Substitute for You Know What lens?

[ChrisR]

I think you would need to do the sandpaper thing Craig.
There's noticeable CA (both types) in the single images but it tends to get eliminated in stacking - depending on the lens. So it's what you're left with, that counts.

[rjlittlefield]

Nice to hear from you, hope you are well.

Thanks -- I have been traveling so not on the forum as much as usual.

I see that ChrisR has posted before me, but since I have this written...

The original frames definitely show some transverse CA, evidenced by color fringes around in-focus hairs in the corner of IMG_0851. There is also some longitudinal CA, evidenced by green vs magenta casts in dark areas in back and in front of focus, above and slightly right of image center in IMG_0081.

With this subject, I can't really tell about the amount of false color that would be shown by a sandpaper test.

Certainly seems to be good quality for the price, though.

--Rik

[DrLazer]

Hello I'm back

Had a little trip to Fred's neck of the woods, to try out the local "culture" hehe. Very nice place, everything is legal - an interesting way to prevent crime.

So I thought I would try this lens out a little more. I've had a good read about "false" color and the sandpaper thing. What I thought would be interesting was to put it head to head with my beloved Canon Macrophoto 35mm f/3.5.

I did a 4x deep stack of a cranefly. I've not quite polished off processing of the results but I will post something soon hopefully.

The Canon lens was around £200 or so, they are not the easiest lenses to find, but they are not rare or anything, just a case of scouting ebay a bit. the microfilm thingie was under £20 delivered. So I wasn't expecting such a close fight.

This was my last use of the canon lens ....

Zebra Jumper by Craig.Taylor, on Flickr

One thing that is definitely noticeable is the comparable sharpness of the lenses - it is a very close call. I spent a long time with one stack aligned with the other in photoshop, clicking the top layer on and off and on and off and on and off for a good 15 to 20 minutes. I really couldn't decide which one was sharper. The main parts I focused on where the compound eyes, which have reflective properties and also a hard change from a very dark to a very light colour (the bg). The corners of the image which is mainly insect-fur if you know what I mean, and the edges of the antennae. honestly it's so close you would think the same lens was used.

Comparing a single frame, the cheapo has considerably more CA, mainly purple finges. Oddly enough they barely exist after stacking. Maybe that was intentional eh Rik?

This got me thinking about comparing lenses. I have seen posts before where John has had two lenses head to head ... if I can recall correctly it was a El-Nik 50mm/2.8 and a Schneider (maybe). The El-Nik was clearly sharper in the test results, and he even commented on how it was, but declared the other lens the winner based on a more stable red channel, and less CA. Personally I just always want the sharpest lens, but maybe that's inexperience on my part.

It crossed my mind to offload the Canon Macrophoto and spend my £200 on something else (maybe a nice landscape lens) but I think I would be silly to do so. The Canon has a built in iris, an RMS threaded mount, it works best wide open at f/3.5 (a clear observation when comparing sharpness on a single frame was that the DOF of the microfilm lens was wafer thin in comparison to the canon, so it's barely an even test in terms of diffraction potential), it's also made of metal, is of solid build quality and it has a conical nose making lighting much easier. The WD is longer ..... basically the Canon is clear winner, but the microfilm lens in my opinion is incredible for under £20 and would make a very suitable studio stacking lens.

Another point I'd like to mention .... I've seen a lot of comments regarding the microfilm lens as "good quality for the price". I don't think this really paints an accurate picture, as for £20, I would have very little expectations and any passable image would be worth £20.
The sharpness is comparable to dedicated macro/micro designed and specific lenses. So a better answer to "is the lens any good" for me would be a straight "yes it is", but I wouldn't recommend using it for anything other than studio work.

[canonian]

Hello I'm back

Had a little trip to Fred's neck of the woods, to try out the local "culture" hehe. Very nice place, everything is legal - an interesting way to prevent crime.

So close by and not coming in for a beer ? shame on you !!
Ever looked at THC chrystals under a microscope or a macrolens?

[abpho]

Hello I'm back.

Thanks for the post. You where using the 101 (20mm f2.8 ), correct? Currently going for $80US with shipping. Are you getting an image circle larger than 18mm (like the E-bay ad mentions)?

