Search found 137 matches

by Epidic
Sat Jan 26, 2008 8:52 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Sensor size: how does it matter?
Replies: 16
Views: 12667

Rik, yes, the math works. I read the link and it appeared that the focal length was scaled in respect to sensor size and magnification was ignored. I could have missed something about magnification, but it seems EI just needs to consider focal length. In that case, as soon as you start to focus, ima...
by Epidic
Fri Jan 25, 2008 6:41 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Sensor size: how does it matter?
Replies: 16
Views: 12667

Rik, I am not sure I have time to do this justice tonight, but I will make a start. I have been busy - and still am. But I want to put down a few thoughts I have had about this. All imaging systems are photon counters. Given equal response, photo site will give the same signal and noise based on the...
by Epidic
Sun Jan 20, 2008 4:43 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Sensor size: how does it matter?
Replies: 16
Views: 12667

Rik: Before I post my reply, I wonder if you can clarify something for me: 1) Same perspective (subject-camera distance) 2) Same FOV (field of view or framing) 3) Same DOF (depth of field) 4) Same shutter speed 5) Same output size (same number of pixels) Is it actually physically possible to keep th...
by Epidic
Thu Jan 17, 2008 7:18 am
Forum: Equipment Discussions
Topic: Don't try this at home!
Replies: 3
Views: 3474

Aren"t we taking dust removal from digital files just a bit far. But do you get brighter whites from this process?
by Epidic
Thu Jan 17, 2008 7:07 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Scanner as a camera
Replies: 6
Views: 3411

As Rik states, illumination of the scanner head (both in terms of intensity and incidence) are a problem. I have seen results of a scanner used in the back of an 8x10 camera. It worked, but not really well. Most likely you are going to have to make your own driver. As far as exposure, if you can dir...
by Epidic
Wed Jan 16, 2008 9:44 am
Forum: Equipment Discussions
Topic: Column, bellows and microscope....
Replies: 5
Views: 3519

You can use an enlarger column, but not all enlargers are easy to convert. some Saunders LPL models and be easily converted. There are columns made for copy work too. I am not sure where you live, but photo retailers may carry this equipment. In the US, places like B&H Photo have this equipment. You...
by Epidic
Wed Jan 16, 2008 9:34 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Making scale bars with no calculations (OT-->diffraction)
Replies: 52
Views: 27544

Graham, I was simply confused as I thought you were taking about image resolving power. In that regard, Graham's explination is not complete. However, it seems you are only discussing resolution at the object plane. (You would be correct in thinking there is no difference between an object and an im...
by Epidic
Tue Jan 15, 2008 1:33 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Sensor size: how does it matter?
Replies: 16
Views: 12667

This "test" requires equal entrance pupil and equal shutter speed. This makes for valid comparisons between systems. Let us take the author's assumption. Entrance pupil determines the amount of light used. The area of the pupil is the collection area and so that determines how much energy enters the...
by Epidic
Tue Jan 15, 2008 11:40 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Sensor size: how does it matter?
Replies: 16
Views: 12667

I have been reading more. I think the author's hypothesis is flawed (his knowledge is certainly incomplete) and has no practical value. What is wrong with teaching the old way by telling folks what effect each parameter has. Linking all of this into a "theory of everything" makes no sense. It does n...
by Epidic
Tue Jan 15, 2008 10:58 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Sensor size: how does it matter?
Replies: 16
Views: 12667

Well Rik, I am going through this essay and all I can say is it is awful. It is starting myths that do not need to be started - f-number is the intensity of light, but entrance pupil is the amount of light?? No clear understanding of display size or viewing distance either. It seems this "system" is...
by Epidic
Tue Jan 15, 2008 9:59 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Sensor size: how does it matter?
Replies: 16
Views: 12667

Sensor size does not affect image quality if you're talking about equivalent exposures. That means same illumination, same camera position, same field size, same exposure time, and same DOF. That is, the pictures look the same even if the subject is moving. Actually, with the same exposure time and...
by Epidic
Tue Jan 15, 2008 8:47 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Making scale bars with no calculations (OT-->diffraction)
Replies: 52
Views: 27544

Will, The objective has a certain NA and hence a certain resolving power and you are correct that this is not necessarily the resolution you will get at the image plane, the resolution at the image plane comes down to the system NA. Typically you may have a high NA objective and a low NA tube lens ...
by Epidic
Sat Jan 12, 2008 6:20 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Making scale bars with no calculations (OT-->diffraction)
Replies: 52
Views: 27544

rjlittlefield wrote:I cannot resist the pun that "diffraction is a fuzzy subject". :roll: :D
--Rik
I hate to interfere, but is that constructive? (But it is a sine we are on the same wavelength. Or is it just a phase you are going through?)


:lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:
by Epidic
Sat Jan 12, 2008 10:44 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Making scale bars with no calculations (OT-->diffraction)
Replies: 52
Views: 27544

Graham, it is a confusing thing (But not as confusing as two members called Graham.). You are right in the sense that the usual way microscopist think about this is resolving power at the subject plane and your description is very clear. Photographers are brought up thinking of resolving power at th...
by Epidic
Sat Jan 12, 2008 9:01 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Making scale bars with no calculations (OT-->diffraction)
Replies: 52
Views: 27544

I am not sure that description is clear as one person is talking about resolution at the object plane and the other the resolution at the image plane. A high NA objective does not necessarily have a high resolving power at the image plane as magnification is always a factor, although resolving power...