DSLR adapters for 23mm photo tube

dhobern · Post by **dhobern** » Mon Nov 07, 2016 1:25 pm

I've searched the forum and may have missed discussion of this - so please feel free to direct me to any earlier messages.

I have been using a 2x DSLR adapter matching this one:

http://www.gtvision.co.uk/epages/es1413 ... ducts/0643

I'm taking photographs with a Canon EOS 6D attached to a zoom stereomicroscope and a compound microscope, both with trinocular heads with 23mm photo tubes.

My current adapter obviously shows vignetting at least for lower magnifications on the compound microscope. More annoyingly, there is a reasonable amount of dust in the internal optics which leaves several large spots in all images.

I'm therefore looking to replace this with an adapter which will hopefully avoid these issues. In doing so, I'd like to select an adapter which will support the best images possible.

As well as the model I am currently using, I have found the similar, or slightly cheaper, AmScope adapter (their site seems to be down, so here is the Amazon link):

https://www.amazon.co.uk/Canon-DSLR-Cam ... B005OZ5NXU

I have also found the following, more (in some cases extremely) expensive, adapters:

Martin Microscope: http://www.martinmicroscope.com/product/mm-slr/

Alexis Scientific Clearshot 600: http://microscope-depot.com/digadapt.asp?DCID=163

LMScope: http://www.lmscope.com/produkt22/lmscop ... Sprache=de

Does anyone here have experience from which they can recommend one of these or any other adapter for such a configuration?

Many thanks,

Donald

Pau · Post by **Pau** » Mon Nov 07, 2016 3:28 pm

Hi Donald, welcome aboard!

The fist question is: what kind of microscope and objectives you have?
It is relevant because many old style finite corrected (160 and so) and some old metallurgical infinite corrected ones need to complete the objective correction with matched compensating eyepieces. If it is your case none of the linked adapters will work well and you'll need the matched compensating eyepiece in the optical path (projective photoeyepieces or visual type eyepieces with a lens over them) as originally intended by the maker. The good news is that 35mm film format is the same than digital FF and most makers produced SLR adapters for their microscopes.

If you have a modern infinite corrected microscope or a Nikon CF you don't need these compensating eyepieces, so in principle the adapters could work well

I have no experience with any of the linked adapters, but the cheaper Amscope doesn't seem adequate for FF camera, take a look at this thread:
http://www.photomacrography.net/forum/v ... p?p=140518

Pau · Post by **Pau** » Mon Nov 07, 2016 3:32 pm

I've just re read your post an most stereos do not use compensating eyepieces so it could be easier. I principle you want to use the trinocular port for convenience, what microscope model and photoport configuration could still be relevant

dhobern · Post by **dhobern** » Mon Nov 07, 2016 3:40 pm

Many thanks, Pau.

These are relatively basic microscopes, from Brunel in the UK. I'd have identified them if I had any idea of comparability. In any case, the main instrument I would currently like to use with a camera is the Brunel SP150, with infinity planachromatic objectives:

http://www.brunelmicroscopes.co.uk/infinity.html

The zoom stereo is a Brunel BSR with a trinocular head:

http://www.brunelmicroscopes.co.uk/bsrstereos.html

Thanks again for any comments.

Best wishes,

Donald

Pau · Post by **Pau** » Mon Nov 07, 2016 4:05 pm

I see that Brunel has a picture with a camera attached and lists a DSLR adapter and a photoeyepiece with no details, you can contact them.

It's easy to determine if your microscope needs compensating eyepieces:

look at a white field (at the microscope or outside it) through one eyepiece. If at the limit it shows an orangeish halo it is compensating, if no halo or very faint and blueish it is no compensating

dhobern · Post by **dhobern** » Mon Nov 07, 2016 4:24 pm

Thanks - the Brunel-supplied eyepiece is the same (same inscription on the side) as the first link in my message (has "NDPL-1(2X)" written on the side).

I note that a Google search for that string takes me to this Amazon product (not sure how that connection is made since the page and reviews don't show that string):

https://www.amazon.com/Microscope-Adapt ... ullets-btf

One of the reviews comments on the same dust issue.

In any case these microscopes do not need compensating eyepieces.

Donald

Pau · Post by **Pau** » Tue Nov 08, 2016 4:34 am

for SLR adapter I was referring to
SP150 Photography Attachment
Total Price: £37.50 / Euro 43.13 (Excluding VAT at 20%) at
http://www.brunelmicroscopessecure.co.u ... SP150.html

They also sell a (unclear) adapter:
http://www.brunelmicroscopessecure.co.u ... pters.html

and a photoeyepiece:
http://www.brunelmicroscopessecure.co.u ... ieces.html (this will work with an empty tube without more optics. although 4X will crop too much the FOV) A Nikon CF 2.5X photoeyepiece will be the best substitute if the microscope doesn't need compensating eyepieces as you say

Brunel site is not very well built...few relevant info, links no working...so you will need to ask them

For FF the more usually recommended magnification of the photo optics is 2.5X to match well the eyepiece FOV

dhobern · Post by **dhobern** » Tue Nov 08, 2016 5:36 am

Thanks again, Pau.

I agree that their site leaves much to be desired. My reason for coming here was to make sure I had a better understanding of alternatives and choices before approaching any supplier.

Would you "normally" (if that can mean anything in this case) expect better results from a good (?expensive?) DSLR adapter or from a Nikon CF PL 2.5X with appropriate tubes/bellows? Clearly the first of these is (for me, at least) much simpler but I'd rather avoid unnecessary compromises.

