Diatoms with my new Canon 600D camera

[Jean-marc]

Hello,

I am not sur it is the right place to post some tests, but I have left my coolpix 995 for my new Canon 600D.
For the moment I am just holding it at the top of my Leitz Vario photoeyepiece http://www.photomacrography.net/forum/v ... eitz+canon.
Although the vario has not found its good position, as I cannot keep the focus when I modify the vario magnification !!?? I think the problem was already discussed before.

So no flash, as I have not connect my camera with the inside homemade flash yet.
Splanapo 40/0,95 DIC, 1/125e, 200iso









The color rendering is far better than with my old fidel Coolpix 995

Jean-Marc

[curt0909]

Much improved. Looking forward to seeing more with your new camera

[Hindpool]

Very fine results Jean-Marc; you are certainly getting the best from the Leitz Vario-Orthomat/Canon E600 combination. I look forward to following your progress with your new outfit.

[Pau]

Although the vario has not found its good position, as I cannot keep the focus when I modify the vario magnification

I think the Vario-Orthomat is designed to work afocally with a lens beween it and the camera, not for direct projection like it seems mounted in the Hindpool's setup.
Do you use it directly mounted in the camera or afocally with a camera taking lens?.
In the second case, you can check if
- is your camera lens focused to infinite?
- is the camera image parfocal with the eyepieces?
- what magnification on sensor do you get: something close or very different the V-O lens scale?

In any case the images seem excellent.

[Jean-marc]

Hello,

Thank you all,

Hindpool it's thank to you if I know how to set the vario and the camera. We keep in contact to tell you the progress of the combinaison.

Pau, I try to answer you with the little knowledge I have about the camera :

I think the Vario-Orthomat is designed to work afocally with a lens beween it and the camera, not for direct projection like it seems mounted in the Hindpool's setup :
Yes I think a lens between the vario and the camera will be useful to avoid some focus problem.

Do you use it directly mounted in the camera or afocally with a camera taking lens?.
I use the camera directly put on the vario without any lens between them.

is your camera lens focused to infinite?
I do not know if the question applies for a reflex camera without its objective.

is the camera image parfocal with the eyepieces?
Yes, it is very important for me

what magnification on sensor do you get: something close or very different the V-O lens scale?
I do not use any sensor magnification yet. I do not know if it is useful ?

Thank you

Jean-Marc

[Charles Krebs]

Jean-marc,

You can't argue with the results... these look great!

In the earlier thread that you referenced...:
http://www.photomacrography.net/forum/v ... eitz+canon
...Dave ("discomorphella") provides some key information about the way this piece was implemented by the manufacturer, with an 83mm lens to be used with the 35mm format. That does seem to make sense. With the 5-12.5X range of the Vario-Orthomat, that would provide a magnification range into a 35mm format camera of 1.65 to 4.12X:

83/250 = 0.33X

0.33 x 5 = 1.65X
0.33 x 12.5 = 4.12X

With an APS sized sensor it might be nice to go just a bit lower, so a 70-75mm lens might be a good choice.

But if your results are this good then "if it ain't broke don't fix it" is an expression we use around here.

I can't help but wonder how things would work overall if you put a 70-75mm achromat pair focused on sensor at "infinity" between the Vario-Orthomat and the camera body.

[arturoag75]

Charlie,
you wrote : 83/250 = 0.33X

what's 83 and 250?
best
arturo

[Jean-marc]

Hello,

I think that 83mm is the distance between the lens and the 24x36 film of the reflex. 250mm is the normal distance of viewing.
The sensor of my reflex is a bit smaller than a 24x36 film, so I need only 70mm focal lens.

Charles will give certainly a better answer.

Charles, thank you, your help and knwoledge help me very well.
I tried with a a bad achromatic lens of about 70mm focal, and I was able to keep parfocality and modify the vario magnification without any problem !
I just have to find a good achromatic 20mm diameter and 70mm focal lens.

JM

[Pau]

I just have to find a good achromatic 20mm diameter and 70mm focal lens.
JM

Because the Vario-Orthomat has a good zoom range, you can use a very cheap and optically good old standard 50mm reflex camera lens.

- 83mm is the Leitz 0.3X lens focal lengh, I don't know where 250 comes from, but FL/250 provides the right magnification factor of the relay lens:
My original Zeiss adapter says 0.25X and its focal lengh is 63mm.

- With a 50mm relay lens you can get magnification from
(5X50)/250= 1X
to
(12.5X50)/250= 2.5X
And I think this is the best magnification range you may want with a APSC sensor. (usually for FN 20mm eyepieces the best fit is 1.6X)

[Charles Krebs]

Edmund optics has a good range of coated achromat doublets. They also have T-mount components that hold the 25mm and 30mm diameter versions.

But unless you plan to go to a full-frame camera (24x36mm sensor) it might be worthwhile to try, as Pau has suggested, a 50mm lens since they are so readily available, inexpensive and optically excellent. This would provide a range (in the camera) from 1X to 2.5X. It would cover sensors sized from 4/3 up to 35mm format. You always are concerned about vignetting when a lens like this is used, so I would try it first with a "temporary" mounting arrangement. If it worked as desired a more permanent, solid mounting arrangement is not hard to do.

