Beginners Question on Mirror Slap

Bob Ballantyne · Post by **Bob Ballantyne** » Sat Mar 13, 2010 7:23 am

Hi:

This is my first posting. I am a retired biology teacher (16 years retired) but active as an outdoor writer and maintaining an interest in photomicrography of protists and other small aquatic invertebrates.

I have had some success with videophotomicrography and photomicrography with a Nikon N65 and appropriate 'scope attachment.

Recently I purchased a digital Nikon (D3000) which mounts and works well with the N65 equuipment except for movement of the whole apparatus, 'scope and all, when the "shutter" releases. It appears as though what I understand is called "mirror slap" is blurring the images. I did not have this trouble with the N65.

I am taking the shots by manually pushing the shutter release, which may be part of the problem. Would an IR remote release help this problem?

Can anyone here suggest combinations of ISO settings, shutter speed, and lens opening for general use when the camera is used on manual mode?

My scope is a Wolfe trinocular.

Any help would be appreciated.

Bob Ballantyne
Pennsylvania

ChrisR · Post by **ChrisR** » Sat Mar 13, 2010 10:56 am

Welcome!

Having had a peek at your manual, some of the "modes" I was about to suggest, aren't available on that model.

Some Nikons have a very clattery Live View mode. If your model has a Live view mode, don't use it!
Don't touch the camera! Use the self-timer. 5 seconds should be enough to let wobbles settle. An electric, or remote/radio release, is a godsend though.

The mirror raising is a major source of vibration, and will be most significant in the first 20th ( to a quarter, say) of a second of your exposure.
So either
1) use very short exposures - though I doubt you'll have enough light, for say 250th of a second or shorter.
3) use much longer exposures, such as a second or more, so the mirror-induced fuzz isn't noticed. During that time of course the washing machine, passing traffic and the like may be a problem
2) or use flash. You still are best to avoid that first tenth of a second. You can do that by using Rear Curtain Flash Sync on the camera. That fires the flash just before the shutter closes. If you have low ambient light, so that nothing is recorded during an exposure long enough to let the wobbles settle (say a second), the flash, while everything is still, will be the only light.

Iso choice is of course a compromise. Normally "as low as you can" would be the advice, but if things are dim you may have no choice. Above 800 or so I imagine you'd start to see noise.

Try it and let us know how it goes

Edited typos

Bob Ballantyne · Post by **Bob Ballantyne** » Sat Mar 13, 2010 11:25 am

Thanks for your help. I'll try some of your ideas.

However, the flash cannot be an option since the camera is mounted to a microscope tube, or perhaps I am missing something about that comment.

Bob Ballantyne

Harold Gough · Post by **Harold Gough** » Sat Mar 13, 2010 11:29 am

Bob,

Good to see you here. Macro lore says that this is worst at shutter speeds of around 1/15 second. A tripod helps to overcome the blur, preferably together with a cable or air release (not so easy on the latest cameras) but a mirror lock-up is really the answer. I use the whole lot with my film set-up, when not using flash, which is the most reliable solution.

Harold

ChrisR · Post by **ChrisR** » Sat Mar 13, 2010 11:37 am

Bob if you read here about peoples' setups, you'll find various contrivances used to get flash working.
Unfortunately I see no Mirror Lockup available to you in the manual except for cleaning the sensor, which is of no use to you for exposures

.

Bob Ballantyne · Post by **Bob Ballantyne** » Sat Mar 13, 2010 12:02 pm

Tripods and flash advice? I am not sure I am getting across the problem. I hope this link provides a photo of the setup. I do not see how those two issues apply to this problem.
Bob B

ChrisR · Post by **ChrisR** » Sat Mar 13, 2010 12:21 pm

I can't find a link! But I have read of folk using a flash in place of the normal bulb arrangement. I'm sure someone will remember better..

LSRasmussen · Post by **LSRasmussen** » Sat Mar 13, 2010 12:21 pm

Bob,

Have a look at :

http://micropix.home.comcast.net/~micro ... index.html

Charles Krebs adresses most if not all of your issues.

Hope this helps,

Lars

Bob Ballantyne · Post by **Bob Ballantyne** » Sat Mar 13, 2010 1:17 pm

Ah ha, now I see the flash business. Thanks for the help.

Bob B

rjlittlefield · Post by **rjlittlefield** » Sat Mar 13, 2010 3:41 pm

Bob, there are also other approaches to flash through a microscope --- more add-on, less integrated.

One trick is to put a piece of ordinary glass between the microscope base and the condenser, angled up at 45 degrees, with the flash shining in horizontally. For continuous viewing, the base lamp shines up through the glass. When the flash goes off, enough of it reflects up through the condenser to make the exposure.

As a variation of this technique, some people set up a "snoot" -- a tube lined with aluminum foil -- to channel light from the camera's built-in flash down to the microscope base so it can get sent back up through the condenser.

I've also seen this approach using a fiber optic bundle instead of the snoot. But most of us have a better supply of aluminum foil than fiber optic bundles.

--Rik

Bob Ballantyne · Post by **Bob Ballantyne** » Sat Mar 13, 2010 4:09 pm

Many thanks. I'll be looking into those techniques, as the previous one, which I downloaded, is a little more sophisticated than I care to be!

Bob B