microscope objective on Sony A55

mikeatnip · Post by **mikeatnip** » Mon Jul 21, 2014 6:03 am

Hi, a newbie here, so posting in the beginners forum.
I have just in the last few weeks dived into macro photography. First bought some reversing rings, then a Quantaray (Sigma) 50mm macro lens and extension tubes. I am doing ok up to about 3X magnification, although still learning (glad I'm not shooting film javascript:emoticon(':D') ).
I actually have a contract to do a book on backyard insects, but the publisher is a small Christian publisher and so I am basically only getting enough to cover my time, and all equipment needed comes from my own pocket.
Here's what I am looking at: It seems the consensus of this forum (and I see a lot of knowledgeable folks hang out around here) is that to get beyond 3-4X the way to go is a microscope objective. I read the sticky on that. My head starts spinning with all the available options and methods ...
My question is this: I have a Sony A55. I have done some manual stacking shots, and know I will probably need a Stackshot if I go 10X. But that is what I am looking at, a 10X for my camera. Is there anyone on here who is already using a 10X objective on a Sony APS-C body? What specific objective should I be looking at? Adapters?
This objective on eBay seems to be what folks are talking about: http://www.ebay.com/itm/CFI-C20-PLAN-10 ... 416b87eb2c
Yet, it is quite a bit cheaper than others that are marked the same. I am probably missing some detail somewhere.
Anyways, maybe there are other options for my A55 that would push me beyond a 3X magnification, with image quality that would be publishable. I am hoping to stay within a few hundred dollars to get set up with a 10X objective. Is that possible?
Thanks in advance for any guidance.
Great site here, glad to find it, by the way.

rjlittlefield · Post by **rjlittlefield** » Mon Jul 21, 2014 12:21 pm

Mike, welcome aboard!

I'm the fellow who wrote the FAQ: How can I hook a microscope objective to my camera?, so I sympathize with the spinning-head problem.

I am not familiar with the MRP70105 objective. I can't find it listed in Nikon's current offerings and mostly what Google returns is a bunch of pages from 4-5 years ago. The current eBay listing says "6.1mm working distance" but what's printed on the lens says "WD 7.0". Extrapolating from other objectives I know about, especially the MRN70100, the MRP70105 is probably OK for your purposes but I can't guarantee that.

In any case, to use one of these infinity objectives you'll need a converging lens ("tube lens") to go behind it. That needs to be 200 mm focal length in order to give 10X. If you don't already have a 200mm lens, then consider using the Raynox DCR-150 as shown at http://www.photomacrography.net/forum/v ... 195#143195, bottom panel.

Those lenses and adapters will set you back a couple hundred dollars.

Using a 10X microscope objective, your DOF will be only about 0.01 mm. So yes, you're going to need some sort of screw driven rail or microscope focus block. Again there is a head-spinning plethora of options. The StackShot is a great piece of equipment but it's around $600. If your budget is tighter than that, and especially if you're up for some DIY fabrication, you can work up a manual system using one of the approaches linked at http://www.photomacrography.net/forum/v ... 5311#55311.

--Rik

mikeatnip · Post by **mikeatnip** » Mon Jul 21, 2014 6:43 pm

Many thanks. I guess I need a crash course in microscope objectives. I did an eBay search on Nikon CFI C20 PLAN 10x, thinking that was all the info I needed to find what I needed.

The Raynox solution makes sense now that I see you've reversed it. I've seen some good comments about the Raynoxes here in this site, but guess I was a bit leery of getting what I thought may just be a revved up version of the macro adapters you can buy on eBay for $20. Evidently, they are not just a branded model of those cheapies.
Back to the infinite objective on a zoom lens. I have Minolta 70-210 1:4.5. I just figured that since it goes soft at the long end it would not really be suitable. However, up to about 150mm it doesnt do too bad. According to the FAQ page on hooking objectives to telephoto lenses, the 10X infinity would still work at the shorter lengths, just not be 10X.
So perhaps my best solution is to find a good infinity objective with corresponding adapters. Use my current telephoto lens at midrange, until I can afford a better quality lens.
I should have around $1000 to invest. The stackshot takes 2/3. Enough left to get a decent objective? I just have to find exactly which one.

Thanks a million!

rjlittlefield · Post by **rjlittlefield** » Mon Jul 21, 2014 8:32 pm

Again I don't have any specific information about the Minolta 70-210, but assuming it's typical of other zoom telephotos there's a good chance that it will work fine at the long end and vignette if you try shortening it very far.

The fact that it goes soft at the long end doesn't worry me because it'll be stopped down to about f/20 by the small hole in the objective. We've never seen significant difference in sharpness across tube lenses for this reason. About the vignetting, you can get a good feel about the potential for that by cutting a 10 mm diameter hole in a piece of cardboard and holding it about 10 mm in front of your lens with the center of the lens looking through the hole. With the telephoto wide open, focused at infinity, and looking at a distant object, you're hoping to have a good image across the whole frame, perhaps with a bit of darkening in the corners.