The Canon 50/1.8 and most of the Nikon 50mm lenses (cheap Nikon to Canon adapters are available) have a 52mm thread. If you added a piece like Ebay 380337831683 or Ebay 160830251667 you would then have a common 42mm(0.75..."T-mount") or a 42mm(1) thread to work with at the front of the lens. It would then be much easier to properly "space" the camera above the V-O optic to achieve parfocality with the viewing eyepieces.

Some examples of a T-mount pieces that could be used is the Baader Varilock http://agenaastro.com/catalogsearch/res ... r+varilock and various t-mount spacer rings http://agenaastro.com/catalogsearch/res ... ead+spacer )

Properly set up with the an additional lens (as Leitz had intended) it would be a extremely versatile arrangement.

(But as I initially said... you have already shown us some excellent results as you are using it now. The one thing I can't tell from your fine diatom examples above is how the very edges and corners perform. This is often where optical problems show up).

[Pau]

Charles, I'm happy that you agree with my sugestion

You always are concerned about vignetting when a lens like this is used, so I would try it first with a "temporary" mounting arrangement.

I don't think that vignette would likely be an issue with a 1.8 or 1.4 50mm lens placed close to the "eyepiece". With my (very different but comparable) setup I need to stop the lens down to f11 to get vignette

...If you added a piece like Ebay 380337831683 or Ebay 160830251667 you would then have a common 42mm(0.75..."T-mount") or a 42mm(1) thread to work with at the front of the lens. It would then be much easier to properly "space" the camera above the V-O optic to achieve parfocality with the viewing eyepieces.

Some examples of a T-mount pieces that could be used is the Baader Varilock http://agenaastro.com/catalogsearch/res ... r+varilock and various t-mount spacer rings http://agenaastro.com/catalogsearch/res ... ead+spacer )

Because both the lens and the eyepiece are focused to infinite in an afocal system, I guess the distance between them may have little to none influence in parfocality. In general the best rule is to place them as close as posible to prevent vignette.

[Charles Krebs]

Because both the lens and the eyepiece are focused to infinite in an afocal system, I guess the distance between them may have little to none influence in parfocality.

Yes! I was erroneously thinking in terms of a projection type eyepiece

I've never seen a Vario-Orthomat. The post (and subsequent thread) from a few years ago by Cactusdave has some very good information.

At the top it offers a rather unusual M45 screw thread where it originally screwed into the shutter/ exposure control part of the camera. The diameter of the upper optic of the eyepiece is 20mm, compared with 14mm on a standard Periplan GF eyepiece...

... To adapt the unit for digital camera use I had an M45 to standard T-thread adapter made so that I could mount a range of different cameras via appropriate T-thread adapters.

45mm is a thread size I have never come across before, but it should not be too hard to come up with a solution.

[arturoag75]

Hello,

I think that 83mm is the distance between the lens and the 24x36 film of the reflex. 250mm is the normal distance of viewing.
The sensor of my reflex is a bit smaller than a 24x36 film, so I need only 70mm focal lens.

Charles will give certainly a better answer.

Charles, thank you, your help and knwoledge help me very well.
I tried with a a bad achromatic lens of about 70mm focal, and I was able to keep parfocality and modify the vario magnification without any problem !
I just have to find a good achromatic 20mm diameter and 70mm focal lens.

JM

thanks for answer

[Jean-marc]

Pau Charles,

Your suggestions and explanation are very good and very helpful.

I tried with my 18-55mm EF objective. With a focal at about 50-55mm it is very good. No vignetting, and I can use the whole range of the vario magnification. The setup is not easy because I have to hold the reflex at the top of the vario, but it works well.
As said Charles, the thread of the Vario is very special : M45x1;
But I just need to find (or to make) a ring male M42x0,75-->female M45x1

Thank you

Regards

JM

[Cactusdave]

I have been following this thread with interest as a regular Vario-Orthomat user. The M42x0,75-->female M45x1 that Jean-marc mentions I had made for me by SRB-Griturn in the UK http://www.srb-griturn.com/made-to-order-245-c.asp since I had nether the skill nor equipment to make my own, I recall they were neither cheap nor ridiculously expensive for this 'one-off' adapter.

I was interested in the suggestion of improving the field of view by interposing a 50mm or similar lens to mimic the lens in the original Photo-Orthomat. It seems a worthwhile experiment, though it might produce a rather unwieldy 'tower' above the phototube as the Vario-Orthomat is quite tall by itself. Also I'm a great fan of the maxim repeated by Charles 'if it ain't broke don't fix it'!

One possible issue with the Vario-Orthomat, not mentioned here is chromatic aberration. I've never been clear what, if any additional compensation for CA the Vario-Orthomat applies. I've sort of assumed that as a Leitz eyepiece it might be similar to the compensating Leitz Periplan eyepieces in this regard, but I have no evidence to support this. I have only ever used the Vario-Orthomat with Leitz objectives, and have done very little with highly corrected objectives such as high power plan-apos that might show this issue up. I have no idea whether CA might be a significant problem when the Vario-Orthomat is used with highly corrected objectives from another manufacturer.