www.photomacrography.net :: View topic - FAQ: How can I hook a microscope objective to my camera?
www.photomacrography.net Forum Index
An online community dedicated to the practices of photomacrography, close-up and macro photography, and photomicrography.
Photomacrography Front Page Amateurmicrography Front Page
Old Forums/Galleries
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
FAQ: How can I hook a microscope objective to my camera?
Goto page 1, 2, 3, 4, 5, 6  Next
 
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Frequently Asked Questions (FAQs)
View previous topic :: View next topic  
Author Message
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 17872
Location: Richland, Washington State, USA

PostPosted: Mon Jan 24, 2011 12:53 am    Post subject: FAQ: How can I hook a microscope objective to my camera? Reply with quote

Lately we've been getting lots of variations of the following question:
Quote:
How do I hook a microscope objective to my camera so I can shoot at 5X and above?

In this FAQ, we'll assume that you do not want to couple your camera to a microscope complete with its stage, condenser and so on, but rather you just want to stick a microscope objective in front of your camera sort of like a high power macro lens. In that case...

There are two fundamentally different approaches:

1. Get an old-style "finite" objective that has sufficiently small chromatic aberration, and stick it on tubes or bellows to get the appropriate extension.

2. Get a new-style "infinite" objective that has sufficiently small chromatic aberration, and stick it in front of an appropriately long "tube lens" such as a telephoto lens focused at infinity.

Notice that I've emphasized the issue of chromatic aberration. Most of the older "finite" objectives and some of the newer "infinite" objectives are specifically designed to have quite a bit of chromatic aberration that is expected to be canceled out by a "correcting eyepiece" or other optics that have just the right amount of opposite aberration. When an objective like that is used by itself, or with other optics that are not matched to it, the result can be some pretty extreme color fringes. Certain lines of objectives are known to be good by themselves. Using an unknown objective is like rolling the dice -- maybe it works, maybe it doesn't. When in doubt, post a request in the Equipment forum to see if anybody knows about the objective you're interested in.

OK, with that main caution out of the way, let's forge ahead.

Here are some pictures that illustrate the major components and strategies.

First, the classic approach of sticking a finite objective on extension.

Shown below is the Nikon CF N Plan Achromat 10X NA 0.30 objective, which is designed to be used on a microscope with 160 mm tube length, and with 0.17 mm cover glass. The "160" designation actually corresponds to 150 mm from the objective to the sensor plane, and despite its specification, this objective works very well with no cover glass.



Here are the components that go into this setup:


A: the objective itself

B: a mechanical adapter from the "RMS" thread of the objective to a standard M42x1 Pentax screw thread

C: M42 extension tubes as needed to make up the total extension

D: A "chipped" adapter that accepts M42x1 threaded optics on the lens side, and presents an interface to the camera that looks like a modern lens. This type of adapter "plays nicely" with the camera, so that all of its fancy metering modes including automatic flash will work properly. Using a purely mechanical adapter, without the chip, you may be limited to manual exposure with trial-and-error settings.

This particular objective (the CF N Plan Achromat 10X NA 0.30) delivers an excellent image over a 1.6 crop-factor sensor when used at 10X magnification with its rated 150 mm extension. It can also be extended beyond 150 mm to produce higher magnifications. However, it does not work well on shorter extensions because the corners develop severe astigmatism.

Some other lenses sacrifice a little resolution but are more tolerant of reduced magnification. One of those is the Nikon Finite Conjugate 10X objective listed by Edmund Optics. Here is that objective on 150 mm extension. Remove the extra tubes to reduce it to about 7X magnification.


Note that other objectives require different adapters and/or different extensions. Here is a Nikon CF M Plan 20X objective that is designed for use with a 210 mm tube and therefore works best with 200 mm extension.


The alternative approach, #2 in our initial list, is to use a new-style "infinite" objective and pair it with an appropriate "tube lens", such as a telephoto lens focused at infinity, to complete the image formation. (Historical note: the term "tube lens" comes from microscopy, where this lens sits at the bottom of what used to be an empty tube in the earlier finite designs.)

