www.photomacrography.net :: View topic - Afocal fail
www.photomacrography.net Forum Index
An online community dedicated to the practices of photomacrography, close-up and macro photography, and photomicrography.
Photomacrography Front Page Amateurmicrography Front Page
Old Forums/Galleries
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Afocal fail
Goto page Previous  1, 2, 3
 
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Beginners Micro
View previous topic :: View next topic  
Author Message
Ichthyophthirius



Joined: 07 Mar 2013
Posts: 800

PostPosted: Thu Dec 14, 2017 12:21 pm    Post subject: Reply with quote

Hi,

I agree; just get a Nikon CFW 10x or CFWN 10x/20 eyepiece. They are non-compensating and have a high eyepoint. They appear regularly on Ebay. If they have a diopter adjustment, just set it at zero (middle position).

They should perform well for afocal with the 30 or 35mm camera objectives.

Regards, Ichty
Back to top
View user's profile Send private message
dragonblade



Joined: 18 Oct 2014
Posts: 140

PostPosted: Thu Dec 14, 2017 6:45 pm    Post subject: Reply with quote

enricosavazzi wrote:

Just to make sure, the idea is that you don't focus with the camera lens, you just leave the camera focus on infinity


Yea I realised that the camera lens is meant to be focused on infinity. Though you could say that there is still focusing involved with the camera lens - obviously focused just once (even though obtaining infinity focus is easy with most lenses!)

Actually, I do look forward to using a manual focus lens like the Meike 35mm for afocal rather than my 14 - 45mm kit zoom. The focus ring on my kit zoom rotates continuously round and round with no stop point. Depending on the shooting circumstances, it can be really challenging to get infinity focus with that particular lens. Of course one way to do this is to simply focus on something far away. But it's not always that simple. Case in point was a lightning storm a few years ago. Previously, I had been shooting lightning on 35mm film for a number of years with old, manual focus Canon FD lenses. And hitting infinity focus with those lenses is dead easy - just rotate the focus ring to the infinity mark and you're done.

The first time I shot lightning on digital was with the kit zoom and it was a nightmare in frustration trying to get infinity focus. It was a really dark night and there were no stars or far away lights to manually focus on. I captured some really interesting lightning formations but they were way out of focus. That was the result of moving the focus indicator in the viewfinder to the mountain icon (for distant objects) far away from the flower icon (for close subjects.) Later during the same storm, I managed to obtain infinity focus by putting the focus icon at an optimal position just before the mountain icon but it took a bit of time and tweaking to get it just right. Regardless, that was the last time I shot lightning with that lens!

enricosavazzi wrote:
(once you have calibrated the photo tube to be parfocal with the eyepieces) use only the focus rack of the microscope.


Initially, I was looking around for a trinocular microscope for afocal but eventually settled on a monocular. So what I'll do first of all is focus the microscope normally (with no camera) making sure I get a sharply focused image in the eyepiece by adjusting the distance between the objective and subject. Then add the camera (with the lens focused to infinity) and continue to use the microscope's focus controls while viewing through the camera's EVF.

I will perform some focusing tests with the Meike lens beforehand. I note that some lenses focus a little past infinity when the focus ring is rotated all the way to the infinity symbol.
Back to top
View user's profile Send private message
enricosavazzi



Joined: 21 Nov 2009
Posts: 1024
Location: Stockholm, Sweden

PostPosted: Fri Dec 15, 2017 1:59 am    Post subject: Reply with quote

[quote="dragonblade"]
enricosavazzi wrote:

Initially, I was looking around for a trinocular microscope for afocal but eventually settled on a monocular. So what I'll do first of all is focus the microscope normally (with no camera) making sure I get a sharply focused image in the eyepiece by adjusting the distance between the objective and subject. Then add the camera (with the lens focused to infinity) and continue to use the microscope's focus controls while viewing through the camera's EVF.

I will perform some focusing tests with the Meike lens beforehand. I note that some lenses focus a little past infinity when the focus ring is rotated all the way to the infinity symbol.

That is the right procedure. A little refocusing may always be required when switching between observation and camera, even if parfocality is correctly set.

At least in some lenses, the capability to focus a little beyond infinity is added for two reasons. One is to compensate for different lens temperatures. The other is to allow for slight errors in infinity focus calibration.
_________________
--ES
Back to top
View user's profile Send private message Visit poster's website
dragonblade



Joined: 18 Oct 2014
Posts: 140

PostPosted: Fri Dec 15, 2017 8:04 am    Post subject: Reply with quote

Enric, out of curiosity, does the focus ring on the Sigma 30mm comes to a stop at infinity or does it keep rotating around continuously?
Back to top
View user's profile Send private message
enricosavazzi



Joined: 21 Nov 2009
Posts: 1024
Location: Stockholm, Sweden

PostPosted: Sat Dec 16, 2017 2:49 am    Post subject: Reply with quote

dragonblade wrote:
Enric, out of curiosity, does the focus ring on the Sigma 30mm comes to a stop at infinity or does it keep rotating around continuously?

It is focus-by-wire, not a mechanical ring, so it rotates forever. There is no focusing scale.
_________________
--ES
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Beginners Micro All times are GMT - 7 Hours
Goto page Previous  1, 2, 3
Page 3 of 3

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group