DIY f1.4 macro 1:1 lens for less than $40

rjlittlefield · Post by **rjlittlefield** » Tue Feb 14, 2017 4:09 pm

Beatsy wrote:But if I put the Otus wide open on the front of that macro, that would give 2:1 at f/2.8, right? Would that out-resolve the 100/2.8 on it's own (given 4.5 micron pixels)?

That's a very good question, which you'll have to test experimentally.

As background information, I'll point again to http://www.photomacrography.net/forum/v ... 164#101164, where it is demonstrated experimentally that the optical image from an f/11 lens contains substantially more detail than is captured by one particular sensor with 4.7 micron pixels and an anti-aliasing filter.

Given optimal sharpening in both cases, I am skeptical that the final image quality will be much different between diffraction-limited f/2.8 and f/6.4 on 4.5 micron pixels, even if your camera does not have an AA filter.

I suspect that a bigger effect will be whatever other aberrations appear in the combo versus the single lens.

--Rik

Lou Jost · Post by **Lou Jost** » Wed Feb 15, 2017 5:48 pm

Beatsy, perhaps my results with these cheap lenses were so good because both are identical or nearly so. Rik has written somewhere on the forum that certain kinds of aberrations cancel out when a lens is absolutely symmetric, and indeed most of the specialized 1:1 lenses are symmetric. This kind of combo is a symmetric super-lens. So it would be interesting to borrow a second Otus or Sony and pair them. You might break resolution records for 1:1 FF lenses.

Deanimator · Post by **Deanimator** » Thu Feb 16, 2017 4:43 pm

A penny shot with a 50mm Minolta manual reversed onto a Tokina 100mm macro:

rjlittlefield · Post by **rjlittlefield** » Thu Feb 16, 2017 5:17 pm

Deanimator, I see you've been lurking for a while (Joined: 23 Oct 2012)!

Welcome to posting!

--Rik

Lou Jost · Post by **Lou Jost** » Thu Feb 16, 2017 5:20 pm

Looks good. It looks like a single shot rather than a stack, right?

I think that Tokina has a fairly deeply recessed front element. Nice to see that this does not cause problems with coupled lenses.

Deanimator · Post by **Deanimator** » Fri Feb 17, 2017 7:40 am

rjlittlefield wrote:Deanimator, I see you've been lurking for a while (Joined: 23 Oct 2012)!

Welcome to posting!

--Rik

Being that this is a fairly specialized forum, I hadn't had anything relevant to contribute until now.

Lately I've been building up my macrophotography tool chest, having recently acquired a decent tripod and head (not in that order) a flash arm and a decent diffuser.

Some day, I'd like to add a microscope objective but that's for another day.

Beatsy · Post by **Beatsy** » Fri Feb 17, 2017 9:12 am

Lou Jost wrote:Beatsy... it would be interesting to borrow a second Otus or Sony and pair them. You might break resolution records for 1:1 FF lenses.

Can't find anyone nearby with either lens. But I've ordered a 72-77mm reversing filter adapter to try the Sony and Zeiss together.

Oh nooooooo - now I'm getting sucked in too!

Deanimator · Post by **Deanimator** » Fri Feb 17, 2017 11:27 am

Lou Jost wrote:Looks good. It looks like a single shot rather than a stack, right?

That's correct. I've got the Combine(xx) freeware, but have only begun using it. I've only used it a couple of times. My results have been mixed, but due entirely to my lack of experience doing focus stacking. With experience, I expect things to improve dramatically.

Lou Jost wrote:I think that Tokina has a fairly deeply recessed front element. Nice to see that this does not cause problems with coupled lenses.

The problem that I've run into is the exceptionally close focus distance. One of the first things I tried to photograph with the 50-100mm combination was an old Ten-Base2 network card. I found that there were places on the board which I couldn't photograph because the capacitors didn't allow me to get close enough to the surface of the board. Obviously, the penny was a much less taxing subject.

This week, I bought a reversing ring for the 50mm alone to give myself some more options.

Most of what I do is object macro, since it's the dead of winter here and I've only even seen one house spider in months.

Thanks for the comments.

Lou Jost · Post by **Lou Jost** » Fri Feb 17, 2017 4:18 pm

Deanimator, how tall are those capacitors?

For the reversed lens, the best results will always be had when the subject is at the flange-to-sensor distance. Whether your 50mm is reversed by itself or on another lens, the working distance should be the same (you will have to play with the focusing to achieve that distance when the lens is reversed by itself).

I don't know the Minolta flange:sensor distance but for a Nikon or Four Thirds (not Micro Four Thirds) lens, it is 40-44mm, which seems more than sufficient for most macro subjects.

Lou Jost · Post by **Lou Jost** » Fri Feb 17, 2017 4:19 pm

Beatsy, it will be fun to see the results of that!

Deanimator · Post by **Deanimator** » Fri Feb 17, 2017 4:27 pm

Lou Jost wrote:Deanimator, how tall are those capacitors?

I'm not sure. It was just an initial experiment, so I didn't put a lot of work into it.

Now that I've finally got a decent flash diffuser, I plan to do some more macro work with the 50-100mm combo this weekend. I'll play with the focus to see what I can accomplish with a little more effort. How should the 50mm be focused? I've got the aperture on it wide open.

Lou Jost wrote:I don't know the Minolta flange:sensor distance but for a Nikon or Four Thirds (not Micro Four Thirds) lens, it is 40-44mm, which seems more than sufficient for most macro subjects.

This is a VERY old MD lens, purchased in the PX in Korea with a Minolta XG1 in 1981. From what I understand, it's a pretty decent lens for the time.

ChrisR · Post by **ChrisR** » Fri Feb 17, 2017 4:41 pm

I'd start with both at infinity, and the front one stopped down some, but it will vignette quite quickly.
Try-it-and-see is the method. You may well find the corners start to degrade, but with some subjects that's not too important.

"Combo" arrangements can produce baffling results. Your pair should behave predictably, but do look at eg Rik's
Stopping Down a Lens Combo

Lou Jost · Post by **Lou Jost** » Fri Feb 17, 2017 5:47 pm

Yes, look at that link mentioned by Chris. And try putting a paper stop (spray-painted matte black) between the lenses rather than stopping down the front lens. Make sure it is small enough to actually be the controlling aperture- look carefully at the edges of the aperture from the back of the 100mm lens and you should be able to see the rougher edges of the paper aperture, not the normal apertures.

Deanimator · Post by **Deanimator** » Sat Feb 18, 2017 8:44 pm

Fine detail of a 100 Yen coin shot with a 50mm Minolta MD reversed onto a Tokina 100mm macro. Sigma flash with a Neewer 8"x10" diffuser.

Exposure was tough since focus was so close, it was hard for the flash to reach the subject.

Next time I'm going to go back to my home made light tent.