Infrared photography - filter or conversion ?

A few thoughts on infra red DSLR photography.  When I saw the images produced by infra red with white vegetation and black skies I wanted to have a go myself.  A "normal" DSLR has a filter on the sensor which passes visible light and blocks infra red to create good visible light images. A bit of online searching suggested that if a camera could "see" the light from a TV remote control, it could take infra red photos. I tested my 2 Pentax DSLRs and found that the K7 showed a bright white light and the K5 a pale orange glow when I pushed the remote buttons. This suggested that the built in infra red blocking filter on the sensor was less effectivwe on the K7.  

I spent £30 on a P007 Creative 720nm filter for my Cokin P holder and I was set!

I got some reasonable IR images with this filter (if you have Dxo Filmpack, try cross processing!). It is a cheap option but there are issues. The biggest problem is that the filter is very dark and when combined with a built-in partial IR filter very little light reaches the sensor. The image is too dark to frame with the viewfinder and long exposures and/or high ISOs are needed even in bright sunlight (the best conditions for IR photography).  It is necessary to guess the framing and focus manually or frame (and focus) the photo and then insert the filter (you are using a tripod for the long exposure anyway). Exposures longer than 10 seconds are not unusual - not good if there is any wind though.

This image was shot at 1/15s, f2.8, iso1600 using an external filter

This is the same image cross processed in Dxo

The alternative is to have an old/spare DSLR converted for infra red photography - old cameras have almost no trade in value and the conversion on the K7 cost me £250.  The difference is chalk and cheese. With a 720nm internal filter conversion, the camera works almost exactly as a standard DSLR, except that it only shoots infra red. Auto focus, internal metering and framing through the viewfinder operate normally and I can take images in daylight at 1/250s, f8 and iso200 - no more tripod or guesswork. 

This image was shot at 1/160s, f11, iso200 using the converted camera

Are there any downsides? Well, you need a body to convert, and then you need to carry the extra weight if you plan to do visible and IR photos on the same shoot (but many APS-C bodies don't weigh much). Check that the lens you want to use will be effective for infra red, ACS has a list of unsuitable lenses on their website.

There are options on the filter installed - from clear quartz to around 850nm hard infra red. 

In theory, clear quartz allows you to shoot visible light but passes infra red so that an external filter works better, 850nm will only give you a monochrome infra red and the others (680, 720 etc) allow some colour but are mainly infra red, These are more suitable for some post processing effects, Google colour channel swapping for examples. Lightroom doesn't have channel swapping facilities but there are somespecial presets available for download, or look for Photoshop tutorials, or GIMP.

Have fun 

JB 

More lens experiments.

Having seen a bit of chat on a Sony E-mount forum about problems with "shutter shock" on the A7r, I thought I would do a few test shots with different lenses, shutter speeds and apertures. There are 8 images and I have taken a central crop from each one at 3000x2000 pixels for a closer inspection. All lenses are close to their minimum focus distance.

The first lens is a Makinon 135mm

f2.8. 1/3200s

f2.8, 1/3200s

f8, 1/125s

f8, 1/125s

Next is a Pentax 50mm

f1.4, 1/800s

f1.4, 1/800s

f8, 1/60s

f8, 1/60s

Next is the Sony FE 28-70mm using deliberately long shutter speeds on a tripod (gorillapod resting on carpet)

f5.6, 1/20s

f5.6, 1/20s

f5.6, 1/10s

f5.6, 1/10s

 Finally, a Cosina 200mm - again with long exposures on the gorillapod

f4, 1/25s

f4, 1/25s

f6.3, 1/8s

f6.3, 1/8s

There is no doubt that the shutter does clunk a bit, but there is little evidence of camera movement in these images, maybe a little in the 200mm 1/8s shot mounted on an imperfect tripod. The image is slightly worse than the f4, 1/25s photo.

In theory the worst shutter speed range is 1/30 to 1/100s - but here, the 1/60s image at f8 on the Pentax 50mm is spectacularly the best image.

My general impression is that you have to be very picky to find a much fault with shutter shock and even then you have to try fairly hard to make it significant.

More old glass - 500 year old windows at "the Vyne"

First an apology - I was playing with the high ISO noise reduction setting on my Sony the other day and forgot to set my picture quality back to RAW+JPG so these images were all shot in high quality jpeg only.

We had heard about the restored Tudor stained glass exhibit at The Vyne, and as it is only a little over half an hour's drive from home thought we would visit on Sunday.

