Large format astrophotography
Posted 09 November 2013 - 08:02 PM
Posted 20 November 2013 - 11:26 PM
Posted 21 November 2013 - 03:29 PM
Anything over 300 is definitely in the area of specialized use. The lenses are unusual and harder to find. Extra long bellows beyond the normal are needed as is physical extension of the camera. Vibration becomes an issue at these magnifications, so extra-solid camera support is also mandatory.
As an example I've attached a photo of my 600mm f/9 telephoto lens. To make this optic work it needs a minimum of 480mm of bellows. To focus closer than infinity (such as landscapes), it needs even more bellows than that. The lens by itself is five pounds. The metal camera and extra fittings place the whole setup around twenty pounds of weight. The camera assembly in its entirety is over two feet long--for a camera that's not compact by any means. At this magnification vibration in the system can easily render the image on film unsharp so it also needs very solid support.
To use this lens for astrophotography it would need a substantial equatorial mount far more robust than what I have. While the requirements of this lens on a camera are tough, it is an amazing optic. (This lens allows me to isolate details in landscape photos with great clarity). Yet it's not for everyone--one look at the setup readily shows the extraordinary requirements needed for a long focal length optic.
Posted 22 November 2013 - 08:20 AM
I quit film astrophotography not a long while ago. Until 2009, I shoot medium format. The reason is exactly what you said, print quality (although I don't do real dark room work myself). I thought about going to large format for years, but I'd never pulled the trigger, primarily because the limited choices of films. Another reason is the worry of camera flexure. I was not convinced that large format cameras can be rigid enough for hour-long exposures. (Your results proves me wrong.) To overcome this, I was thinking about making an astrophoto-only large format camera without using any moving parts like the monorail. I never had a chance to actually do this. On the other hand, I mosaicked digitized medium format images (from 2 6x7 images, to mosaics as large as 20 6x7 images) to achieve the print quality that's equivalent to large formats.
Now I am a completely digital shooter, but your pictures remind me the good old days. Hope one day I will pick up film again. Please do share with us if you make new pictures.
Posted 22 November 2013 - 10:10 AM
Posted 22 November 2013 - 03:48 PM
Jason, that's very likely true. That a normal large format camera with all the moving and folding parts can be used at all for astrophotography still strikes me as amazing. Every instinct would say it couldn't be done and yet surprisingly it can.
The 600 is an extreme example. It's a seriously long lens on a 4x5 and rare to see. Its use is within possibility yet I figure with my equatorial mount it would also be about as stable as a tank balancing on toothpicks. That's why I suggested 300mm as the comfortable and practical limit. I've successfully used my 300mm f/5.6 (pictured at the beginning of the thread) for years without problems.
Posted 26 November 2013 - 02:22 PM
Posted 28 November 2013 - 12:46 AM
Thanks for the compliment Hikari. The Horseman camera is a pleasure to work with. It's my hope to continue to put it to good use for many, many more years to come.
Posted 09 December 2013 - 03:32 PM
Posted 10 December 2013 - 06:10 AM
Posted 10 December 2013 - 10:22 AM
Posted 10 December 2013 - 06:51 PM
The 2.7 focuser worked well for 6x7 work if I remember correctly. I think the 4" focuser was used for 4"x5". Either way, I'd like to see what your getting with this setup. I've contemplated a project using a fast Aero Ektar or equivelent lens and a rigid lensholder with 4x5 film holder.
Post 'em when you get 'em.
Posted 10 December 2013 - 08:47 PM
Posted 11 December 2013 - 01:29 AM
Posted 11 December 2013 - 07:18 PM
Fun stuff Gary.
Posted 12 December 2013 - 11:12 AM
Posted 14 December 2013 - 08:07 PM
Posted 15 December 2013 - 04:49 PM