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Advice on 36-90mm Helicoids
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PostPosted: Fri May 29, 2020 4:56 pm    Post subject: Advice on 36-90mm Helicoids Reply with quote

Hi,

I was just about to pull the trigger on a Chinese M42-M42 36 to 90mm helicoid. Then I thought about that huge extension of 54mm, albeit 27mm each way.

For those using them, could you comment on -

1. Is the focus fine enough for longer focal lengths? For example I have a 17-31 helicoid and I'm happy with the focusing on that, after changing the grease.

2. Wobble?

3. Better off with the 17-31 and use extension tubes?

3. Also, I ordered just a bottle of watch oil a few months ago from China, but it never arrived. From the tracking, it appeared to be still in China after two months. Are they getting somewhere back to normal in China, postage wise? Does anyone have experience of this also?

Thanks.


PostPosted: Fri May 29, 2020 5:48 pm    Post subject: Reply with quote

For my long helicoid I can fit my 50mm/1.2 projection lens so most of the lens is within the helicoid. (the end of it actually sticks out the back of the helicoid at MFD)
I don't think I've ever used the full extension when playing with this lens buts it's hand if i fir a longer focal length...

Cheap deliveries from china are very variable at the best of times. Even during corona I've had free postage things arrive in under a week, and others take months. Most deliveries still seem fairly similar to those of pre-corona days nearly half my little packs arrive before the start of their delivery window, several before the tracking shows anything more than 'reference number issued'.

One of the items I am awaiting shows it was handed over to a UK carrier in late April, but then nothing. The shipping window goes into july so I can be patient and might see it eventually or if not still get my £3 refunded.

Several items I've ordered that were supposedly in the UK have ended up coming rapidly direct from China. I get the impression this ploy is only used by sellers that can guarantee getting it on the next flight. - Many Chinese deliveries seem to wait for a container to fill before forwarding, giving rise to variable delays at various depots along the way.


PostPosted: Fri May 29, 2020 8:52 pm    Post subject: Reply with quote

Thanks DC, that's good advice. It's good to know stuff is getting out even if its still random. I've actually chickened out and ordered a 25-55mm. I could do with one of them too. I suppose I can see how these longer ones work with lumps of brass hanging off the end of them, before going longer.

Cheers.


PostPosted: Sat Jun 06, 2020 9:56 am    Post subject: Reply with quote

DConvert wrote:
For my long helicoid I can fit my 50mm/1.2 projection lens so most of the lens is within the helicoid. (the end of it actually sticks out the back of the helicoid at MFD)
I don't think I've ever used the full extension when playing with this lens buts it's hand if i fir a longer focal length...

Cheap deliveries from china are very variable at the best of times. Even during corona I've had free postage things arrive in under a week, and others take months. Most deliveries still seem fairly similar to those of pre-corona days nearly half my little packs arrive before the start of their delivery window, several before the tracking shows anything more than 'reference number issued'.

One of the items I am awaiting shows it was handed over to a UK carrier in late April, but then nothing. The shipping window goes into july so I can be patient and might see it eventually or if not still get my £3 refunded.

Several items I've ordered that were supposedly in the UK have ended up coming rapidly direct from China. I get the impression this ploy is only used by sellers that can guarantee getting it on the next flight. - Many Chinese deliveries seem to wait for a container to fill before forwarding, giving rise to variable delays at various depots along the way.


UPDATE: Well, my doubts were quashed. I ordered it on 31st May from China and it arrived this morning, 6th June. Impressive. As was the tracking. Every movement was notified and when it hit these shores even the usually silent Royal Mail couldn't wait to tell me what was happening. Looking at the tracking, it caught an early flight out, which I think must be the trick.

And there's either more than one factory churning out unbranded helicoids, or they've upped their game since I last purchased one. This 25-55mm feels slightly better quality and certainly has a smoother helical. In fact I wont have to touch the grease on this one, as I did on the (actually Pixco branded) 17-32mm.

There's only one thing I've noticed with this one and it's to do with the four track guides which control the cylinders extensions. They reveal the very shiny brass helical. Putting an eye to either end sees them glinting away, so it'll be interesting to see if they cause any stray light issues.

Thanks again for your reply DC. It was bang on advice.


PostPosted: Sat Jun 06, 2020 10:47 am    Post subject: Reply with quote

Hi Sciolist
This thread has just appeared at just the right time for me. From someone who knows their helicoids, I need some advice. From my b&w printing days I have a Soligor 35mm f3.5 enlarging lens which I would like to use as a close up lens. An M42 to M42 helicoid would be ideal but what size extension would you suggest? Also a manufacturer and supplier from China?
Thanks.


PostPosted: Sat Jun 06, 2020 11:16 am    Post subject: Reply with quote

DigiChromeEd wrote:
Hi Sciolist
This thread has just appeared at just the right time for me. From someone who knows their helicoids, I need some advice. From my b&w printing days I have a Soligor 35mm f3.5 enlarging lens which I would like to use as a close up lens. An M42 to M42 helicoid would be ideal but what size extension would you suggest? Also a manufacturer and supplier from China?
Thanks.


Well, I found this most recent supplier absolutely fine. Their name on ebay is extremedigital2011. I think they were matching their competitors on price anyway, but they do 'offers' and accepted 5% off for me. £19.99 became £19.00.

With regard to which one, unfortunately I use the helicoid adaptors for standard work, so it would be best to wait for someone else to pipe up, as there are a few calculations to make even without considering macro.

I can't see it on John Jovic's Cornocopia, but your 35mm enlarging lens should have a flange focus distance at infinity of around 35mm. That's a rough guess. You'll need to know that as a start. And you'll need to know the flange focal distance of your camera.

http://www.photocornucopia.com/1061.html

Good luck.


PostPosted: Sat Jun 06, 2020 11:48 am    Post subject: Reply with quote

Like 1 Thank you!