Search found 413 matches

by JKT
Sun Mar 24, 2024 5:19 am
Forum: Equipment Discussions
Topic: Electrical issue with power supply for Godox flash
Replies: 16
Views: 330

Re: Electrical issue with power supply for Godox flash

That 17A is what the flash CAN take. It doesn't need it. A way lower current will work just fine especially considering that you might then avoid extra delays for cooling. You just need to limit the current in some way.
by JKT
Fri Mar 22, 2024 1:05 pm
Forum: Equipment Discussions
Topic: Preparing for season = New toy -> mitutoyo 10x vs 10x HR
Replies: 6
Views: 265

Re: Preparing for season = New toy -> mitutoyo 10x vs 10x HR

I think the main reason for small differences is R6. Both can pretty much saturate the sensor with details. After that it is a question of tube lens quality and corner performance. If you had R7, used longer tube lens or 1.4x or 2x behind the tube lens, you would see the difference much better. Havi...
by JKT
Fri Mar 22, 2024 4:44 am
Forum: Equipment Discussions
Topic: Electrical issue with power supply for Godox flash
Replies: 16
Views: 330

Re: Electrical issue with power supply for Godox flash

That puts the internal resistance at 0.2 Ohm. That's a nice reference even though it is strictly valid only for that flash.
by JKT
Sat Mar 16, 2024 12:08 pm
Forum: Equipment Discussions
Topic: Lens recomendation for film reproduction
Replies: 41
Views: 975

Re: Lens recomendation for film reproduction

About the corner softness: How are you ensuring that you film is flat?
by JKT
Tue Mar 12, 2024 1:53 pm
Forum: Equipment Discussions
Topic: Electrical issue with power supply for Godox flash
Replies: 16
Views: 330

Re: Electrical issue with power supply for Godox flash

I was going to write: "I suspect the worst problem is the likely safety circuit in the power supply. When faced with overcurrent they tend to shut down completely whereas batteries give what they can and soon get the capacitor loaded so much that the current drops. For that reason I used 6V 5A power...
by JKT
Sat Feb 24, 2024 12:06 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Mitutoyo 10x e 5x e Sony A7rV
Replies: 11
Views: 380

Re: Mitutoyo 10x e 5x e Sony A7rV

Nel senso che sul lato destro dell’immagine vedo là rotondità dell’obiettivo If that means what I think it does (on one side you see barrell/pincushion distortion and not on the other), something is seriously de-centered. That could be either inside the lens, but it could also be angular error in t...
by JKT
Mon Feb 19, 2024 11:17 am
Forum: Equipment Discussions
Topic: This 5 pack of 1970-1980s wafers for $40 a suitable test target, or too old/big?
Replies: 11
Views: 624

Re: This 5 pack of 1970-1980s wafers for $40 a suitable test target, or too old/big?

Those looked interesting to me as I need something for magnifications less than m=1.5.
by JKT
Wed Feb 14, 2024 1:07 pm
Forum: Equipment Discussions
Topic: What are these?
Replies: 9
Views: 450

Re: What are these?

Without knowing anything ... teleconverters?

Never mind - that would need a bayonet at the other end too.
by JKT
Wed Feb 14, 2024 8:16 am
Forum: Equipment Discussions
Topic: Horsing around with EF 400mm DO II
Replies: 5
Views: 353

Re: Horsing around with EF 400mm DO II

dickb wrote:
Wed Feb 14, 2024 3:13 am
JKT: I would give the +2 and +3 lenses of the Raynox a try separately, I often got better results with those than the +5 combo.
I suspect I won't. The available magnifications make that pretty much pointless for my purposes. Sorry!
by JKT
Tue Feb 13, 2024 3:12 pm
Forum: Equipment Discussions
Topic: Horsing around with EF 400mm DO II
Replies: 5
Views: 353

Re: Horsing around with EF 400mm DO II

Did you use the +2 lens, the +3 lens or both, for a combined +5? With a full frame camera or APS-C or other? That was +5. Camera was Canon RP (FF). With the results I got, there was no point in pursuing that further. So you used all the lenses at widest aperture, or did you stop either the reversed...
by JKT
Tue Feb 13, 2024 2:10 pm
Forum: Equipment Discussions
Topic: Horsing around with EF 400mm DO II
Replies: 5
Views: 353

Horsing around with EF 400mm DO II

This is just a quick note of some tests I did with EF 400mm DO II as tube lens. Taking lens: Raynox DCR-5320 Pro - horrible. Overall I'd call the look dreamy. There may be some reflections from the setup, but I don't think that can explain the results. So using the close-up lens as intended is a bad...
by JKT
Sun Feb 11, 2024 10:29 am
Forum: Equipment Discussions
Topic: Connection from 2 photos of lenses. How to choose a second (inverted)?
Replies: 32
Views: 1138

Re: Connection from 2 photos of lenses. How to choose a second (inverted)?

so sample variations have an impact on picture quality and this makes lens testing awful time consuming and expensive. It sure does - especially with Mitutoyo - but keep in mind I used 180mm tube and you 211mm one AND the bad part was really just the corners. The quality drop becomes visible at d=3...
by JKT
Sun Feb 11, 2024 1:16 am
Forum: Equipment Discussions
Topic: Connection from 2 photos of lenses. How to choose a second (inverted)?
Replies: 32
Views: 1138

Re: Connection from 2 photos of lenses. How to choose a second (inverted)?

It would not be bad if the forum had a list of similar microscope lenses in one attached topic, divided into categories. For example, category 1 - the best, suitable also for flat objects; 2nd category - good, ideal for 3D objects and so on. Indeed it would not. However, the number of categories wo...
by JKT
Sat Feb 10, 2024 1:40 am
Forum: Equipment Discussions
Topic: Connection from 2 photos of lenses. How to choose a second (inverted)?
Replies: 32
Views: 1138

Re: Connection from 2 photos of lenses. How to choose a second (inverted)?

We have: 1. Plan achromatic microscope lens 2. Camera lens with good chromatic aberration correction We connect them in place. Question: Will a camera lens “convert”/correct chromatic aberrations in a microscope lens? That is, will we get an output image quality comparable to a plan APO chromatic l...
by JKT
Fri Feb 09, 2024 12:45 pm
Forum: Equipment Discussions
Topic: Connection from 2 photos of lenses. How to choose a second (inverted)?
Replies: 32
Views: 1138

Re: Connection from 2 photos of lenses. How to choose a second (inverted)?

No, it won't ... or at least that is the answer to what I think you were asking. A "perfect" tube lens won't correct problems in the taking lens. If it was not "perfect", you might get lucky and the two lenses might compensate each other, but the chance of that happening is rather low... What you ac...