40-60 X Objective lens

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iHasan
Posts: 8
Joined: Tue Oct 31, 2017 10:31 pm

40-60 X Objective lens

Post by iHasan »

Hi every one,
I am planning to buy an objective lens with 40-60 X range, and I found this in eBay
https://www.ebay.com/itm/Seiwa-Optical- ... 264488440

is it a good lens for the price ?

Scarodactyl
Posts: 586
Joined: Sat Apr 14, 2018 10:26 am

Re: 40-60 X Objective lens

Post by Scarodactyl »

Priced a little low, but it is probably not what you want. These are the super long working distance variety and have resolutions that are too low for photography at thst magnification.
Hard to know how good Seiwa's objectives are, not many test reports and iirc results are mixed.

Macro_Cosmos
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Re: 40-60 X Objective lens

Post by Macro_Cosmos »

Price is ok, but that's a 50x with an NA of 0.4, pretty low. You do get longer working distance, but a 50x with an NA of 0.7 is long enough for off-axis epi-illumination. If you have a Mitutoyo 20x normal M Plan which has an NA of 0.42, you will get essentially the same pictorial results by pushing it to 50x with a longer tube lens.

Seiwa objectives have mixed opinions. Based on what I've seen, it's not too good.

iHasan
Posts: 8
Joined: Tue Oct 31, 2017 10:31 pm

Re: 40-60 X Objective lens

Post by iHasan »

Any options for the same range ( and good price :mrgreen:)

iHasan
Posts: 8
Joined: Tue Oct 31, 2017 10:31 pm

Re: 40-60 X Objective lens

Post by iHasan »

Hi,
Could this be a good lens for our photography work

https://www.ebay.com/itm/163710772822

Pau
Site Admin
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Re: 40-60 X Objective lens

Post by Pau »

iHasan wrote:
Fri Nov 13, 2020 3:41 am
Hi,
Could this be a good lens for our photography work

https://www.ebay.com/itm/163710772822
It needs complementary aberration corrections done at a dedicated compensating eyepiece, so they only would be convenient with the adequate microscope, not for macro style work. More recent Olympus UIS and UIS2 series (UMPL... or LMPlanFL marked) don't need them.

This one: https://www.ebay.com/itm/Nikon-M-Plan-4 ... 0005.m1851
is a Nikon CF and can be used without eyepiece but being finite 210mm corrected it needs to be placed at 200mm of the sensor by extension (tubes or bellows)
40/0.5 seems clearly more convenient than 50/0.40 although the image still can't be very sharp on sensor
Pau

iHasan
Posts: 8
Joined: Tue Oct 31, 2017 10:31 pm

Re: 40-60 X Objective lens

Post by iHasan »

What is the difference between this lens and the famous nikon 40x lens?
https://www.ebay.com/itm/Nikon-M-Plan- ... 890.l49292

Pau
Site Admin
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Location: Valencia, Spain

Re: 40-60 X Objective lens

Post by Pau »

Higher resolution (0.65 NA) but much shorter working distance
Pau

viktor j nilsson
Posts: 304
Joined: Fri Mar 01, 2013 1:43 am
Location: Lund, Sweden

Re: 40-60 X Objective lens

Post by viktor j nilsson »

If you check http://www.krebsmicro.com/mplan.pdf you'll see that the 40x 0.65 M plan has a working distance of 1mm, which is uncomfortably short.

iHasan
Posts: 8
Joined: Tue Oct 31, 2017 10:31 pm

Re: 40-60 X Objective lens

Post by iHasan »

One last objective :roll:

I try to learn new things as you give me more advises

I think this one has a good WD and A good NA, but the price is warily low...

https://www.ebay.com/itm/SPI-40-LWD-Mic ... 890.l49292

viktor j nilsson
Posts: 304
Joined: Fri Mar 01, 2013 1:43 am
Location: Lund, Sweden

Re: 40-60 X Objective lens

Post by viktor j nilsson »

iHasan wrote:
Fri Nov 20, 2020 4:42 am
One last objective :roll:

I try to learn new things as you give me more advises

I think this one has a good WD and A good NA, but the price is warily low...

https://www.ebay.com/itm/SPI-40-LWD-Mic ... 890.l49292
Looks like a 160mm finite objective. In this era, the only ones that did not need compensating eyepieces are 1) Nikon CF and CFN objectives; and 2) some low-magnification objectives from Zeiss and Lomo (like the famous Lomo 3,7x).

So if you are looking for a 40x with longish work distance, you basically need to limit your search to a Nikon M plan/BD plan LWD or ELWD; or look for newer infinity-corrected objectives.

Macro_Cosmos
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Location: Andorra la Vella
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Re: 40-60 X Objective lens

Post by Macro_Cosmos »

I have a similar looking 10x branded Edmund Optics, it too has a pastic back cap that says Japan on it. It might be alright, it's a 160mm finite objective. Never tried mine, bought it because it was $5.

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