www.photomacrography.net :: View topic - Diffraction question with stereozoom scope
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 
Diffraction question with stereozoom scope

 
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Beginners Micro
View previous topic :: View next topic  
Author Message
Trimitsis



Joined: 05 Jun 2014
Posts: 4
Location: United States

PostPosted: Thu Mar 01, 2018 7:22 pm    Post subject: Diffraction question with stereozoom scope Reply with quote

I am new to photomicrography, though I have worked at 1:1 happily for many years. I have recently been experimenting with a Meiji EMZ8TR stereo zoom microscope with a Meiji 2.5x photo adapter to a Nikon D810. I am getting images I consider to be soft, and reading the forum I'm coming to think that diffraction is probably my main issue. But I'm confused about how to calculate apertures and diffraction limits with a stereo scope like the Meiji I'm using (as opposed to a compound with objectives that are labeled with NA). I'd be grateful for any insights.

More generally, am I barking up the right tree? If my goal is to photograph plant parts and insects at, say, 5x - 20x magnifications, is a stereo zoom scope adapted to a camera the best way to go? Should I instead be experimenting with microscope objectives stuck on the end of my camera? Or is something like the InfinitProbe TS-160 (http://www.infinity-usa.com/products.aspx?pg=InfiniProbe-TS160) a way to photo-nirvana?

Many thanks!

Milton Trimitsis
_________________
Milton Trimitsis
Back to top
View user's profile Send private message Visit poster's website
Trimitsis



Joined: 05 Jun 2014
Posts: 4
Location: United States

PostPosted: Fri Mar 02, 2018 7:34 am    Post subject: Reply with quote

I forgot to note that the magnification of the attached image is 1.75x (0.7 zoom setting multiplied by 2.5x photo adapter).

Milton
_________________
Milton Trimitsis
Back to top
View user's profile Send private message Visit poster's website
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 18860
Location: Richland, Washington State, USA

PostPosted: Fri Mar 02, 2018 3:24 pm    Post subject: Reply with quote

Milton, welcome aboard!

It is close to impossible to calculate apertures and diffraction limits when working with stereo microscopes. Very few manufacturers publish the specifications that would be needed to do this.

In general, stereo scopes tend to run at apertures that are relatively narrow, compared to compound scopes that are labeled with NA. The narrow aperture provides better DOF and allows a longer working distance at reasonable cost, both of which are good tradeoffs for visual inspection of 3D objects. But of course this comes at the cost of reduced resolution, which is particularly visible when pixel-peeping the images from a high megapixel camera.

You asked:
Quote:
If my goal is to photograph plant parts and insects at, say, 5x - 20x magnifications, is a stereo zoom scope adapted to a camera the best way to go? Should I instead be experimenting with microscope objectives stuck on the end of my camera? Or is something like the InfinitProbe TS-160 (http://www.infinity-usa.com/products.aspx?pg=InfiniProbe-TS160) a way to photo-nirvana?

The short answers are No, Yes, and No.

Pairing a good objective with a good camera is now the most common approach for shooting high quality images of subjects that fit the size ranges of the objectives.

For more information about using microscope objectives with your camera, see our FAQ: How can I hook a microscope objective to my camera?.

You will also need to do focus stacking, which will require some sort of setup for precision focus stepping. A wide variety of approaches for that can be seen in the links at http://www.photomacrography.net/forum/viewtopic.php?p=55311#55311 .

All that said, the subject in your example looks to be not really small enough to use a microscope objective. The lowest magnification objectives that are worth using are 4X, with a maximum subject width around 5 mm when used with an APS-C sized sensor (roughly 22mm x 15 mm). For larger subjects / lower magnification, between 1X and 4X, there are a couple of other approaches that involve either "stacked lenses" (a shorter lens reversed in front of a longer one), or using a high quality enlarging lens reversed on bellows.

Finally, just to be sure that we're on the same page, I'll mention that the convention here at photomacrography.net is that "magnification" means optical magnification, computed as sensor width divided by subject width. For us, magnifications of 5X to 20X, on an APS-C sized sensor, would mean subject sizes of roughly 4 mm down to 1 mm. Is that your intention also?