In the price range you're considering, the best 10X infinity objectives for which I know of solid tests would be either Nikon's MRL00102 (HERE) or MRN70100 (HERE). Both of those will cover your APS-C sized sensor with high quality image. The major difference between those objectives is that the MRL00102 has more working distance, 10.5 mm versus 6.7 mm. Both of them have significant amounts of longitudinal chromatic aberration that produces blue/purple casts in dark areas. (See HERE for some illustration.) I don't know how important this is going to be for your work.

The next (big) step up in objective quality is to the Mitutoyo M Plan Apo 10X NA 0.28 (also discussed in the thread linked above). That lens is almost completely free of false color and has much greater working distance (33.5 mm). It's a great lens, but with a price to match: $865 list price today at Edmund Optics. They are often available used at prices in the $500 range, but you have to be careful because the lenses are easily knocked out of alignment such that they don't give a good image down at the pixel level even though otherwise the lens looks fine. See HERE for illustration. Once that happens they can't be fixed, so it's important to buy with return privileges and have somebody who knows what to expect from a good lens test it carefully on receipt.

--Rik

Chris S. · Post by **Chris S.** » Mon Jul 21, 2014 11:44 pm

A quick note to the forum: It turns out that Mike lives about an hour away from me, and we are arranging a day for him to visit and try out the Bratcam and associated equipment. With luck, this may provide useful perspective.

--Chris

mikeatnip · Post by **mikeatnip** » Tue Jul 22, 2014 4:47 am

Thanks Chris. I sent my phone number by PM. I was having trouble sending it and tried 3 times.

rjlittlefield: I am currently looking at the MRN70100 on Optics Planet. (The other one isnt listed there.) And I will need to go from a 52mm thread to the objective. Then for the experiments!
Thanks again! Great help around here. First day on, and I get some specific direction, plus an offer to see a working setup within driving distance! I guess you call that great customer service!

rjlittlefield · Post by **rjlittlefield** » Tue Jul 22, 2014 7:27 am

Optics Planet is a good place to get the MRN70100. Remember that their illustrations are wrong; they're actually showing the MRL00102. The MRN70100 is small and black; the MRL00102 is bigger and brown. I've heard good reports about SEO Enterprises for sourcing the MRL00102.

But it probably won't matter. Once you see what Chris can do with the Mitutoyo, you'll come away figuring out how to work the budget.

--Rik

mikeatnip · Post by **mikeatnip** » Tue Jul 22, 2014 6:59 pm

Well, actually I had been thinking to find out where I could donate a few dollars for this site, beings I have been saved quite a few hours of research. But if I see Chris' setup and decide I have got to have one like it, you may need to have a page here with my PayPal account linked for donations to come this way!

So the MRN70100 is about $100. The MRL00102 is $225 and the Mitutoyo used will set me back $500 ... It would be interesting to see side by side shots to see some IQ comparisons. I could possibly swing the Mitutoyo if I skimp on something else. I was impressed enough to see what you did with the MRN70100, actually.
Mike

Chris S. · Post by **Chris S.** » Tue Jul 22, 2014 10:12 pm

mikeatnip wrote:But if I see Chris' setup and decide I have got to have one like it. . . .

Everybody needs a Bratcam!

OK--joking aside--I think the larger value of Mike’s pending visit isn’t evangelizing particular equipment choices, but reducing the amount of head-spin involved in being new to photomacrography. As a corollary, some time ago, when I first started using Photoshop, I read books and articles, but found my head swimming. (This was before how-to Photoshop DVD's and Websites were widely available.) What greatly helped was watching over the shoulders of a couple of Photoshop-savvy friends as they worked, while asking a lot of “why” questions. A session or two of this, followed by working on my own and formulating follow-up questions--which were answered during another over-the-shoulder session or two—made a huge difference. After this and some practice, the books and articles made a lot more sense.

My bet is that Mike and I can cover a lot of ground during an afternoon with the Bratcam, and Mike may then find that a lot of things he reads here at PMN make sense much more quickly.

Cheers,

--Chris

mikeatnip · Post by **mikeatnip** » Wed Aug 13, 2014 8:30 pm

rjlittlefield wrote:
In the price range you're considering, the best 10X infinity objectives for which I know of solid tests would be either Nikon's MRL00102 (HERE) or MRN70100 (HERE). Both of those will cover your APS-C sized sensor with high quality image. The major difference between those objectives is that the MRL00102 has more working distance, 10.5 mm versus 6.7 mm. Both of them have significant amounts of longitudinal chromatic aberration that produces blue/purple casts in dark areas. (See HERE for some illustration.) I don't know how important this is going to be for your work.

--Rik

Ok, just bought a MRN70100 from Optics Planet. I cannot find the thread size for the adapter to my (49mm) lens. Chris told me on the phone to just go from the objective to 52mm, and then step down to my 49mm. But I dont remember the objective thread. Help!

rjlittlefield · Post by **rjlittlefield** » Wed Aug 13, 2014 10:40 pm

MRN70100 is an RMS thread, so for example THIS adapter.

--Rik

mikeatnip · Post by **mikeatnip** » Thu Aug 14, 2014 7:37 am

Many thanks! Now just need to figure out if I want to go with a Stackshot or build myself a manual rail (and save a few hundred dollars, but add some frustration).