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Lenses for use at 4-5X on an APS-sized sensor
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rjlittlefield
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Joined: 01 Aug 2006
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Location: Richland, Washington State, USA

PostPosted: Tue Apr 17, 2012 8:43 pm    Post subject: Reply with quote

Babylonia wrote:
Has anybody experienced the quality in using more long enlarger lenses reversed at a long bellows (e.g. using a bellows camera as Sinar) to this 5x enlargement value? I guess it still doesn't give the best quality as the results of e.g. a 50mm reversed EL Nikkor as tested at the first message is not that best, but also the test of the above link to an Apo Rodagon 50mm doesn't give the results as expected.

I cannot point to side by side image tests, but as a general rule high magnification and long working distance do not play well together.

The problem is that to get the same resolution from two setups, you need to have the same aperture (angular width of the entrance cone) and you need to have equally small aberrations.

But it turns out that aberrations scale in proportion to the absolute size of the lens. Given the same designs and just different sizes, if a 25 mm f/4 lens has 1/4 wavelength error, then the corresponding 50 mm f/4 lens will have 1/2 wavelength and 100 mm f/4 would have a full 1 wavelength error. The small lens would be good, the middle lens not very, and the big lens pretty bad.

In practical terms, this means that to get the same image quality, the long & large lens needs to be not only bigger but also better designed and manufactured. This can be done, but it costs more -- potentially quite a lot more. So again it's the old story of three features: You can have long WD, high quality, and modest cost -- but only two at a time (at best).

--Rik
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Babylonia



Joined: 20 Mar 2012
Posts: 48

PostPosted: Thu Apr 19, 2012 3:41 am    Post subject: Reply with quote

Thanks again for your useful answer.
Thinking in a more common sense I should have thought this devaluation in quality using more long focal length lenses myself. Finding the right choice is all about compromises, if not for one character or aspect of a lens than for another. I have to study a lot of the messages with tests at this forum to find the best solutions.

To come close to subjects or maybe to difficult places, does anybody have thoughts or experience in combining endoscopy solutions?
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ray_parkhurst



Joined: 20 Nov 2010
Posts: 2432
Location: Santa Clara, CA, USA

PostPosted: Thu Apr 19, 2012 4:14 am    Post subject: Reply with quote

rjlittlefield wrote:
I cannot point to side by side image tests, but as a general rule high magnification and long working distance do not play well together.


I really like the Nikon MM objectives, which give high mag at around 3" WD. That WD allows a lot of lighting options...Ray
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Babylonia



Joined: 20 Mar 2012
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PostPosted: Thu Apr 19, 2012 7:00 am    Post subject: Reply with quote

Sorry, I don't know what MM means.
As it is one of the most used double characters at this forum (used for millimeters) it doesn't help me by a search option to find more information about it. Can you point to an URL that do give more information about these lenses? Thank you in advance.
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ray_parkhurst



Joined: 20 Nov 2010
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Location: Santa Clara, CA, USA

PostPosted: Thu Apr 19, 2012 7:17 am    Post subject: Reply with quote

Babylonia wrote:
Sorry, I don't know what MM means.
As it is one of the most used double characters at this forum (used for millimeters) it doesn't help me by a search option to find more information about it. Can you point to an URL that do give more information about these lenses? Thank you in advance.


Sorry, "MM" is Measuring Microscope, or more accurately known as Nikon's Measurescope. There are a couple threads on the subject:

http://www.photomacrography.net/forum/viewtopic.php?t=15115&highlight=
http://photomacrography.net/forum/viewtopic.php?p=77743#77743

I picked up 3 of these over time from eBay. All sold fairly cheap. I have the 3x, 5x, and 10x. All have wonderfully long working distance (2" for 10x, 3" for 3x) and are my first choice for imaging details on coins since they don't force me to mess around with my lighting setup.

Ray

PS Here's a link to Nikon site:

http://www.nikon.com/products/instruments/lineup/industrial/measuring_instruments/accesory/microscope_accessory/index.htm
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rjlittlefield
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PostPosted: Fri Aug 24, 2012 10:51 pm    Post subject: Reply with quote

Questions are periodically raised about how the Nikon Finite Conjugate 4X sold by Edmund Optics compares to the lenses tested earlier in this thread. I finally got around to buying and testing one.

The answer is that it's not good. It's actually very similar to the old Nikon E Achromat that I tested earlier. The center is sharp, but the high quality circle is only about 15 mm diameter. The sides and corners of an APS-sized frame are very soft and have obvious color fringing (lateral CA). This one's being returned for refund as unsuitable for my purposes. I've added the test image into the list in the first post of this thread.

For the record, here is what the objective looks like:



I searched for that number MSB50040 that's printed on the objective. Turns out that it's a Nikon model number. The page HERE says in part that
Quote:
Nikon microscopes prior to the Eclipse and Eclipse i-Series used 160mm tube length, finite objectives (CF). These CF objectives have been discontinued from production and are no longer available from our stock. However, a few Achromat objectives, currently available for the YS100 educational microscope, are compatible with the pre-Eclipse microscopes.

When you contact your local authorized Nikon instrument dealer, ask for a quote on these objectives:

Material No. Description

MSB50040 YS ACHRO 4X

So now we know the exact identity of at least one of Edmund Optic's "Nikon Finite Conjugate" objectives. It's an objective for the YS100 microscope.

But according to http://www.nikoninstruments.com/Products/Microscopes/Upright-Microscopes/Biological/YS100, "The YS100 has been discontinued and replaced by the Eclipse E100-LED."