The Nikon CFI Plan Achromat 10X NA 0.25 objective has proved to be an excellent lens for this purpose. It delivers its rated magnification when used with a 200 mm telephoto or other tube lens, and it has been shown able to cover a full-frame sensor (36mm x 24mm) with high quality image when used with an appropriately wide telephoto. With an APS-sized sensor, this objective can also be pushed down to as low as 5X, by using rear lenses as short as 100 mm.

Here is an example configuration, used in conjunction with the Canon EF 55-200 mm f/4.5-5.6 lens set at 200 mm:


On smaller sensors, the objective can also be used with shorter tube lenses to give correspondingly lower magnifications. Here is an example using it in conjunction with an ancient 135 mm f/3.5 preset aperture telephoto, coupled to the camera with an M42x1 chipped adapter.


Note that in all these cases -- finite and infinite alike -- you have essentially no control over the aperture of the objective. The finite configurations simply do not have an adjustable aperture. In the infinity configurations, you can stop down the telephoto, but this will simply cause vignetting rather than increased DOF as you might expect.

Due to the high magnification and the wide aperture, microscope objectives give very shallow DOF -- typically around 0.01 mm for a 10X objective. As a result, most successful uses involve focus stacking, typically with a screw-driven rail or microscope focus block to provide small focus steps.

Traditionally focus stacking has been done using manual methods (turn dial, take picture, repeat many times), but automated systems have recently become available for affordable prices. This StackShot rail is one example:


It is always challenging to avoid motion blur due to camera vibration at high magnifications. Standard advice is to use flash, preferably with mirror lockup and second-curtain sync in a darkened room with a couple of seconds exposure time. It helps to use a powerful flash close to the subject, to take advantage of the ultra-short flash durations provided by modern consumer-grade flashes operating at much less than their rated output. If you have a Canon DSLR that supports LiveView with electronic first shutter curtain (EFSC), and you have a quiet environment, then you may also be able to use continuous illumination.

--Rik

Adding a couple of references for subsequent incorporation:
http://www.photomacrography.net/forum/viewtopic.php?t=12309
http://www.flickr.com/photos/johnhallmen/5379235010/

Further discussion: http://www.photomacrography.net/forum/viewtopic.php?t=23064

Edit: to fix typos
Edit CR: "Further Discussion" link
Edit: tweak wording and availability info
Edit: improve explanation of "tube lens".


Last edited by rjlittlefield on Sat Oct 08, 2016 11:11 pm; edited 5 times in total
Back to top
View user's profile Send private message Visit poster's website
SONYNUT



Joined: 22 Jan 2011
Posts: 627
Location: Minnesota USA

PostPosted: Mon Jan 24, 2011 1:22 am    Post subject: Reply with quote

a infinite can be used in the first set up too..correct?
_________________
..............................................................................
Just shoot it......
Back to top
View user's profile Send private message
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 17872
Location: Richland, Washington State, USA

PostPosted: Mon Jan 24, 2011 1:41 am    Post subject: Reply with quote

No, finites and infinites cannot be swapped. You'll get an image, but it will have degraded contrast and resolution.

--Rik
Back to top
View user's profile Send private message Visit poster's website
ChrisLilley



Joined: 01 May 2010
Posts: 680
Location: Nice, France (I'm British)

PostPosted: Mon Jan 24, 2011 1:53 am    Post subject: Reply with quote

Rik, a very clear and well illustrated introduction.

In view of the first question in the thread, I wonder if its worth emphasizing that infinite objectives MUST have a tube lens and that finite objectives MUST NOT have one.

I wonder about stating that the required extension for finite objectives is always tube length -10mm. (This is alluded to in passing for one common tube length, and then again for the other common tube length, so maybe this is not needed).

The influence of working distance on objective selection might perhaps be mentioned also?