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



Joined: 05 Jun 2014
Posts: 4
Location: United States

PostPosted: Fri Mar 02, 2018 7:14 pm    Post subject: Reply with quote

Rik,

Thanks very much for your reply! I've been trying for some time to find a good resource to learn about photographing at higher magnifications that I can easily achieve with reversed lenses and bellows and such. I thought I was alone in the wilderness until I found this site, which seems to have multiple versions of all the answers to questions I've had.

I realize that the burrs in the photo I attached are kind of big, but it's an image I made to compare to the results I could get with a macro lens, to convince myself that I wasn't imagining the softness in the Meiji image. The subjects I'm after will nicely fill a 24x36 sensor at 5x-10x.

It seems that folks on this site are fond of both Nikon and Mitutoyo 10x infinity objectives. Do you have any advice about which to pursue? Is the Mitutoyo's optical quality significantly better than that of the Nikon, or is one mostly paying for the additional working room?

And do you have any experience using a modern Nikkor 70-200 f/4 zoom as a tube lens? It's something I happen to own, and I know folks seem to say that using a zoom in this application is a crap shoot. If I decide to look for a 200mm prime, how important is the optical quality? Is an old 200 f/4 AI in reasonable condition going to work without being the limiting factor optically?

Thanks again, to you and all the folks sharing their expertise on this forum!

Milton
_________________
Milton Trimitsis
Back to top
View user's profile Send private message Visit poster's website
Lou Jost



Joined: 04 Sep 2015
Posts: 2303
Location: Ecuador

PostPosted: Fri Mar 02, 2018 7:23 pm    Post subject: Reply with quote

I can help answer the question about Nikon tube lenses. I just tested a bunch of them, and a few hours ago I gave a short partial summary of the results here:
http://www.photomacrography.net/forum/viewtopic.php?t=36640&highlight=

As my time permits I'll put example shots there. Short answer is that a cheap Nikon 200 f4 is good enough for APS, but you need to be a bit careful in your choices for full frame sensor. Most objectives don't fill a full frame sensor either, so you need to be careful with that too.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com
Back to top
View user's profile Send private message Visit poster's website
Trimitsis



Joined: 05 Jun 2014
Posts: 4
Location: United States

PostPosted: Fri Mar 02, 2018 7:40 pm    Post subject: Reply with quote

Lou,

Thanks for your note. I had found your earlier thread about testing tube lenses, but I didn't realize that you had posted some of the conclusions. It sounds like it's at least worth giving my 70-200 f/4 ED a test before hunting for a new-to-me 200mm prime. I look forward to seeing your full results.

Milton
_________________
Milton Trimitsis
Back to top
View user's profile Send private message Visit poster's website
Lou Jost



Joined: 04 Sep 2015
Posts: 2303
Location: Ecuador

PostPosted: Fri Mar 02, 2018 9:08 pm    Post subject: Reply with quote

Yes, it is worth trying what you have. I suspect you will get a bit of vignetting in the corners of FF though. Robert O'Toole's recommendation of a Sigma Life-Size Attachment is also worth taking; I have one on the way but it won't get here for a while, so I could not test it, but Robert found it to be better than anything else he had tried.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com
Back to top
View user's profile Send private message Visit poster's website
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 18860
Location: Richland, Washington State, USA

PostPosted: Sat Mar 03, 2018 7:06 pm    Post subject: Reply with quote

Trimitsis wrote:
It seems that folks on this site are fond of both Nikon and Mitutoyo 10x infinity objectives. Do you have any advice about which to pursue? Is the Mitutoyo's optical quality significantly better than that of the Nikon, or is one mostly paying for the additional working room?

The major difference in image quality is that the Mitutoyo's have much less longitudinal CA. With the Nikons, it's pretty much guaranteed that you will get blue/purple color casts in dark areas next to light ones, when working with 3D subjects. See the examples at http://www.photomacrography.net/forum/viewtopic.php?p=147672#147672 .

That said, even the least expensive of the Nikon objectives can still produce high quality images. See for example Blowfly at 5X using Nikon CFI BE 10X .

That was done on an APS-C sensor, but because of the short tube lens (100 mm focal length) the frame width at subject was still 4.46 mm, equivalent to 8.07X on a 36 mm sensor. Coverage on full-frame at 10X should be no problem.

--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 -> Beginners Micro All times are GMT - 7 Hours
Page 1 of 1

 
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