Donald

Ichthyophthirius · Post by **Ichthyophthirius** » Tue Nov 08, 2016 8:03 am

Hi Donald,

Since you have two microscopes, you could go for an afocal adaptation. You can use it for both microscopes.

For afocal, you need a visual eyepiece in the phototube and a camera objective on the camera.

The visual eyepiece in the phototube needs to be parfocal with the two eyepieces in the binoculars. Could you please test this? Put an object on the stage with a 10x eyepiece, focus, swap one of the eyepieces over to the phototube and check that the object is still in focus.

If that is the case, you could photograph directly through the eyepiece in the phototube using the EOS 6D with a camera objective attached.

Good combination:
- 10x WF eyepiece from same manufacturer, preferably for glasses (high eyepoint)
- 50 mm - 60 mm prime lens, focussed to infinity and then autofocus disabled
Both eyepiece and camera lens must be dust-free otherwise it will show in the photos.

In my opinion, it is not worth building expensive adapters to connect your camera to these relatively cheap microscopes. I would go for a copy stand http://www.speedgraphic.co.uk/Portals/1 ... D0F%7D.jpg bought second-hand, and be done with it, at least for the microscope.

For the stereo microscope it's not that convenient as you would have to correct the height of the camera every time. If that is a problem, you would have to make some kind of mechanical connexion between stereo microscope and camera objective. You could use an F-Adapter www.ebay.ie/itm/232067335592 to connect the eyepiece to the filter thread on the camera objective, but because the EOS 6D is very heavy, you would have to give it some extra support, somehow.

Regards,

Ichty

Pau · Post by **Pau** » Tue Nov 08, 2016 9:47 am

Would you "normally" (if that can mean anything in this case) expect better results from a good (?expensive?) DSLR adapter or from a Nikon CF PL 2.5X with appropriate tubes/bellows? Clearly the first of these is (for me, at least) much simpler but I'd rather avoid unnecessary compromises

I can't recommend any of them just because I never tested any of them, in principle if the magnification is adequate (around 2.5X) and it is well designed and made will work. Some ones are so expensive that IMHO it disqualifies them.

My approach will be a Nikon CF Plan 2.5 photo eyepiece like
http://www.ebay.com/itm/NIKON-MICROSCOP ... SwA3dYE0rV
and a system to mount it to the camera. I can be done with bellows, extension tubes or with an old style microscope camera adapter like the Pentax that clamps over the photo tube.
http://www.ebay.com/itm/ASAHI-PENTAX-MI ... SwbsBXoqTa
(likely you will need to adjust the length with a focusing helicoid and extension tubes or a bellows)

With that kind of equipment you will have a first quality and proven setup for a moderate price

Afocal of course also will work nicely, it's a flexible, proven and economic approach. I use it and I often recommend it because it works well with microscopes that need compensating eyepieces and with cameras with smaller sensors or integrated optics, but because you can find at reasonable price excellent photoeyepieces for your FF sensor I think it will be the best way

More info about afocal:
http://www.photomacrography.net/forum/v ... hp?p=99265

dhobern · Post by **dhobern** » Tue Nov 08, 2016 1:47 pm

Many thanks to you both for all the help.

Here is what I am understanding.

1. Use a Nikon CF PL 2.5X in the trinocular tube.

2. Fix some kind of tube clamp around the turret - I have seen this suggested elsewhere on the forum as a possible clamp that would allow connections to be made:

http://www.ebay.co.uk/itm/320686296136? ... 1439.l2649

3. Add tubes (including a helicoid section facilitate tuning) to achieve a distance of around 160mm between the lens and the sensor.

Assuming this is correct, here are some additional questions:

1. The various clamping arrangements I have seen seem to leave a gap through which light can enter around the bottom edge - is this an issue, or should it be blocked?

2. What would be exact distance required from the lens to the sensor?

3. If I have this arrangement, does that mean I can replace the CF PL 2.5X with a 4X or 5X to change magnification? Would the same tube length still work?

Sorry for any or all of this which is stupid. I really appreciate such helpful responses.

Donald

dhobern · Post by **dhobern** » Tue Nov 08, 2016 2:27 pm

Another possible clamp?

http://www.ebay.ie/itm/232067335592

Donald

dhobern · Post by **dhobern** » Tue Nov 08, 2016 3:36 pm

Just realised the second clamp was one that Ichthyophthirius recommended above.

I also think I now understand the Asahi Pentax adapter - this clamps around the outside of the phototube, while still allowing the projection lens to sit inside the phototube - correct?

Donald

Pau · Post by **Pau** » Tue Nov 08, 2016 3:59 pm

Donald, I think you understand well the idea, just to comment few points,

- The first clamp linked will be too wide, the second one will fit better, although I still think that the Pentax adapter will be clearly better: more solid, no centering issues, better clamped and without light gaps

- Yes, you need to close any gap to prevent external light entrance. With afocal methods what they are designed for this is less critical but still convenient.

- You said 160mm from lens to sensor, any reference for it? As actually I don't have any Nikon photoeyepiece I don't know that distance, maybe another member could know it.

- With higher magnification eyepiece you will have more magnification on sensor -in fact more cropped image- This could be convenient is some cases, mainly with low power high NA objectives, but as general rule is much better to switch to higher magnification objective. Providing more secondary magnification doesn't increase resolution and so reduces sharpness, what we call empty magnification
If the other eyepieces are from the same series likely they will focus at the same distance, not sure.

dhobern · Post by **dhobern** » Tue Nov 08, 2016 4:03 pm

Many thanks, Pau.

I'll go with that combination. You've been a great help.

Very best wishes,

Donald