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 Replies: 76 / Views: 10,337 |
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Valued Member
 United States
430 Posts |
I received my $9 El-Omegar 50mm f3.5 lens today. the entire lens casing is plastic. It really is only useful for very close up shots with the bellows fully extended. Here is a uncropped and a 100% cropped shot. maybe I don't need a microscope objective?   |
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Pillar of the Community
 United States
4038 Posts |
That shot is around 3:1 magnification. Up to about this magnification level, lenses like those used for full-coin imaging (eg your 50mm) can do as well as microscope objectives. Above 3x the tables turn and microscope objectives do a better job. You can push an objective like the Nikon M5 to work from 4x (maybe even 3.5x) up to around 7x with good results.
Contact me for photographic equipment or visit my home page at: http://macrocoins.com |
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Valued Member
United States
430 Posts |
I had a very small window of focus available to me with the 50mm. Only with the bellows completely extended I also had to open up the aperture to 5.6 to get enough light in. So is the uncropped shot 3:1 or the 100% cropped shot?
I remember reading and old thread with you and Dave discussing the merits of increased magnification. I don't what I would want to magnify more than this.
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Pillar of the Community
United States
4038 Posts |
The overall shot is about 3:1. The crop looks to be about 10:1. Being able to downsize rather than crop is more important for higher magnifications due to less depth of field and more diffraction effects. So it's always best to decide what magnification you need for final image, and shoot at that magnification. If you like to see the mintmark fill the image, it's best to shoot at 10x rather than crop from a 3x image. But when I say "best" I am talking about overall image quality and sharpness, and to get there at 10x requires some stacking.
Contact me for photographic equipment or visit my home page at: http://macrocoins.com |
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Valued Member
United States
430 Posts |
so here is the microscope stand before alterations   |
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Valued Member
United States
430 Posts |
I don't know why but the photos get "unrotated" when I post them.
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Pillar of the Community
United States
4038 Posts |
Nice stand, I like it. Let's see the modified version! And how easy was it to modify?
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Valued Member
United States
430 Posts |
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Valued Member
United States
430 Posts |
The three bolts holding the trapezoid strip are 8-32. The heads on these bolts were very small to allow the gear strip to go over them. So I replaced them with 6-32 stainless 1/2" bolts.
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Pillar of the Community
United States
1476 Posts |
Looking good.  Is it 'top heavy' at all? |
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Valued Member
United States
430 Posts |
I normally shot with the camera much lower than the last pic, using the 75mm lens. I only need it fully extended using the 105mm lens. I wanted to show this stand has a lot of range.
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Valued Member
United States
430 Posts |
I shoot in M mode. In this mode I cannot adjust the exposure compensation in Live view. Aperture priority makes no sense because I'm setting the aperture on the lens. In Tv mode I can adjust the exposure compensation but it really does nothing. and every time adjust the shutter speed in M it seems I need to readjust the white balance. how can I use exposure compensation with a bellows / manual setup?
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Pillar of the Community
United States
4038 Posts |
In my view Aperture Priority (Av) makes perfect sense. Av mode leaves the lens aperture setting up to the user, and then adjusts other parameters to get correct exposure. It is also the only way I know to make the process work seamlessly in Live View. Using Av mode enables exposure compensation, gives correct exposure simulation in the live image, and doesn't mess with other settings such as white balance.
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Valued Member
United States
430 Posts |
I'm not getting something. My bellows is not an Auto bellows. So in Av mode no info is sent to the lens to adjust the aperture. So Av mode is really a manual mode. Is there some "in camera" aperture adjustment?
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Pillar of the Community
United States
4038 Posts |
No, you are correct. No info is sent, and there is no in-camera adjustment. But no information is required to be sent! Manually adjusting the aperture on the lens is exactly the same as manually adjusting the value on the dial. The camera doesn't care if it is adjusting the aperture, or you are using a manual lens.
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Replies: 76 / Views: 10,337 |
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Posted 05/19/2015 12:14 am