To my mind, this casts some doubt on how long these objectives will continue to be manufactured. I don't care about the 4X because of its performance as shown here, but now I'm a little nervous about the 10X, which I do like. Guess we'll see...

--Rik
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Jay Armbrust



Joined: 30 Jan 2014
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Location: Oakhurst, NJ

PostPosted: Fri Jan 31, 2014 7:31 am    Post subject: Reply with quote

OK, I'm new to this forum, but have been reading for a couple of weeks. I see this is an old topic, but wondered if there was any insight. This seemed to be the ideal thread to carry the question.

I recently purchased the AmScope as a quick, cheap solution to get an RMS thread objective in hand and begin testing setups and working at "micro" levels before investing in higher end glass. In the eBay auction, it is presented as it is pictured in the group shot above, but when the objective arrived, it looked identical to the Cnscope. I am very happy with the results for a knee-jerk purchase, and based on a few tests I have seen on this forum, the Cnscope seems almost as good as optics 3 or more times the cost.

I even wrote the seller, who turned out to BE AmScope. I told them it looks like a Cnscope, and he told me I don't need to be concerned about receiving a "knockoff." Since both claim to be their own brand, I am wondering if they are both possibly contracting the same actual manufacturer(s).
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ChrisR
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PostPosted: Fri Jan 31, 2014 8:09 am    Post subject: Reply with quote

A question is, do Amscope make objectives, or do they assemble microscopes, or just put their name on other peoples'?
It may be different in the US, but this side of the water, generally if an assembler can get an item which satisfies his specification from absolutely anywhere and save a penny, he will do so, and swear it is "his".

You can even buy a Nikon objective from Nikon or one of their sellers, and find that what arrives doesn't match the brochure item.

Good luck, trying to nail it down!
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rjlittlefield
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PostPosted: Fri Jan 31, 2014 1:22 pm    Post subject: Reply with quote

Jay Armbrust wrote:
Since both claim to be their own brand, I am wondering if they are both possibly contracting the same actual manufacturer(s).

I expect that all the objectives that look identical were actually produced on the same assembly line. Even when I ran the tests, there were multiple sources on eBay for objectives that looked identical to the one from "Cnscope" and had very similar prices. Given the good performance of that objective compared to the one I tested from Amscope, I would consider it a small step up if they switched sources.

Quote:
It may be different in the US, but this side of the water, generally if an assembler can get an item which satisfies his specification from absolutely anywhere and save a penny, he will do so, and swear it is "his".

It's the same way here. Sometimes shockingly so. The last time I went auto shopping, I was astonished by the number of different brands offering continuous variable transmissions that appeared identical right down to the font on the labels.

--Rik
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Carmen



Joined: 10 Feb 2015
Posts: 275
Location: Buenos Aires

PostPosted: Thu Feb 12, 2015 3:46 pm    Post subject: Reply with quote

Rik, this critical comparative evaluation is impressive! The resulting photos are worth many thousands of words. Particularly meritorious are the underlying efforts at objectivity, planning and execution.

The inexpensive Cnscope Plan Achromatic chinese lens that was tested appears to be the same one I spotted on e-bay.

I feel fortunate to have your critical reviews of it. Thank you! Very Happy To be honest, I was skeptical at that price, and politely asked the vendor for more info'. The vendor claimed the company name is “RI XIN optical mechanical manufacturer” and working distance of 17mm.

Very Happy
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rjlittlefield
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PostPosted: Thu Feb 12, 2015 5:51 pm    Post subject: Reply with quote

Quote:
I feel fortunate to have your critical reviews of it. Thank you! To be honest, I was skeptical at that price, and politely asked the vendor for more info'. The vendor claimed the company name is “RI XIN optical mechanical manufacturer” and working distance of 17mm.

Thank you for the kind words and the further information.

I've never heard of that manufacturer. Google search on "ri xin optical" turned up a number of companies with either "Rixin" or "Ri Xin" in their names, but none that I could identify as a lens manufacturer. I guess their comment does tend to confirm that the lens is currently being manufactured instead of being sourced from old stock.

About the working distance, the lens that I tested has about 15.5 mm true working distance, measured from the farthest forward point of the (non-removable) lens barrel to an in-focus subject. But that doesn't necessarily mean that it's a different model of lens. On mine, there's an inner part of the lens barrel that is recessed by about 2 mm, and the first glass surface is about 1 mm behind that. The 17 mm quoted to you could just be a less accurate measurement, or it could be provided by the manufacturer from an engineering drawing that references a different surface.

--Rik
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pontop



Joined: 18 Dec 2013
Posts: 83
Location: Uppsala, Sweden

PostPosted: Wed Feb 25, 2015 9:32 am    Post subject: Reply with quote

Did anyone test the Nikon BE Plan 4X (MRN70040) on full frame?

/Bo
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ChrisR
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PostPosted: Wed Feb 25, 2015 10:13 am    Post subject: Reply with quote

Coverage with that one is very good. Remove the "hood" for maximum.
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pontop



Joined: 18 Dec 2013
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PostPosted: Wed Feb 25, 2015 11:31 am    Post subject: Reply with quote

Just pushed "Purchase" Very Happy
Thanks for pushing me over that edge.

/Bo
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Joyful



Joined: 19 Feb 2015
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Location: Cape Town, South Africa

PostPosted: Sun Mar 01, 2015 3:41 am    Post subject: Reply with quote

Rik -

If I get the Nikon 10x and use it with my old Canon 100mm Macro lens will I be able to use the Canon EOS remote camera control for focus stacking or must the tube lens remain on Infinity setting all the time ?

joyful
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