I have the Otamat102. Never used it yet. Found out that it only covers a 9mm image circle. Magnification at 48:1 beyond what I can use with my setup.

[Harold Gough]

I have the Otamat102. Never used it yet. Found out that it only covers a 9mm image circle. Magnification at 48:1 beyond what I can use with my setup.

It covers my m4/3 sensor (17mm) OK.

http://www.photomacrography.net/forum/v ... 158#116158

http://www.photomacrography.net/forum/v ... ght=otamat

Those were at about x4, which is what Rik suggests is the optimum.

Harold

[abpho]

It covers my m4/3 sensor (17mm) OK.

Got it. Makes sense. I can't use it on the "full frame" sensor that I am using then (36x24mm).

[Harold Gough]

It covers my m4/3 sensor (17mm) OK.

Got it. Makes sense. I can't use it on the "full frame" sensor that I am using then (36x24mm).

I can't say either way. All I know is that it covers at least 17mm.

Harold

[rjlittlefield]

Got it. Makes sense. I can't use it on the "full frame" sensor that I am using then (36x24mm).

Sure you can. Just increase the extension so as to cover the same subject area that Harold gets on his four-thirds sensor. At 4X, he's covering a 17.3 mm × 13.0 mm image area from a 4.325 mm x 3.25 mm subject. To make the same image with your full frame sensor, you'll be covering that same subject at about 8X, and that's actually a better match to the lens than what Harold is doing.

I don't know where it says that the lens only covers a 9mm image circle, but that has to be describing the size subject that it works with, not the size of sensor.

According to the eBay listing, the lens is specified as 24X, which would mean that it's intended to blow up a 9 mm circle on microfilm to be a 216 mm circle on the screen of the reader.

For photographic use, the lens would be ideal for more "large format macro", projecting that same 9mm circle on subject to cover a 4"x5" or 5"x7" film or sensor. Using the lens at 4X on a four thirds sensor undoubtedly introduces aberrations. It's "optimum" only in the sense that the result is a better tradeoff than using it at 24X on the small sensor which might be free of aberrations but would be very blurred from diffraction (f/2.8 at 24X gives f/70 effective).

Comparing a single frame, the cheapo has considerably more CA, mainly purple finges. Oddly enough they barely exist after stacking. Maybe that was intentional eh Rik?

There's no code in ZS that specifically attacks CA. Some types of CA just go away automatically when you stack because they occur mainly in out-of-focus areas.

--Rik

[Harold Gough]

Just to add a possible, partial, option for mounting the lens:

I purchased one of these a year ago:

Tiffen Series#5 Adapter Ring 22mm + Retainer ring.

The unthreaded side of the adapter has a push fit (available depth 3mm *) which will go tightly over the barrel of the lens, leaving a female 32mm not a typo) thread to connect into threaded rings/adapters.

* The ca 1mm wide, thin flange could be milled or filed out to allow any depth of barrel to be accomodated.

Harold

[Blame]

I have been scanning this thread and it looks to be a lot of disappointment with microfiche lenses?

Those lenses can be very very good but they are projection lenses - hence the absurdly high magnifications quoted. Best to think of them as infinite and use them reversed with a short tube lens.

I am using a 40/3.5 projection lens and getting a quality field of view of about 16x12mm. This using an 80/4 enlarger as tube lens and 2.25 magnification. Not bad for a lens that resembles the Mitutoyo 5x 0.14NA for specification.

Microfiche was, I think a standard of about 4/3's so you should be aiming for about 2x with FF and 1.3x on APS-c cameras. I think my rig is more limited by the tube lens than the objective.

It is quite possible that a cheap 58mm M42 lens would work perfectly as a tube lens for an APS-c camera.

[Miljenko]

A slight digression: I'm watching for couple of months now a true suicidal, masohistic gold mine for lens testing photomacrographer, an item nr. 330876442432 on Ebay. It would probably take months to test all those 100+ lenses with probably close to that number of disappointments!

[Tim M]

a true suicidal, masohistic gold mine for lens testing photomacrographer

or how about item #130964437942? There you have a smaller "problem", but I see at least a couple J(you know what) brand.

[Miljenko]

... but I see at least a couple J(you know what) brand.

Yeah, but none of those being the most wanted one, famous 21mm variety