, but it was not the same objective.

But the good news is that the original 4X Plan Achromat is back in stock!

So now that you can actually buy one, here is an image, un-cropped, from a full frame Nikon D810. Handheld 5 image stack, single nikon SB-R200 flash. Zerene Stacked DMap.


Image

100% crop. Not record setting sharpness but pretty good!

Image

Nikon D500 this time at 4X, 5 image stack, single flash, tripod. Stacked in Zerene using Dmap.

Image

100% center crop, D500.


Image

Extreme corner crop on D500. Sharpness looks very consistent corner to corner on an APS-C sensor.

Image

The lens is a finite design and really compact so its is easy to use, plus the nose cone comes off for an even smaller profile and more WD.

There is an image quality drop in the corners as you would expect but not as much as you would think. I'm impressed.

Great coverage, look at the pencil image made with my D810! That shocked me more than anything.

CAs are very well controlled and a lot better than more expensive objectives.

Sharpness is not bad at all!

This is an easy buy for someone that wants something that performs well at 4X and doesn't cost a whole lot of money!

When I get some time I plan to compare this to some other 4X objectives that I own when I get some time like my Nikon CFI 4X 0.1, Nikon BE Plan 4X, and CFI 4X 0.13, and CFI E plan 4X, just for fun, it should be interesting.

Objective

Image

The sellers site:


Image

Link for the above:

http://www.amscope.com/accessories/obje ... ens-1.html

Link for an ebay seller with the correct objective: http://www.ebay.com/itm/381613828736

Quick Objective specs from the sellers site:

This is a 4X DIN-standard objective lens for compound microscopes. It features achromatic color-correction, and plan field-correction.

Magnification: 4X
NA: 0.10
Tube Length: 160mm
Cover Glass Thickness: 0.17mm
Brand Name: AmScope Model No: PA4XK-V300

Magnification: 4X
NA: .10
Optical Working Distance: 29.04mm
Thread: RMS
Mechanical Tube Length: 160mm
Cover Glass Thickness:0.17mm
Color Correction: achromatic
Field Correction: plan
Immersion Medium: none
Nosecone: fixed

Note that the nosecone is not fixed but it is removable so you will gain a couple of mm working distance with it off.

Link to my new site with some more images made with this objective:

https://www.closeuphotography.com/seven ... -objective

Comments and questions welcome.

Thanks for looking.

Robert

zzffnn
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Post by zzffnn »

Thank you very much for sharing, Robert. You seemed to indicated that your images were shot without compensating eyepiece, correct?

Is its contrast pretty good as well? I heard some Chinese objectives trade CA with contrast. 4x is a very mature objective design, but still good full frame coverage is not common.

How is its image quality, when pushed down to 2x or 1x? At NA 0.1, such tube length change won't matter.

Also how is its 10x NA 0.25 AmScope sibling, in terms of sensor coverage and IQ?

I have Nikon finite E plan 4x NA 0.1 and wonder if I should get this one. My camera has micro four thirds sensor, so should be very easy going.
Last edited by zzffnn on Thu May 25, 2017 6:46 pm, edited 3 times in total.
Selling my Canon FD 200mm F/2.8 lens

ray_parkhurst
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Post by ray_parkhurst »

I usually shy away from objectives rated for use with cover slips, but perhaps that is not warranted in this case. With the lowish NA it probably doesn't matter.

I have purchased and tested about 10 different Chinese 4x objectives. Some were atrocious, some decent, and a couple looked really good like this one.

RobertOToole
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Post by RobertOToole »

zzffnn wrote:Thank you very much for sharing, Robert. You seemed to indicated that your images were shot without compensating eyepiece, correct?

Is its contrast pretty good as well? I heard some Chinese objectives trade CA with contrast. 4x is a very mature objective design, but still good full frame coverage is not common.

How is its image quality, when pushed down to 2x or 1x? At NA 0.1, such tube length change won't matter.

Also how is its 10x NA 0.25 AmScope sibling, in terms of sensor coverage and IQ?

