Medium Format Lenses on a DSLR

It’s no surprise that photography equipment is expensive.  Think of the engineering and workmanship that goes into lenses and DSLR bodies.   As with everything, there are always levels of expense.   Lets examine lenses specifically.  The professional-class lenses tend to have fewer issues.  Yet, trade-off’s always exist with either professional or consumer glass.  So we spend our time and money looking for the best equipment for our hobby or profession. Sometimes the limitation is money and sometimes it’s just the lack of that ideal piece that we need.  For those willing to sacrifice some modern features there may be options to get top-quality glass at a fraction of the cost of similar modern equipment.

Here’s a Gerbera Daisy, shot with a medium format 55mm lens

As a photographer, I’m always looking for an edge, especially with my infrared images. As an engineer, I’m digging into the technical details of my photos & equipment.  I always look for ways to improve my set-up.  Many IR photographers have their cameras converted to dedicated IR use (with a fixed internal IR filter over the sensor).  These converted IR cameras can be calibrated to autofocus in IR so they shoot just like a stock camera.  The viewfinder can still be used for framing. However, for folks that use an external filter on full-spectrum cameras (like me) this is not an option. Longer wavelength filters block the viewfinder from transmitting visible light.  So I always use the camera in live-view mode and use the LCD and a loupe to focus my lenses manually. Since the same sensor that records the photo is also producing the live-view image, framing and focus are easily managed. I always manually focus my IR images using this LCD technique.  It gives me confidence that my images are, at least,  focused.

In addition to photography, I have spent many years doing serious astrophotography. Several years back I had read about astrophotographers coupling medium format lenses to cooled CCD cameras.  I wondered why these lenses so popular with astrophotographers.  Beyond the obvious point of getting a wider view of the sky, a quick examination of the physical layout quickly made it clear.  Medium format lenses are used primarily because of their longer flange-to-focal plane distance.  On many Astro CCD set-ups filters, guides and other equipment can lie between the telescope and the camera.   As an example, look at my wide-field (530mm) astrophotography set-up below.  See all the equipment between the camera (box on the LHS) and the telescope? If you remove the telescope and replace it with a lens, this lens would require a fair distance between where it mounted to where it focuses.

Below is an example of how a dedicated medium format astro set-up is constructed.  A custom machined the lens mount and motorized focus mounting bracket hold the medium format lens for coupling to the CCD.  This assembly is then attached to an equatorial mount, in place of or in addition to a telescope.

(Image courtesy of Craig & Tammy Temple)

All the astrophotography work had me wondering how medium format lenses would work on a DSLR.  They work very well.  Some significant advantages exist when using medium format lenses on a DSLR.  The largest advantage is cost.  These lenses are seen as obsolete.  So many of the older manual focus, medium format lenses are available quite reasonably. With a little research and patience, some excellent deals can be had. I use the Pentax 67 format, but many others should work equally as well.

Another advantage has to do with the film size of medium format cameras.  Pentax 67 is a later version of the Pentax 6×7 format. This format came from the film size of 6 x 7cm. That’s a whopping 60 x 70mm. A standard DSLR full frame image format is 24 x 36mm. Medium format lenses will overfill a full frame sensor by a substantial amount. Why is that a big deal? Well, think about your lenses. Most of the bad things that happen to images occur on the fringes of the frame (chromatic aberration, coma, vignetting, etc). With a medium format lens, you’re shooting through the sweet spot.  I was pleasantly surprised at the image quality of the vintage medium format lenses that I tried. I have some decent professional DSLR glass.  But any of the medium format lenses that I’ve purchased give equal or better results. Here’s an example, a 2 frame panorama shot with a medium format 55mm prime lens.

This is a heavy snowfall in the desert of Far West Texas. In the distance are the Franklin Mountains that run through El Paso, Texas

Using a medium format lens has another advantage. If you understand how tilt-shift lenses work you may see where I’m going. With an OEM tilt/shift lens overfills the sensor. This allows the lens to be shifted and the image to still fall on the sensor.   With a normal lens, the image will shift off the sensor or become heavily vignetted.  For the price of one shifting adapter, you can shift any of your medium format lenses. If you read my blog last month you’ll know that I prefer to shoot panoramas with a shift lens. For fraction of what I paid for the spectacular Canon EF-24mm TS-E Tilt/Shift lens (also manual focus, by the way), I purchased an adapter and a small fleet of medium format prime lenses.

This is a 3 frame panorama of northern Norway, shot with my Canon 5DII, a 55mm Pentax 67 lens and a shift adapter (see below).

This is a Canon 5D Mk II coupled to a Pentax 67 55mm lens using a shift adapter.

A test shot using my 150mm Pentax 6×7 lens (my oldest medium format lens)

It’s not all roses, though. Most medium format lenses are huge. I mean huge, and they are heavy. They are generally much larger than their 35mm format counterparts.  However, the size is what provides that impressive image circle.

A monster of a 55mm lens and probably one of the sharpest lenses I’ve ever used, in any format.

A disadvantage (for some folks) is that the older medium format lenses are all manual focus. So you have to be comfortable with shooting manual focus on an IR camera (and understand manual camera operation if you plan to do Pano’s).  If you have an IR shooting style like mine, using a manual focus lens is inconsequential.  I manually focus my AF lenses for IR anyway.  You’ll also need to purchase an adapter (either fixed or shift) to interface to a DSLR.  Finding the proper adapter for your camera and preferred lens brand may also be difficult. You also have to do your research to get the lenses that have the best image quality. Just like modern AF lenses, some were lemons and some were stars. I only pick medium format lenses that have the best reviews for image quality or sharpness.  Finally, since many of these lenses are older you have to look out for dust, grease and fungus on the optics. I usually try to purchase the latest model of the particular focal length lens. So do your research, ask questions and shop carefully.

If you can get through all the details and decide to try shooting with medium format lenses, you’ll definitely have some seriously nice glass. You also get them for a fraction of what a similar modern lens might cost.  Hopefully, my experience will shine a light on the pros and cons of using medium format lenses on a DSLR.  If you’re up for a little challenge,  give a medium format lens a try.  You won’t be disappointed.