Home-made Lens: Critique & Advice Please!!

Jason G · Post by **Jason G** » Wed Mar 11, 2009 8:38 am

Sorry to be a pest you good helpful people, but would a maco/close-up lens filter lens work, I take it they are CA-free by definition? I've seen an affordable set of four 52mm lens attachments by Digital Concepts - these should be OK, and even better stacked whilst giving better quality results then I have shown so far? They range from +1 to +10 dioptres from what I can understand...

They are designed for Pentax, but I don't mind making my own connection...

See http://www.amazon.co.uk/Close-Up-MACRO- ... 63&sr=1-12

...any good?

rjlittlefield · Post by **rjlittlefield** » Wed Mar 11, 2009 1:47 pm

Jason G wrote:I take it they are CA-free by definition?

Certainly not "by definition". Some are, some aren't.

To get ones that are, the lenses have to each consist of two lens elements cemented together to form an "achromat". Those tend to be expensive.

The set you've linked to, at £15.99 for a set of 4 lenses, is almost certainly composed of cheap single-element lenses. Used for closeup photography, they will probably work better than a magnifying glass, but not nearly as well as say a projector lens, at least in terms of resolution and CA. Vignetting is a different issue. Nice thin closeup lenses have few problems with vignetting, while it's often a big problem with reversed thick lenses.

BTW, stacking closeup lenses does increase the magnification somewhat, but it also greatly increases the CA. I don't think you'll like the effect.

--Rik

Jason G · Post by **Jason G** » Wed Mar 11, 2009 2:18 pm

Hi Rik,

Thanks for your response.

Yep, I had overlooked the single/two-element thing

I took this today...

...my first Anthomyiidae-family species of the year, taken using a reversed binocular lens.

Would the said kit, if used instead of the bins lens, produce even slightly better results? I would prefer the projector lens option and that ladybird is stunning, but if I can't come across one I'm happy to bridge the gap with an 'improvement' whilst waiting.

With the current photo in mind, would the lens kit improve on my existing setup??

rjlittlefield · Post by **rjlittlefield** » Wed Mar 11, 2009 3:20 pm

Jason G wrote:With the current photo in mind, would the lens kit improve on my existing setup??

Quite possibly, but I can't guarantee it. One reasonable option is to buy the set, try it, and send it back for refund if it's not enough better.

--Rik

Jason G · Post by **Jason G** » Wed Mar 11, 2009 3:25 pm

Thanks Rik!

Forgot to say the fly was about 6mm long, and the slight drop in CA - at least to my eyes - may be down to using about 80% of the zoom length as opposed to all as in my previous image postings.

Thanks for the idea - yep, will give that a try

I remember you saying a box of lenses can be good for learning from...

lothman · Post by **lothman** » Sat Mar 21, 2009 6:21 pm

Another possibility to get a good 2-element CU-lens is to slaughter a binocular.

the front lenses of such 8x50 or 10x50 binoculars are achromats. Mostly they can be dismantled by unscrewing, in this case I had to saw it out.

and they are about +5 to +6. All you have to do now is to glue them in an empty filter ring.

This one I shot years ago with a fuji S602 bridge cam oad such a cu-lens coming from a binocular.

Jason G · Post by **Jason G** » Sat Mar 21, 2009 6:52 pm

Thanks for that Lothman - very well illustrated as usual.

I took a chance and ordered the close-up filter lenses. They are designed for Kodak cameras, so I had to improvise with the lens holder. Anyway I tried it out - and was fairly surprised. Whilst it has a minor drop in sharpness - CA is about 80% down, if not 100% in some like-for-like photos! It does however have pin-cushioning at the edges, but if I crop on-camera from 5mp to 3 in the centre it seems better.

The lens are 43mm Kodak Ektanar lenses.

Green shieldbug - Palomena presina

Dimples around scuttelum

Your thoughts welcome!

Harold Gough · Post by **Harold Gough** » Sat Mar 06, 2010 1:17 pm

Some more on this subject:

http://forum.manualfocus.org/viewtopic.php?id=16225

Harold

PaulFurman · Post by **PaulFurman** » Sat Mar 06, 2010 7:08 pm

This suggestion might not help for stacking lenses but I ran across an interesting looking e-book about tinkering with lenses: http://www.alternativephotography.com/w ... ple-lenses
I actually ordered it a week ago but have not received the download

though I'm sure it'll get sorted out, maybe the author is on vacation or something... Here's a review that explains it does not deal with multiple elements at all: http://www.flickr.com/groups/homemadele ... 150144844/ although knowledge is knowledge so I'm sure there is value in it.

PaulFurman · Post by **PaulFurman** » Thu Mar 11, 2010 1:10 pm

PaulFurman wrote:This suggestion might not help for stacking lenses but I ran across an interesting looking e-book about tinkering with lenses: http://www.alternativephotography.com/w ... ple-lenses
I actually ordered it a week ago but have not received the download though I'm sure it'll get sorted out, maybe the author is on vacation or something... Here's a review that explains it does not deal with multiple elements at all: http://www.flickr.com/groups/homemadele ... 150144844/ although knowledge is knowledge so I'm sure there is value in it.

I did get the download, my spam filter was eating them up <g>. It's an interesting bit of writing, very meticulous. I've learned how better to understand & tinker with my odd assortment of bare lens elements.