Overall this is an excellent FAQ entry (and had it existed when I joined, it would really have helped me).
Back to top
View user's profile Send private message
SONYNUT



Joined: 22 Jan 2011
Posts: 627
Location: Minnesota USA

PostPosted: Mon Jan 24, 2011 2:07 am    Post subject: Reply with quote

the stack shot is nice....i built a bigger longer version years ago for animated shots..i may have to reconfigure it now..lol
_________________
..............................................................................
Just shoot it......
Back to top
View user's profile Send private message
Craig Gerard



Joined: 01 May 2010
Posts: 2877
Location: Australia

PostPosted: Mon Jan 24, 2011 2:10 am    Post subject: Reply with quote

This thread belongs here. I've linked to it so many times that it will be good to find a home for it.

http://www.photomacrography.net/forum/viewtopic.php?t=10661

In addition to Chris Lilley's comments regarding WD (working distance), we should also mention differences in objective thread sizes and currently available commercial adapters offered at fair and reasonable prices.

Craig

*edits: corrected typos
_________________
To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"


Last edited by Craig Gerard on Mon Jan 24, 2011 4:16 am; edited 2 times in total
Back to top
View user's profile Send private message
ChrisLilley



Joined: 01 May 2010
Posts: 680
Location: Nice, France (I'm British)

PostPosted: Mon Jan 24, 2011 2:11 am    Post subject: Reply with quote

Oh - for people using camera systems other than Canon, it may be worth clarifying the advice about 'chipped' adapters.

My understanding is that for Canon DSLR, without a chipped adapter there is no metering (and no focus confirm either).
[Edit: Admin ChrisR - my Canon metering on manual and Aperture Priority work fine]

For Nikon DSLR, the lower end cameras need a chipped adapter for metering. The higher end cameras can also use a mechanical linkage (aperture indexing, AI) and still get metering (centre weight or spot) in manual and in aperture priority modes. So for example an older AI or AIS 200mm Nikkor lens can be used as a tube lens, and will meter on the higher-end bodies despite having no electronic contacts. However, if the lens or adapter is chipped, then colour matrix metering can also be used. All Nikon DSLR give focus confirmation whether there is a chip, or mechanical linkage, or no linkage at all.

I understand that for Pentax DSLR, metering is available for 'A' lenses and adapters which have electronic contacts.

I don't know the equivalent facts for Sony DSLR.
Back to top
View user's profile Send private message
ChrisLilley



Joined: 01 May 2010
Posts: 680
Location: Nice, France (I'm British)

PostPosted: Mon Jan 24, 2011 2:17 am    Post subject: Reply with quote

Quote:
Note that in all these cases -- finite and infinite alike -- you have no essentially no control over the aperture of the objective. The finite configurations simply do not have an adjustable aperture.


It may be worth adding that this is okay, and the objectives are designed to be used wide open like that on a microscope. In other words, clarifying that this is not a problem and that trying to add an iris to an objective is not a worthwhile exercise.
Back to top
View user's profile Send private message
SONYNUT



Joined: 22 Jan 2011
Posts: 627
Location: Minnesota USA

PostPosted: Mon Jan 24, 2011 3:05 am    Post subject: Reply with quote

I guess the big question is..is either one better...

is the infinite the way to go?
_________________
..............................................................................
Just shoot it......
Back to top
View user's profile Send private message
canonian



Joined: 31 Aug 2010
Posts: 890
Location: Rotterdam, Netherlands

PostPosted: Mon Jan 24, 2011 8:06 am    Post subject: Reply with quote

Great and valueable info.
Thanks for sorting this out, Rik.
This post is "Sticky"-worthy.

Unfortunately, since your previous post about this subject (Infinity objective on low-end zoom telephoto works fine) I see a significant
raise in price on fleabay for 2nd hand Nikon CF's and it's almost impossible to get your hands on one in Europe.
Are there other CA corrected micro-objectives which perform as well as the Nikon CF without breaking the bank?