The Vyne is a Tudor house near Basingstoke in Hampshire, which has been owned by the National Trust since 1959.  It was built in the first half of the 1500s and substantially modified in the early 1700s.

The stained glass windows now in The Vyne chapel are part of a series made for the owners of The Vyne between 1515 and 1542, probably originally for the Holy Ghost Chapel in Basingstoke. They were moved during the English Civil War, concealed in chests and hidden in the lake to avoid destruction by the Puritans and then installed at The Vyne. The fine detail is applied as a paint and then fired into the glass.  This paint was becoming eroded and starting to peel, so a major programme of work was recently carried out by the National Trust, restoring the windows to their former glory and preserving them for the future. They are regarded as the finest stained glass of the period in the UK.

Here are 6 photographs depicting the main panels

Left panel upper
Hi res version

Left panel lower
Hi res version

Centre panel upper
Hi res version

Centre panel lower
Hi res version

Right panel upper
Hi res version

Right panel lower
Hi res version

These photos were all shot whilst trying to balance noise, depth of field and shutter speed in a low light environment so I used iso400, mainly f6.3 and shutter speeds varied between 1/13s and 1/300s.

Although the restored stained glass is a major feature, The Vyne is a beautiful National Trust property and well worth a visit - here a a few more views of the house and grounds

Higher res version

Higher res version

Old lenses - a cheap alternative?

This was originally a facebook post in Bluedog photography

I posted a couple of pictures yesterday taken with a lens that I found in box stored in my loft (roof space) and Danielle said she would like to hear a bit more. I got interested in “legacy” lenses when I found that my Pentax DSLRs could use most lenses for Pentax SLRs since the year dot and that for manual (M) mode and manual focussing, lenses were available very cheaply. In PK mount I have a 28mm f2.8, a 135mm f2.8, a 200mm f4 and a 400mm f5.6, made for 35mm film SLRs bought for a total of about AU$300.These lenses are not necessarily light but they are compact compared to modern autofocus lenses. I had some fun with these, going out for a day with a single fixed focal length lens etc. and when I bought a new camera the Sony A7 was an obvious choice as I can work with all my existing lenses.

In the first photo, there is a Pentax K5 with the brilliant Tamron 17-50mm f2.8, the tiny Sony A7 with my old Russian Jupiter8 50mm f2 and a Pentax K7 with the kit 18-55mm f3.5-5.6 . The APS-C Pentax with the Tamron weighs in at a whopping 1300g and the full frame Sony with the Jupiter weighs just 660g. The lenses are the 135 f2.8, the kit 28-70 for the Sony and the 28mm f2.8. Notice the difference in thickness between the Leica M39-NEX adaptor on the Jupiter lens and the PK-NEX adaptor on the 28mm. Rangefinder cameras such as the Leica have no mirror and the lens mount is much closer to the film than in an SLR so the Jupiter has a thin adaptor. The Jupiter is a Russian copy of a pre-war Zeiss Sonnar for a Leica thread – mine is 40 or so years old.

In a normal DSLR, the mount is too far from the sensor to fit rangefinder lenses but legacy SLR glass can work. The Sony is mirrorless and the viewfinder is electronic, meaning that the sensor is very close behind the bayonet mount and with the right adaptor ANY lens can be fitted and used in A or M mode with manual focussing. I have been working in A mode, focussing by hand is enough extra work.

It is recommended to focus at full aperture with minimum DoF and then stop down but this isn't always easy when the aperture ring is on the lens and costs time (my Pentax lenses will stop down automatically with the shutter but I need to stop down manually to set the exposure). On the Sony there is a focus magnifier which I have programmed to button C1 next to the shutter. I am trying to focus at full aperture with magnification and stop down by watching the shutter speed change in the viewfinder. Additionally “focus peaking” indicates points of sharp focus in the Sony viewfinder with a coloured light. With short lenses, the hyperfocal distance markings on the focus ring can be used to preset the focus, saving time.

The second photo is from the Jupiter-8 on the Sony at f2.8 1/60s and iso200 – The bokeh has an interesting vintage look, personal taste.

I really enjoy using these old lenses and I will refine my shooting procedure with time. I spent so much time focussing on this dog he kept moving and I had to do it again. I want to be able to shoot portraits quickly with the Jupiter lens. 

Not every camera can use the old lenses, but if yours can and you are prepared to experiment there are some fine lenses out there (or in your loft) and relatively cheap fun to be had.