Gaoersi and Super Angulon 90mm f/5.6?

[Blair Ware]

I recently bought a used Gen. 1 Gaoersi 6x17 and am having a little trouble mounting a 90mm SA f/5.6 on it. Here is what happens:

When I mount the lens all the pieces between the body and lens flange are close to being fully extended in order for the lens to focus to infinity.

As a result, there is less than half a thread connecting the 24mm deep base and the helecoid which makes me a little worried about the lens falling off. This is now doubly secured by an elegant pair of broccoli elastics.

In addition, I am using a spacer between the lens and the helicoid (3mm or so), but this reduces my ability to close focus as the rear element of the lens bumps into the inside of the helcoid and prevents the helecoid from extending further (minimum focus is now about 2.6m). Overall, the camera as it stands is pretty much unusable for anything close and reduces my ability to use a shorter hyperfocal focus for f/45.

Does anyone have suggestions or experiences that can throw some light on this? Is my base too short for this lens? Thanks.

Blair

[Lachlan 717]

Why are you using a spacer?

Have you removed the locating screw from the rear of the shutter?

Have you looked at this (http://www.photo-i.co.uk/Reviews/cam...i/Page%204.htm)?

Lachlan.

[Blair Ware]

Lachian, the spacer is to give me more distance from the film plane. Without it, I can't screw the helecoid focusing mount into the adatpor and still focus closer than about 10m. If I want to focus closer than 2.5m, then I can't screw the helecoid into the adaptor.

And yes, I read the article on calibrating the focus. It was very good, but didn't provide any further information on how to rectify the problem.

My understanding is that this Super Angulon has a relatively long flange to film distance. Strangely enough, I have heard other Gaoersi owners complain that they can't get their lenses (noteably Fuji f/8) close enough to the film. One problem with the SA is the large rear element which runs into the back side of the helecoid as the helecoid extends for close focusing.

[Lachlan 717]

I find that these are not really close up cameras, either in design or in use.

In my experience, you need to use hyperfocal techniques to get anything closer than 3 or so metres. My DaYi's minimum focus is marked as under 2 metres, but in reality, screwing the lens out past this marking made little difference.

That being said, however, the SA 90mm 5.6 that I use on it doesn't give me any problems at this focus distance... Perhaps it's got a bigger space on the inside of the helical?

If you do want to do close up work with 6x17, I would highly recommend the Ebony 617 or the (much, much cheaper) Shen Hao bellows cameras.

Lachlan.

[Blair Ware]

Lachlan, thanks for relating your experience.

I don't have any problem with the camera not doing close-ups, but not being able to focus any closer than ~2.5m seems unreasonable for a whole range of photographs that are not close-ups. And, to get this particular combination to focus down to this distance requires the lens spacer and a tenuous mounting of the helecoid to the adaptor.

If the whole combination were able to project a few more mm out from the body, there wouldn't be a problem. I could then use those mm to secure the helecoid to the to adaptor.

[Lachlan 717]

If the whole combination were able to project a few more mm out from the body, there wouldn't be a problem. I could then use those mm to secure the helecoid to the to adaptor.

Blair,

The following assumes that you have a Gaoersi with removable nose cones:

I had an issue with mounting an Aperture Iris on to a Sinar board recently. The size of the Iris overlapped the side of the board just enough to prevent the sliding 'holders' from going over the edge of the board.

In order to fix this, I simply found some (approx) 2mm rubber sheet and cut a template to fit between the Iris and the Board. This left a gap for the holders to slide under the Iris.

Have you considered making a light-tight spacer to go behind the lens cone? This will push the lens further out, in effect allowing closer focusing without adapting the helical.

Lachlan.

[Blair Ware]

I've been thinking along those lines. If I can get some neoprene, it would push out the cone and it shoudl remain light tight. The other way to go is to get a Grandagon f/6.8 which has a much shorter flange to film distance.

I'll try the rubber treatment first... I think I have a few old bike tubes kicking around. :)

Blair

[Lachlan 717]

I've been thinking along those lines. If I can get some neoprene, it would push out the cone and it shoudl remain light tight. The other way to go is to get a Grandagon f/6.8 which has a much shorter flange to film distance.

I'll try the rubber treatment first... I think I have a few old bike tubes kicking around. :)

Blair

I used some old light weight conveyer belt rubber; it has the belting in it for spacing and the rubber is spongy enough to compress into the irregularities...

I would think that neoprene would compress too much.

[Blair Ware]

Just finished the process with some success using an old mouse pad. It turned out to be very easy to cut and I used the cone as a pattern. It's given me about 5 mm of much needed extension. The original clamps continue to work but are at a slightly tortured angle and may get replaced in the next iteration.

[Lachlan 717]

Just finished the process with some success using an old mouse pad. It turned out to be very easy to cut and I used the cone as a pattern. It's given me about 5 mm of much needed extension. The original clamps continue to work but are at a slightly tortured angle and may get replaced in the next iteration.

Great news (and a whole lot cheaper than a replacement lens!!)

Keep me posted as to how it goes...

Lachlan.

PS,

Good idea with the mousepad.