Lens stacking

Sometimes I read about strange sounding ways of photography and lens stacking is one of them. The idea is to connect two lenses together in order to get higher magnification for close up shots. This can be done with a cheap stacking ring but it requires lenses to have the same filter thread size.



I tried out combining my Canon EF-S 18-55mm IS f3.5-5.6 and Canon EF 70-210mm f4.0. I attached the 70-200mm to the camera body. The problem with this kind of setup is to find suitable settings for each lens. I left focus to manual on both and did not try to adjust that at all. The zoom settings define the magnification and it should follow this simple formula: magnification = focal length of the primary lens / focal length of the reversed lens. So in case of my lenses I have range of 1.27 - 11.7 magnification - in theory.



There are some practical issues with this combination. Setting the focal length of the primary lens to 70mm vignetting occurs and cuts a good amount of corners off. At 210mm vignetting is gone but the lack of light makes focusing difficult. A good live view helps a bit but I ended up using bright led lamp to lit up the target during focusing. The actual photo is then lit by a flash.

Focusing is done in practice by moving the camera until the right part of the target is sharp. The depth of field is extremely shallow and high magnification shows up any camera shake. Shooting handheld with this long stacked lens is pretty tricky.

I uploaded some of my experimental shots to flickr under stacked tag

More information about the theory
http://www.peterforsell.com/macro.html#Magnification_of_stacked_lenses

Cheap tripod is better than no tripod

I think the first accessory I bought for photography after the camera was a tripod. I had no clue how serious I will be with photographing so I did not feel like investing in an expensive tripod. Instead, I bought the cheapest one.

My choice was a brand new Hama Star 63 and I paid around 12 pounds for it. After half a year usage it is still in one piece but I am somewhat fed up with it. As one might guess, it is not the lightest one. Most of the parts are made of cheap plastic and it is somewhat unstable no matter how much you tighten it.

But even this low level tripod allowed me to take photos which would have been impossible to take hand held. Long exposure shots became possible as well as light painting. I think a tripod is one of the most cost effective photography gear.

Meanwhile, in the laboratory...

I just realized I have been downgrading my photos because of a low quality UV filter. The bokeh looked horrible and focus seemed to be off so ended up setting up a test setup and shooting plenty of frames with different settings. Soon It was quite clear that cheap Jessops branded filter was the culprit. But I also learned quite a lot about how autofocus works and what might cause it to miss the spot. But more later with example photos.

My next purchase

My colleague lent me his Kenko Extension tube set for couple days and I have to say that it is a must have. An extension tube is just an extender without any lenses inside. With the extension tube attached between the camera body and the lens you can sharpen closer and therefore photograph things in bigger size. Unfortunately long extension tube usually prevents auto focus so you have sharpen manually. A set of extension tubes is relatively cheap because of the simple construction and it takes less space in my camera bag than a proper macro lens. 

But how sharp photos you can take with extension tubes? I think it depends how good your lens is. A good prime or a very sharp zoom lens are good candidates. I shot this example with Canon EF 70-200mm F4 L IS USM. The photo of 1 Swiss Franc coin year digits is cropped to show 1:1 size.

f8, 70mm, 1/100s, ISO 100 and full stack of Kenko extension tubes.

As mentioned above I do not own  such tubes, yet. I have been postponing the purchase as I made a promise not buy more photography gear this month. Luckily it is already 18th...

How to photograph the moon

Taking a decent moon photo is not too difficult but you need to have some equipment for it. The most important one is a proper tripod or similar support for the camera. Almost as important is a decent telephoto lens. A sharp 200 mm telephoto lens is a good start for photos like this:

But even if you have the best possible gear you still need to see the moon. So, check the moon phase calendar, weather forecast and head to a dark location. Usually cities have way too much light pollution and this reduces the contrast between the sky and the moon. Find a dark area with solid ground for your tripod.

Then set up your tripod as stable as possible. Do not extend it completely unless really necessary. Select your telephoto lens with longest focal length and remove any filters you have. Even high quality filters can cause unwanted flare.

Use low ISO setting to avoid noise - ISO 100 works well. I do not pay attention to white balance as I shoot on RAW which allows more post processing options. Use mirror lock up if available and use long timer to trigger the shutter. These help to reduce camera shake and therefore improve image quality. The choice between manual and automatic focus is up to you. When using a lens without distance view the autofocus might be a better option.

Finding the right aperture for your lens needs some experiment. Most lenses have their sweet spot around f8-f11. Any higher aperture number causes diffraction which reduces image sharpness. Too low aperture number leads to soft photos especially on cheaper zoom lenses.

After all this setup the last step is to aim the center of the moon and select the right exposure. There are calculators for moon photography but couple test shots give you a good idea anyways. Depending on your camera its exposure metering it might give totally misleading results so feel free to ignore it.

Take plenty of shots with different aperture and exposure times. At the post processing I use only green color component because it seems to have less noise compared to red. I also reduce saturation so the end result is black and white. Apply some sharpening, crop tight and upload to your favorite image gallery for feedback.

Edit: I added more tips for photographing the moon. Take a look!

Photographers legacy

Recently I got to know about Sergey Prokudin-Gorsky and his photographs. What makes his photographs really interesting is that they were meant to be color photographs at the time when color film did not exist. 

He travelled around Russia taking photos of various places using his special camera around 1905-1915. His camera took three exposures for each light component. These sets of three black and white photos were very difficult to merge to a complete color print on his time but couple years ago they were scanned and processed using modern technology. Library of Congress has 'The Empire That Was Russia' exhibition and many of the processed photos can be seen online.

I wonder if Sergey Prokudin-Gorsky thought his photos would have such an important historical value after so many years. In our current lifestyle photos usually became useless as soon as nobody remembers where it was taken and who were on it. In case of digital photography I am not too sure how well digital archives survive for one hundred years. And how to write all the important information on the back of the digital image? In any case, I would be very curious to know what kind of piece of history future generations will find as fascinating as these old color photos.

Depth of Field calculator

Most photographers know the effect of different apertures. The smaller aperture (=bigger f-value) the longer depth of field. But how long is the depth of field precisely?

I was quite surprised how much the distance from the subject affects the length of the depth of field. Let's imagine that we are taking a photo of a flower from one meter distance with 100mm f2.8 on 1.6 crop frame. Based on an online calculator the depth of field is 9.7 mm. But we want to double that because the flower is not completely sharp.

Stepping down to f5.6 gives depth of field of 19.3 mm. Now the dof is twice as long but the exposure time has become four times longer. In case of hand held photography this might be too much.

Another option is to keep aperture at f2.8 but take one step backwards so that the distance is 1.4 meters.  This will give the same depth of field as above but without the expense of longer exposure time.