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Pentax 75 EDHF

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#1 ete83

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Posted 23 January 2022 - 02:15 AM

Hi,

I got an offer for an used Pentax 75 EDHF. I have two questions, first what’s the difference between the SDHF version? And second, I later want to automate my setup (autofocus) and mount a ZWO or a Sony with E-mount to take pictures . Would this be possible with such a classic scope? I read that the formats are a bit different and I am nervous to find adapter’s.

Thanks

#2 Steve_M_M

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Posted 23 January 2022 - 10:11 AM

Here is a nice article that goes over the differences.  https://www.bilibili...read/cv10724679

 

I use my 75 EDHF for imaging with a ZWO ASI183MC Pro and the scope is amazing.  To me, I see a 100% flat field across the entire image, keeping in mind the 183MC is not capturing the entire field.

 

Mounting a ZWO camera has been a bit of trouble for me.  I ended up having the use my 3D printer to print some parts.  It would be much better if there were adapters that connect direct to the focusing tube and output 48mm threads.

 

75EDHF=FPL-51 equivalent

75SDHF=FPL-53 equivalent

 

Also know that finding the dedicated .72x reducer is very difficult and the price will be $400+

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Edited by Steve_M_M, 23 January 2022 - 10:25 AM.

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#3 ete83

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Posted 23 January 2022 - 02:23 PM

Thanks very helpful , I love this classic scope but I fear it’s to complicated to get all the adapters (no 3d printer around).

#4 Steve_M_M

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Posted 23 January 2022 - 03:06 PM

You just need something like this except male 49mm threads.  https://www.ebay.com/itm/384692238761



#5 Steve_M_M

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Posted 23 January 2022 - 08:51 PM

I decided today to spend several hours seeing if I could piece together a set of adapters that would work to connect a ZWO camera to a vintage 75EDHF.  I am going to use the 60.7mm to 49mm adapter that is standard with the 75EDHF as finding anything that is 60.7mm is not going to happen.  So, easiest would be to find M49 Male to M42 Female.  I could find nothing.  If someone does, please post here.  The best I could find would be a M49 Male to M52 Female.  From there, you would think an M52 Male to M42 Female would be easy.  Nope, that part appears to only be available in China.  I am going to keep looking and will order those parts if I don't find anything else.

 

By the way, Sony E mount is easy... https://www.bhphotov...read_macro.html


Edited by Steve_M_M, 23 January 2022 - 08:58 PM.

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#6 ete83

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Posted 24 January 2022 - 12:39 AM

Cool thanks! I will which adapter will come with the scope.

#7 Steve_M_M

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Posted 28 January 2022 - 04:20 PM

OK,  I got the Pentax 75EDHF to accept a ZWO camera without using make shift 3D parts.  The diameter of the adapter the ocular holder threads into is 50mm.  So, you need a 50mm Male to 42mm step down ring.  I didn't really care if the 42mm was M or F, but it didn't matter as I could not find any adapter worldwide that was 50mm to 42mm.  So, I used a 50mm Male to 52mm Female step up ring and then a 52mm Male to 42mm Female step down ring.  I can then attached the ZWO camera direct to the 42mm threads or use regularly available 42mm extensions as needed.


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#8 Defenderslideguitar

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Posted 29 January 2022 - 10:04 PM

Bravo

This is a set up I can replicate  

thanks

Barry



#9 Steve_M_M

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Posted 13 February 2022 - 12:58 PM

Tested last night.  Obviously with a near full moon, it wasn't the best night to be imaging.  I also used the wrong filter by accident (L-Enhance vs L-Pro).  But, I did confirm for sure that everything comes to focus as is and with a reducer in the path.  Ill be going for the tadpole nebula tonight.  

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Edited by Steve_M_M, 13 February 2022 - 12:59 PM.

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#10 photoracer18

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Posted 14 February 2022 - 06:07 PM

Here is a nice article that goes over the differences.  https://www.bilibili...read/cv10724679

 

I use my 75 EDHF for imaging with a ZWO ASI183MC Pro and the scope is amazing.  To me, I see a 100% flat field across the entire image, keeping in mind the 183MC is not capturing the entire field.

 

Mounting a ZWO camera has been a bit of trouble for me.  I ended up having the use my 3D printer to print some parts.  It would be much better if there were adapters that connect direct to the focusing tube and output 48mm threads.

 

75EDHF=FPL-51 equivalent

75SDHF=FPL-53 equivalent

 

Also know that finding the dedicated .72x reducer is very difficult and the price will be $400+

I used to have a 75 EDHS. Looking at that diagram it looks like the EDHS is a Steinheil design at the objective end and not Fraunhofer like the SDHS 




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