I have Nikon finite E plan 4x NA 0.1 and wonder if I should get this one. My camera has micro four thirds sensor, so should be very easy going.

Correct, no eye piece.

Contrast is very good.

Didn't try the lens at anything other than 4X.

I have the Nikon E plan also, I can compare them later.

No experience with the other Amscope objectives.

Thanks for the comments.


Robert

RobertOToole
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Post by RobertOToole »

Hi Ray,
ray_parkhurst wrote:I usually shy away from objectives rated for use with cover slips, but perhaps that is not warranted in this case. With the lowish NA it probably doesn't matter.
Yes, I agree, AFAIK, a 0.17 coverslip isn't necessary and image quality will not suffer.
ray_parkhurst wrote: I have purchased and tested about 10 different Chinese 4x objectives. Some were atrocious, some decent, and a couple looked really good like this one.
Well Ray thanks for making me feel better, I felt guilty with my eight Nikon 4Xs!

My 4X Nikons:

4X 0.20 CFI Plan APO infinity current model
4X 0.20 CF Plan APO 160 0.17 finite made in 2013
4x 0.13 CFN plan chrome finite
4x 0.1 CFI BE plan infinity OFN 18 black
4x 0.1 CFI plan infinity WD=30 gold
4X 0.1 CFI E Plan infinity OFN 20 black
4X 0.1 silver barrel that has horrible CAs

My plan is to try them all and clear out all the units with poor IQ and or coverage.

I have a feeling that the $17 Amscope 4X will beat up a lot of these.


Robert

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Post by Chris S. »

Robert, nice find!

(Especially as an easy entry point for newcomers to this level of magnification. Our Nikon apo 4x/0.20 objectives may well offer twice the resolution, but at roughly 28 times the cost :shock: . As a macro addict, I'll pay up for increased resolution--but these lenses you've found seem like an ideal gateway drug. :D)

This said, if I'm reading the specifications correctly, rated working distance seems off: "Optical Working Distance: 29.04mm." If a DIN-standard objective is parfocal at 45mm, this would mean that the objective can be just under 16mm long. Looks much longer!

Any sense of what the working distance actually is?

--Chris S.

RobertOToole
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Post by RobertOToole »

Chris S. wrote:Robert, nice find!

(Especially as an easy entry point for newcomers to this level of magnification. Our Nikon apo 4x/0.20 objectives may well offer twice the resolution, but at roughly 28 times the cost :shock: . As a macro addict, I'll pay up for increased resolution--but these lenses you've found seem like an ideal gateway drug. :D)

This said, if I'm reading the specifications correctly, rated working distance seems off: "Optical Working Distance: 29.04mm." If a DIN-standard objective is parfocal at 45mm, this would mean that the objective can be just under 16mm long. Looks much longer!

Any sense of what the working distance actually is?

--Chris S.
Good work Chris you are right! The specs are off, I posted something about it on my site, but forgot to include that here.

Free working distance is approximately 16mm from objective tip to subject or 18mm with hood removed.

Yes the Plan APOs are nice, wish the image circle was bigger though!

Robert

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Post by ChrisR »

the one it's not, which looks very similar:

ebay 262340871445
which does this 18MP , about 10MB

https://drive.google.com/file/d/0B7WuJo ... sp=sharing
not terrible but not very good.


The internals of the two objectives are noticeably different. Robert's is much more recessed from the front.
Chris R

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Post by soldevilla »

I have one of these. If it's not the same, it's a very good clone. Since it is not an LWD I have disassembled the part that has the numbers and machined with the lathe until the thread disappears and the first lens is left on the outside. I now have almost 20mm. of extra working distance.

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Post by ChrisR »

Robert's lens is the one on the left, in the second picture:
http://photomacrography.net/forum/viewt ... 998#214998

Indeed the front glass is deep down, in a chromium plated tube!
Chris R

RobertOToole
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Post by RobertOToole »

soldevilla wrote:I have one of these. If it's not the same, it's a very good clone. Since it is not an LWD I have disassembled the part that has the numbers and machined with the lathe until the thread disappears and the first lens is left on the outside. I now have almost 20mm. of extra working distance.
What a great idea!

