Rogier
Rogier Willems
Hi,
I am hacking my Holga 120 Pan and just took my first test shots.
Turns out that the 12-17mm helicoid is to short. Since it only brings objects into focus that are 5 - 25 ft away while fully extended.
My question is what is a better choice.
1. 17 - 31 mm helicoid
2 15mm extension tube with the 12-17 mm helicoid.
My main concern is the "throw" off the helicoid needed. Does the longer helicoid need more turn than my current short one?
Worry is that the 17-31 mm version might be hard to adjust if the length changes dramatically with only a small turn...
Looking forward to your reply
Rogier
I am hacking my Holga 120 Pan and just took my first test shots.
Turns out that the 12-17mm helicoid is to short. Since it only brings objects into focus that are 5 - 25 ft away while fully extended.
My question is what is a better choice.
1. 17 - 31 mm helicoid
2 15mm extension tube with the 12-17 mm helicoid.
My main concern is the "throw" off the helicoid needed. Does the longer helicoid need more turn than my current short one?
Worry is that the 17-31 mm version might be hard to adjust if the length changes dramatically with only a small turn...
Looking forward to your reply
Rogier
sevo
Fokutorendaburando
If it fails to reach infinity (or past) at minimum extension, it is too long, so neither solution would help.
Rogier
Rogier Willems
Hmm I am getting it wrong?
No focus at all at shorter lengths. And focus nearby when fully extended.
17mm tube extension brings 5 - 15 ft in focus.
12mm tube extension brings nothing in focus...
My assumption is that I would need a tube off at least 17mm to get started.
??
No focus at all at shorter lengths. And focus nearby when fully extended.
17mm tube extension brings 5 - 15 ft in focus.
12mm tube extension brings nothing in focus...
My assumption is that I would need a tube off at least 17mm to get started.
??
sevo
Fokutorendaburando
If there is close focus at full extension and focus somewhere past infinity at minimum, infinity must be in between.
Rogier
Rogier Willems
Thanks I will examine my negatives as soon as they are dry.
Here is the first one...
Test-Shot-Holganon-17mm by Rogier Diver, on Flickr
Here is the first one...
Test-Shot-Holganon-17mm by Rogier Diver, on Flickr
Rogier
Rogier Willems
Here we go 12-17mm Helicoid extended at 1/4th seems to be close of infinite focus
2012-10-18-2 by Rogier Diver, on Flickr
2012-10-18-2 by Rogier Diver, on Flickr
sevo
Fokutorendaburando
There you are - you need to shift the lens out by something around 1.25mm. If the threads are deep enough, you could get there with spacers. Otherwise you may have to re-seat the camera side mount. Extension rings won't do (the slimmest I've ever had already were 3-4mm), nor will a 17mm helicoid (you'd want a 13.25mm one, but these don't seem to exist).