Search found 196 matches

by JW
Thu Aug 05, 2021 8:56 am
Forum: Equipment Discussions
Topic: 42 or 58 diameter tubes
Replies: 15
Views: 345

Re: 42 or 58 diameter tubes

Lothman - awesome :D , just what I was looking for - it will be no problem to either tap a hole or countersink a 1/4" hole to insert a screw. My favorite store, Amazon, has them also.
by JW
Wed Aug 04, 2021 7:33 pm
Forum: Technical and Studio Photography -- Macro and Close-up
Topic: Spinel
Replies: 0
Views: 53

Spinel

This spinel exhibits rhombic dodecahedral crystal faces with very small octahedral modifications at the corners. Spinel is almost always forms octahedrons or rarely cubes, well developed spinel dodecahedrons are extremely rare in nature (although very common amongst the garnets). Associated with and...
by JW
Wed Aug 04, 2021 7:46 am
Forum: Equipment Discussions
Topic: 42 or 58 diameter tubes
Replies: 15
Views: 345

Re: 42 or 58 diameter tubes

Thanks for the suggestions on using bar clamps - they could work if only the ID was 64mm or larger, which is what the 58mm tubes require. I've been searching everywhere for reasonably priced clamps that meet both the ID requirement and are capable of accepting a 1/4-20 centered (not off-set) screw. ...
by JW
Tue Aug 03, 2021 12:34 pm
Forum: Technical and Studio Photography -- Macro and Close-up
Topic: Some jahnsites
Replies: 0
Views: 79

Some jahnsites

The Jahnsite mineral group is a complex series of calcium-manganese-magnesium phosphates in which sodium and iron, amongst other transition metals, can be substituted in the Ca, Mn and Mg atom positions. These crystals are a mixture of Ca, Mn, Mg and Na, Fe, Mg dominant compositions, found on the sa...
by JW
Tue Aug 03, 2021 9:35 am
Forum: Equipment Discussions
Topic: 42 or 58 diameter tubes
Replies: 15
Views: 345

Re: 42 or 58 diameter tubes

Davy - That is a good idea to use a bellows, I should have thought of that :oops: . My current one has light leaks and the cloth is beyond repair, but I'll look into getting a tube and maybe doing some home repairs on it. Otherwise, its cable ties to strap down the tubes to a lens plate. Thanks Lou ...
by JW
Mon Aug 02, 2021 8:13 am
Forum: Equipment Discussions
Topic: 42 or 58 diameter tubes
Replies: 15
Views: 345

Re: 42 or 58 diameter tubes

Rik, Chris - unfortunately my 58 mm extension tubes are not threaded, they have Canon EF compatible mounts - seemed like a good idea at the time. The configuration is about 120mm of these tubes attached to the camera's lens mount, followed by a reverse 150 Raynox, then either a 10x or 20x objective ...
by JW
Sun Aug 01, 2021 6:26 pm
Forum: Technical and Studio Photography -- Macro and Close-up
Topic: Ludwigite accidental panoramic
Replies: 0
Views: 51

Ludwigite accidental panoramic

Hunting through a specimen of skarn marble rock from eastern Fresno County, California, I wanted to get images of the clear chondrodite crystals in the white calcite marble, and found one area that featured a nice black ludwigite crystal. After composing some other images, came across a similar situ...
by JW
Sun Aug 01, 2021 6:16 pm
Forum: Equipment Discussions
Topic: 20X Objective Quest
Replies: 9
Views: 370

Re: 20X Objective Quest

Yikes! I'll take a close look at the lens under the microscope, maybe I'll see something...

thanks for the tip, Scarodactyl
by JW
Sun Aug 01, 2021 5:01 pm
Forum: Equipment Discussions
Topic: 42 or 58 diameter tubes
Replies: 15
Views: 345

Re: 42 or 58 diameter tubes

Thanks for the comments! If I wasn't clear, I currently am using 58 mm tubes, which are strong but not stiff, these things seem to wave in the breeze. Since I couldn't find a commercial solution to clamping them down, I thought about going to 42 mm. I am going to get a 200 mm Arca-compatible lens pl...
by JW
Sun Aug 01, 2021 4:55 pm
Forum: Equipment Discussions
Topic: 20X Objective Quest
Replies: 9
Views: 370

Re: 20X Objective Quest

Again, thanks everyone for the comments. I did indeed end up getting the Mitutoyo 20x with the horrible barrel damage. Wasn't as bad as the posted images, and there does not seem to be anything wrong with the objective. Test images show nearly no CA of any type. However, there is a noticeable color ...
by JW
Sat Jul 31, 2021 5:45 pm
Forum: Equipment Discussions
Topic: 42 or 58 diameter tubes
Replies: 15
Views: 345

42 or 58 diameter tubes

For some time 42 has been the answer to the 'ultimate question', but why not 58mm instead? When using 10X or 20x infinite focus objectives, with the usual reversed Raynox 150mm, does tube diameter matter? I would guess that the larger diameter may help to reduce reflections, etc., but could be wrong...
by JW
Tue Jul 20, 2021 5:35 pm
Forum: Equipment Discussions
Topic: 20X Objective Quest
Replies: 9
Views: 370

Re: 20X Objective Quest

Thank you - appreciate the answers. Axial CA is bad for the minerals and crystals that I photograph, so I'll go with the Mitutoyo, if its bad the seller has a return policy
by JW
Tue Jul 20, 2021 3:00 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: DMap intermediate output - ZS
Replies: 3
Views: 172

Re: DMap intermediate output - ZS

Fantastic, thanks Rik!
by JW
Tue Jul 20, 2021 12:56 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: DMap intermediate output - ZS
Replies: 3
Views: 172

DMap intermediate output - ZS

We are all familiar with the need to set DMap Contrast threshold manually about 50% through the process. Rarely (OK, occasionally) I pick the wrong value and the final image looks like crap. Is there a way to go back to the 'set contrast threshold' slider without having to start the stacking process...
by JW
Tue Jul 20, 2021 12:53 pm
Forum: Equipment Discussions
Topic: 20X Objective Quest
Replies: 9
Views: 370

20X Objective Quest

So far I've had two orders for a Mity 20x objective cancelled and refunded in the past month, after receiving confirmation of order and payment :? I've a lead on two additional objective lenses, on is another Mity 20x, but with significant superficial? damage (appears as if a gorilla took a pipe wre...