Robert

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mawyatt
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Post by mawyatt »

Robert,

I've looked at your colored pencil image, and it looks great to me. How do these objectives compare with your Nikons for both FX and DX use around 4X? Are they still available from the site you mentioned above?

I have Mitutoyo 5X inf. that I use a Vivitar 135mm to get to 3.375, or a Raynox 250 (125mm) to get to 3.125. I have a Canon 35mm F2.8 macro that covers 1.5 to 6X on a bellows, but gets significantly outperformed by the Nikon PlanApo 4X/0.20 from 2.5 to 6 according to the Coinimaging site.

Wondering if trying this would be worthwhile.

Best,

Mike

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Post by ray_parkhurst »

mawyatt wrote:...I have a Canon 35mm F2.8 macro that covers 1.5 to 6X on a bellows, but gets significantly outperformed by the Nikon PlanApo 4X/0.20 from 2.5 to 6 according to the Coinimaging site...
This is only true in the center of APS-C. Even at the PlanApo optimum magnification of 4x, the 35MP is superior at the corners of APS-C for sharpness. The comparison is even more tilted toward the 35MP at other magnifications, and I would assume also for FF or larger sensors.

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mawyatt
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Post by mawyatt »

ray_parkhurst wrote:
mawyatt wrote:...I have a Canon 35mm F2.8 macro that covers 1.5 to 6X on a bellows, but gets significantly outperformed by the Nikon PlanApo 4X/0.20 from 2.5 to 6 according to the Coinimaging site...
This is only true in the center of APS-C. Even at the PlanApo optimum magnification of 4x, the 35MP is superior at the corners of APS-C for sharpness. The comparison is even more tilted toward the 35MP at other magnifications, and I would assume also for FF or larger sensors.
Ray,

The corners are certainly better on the Canon, so is CA, but Nikon has the edge in resolution and sharpness. I wonder how they would compare with a typical stack, since some things get better when stacked? Would be interesting on a fixed subject with many stacks around 4X.


I could get a 160mm and use it as a tube for Mitutoyo 5X to get around 4X, I'm pretty sure the result would be good...if the 160 turned out to be a good tube lens. After my experience with the Rokinon 135, I'm not sure how to predict a good tube lens other than trying it out. Per Lou's suggestion the Vivitar Komine 135 works well, as probably does the Ziess 135mm Jena, but these are 135 not 160.

Anyone have suggestions on a known good 160mm lens as a tube?

Best,

Mike

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Post by ray_parkhurst »

mawyatt wrote:
Ray,

The corners are certainly better on the Canon, so is CA, but Nikon has the edge in resolution and sharpness. I wonder how they would compare with a typical stack, since some things get better when stacked? Would be interesting on a fixed subject with many stacks around 4X.


I could get a 160mm and use it as a tube for Mitutoyo 5X to get around 4X, I'm pretty sure the result would be good...if the 160 turned out to be a good tube lens. After my experience with the Rokinon 135, I'm not sure how to predict a good tube lens other than trying it out. Per Lou's suggestion the Vivitar Komine 135 works well, as probably does the Ziess 135mm Jena, but these are 135 not 160.

Anyone have suggestions on a known good 160mm lens as a tube?

Best,

Mike
My results have been good with a simple Achromat as a tube lens. I picked up some 180mm Meopta achromats a while back that are just the right diameter to fit into the end of my Canon bellows. They work superbly as tube lenses. I suspect you could find a 160mm achromat that would do well.

Regarding stacking with both the 4xPlanApo and the 35MP, I can say the degradation in the corners of my 4x on APS-C is not so severe. I've shot several superb stacks with it. I don't remember doing any work with the 35MP at 4x, since the Nikon is my go-to lens at that mag. But my comments were really geared more toward FF and larger, which I know you and others are using.

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