________
Fred


Last edited by canonian on Mon Jan 24, 2011 9:23 am; edited 1 time in total
Back to top
View user's profile Send private message Visit poster's website
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 17872
Location: Richland, Washington State, USA

PostPosted: Mon Jan 24, 2011 8:26 am    Post subject: Reply with quote

Thanks for the feedback and suggestions, guys. Keep 'em coming in. I'll let this sit for a day or two to collect more info, and then I'll clean up the FAQ, remove what by then will be outdated comments, and we can repeat the exercise until we get a good reference version.

SONYNUT, see http://www.photomacrography.net/forum/viewtopic.php?p=59673#59673. It's true that low mag, low NA objectives like 4X NA 0.10 can be swapped around without much degradation, but even at 10X there's a significant hit in quality. Since the major purpose of using an objective in the first place is higher quality than you can get with an ordinary lens reversed on bellows, losing that quality in a mismatch is not a good idea.

--Rik
Back to top
View user's profile Send private message Visit poster's website
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 3796
Location: Valencia, Spain

PostPosted: Mon Jan 24, 2011 11:58 am    Post subject: Reply with quote

ChrisLilley wrote:
My understanding is that for Canon DSLR, without a chipped adapter there is no metering (and no focus confirm either).^

No, any Canon EOS can meter acurately with any lens or adapter (or without anything mounted in the bajonet)
I don't use chipped ones.
With a chipped adapter you only gain focus confirmation (but not with the small effective NAs we use un high magnification macro) and some light metering modes like spot (not sure about the last tip).
If I was going to buy a new adapter I would go for a chipped one, but I don't really need it.
_________________
Pau
Back to top
View user's profile Send private message
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 3796
Location: Valencia, Spain

PostPosted: Mon Jan 24, 2011 12:11 pm    Post subject: Reply with quote

Rick, congratulations, I can't imagine a more clear explanation. Dou did it again!. Now we only will need to link this FAQ in place of repeat the explanations.
_________________
Pau
Back to top
View user's profile Send private message
pierre



Joined: 04 Jan 2010
Posts: 227
Location: France, Var, Toulon

PostPosted: Mon Jan 24, 2011 12:23 pm    Post subject: Reply with quote

Neat and clear !

Impressive piece of work Rik.
_________________
Regards

Pierre
Back to top
View user's profile Send private message
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 17872
Location: Richland, Washington State, USA

PostPosted: Mon Jan 24, 2011 12:26 pm    Post subject: Reply with quote

Pau wrote:
ChrisLilley wrote:
My understanding is that for Canon DSLR, without a chipped adapter there is no metering (and no focus confirm either).^

No, any Canon EOS can meter acurately with any lens or adapter (or without anything mounted in the bajonet)
I don't use chipped ones.
With a chipped adapter you only gain focus confirmation (but not with the small effective NAs we use un high magnification macro) and some light metering modes like spot (not sure about the last tip).
If I was going to buy a new adapter I would go for a chipped one, but I don't really need it.

From memory... I used to use a non-chipped adapter with my Canon 300D. The basic metering worked fine, but ETTL flash did not. (This aspect caused several new flash units to be returned as unsuitable for my purposes.) When I upgraded to the T1i, I was surprised to find that LiveView presented some additional odd behaviors, for example with LiveView showing a preview image that was several f-stops darker than the real exposure would be. After I upgraded to a chipped adapter, such problems no longer call themselves to my attention. So I'm pretty sure that least with the T1i there is more to the chipped adapter than AF confirmation. I'll check this aspect before finalizing the FAQ. From an economic standpoint, it's no big deal since the chipped adapter for Canon cost me only $18.70, shipping included. For Nikon the economics are less favorable. The cheapest M42 adapter I could find for Nikon that was both chipped and corrected to allow infinity focus was $56.30. Having tired of pointless frustrations, I bought it anyway.

--Rik
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Frequently Asked Questions (FAQs) All times are GMT - 7 Hours
Goto page 1, 2, 3, 4, 5, 6  Next
Page 1 of 6

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group